1995_National_Power_ICs_Databook 1995 National Power ICs Databook

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POWER Ie's

DATABOOK
1995 Edition

Linear Voltage Regulators
Low Dropout Voltage Regulators'
Switching Voltage Regulators
Motion Control
Surface Mount
Appendices/Physical Dimensions

••
••II

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iii

Table of Contents
Alphanumeric Index ..•.••.....•..••................•...••...•..•..•....••.....
vi
Additional Available Linear Devices ...•..............•...................•......
ix
Industry Package Cross Reference Guide •..................•..................•.
xxvii
Section 1 Linear Voltage Regulators
Linear Voltage Regulators Definition of Terms. . . • .. . . .. . ... .. .. . .. . . . .. .. . . . . . .. .
1-3
Linear Voltage Regulators Selection Guide. . . . . . . .. . . . .. . . .. . . . . . .. . . . . . . . . .. . . . .
1-4
LM1 05/LM205/LM305/LM305A1LM376 Voltage Regulators. . . . . . . . . . . . . . . . . . . . . . .
1-8
LM109/LM309 5-Volt Regulators......... .•... .................................
1-14
1-20
LM117ILM317ILM317A 3-Terminal Adjustable Regulators ........................
LM117HV/LM317HV 3-Terminal Adjustable Regulators.................... .... ...
1-32
LM120/LM320 Series 3-Terminal Negative Regulators •.....•..•... ;.......... ...•
1-42
LM123/LM323A1LM323 3-Amp; 5-Volt Positive Regulators ........... ;............
1-51
LM125/LM325 Dual Voltage Regulators ........ ;................................
1-57
1-64
LM133/LM333 3-Amp Adjustable Negative Regulators .........•......•......... ,.
LM1371LM337 3-Terminal Adjustable Negative Regulators........................
1-71
LM137HViLM337HV 3-Terminal Adjustable Negative Regulators (High Voltage)......
1-77
LM138/LM338 5-Amp Adjustable Regulators ....................................
1-83
. LM140AlLM140/LM340AlLM340/LM7800C Series 3-Terminal Positive Regulators..
1-95
LM140L/LM340L Series 3-Terminal Positive Regulators........................... 1-106
LM145/LM345 Negative 3-Amp Regulators ......................... ; . . . . . . . . . . . . 1-110
LM150/LM350/LM350A3-Amp Adjustable Regulators. . . . . . • . . . . . . . . . . . • . . . . . . . . . 1-114
LM317L 3-Terminal Adjustable Regulator. .. . . • . . . . . . . . . . .. .. .. . • . .. . . . .. . . . . . . . .1-126
LM320L, LM79LXXAC Series 3-TerminarNegative Regulators.. .....•........... ... 1-137
LM337L 3-Terminal Adjustable Regulator ...... ~ . . . .. . • . . .. .. .. . • . • . . . . . . . . . . . ... . '1-141'
LM341/LM78MXX Series 3-Terminal Positive Regulators ....•.......... :'..........
1-143
LM723/LM723C Voltage Regulators. . .. . . . . . . . . . . . . .. . . .. . . . . . . . . .. . . . . . . . . . . . . 1-149
LM78LXX Series 3-Terminal Positive Regulators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-158
LM78XX Series Voltage Regulators. . . .. . . .. . . . . . . . . .. . . .. .. . • .. . . .. • . . . . . . . . . . . 1-168
LM79MXX Series 3-Terminal Negative Regulators.. ...•.........•.. ... ......... ..
1-171
LM79XX Series 3-Terminal Negative Regulators................... .......... .... . 1-178
Section 2 Low Dropout Voltage Regulators
Low Dropout Voltage Regulators-Definition of Terms ............................ .
2-3
2-4
Low Dropout Regulators-Selection Guide ...................................... .
LM330 3-Terminal Positive Regulator .......................................... .
2-5
LM2925 Low Dropout Regulator with Delayed Reset ............................. .
2-9
LM2926/LM2927 Low Dropout Regulators with Delayed Reset .................... .
2-15
LM2930 3-Terminal Positive Regulator ......................................... .
2-23
LM2931 Series Low Dropout Regulators ........................................ .
2-29
LM2935 Low Dropout Dual Regulator ................•.........•................
2-37
LM2936 Ultra-Low Quiescent Current 5V Regulator .............................. .
2-45
LM2937 500 mA Low Dropout Regulator ...•.....•.........................•.....
2-50
LM2940/LM2940C 1A Low Dropout Regulators ................................. .
2-55
LM2941 ILM2941 C 1A Low Dropout Adjustable Regulators .....................•..
2-65
2-72
LM2984 Microprocessor Power Supply System ........•..........•...............
LM2990 Negative Low Dropout Regulator .......•...............................
2-85
LM2991 Negative Low Dropout Adjustable Regulator ..........•.............•.....
2-92
LM3420-4.2, -8.4, -12.6 Lithium-Ion Battery Charge Controller ....•.................
2-99
LM3940 1A Low Dropout Regulator for 5V to 3.3V Conversion ..................... . 2-111
LP29501 A-XX and LP2951 I A-XX Series of Adjustable Micropower Voltage
Regulators ..........•...•..........•..•...•..•..............•............. 2-116

iv·

Table of Contents (Continued)
Section 2 Low Dropout Voltage Regulators (Continued)
LP2952/LP2952A/LP2953/LP2953A Adjustable Micropower Low-Dropout Voltage
Regulators.................................................................
LP2954/LP2954A 5V Micropower Low-Dropout Voltage Regulators. . . . . . . . . . . . . . . . .
LP2956/LP2956A Dual Micropower Low-Dropout Voltage Regulators . . . . . . . . . . . . . . .
LP2957 ILP2957 A 5V Low-Dropout Regulator for JLP Applications. . . . . . . . . . . . . . . . . . .
LP2980 Micropower SOT, 50 mA Ultra Low-Dropout Regulator. . . . . . . . . . . . . . . . . . . . .
Section 3 Switching Voltage Regulators
Switching Voltage Regulators Definition of Terms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Switching Voltage Regulators Selection Guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LH1605/LH1605C 5 Amp, High Efficiency Switching Regulators. . . . . . . . . . . . . . . . . . . .
LM2524D/LM3524D Regulating Pulse Width Modulators.. ... . . . .. . . . .. . . . .. .. ... .
LM2574/LM2574HV Series SIMPLE SWITCHER 0.5A Step-Down Voltage Regulators.
LM1575/LM1575HV/LM2575/LM2575HV SIMPLE SWITCHER 1A Step-Down
Voltage Regulators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LM2576/LM2576HV SIMPLE SWITCHER 3A Step-Down Voltage Regulators ........
LM1577 ILM2577 SIMPLE SWITCHER Step-Up Voltage Regulators. . . . . . . . . . . . . . . . .
LM1578A/LM2578A/LM3578ASwitching Regulators.............................
LM2587 SIMPLE SWITCHER 5A Flyback Regulator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LM3001 Primary-Side PWM Driver ............. '" .. . .. . . . . .. . . . .. . .. .. .. .. .....
LM3101 Secondary-Side PWM Controller........................................
LM3411 Precision Secondary Regulator/Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LM431 A Adjustable Precision Zener Shunt Regulator .............................
LM78S40 Universal Switching Regulator Subsystem. . . . . . . . . . . . . . . . . . . . . . . . . . . .. .
LMC7660 Switched Capacitor Voltage Converter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Section 4 Motion Control
Motion Control and Motor Drive Selection Guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LM12 80W Operational Amplifier ......... , .... '" .................. ;.. .. . . . ... .
LM628/LM629 Precision Motion Controller......................................
LM18293 Four Channel Push-Pull Driver. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LMD18200 3A, 55V H-Bridge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LMD18201 3A, 55V H-Bridge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LMD18245 3A, 55V DMOS Full-Bridge Motor Driver. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Section 5 Surface Mount
Packing Considerations (Methods, Materials and Recycling) . . . . . . . . . . . . . . . . . . . . . . . .
Board Mount of Surface Mount Components ............................. '. . . . . . . .
Recommended Soldering Profiles-Surface Mount ...............................
AN-450 Small Outline (SO) Package Surface Mounting Methods-Parameters and '
Their Effect on Product Reliability .......................................... .'. .
Land Pattern Recommendations ...............................................
Section 6 Appendices/Physical Dimensions
Appendix A General Product Marking and Code Explanation .......................
Appendix B Devicel Application Literature Cross-Reference. . . . . . . . . . . . . . . . . . . . . . . .
Appendix C Summary of Commercial Reliability Programs. . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix D Military Aerospace Programs from National Semiconductor... . . .. .. .. .. .
Appendix E Understanding Integrated Circuit Package Power Capabilities. . . . . . . . . .. .
Appendix F How to Get the Right Information from a Datasheet . . . . . . . . . . . . . . . . . . . . .
Appendix H Safe Operating Areas for Peripheral Drivers .......................... "
Physical Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bookshelf
Distributors
v

2-131
2-146
2-153
2-166
2-177
3-3
3-5
3-7
3-10
3-27
3-45
3-63
3-80
3-102
3-116
3-140
3-160
3-177
3-188
3-195
3-202
4-3
4-4
4-17
4-38
4-44
4-53
4-59
5-3
5-19
5-23
5-24
5-35
6-3
6-4
6-10
6-11
6-2,1
6-26
6-30
6-38

Alpha-Numeric Index
AN-450 Small Outline (SO) Package Surface Mounting Methods-Parameters and Their
Effect on Product Reliability: .............. ; .............................................. 5-24
Board Mount of Surface Mount Components ................................... '.............. 5-19
Land 'Pattern Recommendations ........•.................................................. 5-35
LH1605 5 Amp, High Efficiency Switching Regulator ............................................ 3-7
LM12 80W Operational Amplifier ..... : .........................................•............ 4-4
LM78LXX Series 3-Terminal Positive Regulators ............................................. 1-158
LM78MXX Series 3-Terminal Positive Regulator ............................................. 1-143
LM78S40 Universal Switching Regulator Subsystem .................. '.. ,: .................... 3-195
LM78XX Series Voltage Regulators ........................................................ 1-168
LM79LXXAC Series 3-Terminal Negative Regulator .......................................... 1-137
LM79MXX Series 3-Terminal Negative Regulators ........................................... 1-171
LM79XX Series 3-Terminal Negative Regulators ... ; ......................................... 1-178
LM1 05 Voltage Regulator ... ; ....................................................... ; ....... 1-8
LM1 09 5-Volt Regulator ................................................ '... '................ 1-14
LM117 3-Terminal Adjustable Regulator ..................................................... 1-20
LM117HV 3-Terminal Adjustable Regulator .............................. , ................... 1-32
LM 120 Series 3-Terminal Negative Regulator ................................................ 1-42
LM123 3-Amp, 5-Volt Positive Regulator ..................................................... 1-51
LM125 Dual Voltage Regulator .......................................•....... , ............. 1-57
LM13'3 3-Amp Adjustable Negative Regulator ................................................ 1-64
LM137 3-Terminal Adjustable Negative Regulator ............................................ 1-71
LM137HV 3-Terminal Adjustable Negative Regulator (High Voltage) ............................. 1-77
LM138 5-Amp Adjustable Regulator ......................................................... 1-83
LM140 Series 3-Terminal Positive Regulator ................................................. 1-95
LM 140L Series 3-Terminal Positive Regulator ............................................... 1-106
LM145 Negative 3-Amp Regulator ......................................................... 1-110
LM150 3-Amp Adjustable.Regulator ........................................................ 1-114
LM205 Voltage Regulator ....................................................... ; ........... 1-8
LM305 Voltage Regulator .............................................. " .................... 1-8
LM309 5-Volt Regulator .................................................................... 1-14
LM317 3-Terminal Adjustable Regulator ..................................................... 1-20
LM317HV 3-Terminal Adjustable Regulator .................................................. 1-32
LM317L 3-Terminal Adjustable Regulator ............................... ,.................... 1-126
LM320 Series 3-Terminal Negative Regulator ................................................ 1-42
LM320LSeries 3-Terminal Negative Regulator ........................................ , ..... 1-137
LM323 3~Amp, 5-Volt Positive Regulator ............. '.......................•................ 1-51
LM325 Dual Voltage Regulator ...........•.........' .....................•.................. 1-57
LM330 3-Terminal Positive Regulator ........................................................ 2-5
LM333 3-Amp Adjustable Negative Regulator ................................................ 1-64
LM337 3-Terminal Adjustable Negative Regulator ............................................ 1-71
LM337HV 3-Terminal Adjustable Negative Regulator (High Voltage) ............................. 1-77
LM337L 3-Terminal Adjustable Regulator ................................................... 1-141
LM338, 5-Amp Adjustable Regulator ......................................................... 1-83
LM340 Series 3-Terminal Positive Regulator ...........................' ....................... 1-95
LM340L Series 3-Terminal Positive Regulator ........... '.................................... 1-106
LM341 Series 3-Terminal Positive Regulator ................................................ 1-143
LM345 Negative 3-Amp Regulator ......................................................... 1-110
LM350 3-Amp Adjustable Regulator ....................................................... 1-114
LM376 Voltage Regulator ... '............................................................. '... 1-8
LM431 A Adjustable Precision Zener Shunt Regulator ........................................ 3-188

vi

Alpha-Numeric

Index{continUed)

LM628 Precision Motion Controller ........................................................,. 4-17
LM629 Precision Motion Controller .............................................. .' .......... 4-17
LM723 Voltage Regulator .....•........•................................................. 1-149
LM1575 SIMPLE SWITCHER 1A Step-Down Voltage Regulator ................................ 3-45
LM1575HV SIMPLE SWITCHER 1A Step-Down Voltage Regulator .............................. 3-45
LM1577 SIMPLE SWITCHER Step-Up Voltage Regulator ...................................... 3-80
LM1578A Switching Regulator .......................................................•.... 3-102
LM2524D Regulating Pulse Width Modulator ................................................. 3-10
LM2574 SIMPLE SWITCHER O.5A Step-Down Voltage Regulator ............................... 3-27
LM2574HV SIMPLE SWITCHER 0.5A Step-Down Voltage Regulator ............................ 3-27
LM2575 SIMPLE SWITCHER 1A Step-Down Voltage Regulator ................................ 3-45
LM2575HV SIMPLE SWITCHER 1A Step-Down Voltage Regulator ...•.....•........••....•..... 3-45
LM2576 SIMPLE SWITCHER 3A Step-Down Voltage Regulator ................................ 3-63
LM2576HV SIMPLE SWITCHER 3A Step-Down Voltage Regulator .............................. 3-63
LM2577 SIMPLE SWITCHER Step-Up Voltage Regulator .......................•..•........... 3-80
LM2578A Switching Regulator .....................•..•.......................•.....••.•.. 3-102
LM2587 SIMPLE SWITCHER 5A Flyback Regulator ......................................... :3-116
LM2925 Low Dropout Regulator with Delayed Reset •..•.....•.....•.........•.....•..•........ 2-9
LM2926 Low Dropout Regulator with Delayed Reset .......................................... 2-15
LM2927 Low Dropout Regulator with Delayed ReseJ .......................................... 2-15
LM2930 3-Terminal Positive Regulator ...................................................... 2-23
LM2931 Series Low Dropout Regulators ..................................................... 2-29
LM2935 Low Dropout Dual Regulator ........•.............................................. 2-37
LM2936 Ultra-Low Quiescent Current 5V Regulator ...................•..•..•.........•..•.•.. 2-45
LM2937 500 mA Low Dropout Regulator ...•..•..•.................•.....•.............•.... 2-50
LM2940/LM2940C 1A Low Dropout Regulators .............................................. 2-55
LM2941/LM2941 C 1A Low Dropout Adjustable Regulators ..................•...........••..•. 2-65
LM2984 Microprocessor Power Supply System .............••..... , .........•.•... " ...••..•. 2-72
LM2990 Negative Low Dropout Regulator ............................................•....•. 2-85
LM2991 Negative Low Dropout Adjustable Regulator ............................•............. 2-92
LM3001 Primary-Side PWM Driver ............................................•....•....... 3-140
LM3101 Secondary-Side PWM Controller ........................................•.•........ 3-160
LM3411 Precision Secondary RegulatorI Driver .............................................. 3-177
LM3420-4.2, -8.4, -12.6 Lithium-Ion Battery Charge Controller •..........................•...... 2-99
LM3524D Regulating Pulse Width Modulator ................................................. 3-10
LM3578A Switching Regulator ............................................................ 3-102
LM3940 1A Low Dropout Regulator for 5V to 3.3V Conversion ...............•.....••....•..... 2-111
LM7800C Series 3-Terminal Positive Regulator ............................................... 1-95
LM18293 Four Channel Push-Pull Driver ......................•.•.•....•.......•......•....•. 4-38
LMC7660 Switched Capacitor Voltage Converter ............................................ 3-202
LMD18200 3A, 55V H-Bridge ............................................•..............•.. 4-44
LMD18201 3A, 55V H-Bridge ...........................•.................................. 4-53
LMD18245 3A, 55V DMOS Full-Bridge Motor Driver .........•.......•..................•••.••. 4-59
LP29501A-XX Series of Adjustable Micropower Voltage Regulators .•............•••..........• 2-116
LP2951 I A-XX Series of Adjustable Micropower Voltage Regulators ............................ 2-116
LP2952 Adjustable Micropower Low-Dropout Voltage Regulator ............................... 2-131
LP2953 Adjustable Micropower Low-Dropout Voltage Regulator ....•.......................... 2-131
LP2954 5V Micropower Low-Dropout Voltage Regulator ...•...........•...•......•..•..•..... 2-146
LP2956 Dual Micropower Low-Dropout Voltage Regulator ..•.••....•.......•.•..••.•.••••.••. 2-153
LP2957 5V Low-Dropout Regulator foq.c.P Applications ....................................... 2-166
LP2980 Micropower SOT, 50 mA Ultra Low-Dropout Regulator ..•.......••..•.......•........• 2-177

vii

Alpha-Numeric

Index(ContinUed)

Packing Considerations (Methods, Materials and Recycling) ...................................... 5-3
Recommended Soldering Profiles-Surface Mount ............................................ 5-23

viii

Additional Available Linear Devices
54ACT715 Programmable Video Sync Generator ...... Section 2
74ACT715 Programmable Video Sync Generator ...... Section 2
ADC0800 8-Bit AID Converter ...................... Section 2
ADC0801 8-Bit p.P Compatible AID Converter ........ Section 2
ADC0802 8-Bit p.P Compatible AID Converter ........ Section 2
ADC0803 8-Bit p.P Compatible AID Converter ........ Section 2
ADC0804 8-Bit p.P Compatible AID Converter ........ Section 2
ADC0805 8-Bit p.P Compatible AID Converter . , ...... Section 2
ADC0808 8-Bit p.P Compatible AID Converter with
8-Channel Multiplexer ........................... Section 2
ADC0809 8-Bit p.P Compatible A/D Converter with
8-Channel Multiplexer ........................... Section 2
ADC0811 8-Bit Serial I/O AID Converter with
11-Channel Multiplexer .......................... Section 2
ADC0816 8-Bit p.P Compatible AID Converter with
16-Channel Multiplexer .......................... Section 2
ADC0817 8-Bit p.P Compatible AID Converter with
16-Channel Multiplexer .......................... Section 2
ADC0819 8-Bit Serial I/O AID Converter with
19-Channel Multiplexer .......................... Section 2
ADC0820 8-Bit High Speed p.P Compatible AID
Converter with Track/Hold Function ............... Section 2
ADC0831 8-Bit Serial I/O AID Converter with
Multiplexer Options ............................. Section 2
ADC0832 8-Bit Serial I/O AID Converter with
Multiplexer Options ............................. Section 2
ADC0833 8-Bit Serial I/O AID Converter with
4-Channel Multiplexer ........................... Section 2
ADC0834 8-Bit Serial I/O A)D Converter with
Multiplexer Options ............................. Section 2
ADC0838 8-Bit Serial I/O AID Converter with
Multiplexer Options ............................. Section 2
ADCOB41 8-Bit p.P Compatible AID Converter ........ Section 2
ADC0844 8-Bit p.P Compatible AID Converter with
Multiplexer Options ............................. Section 2
ADC0848 8-Bit p.P Compatible AID Converter with
Multiplexer Options ............................. Section 2
ADC0851 8-Bit Analog Data Acquisition and Monitoring
System ..............................•......... Section 1
ADC0852 Multiplexed Comparator with 8-Bit
Reference Divider ............................... Section.2
ADC0854 Multiplexed Comparator with 8-Bit
Reference Divider .... " ......................... Section 2.
ADC0858 8-Bit Analog Data Acquisition and Monitoring
System ........................................ Section 1
ADC08031 8-Bit High-Speed Serial I/O AID Converter
with Multiplexer Options, Voltage Reference, and
Track/Hold Function ............................ Section 2
ADCOB032 8-Bit High-Speed Serial I/O AID Converter
with Multiplexer Options, Voltage Reference, and
Track/Hold Function ............................ Section 2

ix

Application Specific Analog Products
Application Specific Analog Products
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data.Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition

Data Acquisition

Data Acquisition

Additional Available Linear Devices (Continued)
ADC08034 8"Bit High-Speed S9riall/0 AID Converter
with Multiplexer Options, Voltage Reference, and
Track/Hold Function •.•••••••.•••.••.•.•.•••••.. Section 2
ADC08038 8-Bit High-Speed Serial 110 A/D Converter.
with Multiplexer Options, Voltage Reference, and
Track/Hold Function ••••••.........•........••••. Section 2
ADC08061 500 ns AID Converter with S/H Function
and Input Multiplexer ••••.•...•.•.•.. ; ., .•••.••.. Section 2
ADC08062 500 ns A/D Converter with S/H Function
and Input Multiplexer ..................... : .....• Section 2
ADC08131 8-Bit High-Speed Serial I/O AID Converter
with Multiplexer Options, Voltage Reference,. and
Track/Hold Function ............................ Section 2
ADC08134 8-Bit High-Speed Serial I/O AID Converter
with Multiplexer Options, Voltage Reference, and
Track/Hold Function •.....•..•..••....•.•....•.. Section 2
ADC08138 8-Bit High-Speed Serial I/O AID Converter
with Multiplexer Options, Voltage Reference, and
Track/Hold Function ............................ Section 2
ADC08161 500 ns AID Converter with S/H Function
and 2.5V Bandgap Reference ....•••.......•..•.. Section 2 .
ADC08231 8-Bit 2 p.s Serial I/O AID Converter with
MUX, Reference, and Track/Hold ..........•...... Section 2
ADC08234 8-Bit 2 P.s Serial 110 A/D Converter with
MUX, Reference, and Track/Hold .•...••.........• Section 2
ADC082388-Bit 2 p.s Serial I/O AID Converter with
MUX, Reference, and Track/Hold .•.•........•.•.. Section 2
ADC12H030 Self-Calibrating 12-Bit Plus Sign Serial
I/O A/D Converter with MUX and Sample/Hold ..... Section 2
ADC1.2H032 Self-Calibrating 12-Bit Plus Sign Serial
I/O AID Converter with MUX and Sample/Hold ...•. Section 2
ADC12H034 Self-Calibrating 12-Bit Plus Sign Serial
I/O AID Converter with MUX and Sample/Hold ..... Section 2
ADC12H038 Self-Calibrating 12-Bit Plus Sign Serial
: I/O AID Converter with MUX and Sample/Hold ...... Section 2
ADC12L030 3.3V Self-Calibrating 12-Bit Plus Sign
Serial I/O AID Converter with MUX and
Sample/Hold ••.••.•.....•........•..•.•... , .•.. Section 2
ADC12L032 3:3V Self-Calibrating 12-Bit Plus Sign
Serial I/O AID Converter with MUX and
Sample/Hold ....••...............•.....•........ Section 2
ADC12L034 3.3V Self-Calibrating 12-Bit Plus Sign
Serial I/O AID Converter with MUX and
Sample/Hold ..•..•...•.•....................... Section 2
ADC12L038 3.3V Self-Calibrating 12-Bit Plus Sign
Serial 110 A/D Converter with MUX and
.,: ..
Sample/Hold ................................... Section 2
ADC1001 10-Bit p.P Compatible AID Converter ....... Section 2
ADC1005 10-Bit p.P Compatible AID Converter .•...... Section 2
ADC1031 1O-Bit Serial 110 A/D Converter with Analog i
Multiplexer and Track/Hold Function •••••. ~ ....•.• Section 2

x

Data Acquisition

Data Acquisition
Data Acquisition
Data Acquisition

Data Acquisition

. Data Acquisition

Data Acquisition
Data· Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition

Data Acquisition

Data Acquisition

Data Acquisition

Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition

Additional Available Linear Devices (Continued)
ADC1034 1O-Bit Serial I/O A/D Converter with Analog
Multiplexer and Track/Hold Function .............. Section 2
ADC1038 1O-Bit Serial I/O AID Converter with Analog
Multiplexer and Track/Hold Function .............. Section 2
ADC1061 10-Bit High-Speed j.tP-Compatible AID
Converter with Track/Hold Function ............... Section 2
ADC1205 12-Bit Plus Sign j.tP Compatible AID
Converter ...................................... Section 2
ADC1225 12-Bit Plus Sign j.tP Compatible AID
Converter ...................................... Section 2
ADC1241 Self-Calibrating 12-Bit Plus Sign
j.tP-Compatible AID Converter with Sample/Hold ... Section 2
ADC1242 12-Bit Plus Sign Sampling AID Converter ... Section 2
ADC1251 Self-Calibrating 12-Bit Plus Sign A/D
Converter with Sample/Hold ..................... Section 2
ADC10061 1O-Bit 600 ns AID Converter with Input
Multiplexer and Sample/Hold ..................... Section 2
ADC10062 1O-Bit 600 ns AID Converter with Input
Multiplexer and Sample/Hold ..................... Section 2
ADC10064 10-Bit 600 ns AID Converter with Input
Multiplexer and Sample/ Hold ..................... Section 2
ADC1 0154 1O-Bit Plus Sign 4 j.ts ADC with 4- or
8-Channel MUX, Track/Hold and Reference ........ Section 2
ADC1 0158 10-Bit Plus Sign 4 j.ts ADC with 4- or
8-Channel MUX, Track/Hold and Reference. " ..... Section 2
ADC10461 10-Bit 600 ns AID Converter with Input
Multiplexer and Sample/Hold ..................... Section 2
ADC10462 1O-Bit 600 ns AID Converter with Input
Multiplexer and Sample/Hold ..................... Section 2
ADC10464 10-Bit 600 ns AID Converter with Input
Multiplexer and Sample/Hold ..................... Section 2
ADC10662 1O-Bit 360 ns AID Converter with Input
Multiplexer and Sample/Hold ....•................ Section 2
ADC10664 1O-Bit 360 ns AID Converter with Input
Multiplexer and Sample/Hold ..................... Section 2
ADC10731 10-Bit Plus Sign Serial 110 A/D Converter
with MUX, Sample/Hold and Reference ............ Section 2
ADC1073210-Bit Plus Sign Serial I/O AID Converter
with MUX, Sample/Hold and Reference ............ Section 2
ADC10734 10-Bit Plus Sign Serial 110 AID Converter
with MUX, Sample/Hold and Reference ............ Section 2
ADC1073810-Bit Plus Sign Serial 110 AID Converter
with MUX, Sample/Hold and Reference ............ Section 2
ADC1083110-Bit Plus Sign Serial I/O AID Converter
with MUX, Sample/Hold and Reference ............ Section 2
ADC10832 10-Bit Plus Sign Serial I/O AID Converter
with MUX, Sample/Hold and Reference ............ Section 2
ADC10834 10-Bit Plus Sign Serial I/O AID Converter
with MUX, Sample/Hold and Reference .. " ........ Section 2
ADC10838 1O-Bit Plus Sign Serial I/O AID Converter
with MUX, Sample/Hold and Reference ............ Section 2

xi

Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
. Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
. Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition

Additional Available Linear Devices (Continued)
ADC12030 Self-Calibrating 12-Bit Plus Sign Serial 110
. AID Converter with MUX and Sample/Hold ........ Section 2 '
ADC12032 Self-Calibrating 12-Bit Plus Sign Serial 110
AID Converter with MUX and Sample/Hold' ........ Section 2
ADC12034 Self-Calibrating 12-Bit Plus Sign Serial 110
AID Converter with MUX and Sample/Hold ........ Section 2
ADC1203B Self-Calibrating 12-Bit Plus Sign Serial 110
AID Converter with MUX and Sample/Hold .•...... Section 2
ADC12062 12-Bit, 1 MHz, 75 mW AID Converter with
, Input Multiplexer and Sample/Hold ................ Section 2
ADC12130 Self-Calibrating 12-Bit Plus Sign Serial 110
AID Converter with MUX and Sample/Hold ........ Section 2 '
ADC12132 Self-Calibrating 12-Bit Plus Sign Serial 110
A/D Converter with MUX and Sample/Hold ........ Section 2
ADC1213B Self-Calibrating 12-Bit Plus Sign Serial 110
AID Converter with MUX and Sample/Hold ........ Section 2
ADC12441 Dynamically-Tested Self-Calibrating 12-Bit
Plus Sign AID Converter with Sample/Hold ........ Section 2
ADC12451 Dynamically-Tested Self-Calibrating 12-Bit
Plus Sign AID Converter with Sample/Hold ....... '.Section 2
ADC12662 12-Bit, 1.5 MHz, 200 mW AID Converter
with Input Multiplexer and Sample/Hold ............ Section 2
ADC16071 16-Bit Delta-Sigma 192 ks/s
Analog-to-Digital Converter ....................... Section 2
ADC16471 16-Bit Delta-Sigma 192 ks/s
Analog-to-Digital Converter ....................... Section 2
AH0014 Dual DPDT-TTL/DTL Compatible MOS
Analog Switch .................................. Section B
AH0015 Quad SPST-TTLlDTL Compatible MOS
Analog Switch .................................. Section B
AH0019 Dual DPST-TTLlDTL Compatible MOS
Analog Switch .................................. Section B
AH5010 Monolithic Analog Current Switch .. , ......... Section B
AH5011 Monolithic Analog Current Switch ............ Section B
AH5012 Monolithic Analog Current Switch ............ Section B
AH5020C Monolithic Analog Current Switch .......... Section B
AN~450 Small Outline (SO) Package Surface Mounting
Methods-Parameters and Their Effect on Product
Reliability ................•....... , ............. Section 9
AN-450 Small Outline (SO) Package Surface Mounting
Methods-Parameters and Their Effect on Product
Reliability ...................................... Section 5
AN-450 Small Outline (SO) Package Surface Mounting
Methods-Parameters and Their Effect on Product
Reliability ...................................... Section 6
Board Mount of Surface Mount Components .......... Section 6
Board Mount ()f Surface Mount Components,.......... Section 5
Board Mount of Surface Mount Components .......... Section '9
DACOBOO B-Bit D/ A Converter ...................... Section 3
DACOB01 B-Bit D/A Converter ...................... Section 3
DACOB02 B-Bit D/ A Converter ...................... Section 3

xii

Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
. Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
, Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data AcqiJisition
Data Acquisition
Data Acquisition

Data Acquisition

Application Specific Analog Products

Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Data Acquisition
Data Acquisition
, Data Acquisition
Data Acquisition

Additional Available Linear Devices (Continued)
DAC0806 8-Bit DI A Converter .......... I • • • • • • • • • • • Section 3
DAC0807 8-Bit DI A Converter ... ; .................. Section 3
DAC0808 8-Bit DI A Converter ...................... Section 3
DAC0830 8-Bit /-fop Compatible Double-Buffered DIA
Converter ...................................... Section 3
DAC0831 8-Bit /-fop Compatible Double-Buffered DI A
Converter ........'............•................. Section 3
DAC0832 8-Bit /-fop Compatible Double-Buffered DI A
Converter ...................................... Section 3
DAC0854 Quad 8-Bit Voltage-Output Serial DI A
Converter with Readback ........................ Section 3
DAC0890 Dual 8-Bit /-foP-Compatible DI A Converter '" Section 3
DAC1006 /-foP Compatible, Double-Buffered DI A
Converter ................. ; ............ : ....... Section 3
DAC1007 /-foP Compatible, Double-Buffered DI A
Converter .......... '............................ Section 3
DAC1008 /-foP Compatible, Double-Buffered DI A
Converter ........ ' I • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Section 3
DAC1020 10-Bit Binary Multiplying DI A Converter ..... Section 3
DAC1021 1O-Bit Binary Multiplying DIA Converter ..... Section 3
DAC102210-Bit Binary Multiplying D/A Converter ..... Section 3
DAC1054 Quad 1O-Bit Voltage-Output Serial DIA
Converter with Readback " ............•. '........ Section 3
DAC1208 12-Bit /-foP Compatible Double-Buffered DI A
Converter ...................................... Section 3
DAC1209 12-Bit /-foP Compatible Double-Buffered DI A
Converter ... '................................... Section 3
DAC1210 12-Bit /-foP Compatible Double-Buffered DIA
Converter ........' ........................•..... Section 3
DAC1218 12-Bit Binary Multiplying DI A Converter ..... Section 3
DAC1219 12-Bit Binary Multiplying DI A Converter ..... Section 3
DAC1220 12-Bit Binary Multiplying DI A Converter ..... Section 3
DAC1222 12-Bit Binary Multiplying DI A Converter ..... Section 3
DAC1230 12-Bit /-foP Compatible Double-Buffered DIA
Converter ....... : .............................. Section 3
DAC1231 12-Bit /-foP Compatible Double-Buffered D/A
Converter ............................ ; ......... Section 3
DAC1232 12-Bit /-foP Compatible Double-Buffered DI A
Converter .............•.......................• Section 3
DH0006 Current Driver ............................ Section 5
DH0034 High Speed Dual Level Translator ........... Section 5
DH0035 Pin Diode Driver ........................... Section 5
DP7310 Octal Latched Peripheral Driver ............. Section 3
DP7311 Octal Latched Peripheral Driver ............. Section 3
DP831 0 Octal Latched Peripheral Driver ............. Section 3
DP8311 Octal Latched Peripheral Driver ............. Section 3
DS0026 5 MHz Two Phase MOS Clock Drivers ........ Section 4
DS1631 CMOS Dual Peripheral Driver ............... Section 3
DS1632 CMOS Dual Peripheral Driver ............... Section 3
DS1633 CMOS Dual Peripheral Driver ............... Section 3
DS1634 CMOS Dual Peripheral Driver ............... Section 3

xiii

Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Applica:tion Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products

Additional Available Linear Devices (Continued)
.oS2003 High CurrentlVoltage Darlington Driver, ...... Section 3
DS2004 High CurrentlVoltage Darlington Driver ....... Section 3
DS3631 CMOS Dual Peripheral Driver ............... Section 3
DS3632 CMOS Dual Peripheral Driver ............. ; . Section 3
DS3633 CMOS Dual Peripheral Driver .............•. Section 3
DS3634 CMOS Dual Peripheral Driver ............... Section 3
DS3658 Quad High Current Peripheral Driver ......... Section 3
DS3668 Quad Fault Protected Peripheral Driver ....... Section 3
DS3680 Quad Negative Voltage Relay Driver ., ....... Section 3
DS9667 High CurrentlVoltage Darlington Driver ....... Section 3
DS55451 Series Dual Peripheral Driver .............. Section 3
DS55452 Series Dual Peripheral Driver .............. Section 3
DS55453 Series Dual Peripheral Driver .............. Section 3
DS55454 Series Dual Peripheral Driver ..........•... Section 3
DS75451 Series Dual Peripheral Driver .............. Section 3
DS75452 Series Dual Peripheral Driver .............. Section 3
DS75453 Series Dual Peripheral Driver ............ ,. Section 3
DS75454 Series Dual Peripheral Driver .............. Section 3
DS75491 MOS-to-LED Quad Segment Driver ...... , .. Section 4
DS75492 MOS-to-LED Hex Digit Driver .............. Section 4
DS75494 Hex Digit Driver ................ , ......... Section 4
Land Pattern Recommendations .................... Section 5
Land Pattern Recommendations ............. ; ...... Section 9
Land Pattern Recommendations .................... Section 6
LF111 Voltage Comparator ........... ",' .... ; ...... Section 3
LF147 Wide Bandwidth Quad JFET Input Operational
Amplifier ... '.' ................................... Section 1
LF155 Series Monolithic JFET Input Operational
Amplifiers ............................... , ...... Section 1
LF156 Series Monolithic JFET Input Operational
Amplifiers ................................. '.' ... Section 1
Lf157 Series Monolithic J FET Input Operational
Amplifiers ...........................•... , ...... Section 1
LF198 Monolithic Sample and Hold Circuit ............ Section 6
LF211 Voltage Comparator ......................... Section 3
LF298 Monolithic Sample and Hold Circuit. ........... Section 6 .
LF311 Voltage Comparator ......................... Section 3
LF347 Wide Bandwidth Quad JFET Input Operational
Amplifier. , ........................... , , ........ Section 1
LF351 Wide Bandwidth JFET Input Operational
Amplifier ............. , ............... ; ......... Section 1
LF353 Wide Bandwidth Dual JFET Input Operational
Amplifier .... ,; .:..... '.' ...,.................. ,' ....... Section 1
LF398 Monolithic Sample and Hold Circuit. ........... Section 6
lF411 low Offset; low Drift JFET Input Operational
Amplifier ........ , .. ~ ....... , .'.................,. Section 1
lF412 low Offset, Low Drift Dual JFET Operational,
Amplifier .............. ', •.. , ............. , ...... Section 1
lF441 low Power JFET Input Operational Amplifier ... Section 1
LF442 .Dual'low Power JFET Input Operational,
Amplifier ............. '..... '. ;', ........... , .....• Section 1

xiv

Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application SPEilcific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Data Acquisition
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
. Operational Amplifiers
Operational Amplifiers
Data Acquisition
Operational Amplifiers
Data AcquiSition
Operational Amplifiers
Operational Amplifiers
Opera~ional

Amplifiers

Operational Amplifiers
Data Acquisition
Operational Amplifiers
'"

Operational Amplifiers
Operational Amplifiers
'Operational Amplifiers

Additional Available Linear Devices (Continued)
LF444 Quad Low Power JFET Input Operational
Amplifier ................•...................... Section 1
LF451 Wide-Bandwidth JFET Input Operational
Amplifier .................................•..... Section 1
LF453 Wide-Bandwidth Dual JFET Input Operational
Amplifier ....................................... Section 1
LF11201 Quad SPST JFET Analog Switch .........•. Section a
LF11202 Quad SPST JFET Analog Switch .........•. Section a
LF11331 Quad SPST JFET Analog Switch ........... Section a
LF11332 Quad SPST JFET Analog Switch ........•.. Section a
LF11'333 Quad SPST JFET Analog Switch ........... Section a
LF13006 Digital Gain Set. .......................... Section 6
LF13007 Digital Gain Set ........................... Section 6
LF13201 Quad SPST JFET Analog Switch .. : ........ Section a
LF13202 Quad SPST JFET Analog Switch ...•...•... Section a
LF13331 Quad SPST JFET Analog Switch ..' ....•..•• Section a,
LF13332 Quad SPST JFET Analog Switch ..•........ Section a
LF13333 Quad SPST JFET Analog Switch ..•........ Section a
LF1350a a-Channel Analog Multiplexer .......•...... Section a
LF13509 4-Channel Differential Analog Multiplexer .... Section a
LH0002 Buffer .................................... Section 2
LH0003 Wide Bandwidth Operational Amplifier ........ Section 1
LH0004 High Voltage Operational Amplifier .•...•.••.. Section 1 .
LH0021 1.0 Amp Power Operational Amplifier ......... Section 1
LH0024 High Slew Rate Operational Amplifier ........ Section 1
LH0032 Ultra Fast FET-Input Operational Amplifier .... Section 1
LH0033 Fast and Ultra Fast Buffers ..........••..... Section 2
LH0041 0.2 Amp Power Operational Amplifier ..•...... Section 1
LH0042 Low Cost FET Operational Amplifier ......... Section 1
LH0063 Fast and Ultra Fast Buffers ................. Section 2
LH0070 Series BCD Buffered Reference ....•....•..• Section 4
LH0071 Series Precision Buffered Reference ......... Section 4
LH0094 Multifunction Converter ............•........ Section 5
LH0101 Power Operational Amplifier ............•... Section 1
LH2111 Dual Voltage Comparator ............ ; ...... Section 3
LH2311 Dual Voltage Comparator ................... Section 3
LH4001 Wideband Current Buffer ................... Section 2
LH4002 Wideband Video Buffer ..................... Section 2
LM100perationai Amplifier and Voltage Reference .••. Section 1
LM12H45412-Bit + Sign Data Acquisition System
with Self-Calibration ............................. Section 1
LM12H45a12-Bit + Sign Data Acquisition System
with Self-Calibration ...................•.......... Section 1
LM12L43a 12-Bit + Sign Data Acquisition System with
Serial 1/0 and Self-Calibration •................... Section 1
LM12L454 12-Bit + Sign Data Acquisition System with
Self-Calibration .......................•......•.. Section 1
LM12L45a 12-Bit + Sign Data Acquisition System with
. Self-Calibration ................................. Section 1
LM34 Precision Fahrenheit Temperature Sensor ...•.. Section 5
LM35 Precision Centigrade Temperature Sensor ...•.. Section 5

xv

Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Data Acquisition
Data Acquisition
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition

Additional Available Linear Devices (Continued)
LM45 SOT-23 Precision Centigrade Temperature
Sensor......... "......................•......... Section 5
Data Acquisition
LM50 Single Supply Precision Centigrade Temperature
Sensor .. ;.'..•. '................................ Section 5
Data Acquisition
Operational Amplifiers
LM101A Operational Amplifier ..•..................• Section 1
Operational Amplifiers
LM102 Voltage Follower ........... , ............... Section 2
LM106 Voltage Comparator ........................ Section 3
Operational Amplifiers
LM107 Operational Amplifier ....................... Section 1
Operational Amplifiers
Operational Amplifiers
LM108 Operational Amplifier ............ , .......... Section 1
Operational Amplifiers
LM110 Voltage Follower ........................... Section.2
Operational Amplifiers
LM111 Voltage Comparator ........................ Section 3
LM 113 Reference Diode ....................... , ... Section 4
Data Acquisition
Operational Amplifiers
LM 118 Operational Amplifier ....................... Section 1
LM 119 High Speed Dual Comparator ......••........ Section 3
Operational Amplifiers
LM 122 Precision Timer ............................ Section 4
Application Specific Analog Products
. Operational Amplifiers
LM 124 Low Power Quad Operational Amplifier ........ Section 1
LM 129 Precision Reference ........................ Section 4
Data Acquisition
LM131 Precision Voltage-to-Frequency Converter ..... Section 2
Data Acquisition
LM 134 3-Terminal Adjustable Current Source ......... Section 4
Data Acquisition
LM 134 3-Terminal Adjustable Current Source ......... Section 5
Data Acquisition
LM135 Precision Temperature Sensor ............... Section 5
Data Acquisition
LM136.2.5V Reference Diode ...................... Section 4
Data Acquisition
Data Acquisition
LM136-5.0V Reference Diode .......... ; ........... Section 4 .
LM139 Low Power Low Offset Voltage Quad
Operational Amplifi~rs
.Comparator .... '.' ........................•........ Section 3
LM143Hgh Voltage Operational Amplifier ...•........ Section 1
Operational Amplifiers
Operational Amplifiers
LM 146 Programmable Quad Operational Amplifier ..... Section 1
Operational Amplifiers
LM148 Quad 741 Operational Amplifier .............. Section 1
LM14~ Wide Band Decompensated (Av(MIN) = 5) ..•. Section 1
Operational Amplifiers
LM 158, Low Power Dual Operational Amplifier ... '...... Section 1
Operational Amplifiers
LM 160 High Speed Differential Comparator ........... Section 3
Operational Amplifiers
LM161 High Speed Differential Comparator ........... Section 3
Operational Amplifiers
Data Acquisition
LM169Precision Voltage Reference ................. Section 4
LM185.Adjustable Micropower Voltage Reference ..... Section 4
Data Acquisition
LM185-1.2Micropower Voltage Reference Diode ..... Section 4
Data Acquisition
Data Acquisition
LM185-2.5 MicropowerVoltage Reference Diode ..... Section 4
LM193 Low Power Low Offset Voltage Dual
Comparator .....................•...' •........ ' .. ' Section 3
Operational Amplifiers
LM194 Supermatch Pair ............................ Section 5
Operational Amplifiers
LM 195 Ultra Reliable Power Transistor ............... Section 5
Operational Amplifiers
LM199Precision Reference ................ , ....... Section 4
Data Acquisition
LM201 A Operational Amplifier ...................... Section 1 .
Operational Amplifiers
Operational Amplifiers
LM207 Operational Amplifier ....................... Section 1
. Operational Amplifiers
LM208 Operational Amplifier ..................•.... Section 1 .
Operational Amplifiers
LM210 Voltage Follower ........................... Section 2
Operational Amplifiers
LM211 Voltage Comparator ........................ Section 3
LM218 Operational Amplifier ....................... Section 1
Operational Amplifiers
LM219 High Speed Dual Comparator ................ Section 3
Operational Amplifiers
Operational Amplifiers
LM221 Precision Preamplifier ......... , ............. Section 1
LM224 Low Power Quad Operational Amplifier ........ Section 1 .
Operational Amplifiers
Data Acquisition
LM231. Precision Voltage-to-Frequency Converter ..... Section 2

xvi

Additional Available Linear Devices (Continued)
LM234 3-Terminal Adjustable Current Source .......... Section 4
Data Acquisition
Data Acquisition
LM234 3-Terminal Adjustable Current Source ......... Section 5
LM235 Precision Temperature Sensor ............... Section 5
Data Acquisition
Data Acquisition
LM236-2.5V Reference Diode ...................... Section 4
Data Acquisition
LM236-5.0V Reference Diode ...................... Section 4
LM239 Low Power Low Offset Voltage Quad
Operational Amplifiers
Comparator .................................... Section.3
LM246 Programmable Quad Operational Amplifier ..... Section 1
Operational Amplifiers
LM248 Quad 741 Operational Amplifier .............. Section 1
Operational Amplifiers
Operational Amplifiers
LM258 Low Power Dual Operational Amplifier ......... Section 1
LM261 High Speed Differential Comparator ........... Section 3
Operational Amplifiers
LM285 Adjustable Micropower Voltage Reference ..... Section 4
Data Acquisition
LM285-1.2 Micropower Voltage Reference Diode ..... Section 4
Data Acquisition
Data Acquisition
LM285-2.5 Micropower Voltage Reference Diode ..... Section 4
LM293 Low Power Low Offset Voltage Dual
Comparator .................................... Section 3
Operational Amplifiers
Data Acquisition
LM299 Precision Reference ........................ Section 4
LM301A Operational Amplifier ...................... Section 1
Operational Amplifiers
LM302 Voltage Follower ........................... Section 2
Operational Amplifiers
Operational Amplifiers
LM306 Voltage. Comparator ........................ Section 3
Operational Amplifiers
LM307 Operational Amplifier ....................... Section 1
Operational Amplifiers
LM308 Operational Amplifier ....................... Section 1
Operational Amplifiers
LM310 Voltage Follower .....................•..... Section 2
Operational Amplifiers
LM311 Voltage Comparator ........................ Section 3
LM313 Reference Diode .................. , .......... Section 4
Data Acquisition
LM318 Operational Amplifier ................... : ... Section 1
Operational Amplifiers
Operational Amplifiers
LM319 High Speed Dual Comparator ................ Section 3
Operational Amplifiers
LM321 Precision Preamplifier ....................... Section 1
LM322 Precision Timer ............................ Section 4
Application Specific Analog Products
LM324 Low Power Quad Operational Amplifier ........ Section 1
Operational Amplifiers
LM329 Precision Reference ........................ Section 4
Data Acquisition
Data Acquisition
LM331 Precision Voltage-to-Frequency Converter ..... Section 2
Data Acquisition
LM334 3-Terminal Adjustable Current Source ......... Section 4
LM334 3-Terminal Adjustable Current Source ......... Section 5
Data Acquisition
Data Acquisition
LM335 Precision Temperature Sensor ............... Section 5
. Data Acquisition
LM336-2.5V Reference Diode ...................... Section 4
Data Acquisition
LM336-5.0V Reference Diode ........... ; .......... Section 4
LM339 Low Power Low Offset Voltage Quad
Operational Amplifiers
Comparator .................................... Section 3
LM343 High Voltage Operational Amplifier ........... Section 1
Operational Amplifiers
LM346 Programmable Quad Operational Amplifier ..... Section 1 .
Operational Amplifiers
Operational Amplifiers
LM348 Quad 741 Operational Amplifier .............. Section 1
. Operational Amplifiers
LM349 Wide Band Decompensated (Av(MIN) = 5) .... Section 1
LM358 Low Power Dual Operational Amplifier ......... Section 1
Operational Amplifiers
LM359 Dual, High Speed, Programmable Current
Mode (Norton) Amplifier ......................... Section 1
Operational Amplifiers
LM360 High Speed Differential Comparator ........... Section 3
Operational Amplifiers
LM361 High Speed Differential Comparator ........... Section 3
Operational Amplifiers
Data Acquisition
LM368-2.5 Precision Voltage Reference ............. Section 4 .
LM368-5.0 Precision Voltage Reference ............. Section 4
Data Acquisition
Data Acquisition
LM368"10 Precision Voltage Reference .............. Section 4.

xvii

Additional Available Linear Devices (Continued) ,
LM369 Precision Voltage Reference .•.•...•••.•...•. Section 4
LM380 Audio Power Amplifier ......... : •.•.. '........ Section 1
LM383.7W Audio Power Amplifier .........•...•••... Section 1
LM384 5W Audio Power Amplifier ...........•...•... Section 1
LM385,Adjustabie Micropower Voltage Reference .... '. Section 4
LM385-1.2 Micropower Voltage Reference Diode ...•. Section 4
LM385-2.5 Micropower Voltage Reference Diode '..... Section 4
LM386 Low Voltage Audio Power Amplifier: .•..•.•.•. Section 1
LM387/LM387A Low Noise Dual Preamplifier .•....... Section 1
LM3881.5W Audio Power Amplifier •.•...•........ '.. Section ,1
LM389 Low Voltage Audio Power Amplifier with NPN
Transistor Array •............................... Section 1
LM390 1W Battery Operated Audio Power Amplifier •.. Section 1
LM391 Audio Power Driver •.....•.........•........ Section 1
LM392 Low Power Operational AmplifierlVoltage
Comparator .... ; .............•...•.•.•.....•.•. Section 1
L:.M393 Low Power Low Offset Voltage Dual
Comparator .......................•.•.. ~ ; ...... Section 3
LM394 SupermatchPair ...................• , ....•. Section 5
LM395 Ultra Reliable Power Transistor .... '... ~ . ~ ...•• Section 5
LM399 Precision Reference .........•.•.•.....•...• Section 4
LM555 Tinier ............................... ; ..... Section 4
LM555C Timer . ~ ... '................... ', ....•...... Section 4
LM556 Dual Timer .......•..............••.....'.... Section 4
LM556C Dual Timer ...................•..... "•.• ',' . Section 4
LM565 Phase Locked Loop •.......•......• : .•..•.• Section 4
LM565C Phase Locked Loop •........ : •...•........ Section 4
LM566C Voltage Controlled Oscillator .... :\ •......•. Section 4
LM567 Tone Decoder .... ~ ....•• '...•.. :; ..• : ....... Section4
LM567C Tone Decoder ...•............. '.... '....... Section 4 '
LM611' Operational Amplifier and Adjustable,
Reference ......................... '.. : .......... Section 1
LM612 Dual-Channel Comparator and Reference ..... Section 3
LM613 Dual Operational Amplifier, Dual Comparator,
and Adjustable Reference .........•...•.........• Section 3
LM613 Dual Operational Amplifier, Dual Comparator,
and Adjustable Reference .......... :'..,.; '.....• '.... Section 1
LM614 Quad Operational Amplifier and Adjustable
Reference .........................'...... '.... '... Section 1
LM615 Quad Comparator and Adjustable Reference ... Section 3
LM~75 Power Operational Amplifier .... , •. '•... '; ...... Section 1
LM7090perationai Amplifier ......... :.,;:.' ........ Section 1
LM710 Voltage Comparator ......................•. Section 3
LM725'Operationai Amplifier .•........... '.•.•...... Section 1
LM741 Operational Amplifier ..............•........ Section 1
LM747 Dual Operational Amplifier ......... ·... : ...... Section 1
LM748 Operational Amplifier .........•. '..•.••...... Section 1
LM759Power Operational Amplifier ••... , ..; •.•...•.• Section 1
LM760 High Speed Differential Comparator ...•....... Section 3
LM831 Low Voltage Audio Power Amplifier .•.•. , ... '.. Section 1
LM833 Dual Audio Operational Amplifier .: •.... ; ...... Section 1

xviii

Data Acquisition
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Data Acquisition
Da:ta Acquisition
Data Acquisition
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products.
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Data Acquisition
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application·Specific Analog 'Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
. Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
, Application Specific Analog Products
Application Specific Analog Products

Additional Available Linear Devices (Continued)
LM837 Low Noise Quad Operational Amplifier ........ Section 1
LM903 Fluid Level Detector ......•...........•...•. Section 3
LM1036 Dual DC Operated TonelVolume/Balance
Circuit ........ '...............••................ Section 1
LM 1042 Fluid Level Detector ....................... Section 3
LM1131 Dual Dolby B-Type Noise Reduction
Processor ....................•...............•. Section 1
LM1201 Video Amplifier System .................... Section 2
LM1202 230 MHz Video Amplifier System ............ Section 2
LM1203 RGB Video Amplifier System ..............•. Section 2
LM1203A 150 MHz RGB Video Amplifier System ...... Section 2
LM1203B 100 MHz RGB Video Amplifier System ....•. Section 2
LM1204150 MHz RGB Video Amplifier System ....... Section 2
LM1205 130 MHz RGB Video Amplifier System with
Blanking ..............•.......•......•......••. Section 2
LM1207 85 MHz RGB Video Amplifier System with
Blanking ............... '........................ Section 2
LM1208130 MHz RGB Video Amplifier System with
Blanking ....................................... Section 2
LM1209 100 MHz RGB Video Amplifier System with
Blanking .................. '..................... Section 2
LM1212 230 MHz Video Amplifier System with OSD
Blanking ..............•...........•..........•. Section 2
LM1.281 85 MHz RGB Video Amplifier System with On
Screen Display (OSD) ........................... Section 2
LM1291 Video PLL System for Continuous Sync
Monitors ....................................... Section 2
LM 1295 DC Controlled Geometry Correction System
for Continuous Sync Monitors ..•.....•........... Section 2
LM1391 Phase-Locked Loop ....................... Section 2
LM 1458 Dual Operational Amplifier .................. Section 1
LM1496 Balanced Modulator-Demodulator ........... Section 4
LM1558 Dual Operational Amplifier ....•..........•.. Section 1
LM1577 SIMPLE SWITCHER Step-Up Voltage
Regulator ............................•........• Section 3
LM1596 Balanced Modulator-Demodulator ........... Section 4
LM 1801 Battery Operated Power Comparator ......... Section 3
LM1815 Adaptive Variable Reluctance Sensor
Amplifier •......................•............... Section 3
LM1819 Air-Core Meter Driver ............•......... Section 3
LM1823 Video IF Amplifier/PLL Detector System ..•.. Section 2
LM1830 Fluid Detector ............................ Section 3
LM1851 Ground Fault Interrupter ....•............... Section 4
LM1865 Advanced FM IF System ................... Section 4
LM1868 AM/FM Radio System ......•.....••....... Section 4
LM1875 20 Watt Power Audio Amplifier •............. gection 1
LM1875 20W Audio Power Amplifier ...•.•........... Section 1
LM1876 Dual 20W Audio Power Amplifier with Mute
and Standby Modes ............................. Section 1
LM1877 Dual Audio Power Amplifier .•..............•Section 1
LM 1877 Dual Power Audio Amplifier ................. Section 1

xix

Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog
Application Specific Analog
Application Specific Analog
Application Specific Analog
Application Specific Analog
Application Specific Analog
Application Specific Analog

Products
Products
Products
Products
Products
Products
Products

Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Application Specific Analog Products
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers

Additional Available Linear Devices (Conti~ued)
LM 1881' Video Sync Separator .. '. " ... : .. ~ '; ......... Section 2
Allplication Specific Analog Products
LM 1882 Programmable Video Sync Generator ........ Section 2 ' Application Specific Ana.log Products
LM 1893 Carrier-Current Transceiver ................. Section 4
Application Specific Analog Products
LM1894 Dynamic Noise Reduction System DNR® ..... Section 1
Application Specific Analog Products
Application Specific Analog Products
LM1896 Dual Audio Power Ampiifier .......... ; ....... Section 1
LM 1896 Dual Power Audio Amplifier ................. Section 1, ' ' . . Operational Amplifiers
LM19211 Amp Industrial Switch ........ ;' ... : ....... Section 3
Application Specific Analog Products
Application SpeCific Analog Products
LM1946 Over/Under Current LirriifDiagnostic Circuit, .. Section 3
LM1949 Injector Drive Controller,; .................... Section 3 ,ApplicationSpecificAnalog Products
Application Specific Analog Products
LM1950 750 rnA High Side'Switch .................... Section 3
LM1951 Solid State 1 Amp Switch: .... '.. ; ........... Section 3
Application Specific Analog Products
. ."
LM1971 jLPot 62 dB Digitally Controlled Audio '
Attenuator with Mute •. '............ '... : . ; ..... ' ... Section 1
Application Specific Analog Products
LM1972 JLPot 2-Channel 78 dB Audio Attenuator with,
Mute ...... ":: ....•......... '; .. '...... ;'; ... '........ Section 1
Application Specific Analog Products
LM1973 JLPot 3-Channel 76 dB Audio Attenuator with
Mute .. : '.................. "' ...";'.:; ......... :; •........ Section 1
Application Specific Analog Products
LM2416 Triple 50 MHz CRT Driver .................. Section 2 'Application SpecificfAnalog Products
LM241'6C Triple 50 MHz' CRT Driver ....... ; ......... Section 2 , Application Specific Analog Products
Application Specific Analog Products
LM2418 Triple 30 MHz CRT Driver .................. Section 2
Application Specific Analog Products
LM2419 Triple 65 MHz CRT Driver: .......... ; ': ...... Section 2
LM2427 Triple 80 MHz CRT Driver .................. Section 2' Application Specific Analog Products
LM2577 SIMPLE SWITCHER Step-Up Voltage,
Regulator ...........•.•..................... ; .. Section 3 ", Application Speci~ic'Analog Products
LM2876 High-Performance-40W Audio Power Amplifier
with Mute ...................................... Section 1
Application Specific Analog Products
Operational Amplifiers
LM2877 Dual 4 Watt Power Audio Amplifie(. ;': ........ Section 1
LM2877 Dual 4W Audio Power Amplifier ............. Section 1 ' , Application Specific Analog Products
LM2878 Dual 5 Watt Power Audio Amplifier ... ; ....... Section 1
Operational Amplifiers
LM2878 Dual5W Audio Power Amplifier ............. Section 1
Application Specific Analog Products
Operational Amplifiers
LM2879 Dual 8 Watt Audio Amplifier ..... : ........... Section 1
LM2879 Dual 8W Audio Power Amplifier .' ............ Section 1
Application Specific Analog Products
LM2889 TV Video Modulator ............ ; .......... Section 2
Application Specific Analog Products
Application Specific Analog Products
LM2893 Carrier-Current Transceiver ................. Section 4
Application Specific Analog 'Products
LM2896 Dual Audio Power ftmplifier ...... /; ......... Section 1
Operational Amplifiers
'LM2896 Dual Power Audio Amplifier .....' ......•.' .... Section 1 '
LM2900 Quad Amplifier ............................ Section 1
Operational Amplifiers
','"
LM2901 Low Power Low Offset Voltage Quad
, ,Comparator ........... .'.....•......... '......... Section 3
Operational Amplifiers
'LM2902 Low Power Quad Operational Amplifier ....... Section 1 .
Operational Amplifiers
LM2903 Low Power Low Offset Voltage Dual
" Comparator ...... '.'; .. : .......................... Section 3
Operational Amplifiers
LM2904 Low Power Dual Operational Amplifier ....... Section 1
Operational Amplifiers
LM2907, Frequency to Voltage Converter ............. Section 3
Application Specific Analog PrOducts
·LM2917 Frequency to Voltage Converter ............. Section 3 ,Application Specific Analog Products
LM2924 Low Power Operational AmplifierlVoltage
, Comparator .. ,: ......... : ....•.... ; ....... : ...... Section 1
Operational Amplifiers
LM2925 Low Dropout Regulator with Delayed Reset ... Section 3 'Application Specific Analog Products
LM2926 Low Dropout Begulator with Delayed Reset ... Section 3
Application Specific Analog Products
Application Specific,Analog Products
LM2927 Low Dropout Begulator with Delayed Reset ... Section 3
LM2931 Series Low Dropout Regulators. ;: ... : ...... Section 3
Application Specific Analog Products
/'

"xx

Additional Available Linear Devices (Continued)
LM2935 Low Dropout Dual Regulator ................ Section 3 , Application Specific Analog Products
LM2936 Ultra-Low Quiescent Current 5V Regulator .... Section 3
Application Specific Analog Products
Application Specific Analog Products
LM2937 500 mA Low Dropout Regulator ............. Section 3
LM2940/LM2940C 1A Low Dropout Regulators ....... Section 3
Application Specific Analog Products
Application Specific Analog Products
LM2984 Microprocessor Power Supply System ....... Section 3
Operational Amplifiers
LM3045 Transistor Array •.......................... Section 1
LM3045 Transistor Array ........................... Section 5
Operational Amplifiers
Operational Amplifiers
LM3046 Transistor Array ........................... Section 5
LM3046 Transistor Array ........................... Section 1
Operational Amplifiers
LM3080 Operational Transconductance Amplifier ..... Section 1
Operational Amplifiers
LM3086 Transistor Array ........................... Section 1
Operational Amplifiers
LM3086 Transistor Array ........................... Section 5
Operational Amplifiers
LM3146 High Voltage Transistor Array ............... Section 5
Operational Amplifiers
LM3301 Quad Amplifier ............................ Section 1
Operational Amplifiers
LM3302 Low Power Low Offset Voltage Quad '
Operational Amplifiers
Comparator .................................... Section 3
Operational Amplifiers
LM3303 Quad Operational Amplifier ................. Section 1
LM3403 Quad Operational Amplifier ................. Section 1
Operational Amplifiers
LM3875 High Performance 40 Watt Audio Power
Amplifier ....................................... Section 1
Operational Amplifiers
LM3875 High Performance 56W Audio Power
Amplifier ....................................... Section 1
Application Specific Analog Products
LM3876 High Performance 56W Audio Power Amplifier
with Mute ...................................... Section 1
Application Specific Analog Products
LM3886 High-Performance 68W Audio Power Amplifier,
with Mute ...................................... Section 1
Application Specific Analog Products
LM3900 Quad Amplifier ............................ Section 1
Operational Amplifiers
LM3905 Precision Timer ........................... Section 4
Application Specific Analog Products
LM3909 LED Flasher/Oscillator ..............•...... Section 4 ' Application Specific ,Analog Products
LM3914 Dot/Bar Display Driver ..................... Section 4
Application Specific Analog Products
LM3915 Dot/Bar Display Driver ..................... Section 4
Application Specific Analog Products
LM3916 Dot/Bar Display Driver ..................... Section 4
Application Specific Analog Products
LM3999 Precision Reference ....................... Section 4
Data Acquisition
LM4040 Precision Mic'ropower Shunt Voltage
Reference ...........................'.......... Section 4
Data Acquisition
LM4041 Precision Micropower Shunt Voltage
Reference ..... , ............................... Section 4
Data Acquisition
Operational ,Amplifiers
LM4250 Programmable Operational Amplifier ......... Section 1
LM4431 Micropower,Shunt Voltage Reference ........ Section 4
Data Acquisition
LM4700 Overture™ 30W Audio Power Amplifier with
Mute and Standby Modes ........................ Section 1
Application Specific Analog Products
LM4860 1W Audio Power Amplifier with Shutdown
"Mode ... '.................... , .................. Section 1
Application Specific Analog Products
LM4861 YzW Audio Power Amplifier with Shutdown
Mode .......... : ............................... Section 1
Application Specific Analog Products
LM4862 350 mW Audio Power Amplifier with Shutdown
,Mode ...... '.............................•...... Section 1
Application Specific Analog Products
LM4880 Dual 200 mW Audio Power Amplifier with
Shutdown Mode .... ; ........................... Section 1
Application Specific Analog Products
LM61 04 Quad Gray Scale Current Feedback'
Amplifier ................................•...... Section 4
Operational Amplifiers

xxi

Additional Available 'Linear Devices (Continued)
LM61 04 Quad Gray Scale Current Feedback
, Amplifier ................. ;'... '.................. Section 2
LM61 04 Quad Gray Scale Current Feedback'
Amplifier .. ' ..................•,.... .' ............. Section 1
LM6118 Fast Settling Dual Operational Amplifier ......Section 1
LM6121 High Speed Buffer .....................,.... Section 2
LM6121 High Speed Buffer ........... ; ..........,... Section 2
LM6125 High Speed Buffer ......................... Section 2
LM6125 High Speed Buffer ......................... Section 2
LM6132 Dual High Speed/Low Power 7 MHz
Rail-to-Rail 110 Operational Amplifier •....•........ Section 1
LM6134 Quad High Speed/Low Power 7 MHz
Rail-to-RaiIIlO Operational Amplifier ............. Section 1
LM6142 Dual High Speed/Low Power 17 MHz
Rail-to-Raillnput-Output Operational Amplifier ...... Section 1
LM6142 Dual High Speed/Low Power 17 MHz
Rail-to-Raillnput-Output Operational Amplifier ...... Section 1
LM6144 Quad High Speed/Low Power 17 MHz
Rail-to-Raillnput-Output Operational Amplifier ...... Section 1
LM6144 Quad High Speed/Low Power 17 MHz
Rail-to-Raillnput-Output Operational Amplifier ...... Section 1
LM6152 Dual High Speed/Low Power 45 MHz
Rail-to-Raillnput-Output Operational Amplifier ... ,.: .Section 1:
LM61.52 Dual High Speed/Low Power 45 MHz
Rail-to-RailIlO Operational Amplifier .............. Section 2
LM6154 Quad High Speed/Low Power 45 MHz
Rail-to-RailIlO Operational Amplifier .....•........ Section 2
LM6154 Quad High Speed/Low Power 45 MHz :
Rail-to-Raillnput;,Output Operational Amplifier ...... Section 1
LM6161 High Speed Operational Amplifier ..•. .' ..•... Section 1
LM6161 High Speed Operational Amplifier ........... Section 2
LM6162 High Speed Operational Amplifier ........... Section 2
LM6162 High Speed Operational Amplifier .. : ........ Section 1
LM6164 High Speed Operational Amplifier ..........• Section 1 '
LM6164 High Speed Operational Amplifier ........... Section 2
LM6165 High Speed Operational Amplifier .•....... : . Section 2
LM6165 High Speed Operational Amplifier .......' .... Section 1
LM6171 Voltage Feedback Low Distortion Low Power
Operational Amplifier ..................... , ...... Section 1
LM6171 Voltage Feedback Low Distortion Low Power
Operational Amplifier ................... ; ........ Section 2
LM6181 100 mA, 100 MHz Current Feedback
Amplifier .' ....... '.' .... ; ...........•.•........... Section 2
LM6181 100 mA, 100 MHz Current Feedback
Amplifier ...... : ....... '... '........•............. Section 1
LM6182 Dual 100 mA Output, 100 MHz Dual Current
Feedback Amplifier .............•....... ; ....... Section 1
LM6182 Dual 100 mA Output, 100 MHz Dual Current
Feedback Amplifier .•. ,.; ...... ; ................. Section 2
LM6218 Fast Settling Dual Operational Amplifier .....• Section 1
LM6221 High Speed Buffer ......................... Section 2

xxii

Application Specific Analog Products
, Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
, Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers

Additional Available Linear Devices(continued)
LM6221 High Speed Buffer ......................... Section 2
LM6225 High Speed Buffer .....•................... Section 2
LM6225 High Speed Buffer ......................... Section 2
LM6261 High Speed Operational Amplifier ........... Section 1
LM6261 High Speed Operational Amplifier ........... Section 2
LM6262 High Speed Operational Amplifier ........... Section 2
LM6262 High Speed Operational Amplifier ........... Section 1
LM6264 High Speed Operational Amplifier ........... Section 1
LM6264 High Speed Operational Amplifier ........... Section 2
LM6265 High Speed Operational Amplifier ........... Section 2
LM6265 High Speed Operational Amplifier ........... Section 1
LM6313 High Speed, High Power Operational
Amplifier ....................................... Section 1
LM6321 High Speed Buffer ......................... Section 2
LM6321 High Speed Buffer ......................... Section 2
LM6325 High Speed Buffer ................•........ Section 2
LM6325 High Speed Buffer ......................... Section 2
LM6361 High Speed Operational Amplifier ........... Section 1
LM6361 High Speed Operational Amplifier ........... Section 2
LM6362 High Speed Operational Amplifier ........... Section 2
LM6362 High Speed Operational Amplifier ........... Section 1
LM6364 High Speed Operational Amplifier ........... Section 1
LM6364 High Speed Operational Amplifier ........... Section 2
LM6365 High Speed Operational Amplifier ........... Section 2
LM6365 High Speed Operational Amplifier ........... Section 1
LM6511 180 ns 3V Comparator ..................... Section 3
LM7121 Tiny Very High Speed Low Power Voltage
Feedback Amplifier ............................. Section 1
LM7131 Tiny High Speed Single Supply Operational
. Amplifier ....................................... Section 1
LM7131 Tiny High Speed Single Supply Operational
Amplifier ....................................... Section 2
LM7171 Very High Speed High Output Current Voltage
Feedback Amplifier ............................. Section 2
LM7171 Very High Speed High Output Current Voltage
Feedback Amplifier ............................. Section 1
LM8305 STN LCD Display Bias Voltage Source ....... Section 2
LM8305 STN LCD Display Bias Voltage Source ....... Section 4
LM9044 Lambda Sensor Interface Amplifier .......... Section 3
LM9061 Power MOSFET Driver with Lossless
Protection ...................................... Section 3
LM9140 Precision Micropower Shunt Voltage
Reference ..................................... Section 4
LM 12434 12-Bit + Sign Data AcquiSition System with
Serial 110 and Self-Calibration .................... Section 1
LM 12454 12-Bit + Sign Data Acquisition System with
Self-Calibration ................................. Section 1
LM 12458 12-Bit + Sign Data AcquiSition System with
Self-Calibration ................................. Section 1
LM13600 Dual Operational Transconductance
Amplifier with Linearizing Diodes and Buffers ....... Section 1

xxiii

Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Application Specific Analog Products
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Operational Amplifiers

Additional Available Linear Devices (Continued)
LM13700 Dual Operational Transconductance'
Amplifier with Linearizing Diodes and Buffers ....... Section 1
LM77000 Power Operational Amplifier ............... Section 1
LMC555 CMOS Timer ............................. Section 4
LMC567 Low Power Tone Decoder .................. Section 4
LMC568 Low Power Phase-LoCked Loop ............. Section 4
LMC660CMOS Quad Operational Amplifier .......... Section 1
LMC662 CMOS Dual Operational Amplifier ........... Section 1
LMC835 Digital Controlled Graphic Equalizer ......... Section 1
LMC1982 Digitally-Controlled Stereo Tone and Volume
Circuit with Two Selectable Stereo Inputs .......... Section 1
LMC1983 Digitally-Controlled Stereo Tone and Volume
Circuit with Three Selectable Stereo Inputs ......... Section 1
LMC1992 Digitally-controlled Stereo Tone and Volume
Circuit with Four-Channel Input-Selector ........... Section 1
LMC6001 Ultra Ultra-Low Input Current Amplifier ...... Section 1
LMC6008 8 Channel Buffer ................... ~ ..... Section 4
LMC6008 8 Channel Buffer ......................... Section 2
LMC6022 Low Power CMOS Dual Operational
Amplifier ............ ; '................ '.........'. Section 1
LMC6024 Low Power CMOS Quad Operational
Amplifier ..•.................................... Section 1
LMC6032 CMOS Dual Operational Amplifier .......... Section 1
LMC6034 CMOS Quad Operational Amplifier ......... Section 1
LMC6041 CMOS Single Micropower Operational
Amplifier ....................................... Section 1
LMC6042 CMOS Dual Micropower Operational
Amplifier ........................................ Section 1
LMC6044 CMOS Quad Micropower Operational
Amplifier .... :~, ................................ Section 1
LMC6061 Precision CMOS Single Micropower
Operational Amplifier ............................ Section 1
LMC6062 Precision CMOS Dual Micropower
Operational Amplifier .......... ;' ................. Section 1
LMC6064 Precision CMOS Quad Micropower
Operational Amplifier ............................ Section 1
LMC6081 Precision CMOS Single Operational
Amplifier ....................................... Section 1
LMC6082.Precision CMOS Dual Operational
Amplifier ....................................... Section 1
LMC6084 Precision CMOS Quad Operational
Amplifier ....................................... Section 1
LMC6462 Dual Micropower, Rail-to-Raillnput and
Output CMOS Operational Amplifier ............... Section 1
LMC6464 Quad Micropower, Rail-to-Raillnput and
Output CMOS Operational Amplifier ............... Section 1
LMC6482 CMOS Dual Rail-to-Raillnput and Output
Operational Amplifier ............................ Section 1
LMC6484 CMOS Quad Rail-to-Rail Input and Output
Operational Amplifier ............................ Section 1

xxiv

Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers

AddotiOril~~

A'Valuiable lunlear Devices(ContinUed)

LMC6492 Dual CMOS Rail-to-Raillnput and Output
Operational Amplifier ............................ Section 1
LMC6494 Quad CMOS Rail-to-Rail Input and Output
Operational Amplifier ............................ Section 1
LMC6572 Dual Low Voltage (3V) Operational
Amplifier ....................................... Section 1
LMC6574 Quad Low Voltage (2.7V) Operational
Amplifier ....................................... Section 1
LMC6582 Dual Low Voltage, Rail-to-Raillnput and
Output CMOS Operational Amplifier ............... Section 1
LMC6584 Quad Low Voltage, Rail-to-Raillnput and
Output CMOS Operational Amplifier ............... Section 1
LMC6681 Single Low Voltage, Rail-to-Raillnput and
Output CMOS Amplifier with Powerdown ........... Section 1
LMC6682 Dual Low Voltage, Rail-to-Raillnput and
Output CMOS Amplifier with Powerdown ........... Section 1
LMC6684 Quad Low Voltage, Rail-to-Raillnput and
Output CMOS Amplifier with Powerdown ........... Section 1
LMC6762 Dual Micropower, Rail-to-Raillnput and
Output CMOS Comparator ....................... Section 3
LMC6764 Quad Micropower, Rail-to-Raillnput and
Output CMOS Comparator ....................... Section 3
LMC6772 Dual Micropower Rail-to-Raillnput and Open
Drain Output CMOS Comparator .................. Section 3
LMC6774 Quad Micropower Rail-to-Raillnput and
Open Drain Output CMOS Comparator ............. Section 3
LMC7101 Tiny Low Power Operational Amplifier with
Rail-to-Raillnput and Output ..................... Section 1
LMC7111 Tiny CMOS Operational Amplifier with
Rail-to-Raillnput and Output ...................... Section 1
LMC7211 Tiny CMOS Comparator with Rail-to-Rail
Input ........................................... Section 3
LMC7221 Tiny CMOS Comparator with Rail-to-Rail
Input and Open Drain Output ..................... Section 3
LMD18400 Quad High Side Driver ................... Section 3
LMF40 High Performance 4th-Order Switched
Capacitor Butterworth Low-Pass Filter ............. Section 7
LMF60 High Performance 6th-Order Switched
Capacitor Butterworth Low-Pass Filter ............. Section 7
LMF90 4th-Order Elliptic Notch Filter ................ Section 7
LMF100 High Performance Dual Switched Capacitor
Filter .......................................... Section 7
LMF380 Triple One-Third Octave Switched Capacitor
Active Filter .................................... Section 7
LP311 Voltage Comparator ......................... Section 3
LP339 Ultra-Low Power Quad Comparator ........... Section 3
LP395 Ultra Reliable Power Transistor ............... Section 5
LP2950! A-XX Series of Adjustable Micropower
Voltage Regulators .............................. Section 3
LP2951! A-XX Series of Adjustable Micropower
Voltage Regulators .............................. Section 3

xxv

Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Data Acquisition
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Application Specific Analog Products

Additional Available Linear Devices (Continued)
LPC660 Low Power CMOS Quad Operational
Amplifier .......•....••.....•.••...•••....•••... Section 1
LPC661 Low Power CMOS Operational Amplifier ..... ; Section 1
LPC662 LowPower CMOS Dual Operational
Amplifier •....•.•....•.•.......•................ Section 1
MF4 4th Order Switched Capacitor Butterworth
Lowpass Filter •...•...............•............. Section 7
MF5 Universal Monolithic Switched Capacitor Filter .... Section 7
MF6 6th Order Switched Capacitor Butterworth
Lowpass Filter ...•...........•.................. Section 7
MF8 4th Order Switched Capacitor Bandpass Filter .... Section 7
MF10 Universal Monolithic Dual Switched Capacitor
Filter .........•....•......•••.....••......•.... Section 7
MM5368 CMOS Oscillator Divider Circuit ............. Section 4
MM5369 17 Stage Oscillator/Divider •.....••........ Section 4
MM5450 LED.Display Driver ...••••...•.••.....•.... Section 4
MM5451 LED Display Driver ........................ Section 4
MM5452 Liquid Crystal Display Driver .•••.•....•..... Section 4
MM5453 Liquid Crystal Display Driver ................ Section 4
MM5480 LED Display Driver ..•..................... Section 4
MM5481 LED Display Driver ••. ; ...........•.....••. Section 4
MM5483 Liquid Crystal Display Driver ..•.•.....••.... Section 4
MM548416-Segment LED Display Driver ...•........ Section 4
MM5486 LED Display Driver .••.••...•••.......•.... Section 4
MM58241 High Voltage Display Driver ............... Section 4
MM58341 High Voltage Display Driver ............... Section 4
MM58342 High Voltage Display Driver •.....•.....•.. Section 4
OP07 Low Offset, Low Drift Operational Amplifier ..... Section 1
Packing Considerations (Methods, Materials and
Recycling) .....•................•.............. Section 6
Packing Considerations (Methods, Materials and
Recycling) .............•........••.............. Section 5
Packing Considerations (Methods, Materials and
Recycling) .....•.....•......................... Section 9
Recommended Soldering Profiles-Surface Mount .... Section 9
Recommended Soldering Profiles-Surface Mount ..•. Section 5
Recommended Soldering Profiles-Surface Mount .... Section 6
TL081 Wide Bandwidth JFET Input Operational
Amplifier ..•.....••........•.......•...... ~ .•... Section 1
TL082 Wide Bandwidth Dual JFET Input Operational
Amplifier ....................................... Section 1

xxvi

Operational Amplifiers
Operational Amplifiers
Operational Amplifiers
Data Acquisition
Data AcqUisition
Data Acquisition
Data Acquisition
Data Acquisition
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Application Specific Analog Products
Data Acquisition
Data Acquisition
Application Specific Analog Products
Operational Amplifiers
Operational Amplifiers
Operational Amplifiers

t(JNational Semiconductor

Industry Package Cross-Reference Guide

NSC

CJ
mww

~=

NSC

,.,.A

@

CJ
~

?

0
0

m

Motorola

TI

AMD

Sprague

D

R

4/16 Lead
Glass/Metal DIP

D

D

I

L

Glass/Metal
Flat Pack

F

F

Q

F

F,
S

F

TO·99, TO·100, TO·5

H

H

T,
K,
L,
DB

G

L

H

8·, 14· and 16·Lead
Low Temperature
Ceramic DIP

J

F

U

J

D

H

P

A,
B,
M

~
1110111

Signetics

R,
D

(Steel)
K

TO·3

KS

KC

K

DA

N

T,
P

N,

K

K

(Aluminum)

8·, 14· and 16·Lead
Plastic DIP

xxvii

V

P

P,

N

NSC

NSC

90
~;

t=
~
mm

TO-263
3-&5-lead

p.A

Signetics

Motorola

TI

AMD

Sprague

5

TO-220
3-&5-lead

U

T

TO-220
11-, 15-&23-Lead

low Temperature
Glass Hermetic
Flat Pack

U

KC

T

W

F

F

,
TO-92
(Plastic)

W

i=

"

Z

W

5

P

lP

M

5

5,
D

D

D

l

DW

lW

0

0

fUUUUUiid

RRRRRRRRRR

50

(Narrow Body)
(Wide Body)

WM

D
•
1::1 1::1 1::1 1::1 I::IIHI1::1 I:U:I

IUUUiAAAAR:RJ
~.

"

50T-23
5-lead

M5

:

xxviii

3'

NSC

NSC
",A

Co

Signetics

Motorola

TI

AMD

Sprague

-

c
(II

-<

"U

II)

n

;lII;"
II)

CD

CD

0

~

PCC

V

Q

A

FN

FN

L

EP

0

(II
(II

•
:::u

CD
CD

n;

~

~

n

CD
Ci)

c

a::
CD
LCC
Leadless Ceramic
Chip Carrier

E

L1

II~~~~~~~II

xxix

G

U

FKI
FG/FH

L

EK

Section 1
Linear Voltage
Regulators

•

Section 1 Contents
Linear Voltage Regulators Definition of Terms .................. , ........... ..... .......
Linear Voltage Regulators Selection Guide ............................................
LM105/LM205/LM305/LM305A/LM376 Voltage Regulators..... .... ... ........ ........
LM109/LM309 5-Volt Regulators... .............. ...... ... .......... .... .. .... ..... ..
LM 1171 LM3171 LM317A 3-Terminal Adjustable Regulators ..................... . . . . . . . . .
LM117HV/LM317HV 3-Terminal Adjustable Regulators.. . ... .... .......... .. .... .......
LM120/LM320 Series 3-Terminal Negative Regulators.. .. ................... ......... ..
LM123/LM323A1LM323 3-Amp, 5-Volt Positive Regulators... .............. .. .... .......
LM125/LM325 Dual Voltage Regulators................. ........ ..... .... .. .... .......
LM133/LM333 3-Amp Adjustable Negative Regulators.. .............. ....... ..... ..... .
LM137/LM337 3-Terminal Adjustable Negative Regulators................... ......... ..
LM137HV/LM337HV 3-Terminal Adjustable Negative Regulators (High Voltage). ......... ..
LM 1381 LM338 5-Amp Adjustable R'egulators. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .
LM140A/LM140/LM340A/LM340/LM7800C Series 3-Terminal Positive Regulators........
LM140LlLM340L Series 3-Terminal Positive Regulators... .......... ......... ...... ... ..
LM145/LM345 Negative 3-Amp Regulators.... .......... ................... ...... .....
LM150/LM350/LM350A 3-Amp Adjustable Regulators... ............... .... .. .... ......
LM317L 3-Terminal Adjustable Regulator.................... ..... .....................
LM320L, LM79LXXAC Series 3-Terminal Negative Regulators. . . . . . . . . . . . . . . . . . . . . . . . . . . .
LM337L 3-Terminal Adjustable Regulator........... ..... ................... ...... ... ..
LM341/LM78MXX Series 3-Terminal Positive Regulators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
LM723/LM723C Voltage Regulators. . .. . . . .. . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . .
LM78LXX Series 3-Terminal Positive Regulators.. ... ........... ... ...... .... ...... .....
LM78XX Series Voltage Regulators. .. .. . . . . . . . . .. . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . ..
LM79MXX Series 3-Terminal Negative Regulators.. .. ... ................... .. ..........
LM79XX Series 3-Terminal Negative Regulators......... ...............................

1-2

1-3
1-4
1-8
1-14
1-20
1-32
1-42
1-51
1-57
1-64
1-71
1-77
1-83
1-95
1-106
1-110
1-114
1-126
1-137
1-141
1-143
1-149
1-158
1-168
1-171
1-178

t!lNational Semiconductor

Voltage Regulators
Definition of Terms
Current-Limit Sense Voltage: The voltage across the current limit terminals required to cause the regulator to current-limit with a short circuited output. This voltage is used
to determine the value of the external current-limit resistor
when external booster transistors are used.
Droj)out Voltage: The input-output voltage differential !!It
which the circuit ceases to regulate against further reductions in input voltage.
Feedback Sense Voltage: The voltage, referred to ground,
on the feedback terminal of the regulator while it is operating in regulation.

Output-Input Voltage Differential: The voltage difference
between the unregulated input voltage and the regulated
output voltage for which the regulator will operate within
specifications.
Output Noise Voltage: The RMS ac voltage at the output
with constant load and no input ripple, measured over a
specified frequency range.
'
Output Voltage Range: The range of regulated output voltages over which the specifications apply.
Output Voltage Scale Factor: The output'voltage obtained
for a unit value of resistance between the adjustment terminal and ground.
Quiescent Current: That part of input current to the regulator that is not delivered to the load.

Input Voltage Range: The range of dc input voltages over
which the regulator will operate within specifications.
Line Regulation: The change in output voltage for 'a
change in the input voltage. The measurement is made under conditions of low dissipation or by using pulse techniques such that the average chip temperature is not significantly affected.
Load RegLiiatlon: The change in output voltage for a
change in load current at constant chip temperature.•

Ripple ReJection: The line regulati,on for ac input signals at
or above a given frequency with a specified value of bypass
capacitor on the reference bypass terminal.
Standby Current Drain: That part of the operating current
of the regulator which does not contribute to'the load current. (See Quiescent Current) ,
Temperature Stability: The percent~ge change in output
voltage for a thermal variation from room temperature to
either temperl\ture extreme.

Lorig Term Stability: Output voltage stability under accelerated life-test conditions at 125°C with maximum rated voltages and power dissipation for 1000 hours.
Maximum Power Dissipation: The maximum total device
dissipation for which the regulator will operate within specifiCations. '

Thermal Regulation: Percentage change in output voltage
for a given change in power dissipation 'over a specified time
period.

1-3

tfI

National Semiconductor

Linear Voltage Regulators Selection Guide
Adjustable Positive Voltage Regulators
Output
Current
(A)

, '5.0
,3.0

1.5

0.5

0.1

.,

Output
Voltage
(Y)

Input
Voltage
(Y)'

LM138

1.21032

Ditt.

~

40

-5510 +150

LM338

1.21032

Ditt.

~

40

Oto +125

LM,,50

1.21032

Ditt.

~

35

-55to +150

LM350

1.21032

Ditt.

~

35

010 +125

LM350A

1.21032

Ditt.

~

35

Device

Operating
Temperature
, (TJ DC)

Package
Availability' •

Page
No.

K2 .

1-83

K2, T3

1-83

K2

. 1-114

K2, T3

1-114

-4010 +125

T3

1-114
1-20

LM117

1.21037

Ditt.

~

40

-55'10 +150

K2 '

LM117A

~.2

to 37

Ditt.

~

40

-5510 +150

K2 .. ••

1-20

LM117HV

1.21057

Ditt.

~

60

-5510 +,150

K2'"

1-32 '

LM317

1.21037

Ditt.

~

40

Oto +125

K2;S3, T3

1-20

40

-4010 +125

LM317A

1.21037

Ditt.

~

'LM317HV

1.2to 57

Diff.

~60

Oto +125

T3

1-20

K2,T3

1-32

H3, E20'"

1-20

H3'"

1-20

LM117

1.2 to 37

Ditt.

~

40

.LM117A

1.2 to 37

Ditt.

~

40

,-55to +150

LM117HV

1.2to 57

Diff.

~60

-55 to +150

H3

1-32

LM317

1.2t037

Ditt.

~

40

Oto.+125,

H3

1·20

LM317A

1.2 to 37

Ditt.

~

40

-4010 +125

H3

1-20

LM317HV

1.2to 57

Ditt.

~

60

010 +125

H3

1-32

LM317L

1.2to 37

Ditt.

~

40

-4010 +125

M8,Z3

1·20

-55~0

+150

'In cases where the regulator is "floating" the maximum input-to-output voltsge differential is listed.
"Under Pacl B.5V

rsc""~mA
A50

tSolid tantaium.

AZ

*125 turns = 22 on Arnold
Engineering A262123-2
molybdenum permally
core. TL/H/7755-11

TL/H/7755-12

1.0A Regulator with Protective Diodes

oz·

UTA3305

,-------1I4---~t_-~t_--~t_~t_~t_-vOuT ·2.V~

01+

UTR330S

cz
4JpF

tprotects against shorted
input or inductive loads on
unregulated supply.

V,.-.--4I....- - - - I

'Protects against input

C3

I,..

HZ

35V

l~"

voltag~ re~ersal.

*Protects against output
voltage reversal.

TLlH17755-13

•

Linear Regulator with Foldback Current Limiting

VIN> l8V

TLlH17755-14

1-13

til

Nat ion a I S e m i co nd u c tor

LM109/LM309 5-Volt Regulator
General Description
The LM109 series are complete 5V regulators fabricated on
a single silicon chip. They are designed for local regulation
on digital logic cards, eliminating the distribution problems
association with single-point regulation. The devices are
available in two standard· transistor packages. In the solidkovar TO-5 header, it can deliver output currents in excess
of 200 mA, if adequate heat sinking is provided. With the
TO-3 power package, the available output current is greater
than 1A.
The regulators are essentially blowout proof. Current limiting
is included to limit the peak output current to a safe value. In
addition, thermal shutdown is provided to keep the IC from
overheating. If internal diSSipation becomes too great, the
regulator will shut down to prevent excessive heating.
Considerable effort was expended to make these devices
easy to use and to minimize the number of external components. It is not necessary to bypass the output, although this
does improve transient response somewhat. Input bypassing is needed, however, if the regulator is located very

far from the filter capacitor of the power supply. Stability is
also achieved by methods that provide very good rejection
of load or line transients as are usually seen with TTL logic.
Although deSigned primarily as a fixed-voltage regulator, the
output of the LM109 series can be set to voltages above 5V,
as shown. It is also possible to use the circuits as the control element in preCision regulators, taking advantage of the
good current-handling capability and the thermal overload
protection.

Features
• Specified to be compatible, worst case, with TTL and
DTL
• Output current in excess of 1A
• Internal thermal overload protection
• No external components required

Schematic Diagram
r-----~--------~----_1~------t_--~INPUT

RI4
O.l
}-----------~~~----~------~--OUTPUT

40

04
6 lV

~--4---~--~~--6-~~---4--~~--4__GROUNO

TLlH17138-1

1-14

r-

....
o

Ei:

Absolute Maximum Ratings
Operating Junction Temperature Range
-55·C to
LM109
O·Cto
LMS09
-65·C to
Storage Tem~erature Range
Lead Temperature (Soldering, 10 sec.)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
(Note 3)
Input Voltage
35V
Power Dissipation
Internally Limited

....rCD

+ 150·C
+ 125·C
+ 150"C

Ei:
Co)

o

CD

300·C

Electrical Characteristics. (Note 1)
Parameter

LM109

Conditions

Output Voltage

Ti = 25·C

Line Regulation

Tj = 25·C
7.10V '" VIN :s;: 25V

Load Regulation
TO-S9 Package
TO-S Package

Tj = 25·C
5 mA :s;: lOUT :s;: 0.5A
5 mA:S;: IOUT:S;: 1.5A

Output Voltage

7.40V :s;: VIN :s;: 25V,
5 mA :s;: lOUT :s;: IMAX'
P < PMAX

Quiescent Current

7.40V :s;: VIN :s;: 25V

Quiescent Current Change

7.40V :s;: VIN :s;: 25V
5 mA :s;: lOUT :s;: IMAX

Output Noise Voltage

TA = 25·C
10Hz:s;: f:S;: 100kHz

Max

Min

Typ

Max

4.7

5.05

5.S

4.8

5.05

5.2

V

4.0

50

4.0

50

mV

15
15

50
100

15
15

50
100

mV
mV

5.25

V

10

mA

0.5
0.8

mA
mA

4.6

5.4

5.2

4.75

10

5.2

0.5
0.8
40
10

Tj = 25·C

Units

Typ

Long Term Stability
Ripple Rejection

LM309

Min

40

/LV

20

mV

50

50

dB

Thermal Resistance,
(Note 2)
Junction to Case
·C/W
TO-39 Package
15
15
·C/W
TO-S Package
2.5
2.5
Note 1: Unless otherwise specified,these specifications apply -55'C " TI " + 150'C for the LM109 and O'C " Tj " + 125'C for the LM309; VIN = 10V; and
lOUT = 0.1 A for the T0-39 package or lOUT = 0.5A for the T0-3 package. For the T0-39 package, IMAX = 0.2A and PMAX = 2.0W. For the TO-3 package, IMAX
= LOA and PMAX = 20W.
Note 2: W~hout a heat sink, the thermal resistance of the T0-39 package is about 15O'C/W. while that of the T0-3 package is approximately 35'C/W. With a heat
sink, the effective thermal resistance can only approach the values specified, depending on the efficiency of the sink.
Note 3: Refer to RETS109H drawing for LM109H or RETS109K drawing for LM109K military specifications.

Connection Diagrams
Metal Can Packages

-•

GND

2

INPUT

1

..,

A.

OUTPUTA~CCASEI

OUTPUT

3

•

§;c}

GND
CCASEI

-

TLlH17138-3
Order Number LM109K STEEL or LM309K STEEL
See NS Package Number K02A
Order Number LM109K/883
See NS Package Number K02C

Order Number LM109H, LM109H/883 or LM309H
See NS Package Number H03A

1-15

II

CD

CI
CO)

:::&
-I

g
....

:::&
....

r-----------------------------------------------------------------------------------~~--~

Application Hints
a. Bypass the Input cif the LM109 to ground with ~ 0.2 ""F
ceramic or solid tantalum capaCitor if main filter capaCitor
.is more than 4 inches away.
b. Avoid Insertion of regulator Into "live" socket if inpu,t
voltage is greater than ',OV. Tile outpu~ ~II rise t~ within
2V of the unregulated input if the ground 'pin does not
make contact, possibly damaging the load. The LM109
may also be damaged if a large output capacitor is
charged up, then discharged through the internal clamp
zener when the ground pin makes contact.

e;: Preventlnglatchoff for loads connected to negative
, voltage:
'
If the ~utput of the LM109 is pulled negative by a high current supply so that the output pin is more than O.SV negative
with respect to the ground pin, the LM109 can latch off. This
can be prevented by clamping the ground pin to the output
pin with a germanium or Schottky diode as shown. A silicon
diode (1 N4001) at the output is also needed to keep the
positive Ol,ltput from being pulled too'far negative. The 100
resistor will raise + VOUT by :::: O.OSV.

c. The output clamp zener is designed to, absorb lran-'
sients only. It will not clamp' the output effectively 'if a
failure occurs in the internal power transistor structure.
Zener dynamic, impedance is :::: 40. Continuous 'RMS
current into the' zener should not exceed 'O.SA.
.
. d. Paralleling of .LM 109s for higher output current is not
recommended. Current sharing will be almos.t nonexis-,
tent, leading to a current limit mode operation for devices
with the. highest Initial output voltage. The current limit
devices may also heat up to the thermal shutdown point
. (:::: 17S'C). Long term reliability cannot be guaranteed
under these conditions.
'

LMID9

I-.....:...--r--~~-+VOUT
D2

IN4DDI

:COM-...............- - -....- .

I-VIN

.......- - - -....--VOUT
TL/H17138-7

Crowbar Overvoltage Protection
Input c:rowbar

+VIN

Output Crowbar

,I--e--+V.OUT

+VIN

.~-"-",,,,,,-+VOUT

,..
TLlH17138-8

'Zener is inlernal to LM1'09. '

"01 must be able to withstand 7A continuous current If fu;l~g is not UBed at regulator Input. LMI 09. bond wires will fuse at currents above 7A.
t02 is selected for surge capability. Consideration must'lie giv~n to filler c.ij,acHor size, transformer impedance, and fuse blowing ti~.
.'

ttTrip pointis :::: 7.SV.

'I.,'

'

...

,

TUH/7138-9

Typical Performance Characteristics
Maximum Average
Power Dissipation (LM109K)
24 r-"T"""-r-r-Y-..,--r-r---,

Maximum Average
Power Dissipation (LM309K)

Output Impedance

24

'0'

VIN-'OV
IL-ZODmA

2al--~-+-'"'t--t----i

g

3

i!!i

11,....,.:t-+~

9

12,-.,-.....,..."'.

i

100

~~r~~~~
1~3
2&

.wIIEITTEMI'ERATURE rCI

&0

7&

100

10

12&

lao

1k

1Il10

lDBk

1M

FREOUENCY IHzI

.wIIENT TEMPERATURE I'CI

TLlHI7138-IO

Maximum Average
Power Dissipation (LM109H)

Maximum Average
Power Dissipation (LM309H)

Ripple Rejection
120
VIN=lov

a;

'"~

100

.r
V

e .-;/
so
80

6VIN-3Vp·p

.....

~

•• ..-IL-5mA

~

1:1
w

..

Ti'ZSi C

~

a~~~~~~~~~

-&0 -2&

a

25

50

75

IL'?\
40

I

20

100

10

lao 125 1&0

lk
'Il10
'OOk
FREOUENCY IHzI

AMBIENT TEMPERATURE rCI

AMBIENT TEMPERATURE rCI

,M
TLlH171 38-1 1

Current Limit
Characteristics (Note 1)

Thermally Induced Output
Voltage Variation

3r--r--,--.--.--.-.

a~
1D~

Ripple Rejection
0

J. .1.

I
C
ELECTRONIC:H-;TA'2S
.... t.o-~

k~:~LATlON

t

: /

V

'~~nT:~IO~

:-1

:--

I

0

0

I
S

10 1& 20
TIME (mol

'\.

"- .........

YIN"aV

Tj,2&'C

4IL"1A
.5

-

.!

X" "'1ijN':"'~;;'" - r-r: -,..- It
Of-- f- f- Vt'2IV

za

&0

Z&

30

"'f

aH•

o

0.5

1.0

I.S

OUTPUT CURRENT CAl
TL/H17138-12

Note 1: Current limiting foldback characteristics
are determined by inpul outpul differential. not by oulput voltage.

1-17

•

Typical Performance Characteristics
!

U

§'

!
iii

r.a
1.5

....

~

i

Ii

Input-output Differential (V)

_

--:::

ILJIA'

"~;:: "...... ::::

IL-ZOIIA
,

1.0

.

,

(Continued)

"

,

'".

Output Voltage (V) " ,

Output Voltage (V)

5.21....

.1.111 '

,

.

:

IL'IA

;

&.150

V

~ 1.02&

T"

;

~'

~5.DOD

"

~,

l

&.15

IL'illlA

....es.DI
.

"

T,'-irc

;

S

U5

.'

.4.1125

~VOU~" lOOmr

J

"'11\1.

0
-7& -10 -2i 0 25 50 75 100 IZ5 150
JUNCTION TEIlPERATliRE ri:J

......

'l,..-

~4.15

',.'

g •.150

--' VIN'IIV

~
w

Tj-' 5 C

;: '.17& :,

IL j2D1 mA
a.&

rc

•

7
INPUT VOLTAGE.IV'

4.7!7i -50 -25 0 Zi 51 7& 110 125 I"
JUNenON TEMPERATUR'E rCl

9

TL/H17138-13

Quiescent Current
5.3

".-

C
A

Ii

i.1

.

rI'
tI 4.9

5 &.1

~~

II!

g;
!i

is.z

ILLO

IL-'

A ~

T,'-I5'C

.

..

Tj'I&rC

4.1

~ i"'""

4.75

4'!7& -10 -25 0 25 5' 75 III 125 Ii.
JUNenON TEMPERATURE I'CI

10

-

-

f-:-

il

21 31
2D
INPUTVOLTAGEIVI.

.'

3!1

i! ,
. !:iz 200 -

CC

-j

,.

IlL. '"

:

ii.·

. , g-=~ZOD

.

2

3

.'

VIN'IIV

"1\

T,"2&'C' '

~I

,

tr-tf·'oons.,

'~i
,>:, 20D ro- ·1 1 1
4

,
I
IOIk

C

,OU

I

100
Ik
Ilk
FREUU.EICY/IAIIOIMOT" 'HII

r- Cp O.I.F

~:.

,\V'IN""V

0

I 11111 I

0.01
II

"

i

OJ
0

l-

;:

I

IL-SmA

!:;!:i .10

....
..

"

.... ...
U

TOT LN ISE

Load Transient Response

CL'D.I.F
~ 10 , T,'WC
!>,.;
-co I
,IL'IA
=~

r{

;;;!

"~

,

TLlH/7138-14

Line Transient Response

....~1:.. •
....
.....

.!!

...~
,.,

10

0.1

~

41

I

,>
.'

.

Ii

i~

..~
~

m
4.8
is

III

NOISE o NSI Y

...

J!

il
I; 5.0
r! '

~~

ii

Tj-25·C

~

~

~

,"" ~

-I
"'w
~

1.0

i--

Tf' 25'C
5,3

. / ~ ...... '\

Output Voltage Noise,

Quiescent Current
5.4

VIN~ IOV

......

•

0

I

TlMEIJd)

'I

,

Z' 3
TtMEIJd)

'5

•

..
TL/HI713B-15

\
"

,

1-18

Typical Applications
Fixed 5V Regulator

Adjustable Output Regulator

T
..:...-t~:-- OUTPU
~V

INPUT --4.......;-4

INPUT---4I~"'"t

....-4...-0UTPUT
5V=VOUT"'z.sV

CI*

Cl
O.22I'F

C2 ~ 1.IIj.F t
SOLID

I.DIlF

SOLID

TANTALUM

TANTALUM

Tl/H1713B-4

Tl/H11138-2
'Required il regulalor is localed more than 4" from power supply lilter capacilor.
t Although no oulpul capacilor is needed lor stability, it does improve transient raspon,se.
.

C2 should be used whenever long wires are used to connect to the load, or
when transient response is critical.

Note: Pin 3 electrically connected to case,

High Stability Regulator'

OUTPUT

t-----~--~t_----------------------~---IOV

....._~_...

$IA'

H2
6K

.1105%

H4t
510, '

0.2%

el'

10jlF '

01

INa21
I.ZV

'Regulation better than 0.01 %, load, line and temperature, can be obtained.
tOetermines zener ~"enl May be adjusted to minimize thermal drill

TlIH/7138-5

*Solld tantalum.

Current Regulator

AI*
....._ - -. ._-OUT'U1'
, Tl/H17138-6

'Determines output current II wirewound resislor-is used, bypass with 0.1 "F.

H9

II

~
..-

r-~----~------------------~--------------~--------------------------------------~

CO)

~

~

f}1National Semiconductor

..-

CO).

LM117/LM317A/LM317
;:::
.... 3-Terminal.Adjustable Regulator

:&
...I

....

~

General Des(:ription

The LM117 series of adjusta'ble 3-termlnal positive voltage
regulators is capable of supplying in excess of 1.5A over a
1.2V to 37V output range. They are exceptionally easy to
use and require only tWo external resistors to set the output
voltage. Further, both line and loed regulation are better
than standard fixed regulators. Also, the LM117 is packaged
in standard transistor packages which are easily mounted
and handled.
In addition to higher performance than fIXed regulators, the
LM 117 series offers full overload protection available only in
IC's. Included on the chip are current limit, thermal overload
protection and safe area protection. All overload protection
circuitry remains fully functional even if the adjustment terminal is disconnected.
Normally, no capacitors are needed unless the device is
situated more than 6 Inches from the input filter capaCitors
in which case an input bypass is needed. An optional output
capaCitor can be added to improve transient response. The
adjustment terminal can· be bypassed to achieve very high
ripple rejection ratios which are difficult to achieve with standard 3-terminal regulators.
Besides replacing fixed regulators, the LM117Is useful in a
wide variety of other applications. Since the regulator is
"floating" and sees only the input-to-output differential. voltage, supplies of several hundred volts can· be regulated as
long as the maximum input to output differential is not exceeded, i.e., avoid short-circuiting the output.
Also, it makes an especially simple adjustable switching regulator, a programmable output regulator, or by connecting a
fixed resistor between the adjustment pin and output, the
LM117 can be used as a precision current regulator. Supplies with electronic shutdown can be achieved ~y clamping

the adjustment terminal to ground which programs the out~
put to 1.2V where most loads draw little current.
For applications requiring greater output current, see LM 150
series (3A) and LM138 series (5A) data sheets. For the negative complement, see LM137 series data sheet.
LM117 Series Pack8ges and Power Capability
Part Number
Suffix

Package

K
H
T
E
S

TO-3
TO-39
TO-220
LCC
TO-263

Rated
Power
Dissipation
20W
2W
20W
2W
4W

Design
Load
Current
1.5A
0.5A
1.5A
0.5A
1.5A

Features
.. Guaranteed 1% output voltage tolerance
(LM317A)
.
• Guaranteed max. 0.01 %IV line regulation
(LM317A)
• Guaranteed max. 0.3% load regulation
(LM117)
• Guaranteed 1.SA output current
• .Adjustable output down to 1.2V
• Current limit constant with temperature
• P+ Product Enhancement tested
• 80 qB ripple rejection
• ' Output is short-circuit protected

Typical Applications
1.2V-25V Adjustable Regulator

Digitally Selected Outputs

1-"-"-VOUTtt

~--_4~VOUT

VIN------I

R1

R1

240

240

+

-

TL/H/9063-1

Full output curren1 not available at high Input-output voltages
'Needed if device Is more than 6 inches from filter capacitors.
tOplional--improves translent response. Output capacitors in the range of
1 p.F to 1000 p.F of aluminum or tantalum electrofytic are commonly used
to provide improved output Impedance and rejection of transients.
ttVOUT

= 1.25V ( 1 + ~) + IADJ(A21

INPUTS
TL/H/9063-2

'Sets maximum VOUT

1-20

Absolute Maximum Ratings (Note 1)

Operating Temperature Range

It Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
(Note 2)

LMl17

-55'C:s; TJ :s; +150'C

LM317A

-40'C:s; TJ :s; +125'C

Power Dissipation

LM317

Preconditioning

Internally Limited
+40V, -0.3V

Input-Output Voltage Differential
Storage Temperature

O'C:s; TJ:S; +125'C

Thermal Limit Burn-In

All Devices 100%

- 65'C. to + 150'C

Lead Temperature
Metal Package (Soldering, 10 seconds)
Plastic Package (Soldering, 4 seconds)

300'C
260'C

ESD Tolerance (Note 5)

3kV

Electrical Characteristics
Specifications with standard type face are for TJ = 25'C, and those with boldface type apply over full Operating Temperature Range. Unless otherwise specified, VIN - VOUT = 5V, and lOUT = 10 mAo (Note 3)
. Parameter

LM117 (Note 2)

Conditions
Min

Typ

Units
Max

Reference Voltage

V
3V :s; (VIN - VOUT) :s; 40V,
10 mA:S; IOUT:S; IMAX' P :s; PMAX

Line Regulation

Load Regulation

Thermal Regulation

1.20

3V :s; (VIN - VOUT) :s; 40V (Note 4)

10 mA :s; lOUT :s; IMAX (Note 4)

20 ms Pulse

Adjustment Pin Current

1.25

1.30

V

0.01

0.02

%N

0.02

0.05

%N

0.1

0.3

%

0.3

1

%

0.03

0.07

%/W

50

100

p.A

0.2

5

p.A

3.5

5

mA

3.4
1.B

A
A

Adjustment Pin Current Change

10mA:S; IOUT:S; IMAX
3V :s; (VIN - VOUT) :s; 40V

Temperature Stability

TMIN :s; TJ :s; TMAX

Minimum Load Current

(VIN - VOUT)

Current Limit

(VIN - VOUT) :s; 15V
KPackage
H, K Packages

1.5 .
0.5

2.2
O.B

(VIN - VOUT) = 40V
KPackage
H, K Packages

0.3
0.15

0.4
0.2

A
A

0.003

%

65

dB

BO

dB

=

1

40V

RMS Output Noise, % of VOUT

10Hz:s; f:S; 10kHz

Ripple Rejection Ratio

VOUT = 10V, f
CADJ = 0 p.F

=

120 Hz,

VOUT = 10V, f = 120 Hz,
CADJ = 10 p.F

66

%

Long-Term Stability

TJ = 125'C,1000 hrs

0.3

1

%

Thermal Resistance,
Junction-to-Case

KPackage
H Package
E Package

2.3
12

3
15

'C/W
'C/W

KPackage
H Package
EPackage

35
140

Thermal ReSistance, Junctionto-Ambient (NO Heat Sink)

'C/W

1-21

'C/W
'C/W
'C/W

•

.....
.....

CO)

:::E

....I

~
.....

Electrical Characteristics

(Continued)
Specifications with standard type face are for TJ = 25'C, and those,with boldface type apply over full Operating T~mpera·
ture Range. Unless otherwise specified, VIN - VOUT = 5V, and lOUT = ,10 mAo (Note 3)

CO)

LM317A

Conditions

Parameter

:::E

....I

.....
.....
.....
.....

Reference Voltage
3V ,,; (VIN - VOUT) ,,; 40V,
10 mA,,; lOUT"; IMAX' P"; PMAX

::i
Line Regulation

Min

Typ

Max

1.238

1.250

1.262

1.225

1.250

1.270

3V ,,; (YIN - VOUT) ,,; 40V (Note 4)

Load Regulation

10 mA ,,; lOUT"; IMAX (Note 4)

20,msPuise

Thermal Regulation
Adjustment Pin Current

%IV
%IV

0.1

0.5

0.1

0.5

%

0.3

1

0.3,

US

%

0.04

0.07

0.04

0.07

%/W

60

100

50

100

fJ-A

0.2

5

0.2

5

fJ-A

3.5

10, ,

3.5

10

mA

3.4
1.S

1.5
0.6

2.2
0.8

3.4
1.8

A
A

0.15
0.075

0.4
0.2

A
A

0.003

0.003

.%

65

65

dB

SO

dB

(YIN ,- VOUT) ,,; 15V
K, T Packages
H, P Packages

1.5
0.5

2.2
O.S'

evlN ~ VOUT) = 40V
K, T Packages
H, P Packages

0.15
0.075

0.4
0.2

120 Hz,

VOUT = 10V, f
CADJ = 10 fJ-F

=

120 Hz,

=

Long-Term Stability

TJ

Thermal Resistance, Junctionto-Case

KPackage
H Package
TPackage
P Package

Thermal Resistance, Junctionto-Ambient (No Heat Sirik)

KPackage
H Package
TPackage
P Package (Note 6)

: 0.01

1

66

125'C, 1000 hrs

V

0.04

Curren't Limit

=

1.25, 1.30

0.07

(VIN - VOUT)

10Hz"; f,,; 10kHz

1.20

0.02

TMIN ,,; TJ ,,; TMAX

VOUT = 10V, f
CADJ = 0 fJ-F

V

0.01

Minimum Load Current

RMS Output Noise, % of VOUT

Units
Max

0.02

Temperature Stability

40V

Typ

0.01

10 mA ,,; lOUT"; IMAX
3V ,,; (VIN - VOUT) ,,; 40V

Ripple Rejection Ratio

Min

0.005

Adjustment Pin Current Change

=

LM317

%

1

SO

66

0.3

1

0.3

1

%

15
5

2.3
12
4

3
15

'C/W

12
4
35
140
'50

35
140
50
50

'C/W
'C/W
'C/W

'C/W
'C/W
'C/W
'C/W

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
The guaranteed specHications apply only for the test conditions listed.
Note 2: Reier to RETS117H drawing for the LMl17H, or the RETSl17K for the LM117K military specifications.
Note 3: Although power dissipation is intemally limited, these specifications are applicable fo; maximum power dissipations of 2W for the TO·39 and 20W for the
TO·3 and TO·220. IMAX is 1.SA for the TO·3 and TO-220 packages and O.SA for the T0-39 package. All limits (i.e., the numbers in lhe Min. and Max, columns) are
guaran1eed to National's AOQL (Average Outgoing Quality Level).
' ,
Note .4: Regulation is measured at a constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating effects are
covered under the

specifi~ations

for thermal' regulation.

Note 5: Human body model, 100 pF discharged through a 1.5 kll resistor.
Note 6: If the TO·263 package is used, the thennal resistance can be reduced by increasing the PC board copper area thermally connected 10 the package: USing
0.5 square inches of copper area. 6JA Is SO'C/W; wHh 1 square inch of copper area, 6JA is 37'C/W; and with 1.6 or more square inches of copper area, 6JA is
3Z'CIW.

1-22

Typical Performance Characteristics
Output Capacitor = 0 f£F unless otherwise noted

Load Regulation

Adjustment Current

Current Limit

lal.la.SAI-

§
~

:;:

~"

-02

~
"

..
~
~

10UT-1.S....... ~

!

~:U~ :&~OV1··1

"

I

-1,0
-7& -50 -2& 0

i13
...
...
..~

2

~

> -0.6

-0.8 -

1

5
~

-0.4

S
~

,........

1.250

i!

Minimum Operating Current

t"-.

..

r-..

124a

1.0 L...L-L-..L..L=~-,---'-.;:I
2& &0 7& 100 125 1&0
-75 -50 -2&

iii

r-.... ~.~

I

'"..
ti

...;;:..

I
.V'N-VOUT" 5V

o

10

1&

"
20

25

80

30

.
""
.......""

!~
~

>;::

...c

:!

~IO-l 11I1I!lIi!l!l!lI!II~
10-2

...

~~

FREQUENCY 1Hz)

lak

lOOk

CADI" 10,.1'

1M

0.6
0
-1.0

=

!

VOUT" 10V

20

0.01

0.1

Load Transient Response

.
.. .

!~
~!

..

:;~
~

5
~

....

~

f~m

_ .. ..
c 0.5

...
13

40

!l

1 1 1 1

-r-

~.

1.0

30

3
'2

>-

-1.5

TlMEfps)

10

I

OUTPUT CURRENT (AI

T;=25'C

20

I-

1=12DHz

o

1M

SOmA

ID

I-

VIN = 15V

Tj= Z5'C

I
AI e~ -1!F:e~DJL,~F
l\,\=L • 0: CADJ " a
1/
VQUT!'O~
fGur

~

"'"

40

z~

>5

lOOk

1.0

~> -0.5

!i

10k

"'

11111111

60

Line Transient Response
1.6

...

lk

Ik

4a

30

80

FREQUENCY 1Hz)

101~=

100

;;;

~

20

laa

20

'." "ti
..;;:

\r\.

la

~

10

I

100

= SaDIRA

o

35

S 100

10-3

~ ~Tj'2S"e

INPUT -OUTPUT DIFFERENTIAL IVI .

"'-,

40

Output Impedance

s

-~ l '

10

CADJ" 10,.1' ~IN' 15V

OUTPUT VOLTAGE IVI

~

1.0
0.5

~

q-:.&IJ'C

Ripple Rejection

lOUT

~

lOUT == 500mA

20 1-"'20H,
Tj' 2&'C

o

2.0

0

1""-- VOUT-IOV
L
Tj' 2S"C
/ / r-..CADJ • a I"\:
r-... \

80

z

60

It

,-

2.&

Ripple Rejection
100

CADJ"~

"

..~

1.&

TI'=-&,:

TEMPERATURE rCI

Ripple Rejection

40

.
13

1.220
-7& -sa -25 0 25 sa 75 100 12& 1&0

100

ti

3.5
3.0

;;

TEMPERATURE I'CI

~
~

4.0

0-

0Z

\

4.5

.!!

~

~ 1.230

~'

I I
TEMPERATURE I"CI

Temperature Stability

w

..

I

40

. INPUT-QUTPUT DIFFERENTIAL IVI

~

'""

V

45

-1& -50 -2& 0 2& 50 7& 100 125 1&0

1260

z

V
L

50

!)

211

10

0

Dropout Voltage

80

&&

3&

0
25 50 75 100 125 150

TEMPERATURE I'C)

iii

-....

60

0.2

-I
-2

-~

"

-3
1.5
1.0
·.0.5

et

'OICA~J'fr- r--

:::CL ·1.F:CADJ-lo,.1' bV'N '15V
VDur -IOV
'NL -SOmA
Tj"25'C _

~

I
1/

I I

1\1
\

'a

10

20'

30

4a

TlME,..,
TUH/9063-4

1·23

II

....
:E
........

~ r-~------------------------------------------------------------------~

C') ,

~,

....

C')

:E

....
....
r-.
........

....==

Application Hints
tween 500 'pF and 5000 pF. A 1 p.F solid tantalum (or 25 p.F
aluminum electrolytic) on the output swamps this effect and
inswes stability. Any increase of the load capacitance larger
than 10 p.F will merely improve the loop stability and output
,impedance.
'

In operation, the LM117 develops a nominal 1.25V reference voltage, VREF, between the output and adjustment terminal. The reference voltage is impressed across program
resistor R1 and, since the voltage is constant, a constant
current I, then flows through the output set resistor R2, giving an output voltage of
VOUT= VREF (1

+ :~) +

Load Regulation
The\M117 is capable of providing extremely good load regulation but a few precautions are needed to obtain maxi,mum performance. The current set resistor connected betWeen the adjustment terminal and the output terminal (usu'ally 2400) should be tied directly to the output (case) of the
regulator rather than near the load. This eliminates line
drops from appearing effectively in series with the reference
'and degrading regulation. For example, a 15V regulator with
0:050 resistance between the regulator and load will have a
load regulation due to line resistance of 0.050 X IL. If the
set resistor is connected near the load the effective line
resistance will be 0.050 (1 + R2/R1) or in, this case, 11.5
times worse.

IADJR2

Figure 2 shows the effect of resistance between the regulator and 2400 set resistor.
TLfHf9063-5

RS

FIGURE 1
Since ;the 100 p.A current from the· adjustment terminal represents an error term, the LM117was deSigned to minimize
IADJ and make it very·constant with line and load changes.
To do'this, all quiescent operating current is returned to the
output establishing a minimum load current requirement. If
there is insufficient load on the output, the output will ri~e.

t-N~

_ _ VOUT

Rl
240

External Capacitors
An input bypass capacitor is recommended. A 0.1 p.F disc
or 1 p.F solid tantalum on the input is suitable input bypassing for almost all applications. The device is more sensitive
to the absence of input bypassing when adjustment or out-'
put capacitors are used but the above values will eliminate
the po~sibility of problems.
The adjustment.terrninal can be bypassed to ground on the
LM117 to improve ripple rejection. This bypass capacitor
prevents ripple' from being amplified as the output voltage is
increased. With a 10 p.F bypass capacitor 80 dB ripple rejectionis obtainable at any output level. Increas~s over
10 p.F do not appreciably improve the ripple rejection at
frequencies above 120 Hz. If the bypass capacitor is used, it
is sometimes' necessary to include protection diodes to pnivent the capacitor from discharging through internal low current paths and damaging,the device.

TLfHf9D63-6

FIGURE 2. Regulator with Line Resistance
In Output Lead
With the TO-3 package, it is easy to minimize the resistance
from the case to the set resistor, by using two separate
leads to the case. However, with the TO-5 package, care
should be taken to minimize the wire length of the output
lead. The ground of R2 can be returned near the ground of
the load to provide remote ground senSing and improve
load regulation.
Protection Diodes
When external capacitors are used with any IC regulator it is
sometimes necessary to add protection diodes to prevent
the capacitors from discharging through low current points
into the regulator. Most 10 p.F capaCitors have low enough
internal series resistance to deliver 20A spikes when shorted. Although the surge is short, there is enough energy to
d,amage parts of the IC.
When' an output capacitor is connected to a regulator and
the input is shorted, the output capaCitor will discharge into
the output of the regulator. The discharge current depends
on the value of the capaCitor, the output voltage of the regulator, and the rate of decrease of VIN. In the LM117, this
discharge path is through a large junction that is able to
sustain 15A surge with no problem. This is not true of other
types of positive regulators. For output capacitors of 25 ",F
or less, there is no need to use diodes.

In general, the best type of capaCitors to use is solid ta~ia­
lum. Solid tantalum capacitors have low impedance even at
high frequen,cies. Depending ,upon capacitor construction, it
takes about 25 p.F in aluminum electrolytic to equal 1 p.F '
solid tantalum at high frequencies. Ceramic capacitors are
also good at high frequencies; but some types have a large
decrease in ,capacitance at frequencies around 0.5 MHz.
For this reason, 0.01 p.F disc may seem to work better than
a 0.1 p.F disc as a bypass.
,
' ,
Although the LM117 is stallie with no output capacitors, like
any feedback circuit, certain values of ,external capaci1anc~
can cause excessive ringing. This occurs with values be-

1-24

r3:

Application Hints (Continued)
The bypass capacitor on the adjustment terminal can discharge through a low current junction. Discharge occurs
when either the input or output is shorted. Internal to the
LM117 is a 50n resistor which limits the peak discharge

current. No protection is needed for output voltages of 25V
or less and 10 !£F capacitance. Figure 3 shows an LM117
with protection diodes included for use with outputs greater
than 25V and high values of output capacitance.

.1
IN40D2

....
....

~
ri:

....
Co)

~

ri:

....
......
Co)

H~.....--~,....VOUT

""""""'T'-....I

Tel

VOUT= 1.25V(1

+~)

+

IADJR2

01 protects against C1

02 protects against C2

TLIH/9063-7

FIGURE 3. Regulator with Protection Diodes

Schematic Diagram

-

1-25

TLIH/9063-8

•

Typical Applications (Continued)
5V Logic Regulator.wlth Electronic Shutdown·

Slow TurnoOn 15V Regulator

- .

.,

H ....."""4..... ~9uT

......-p--..~f----------4~~2JT

L-.-T-.......

lN4002

Ik

Cl

2M

TLIH/9063-9

TLIH/9063-3

'Min, output ::: 1,2V

. High Stability 10V Regulator

AdJustable Regulator with Improved
Ripple ReJection

.....__......... ~lJ'T

~dC-"--"

........;::.---'

Rl

2k
5%

DI*
lN4002

R2
1.Ii1l
1%

R3

tSolid tantalum
'DiScharg~

la7
,%

-

Cl if output is ~hor\ed to ground
I"

-

TLIH/9063-10

•

TL/H/9063-11

High Current AdJustable Regulator
3-LMI·SS'S IN PARALLEL

. R3
500

.....t-----t----+----...-VOUT
IN4002

*

tSolid tantalum
'Minimum loed current

= 30 rnA

tOptlonal--lmproves ripple rejection

,1-26

TLIH/9063-12

.-----------------------------------------------------------------------------~~.

....
....
.....

i:

-

Typical Applications (Continued)

o to 30V Regulator

r-

Power FolloYfer

Ei:

....

IOV-40V

Co)

~
r-

VOUT
CI

-=!=" O.I~r-F_.-+..,

==
....
Co)

. .....

INPUT -,.".,,.,,.........
RI
10k

LMI17
R2

Full output current not available at high input-oulput voltages

2.4

-IOV
TUH/9063-13

TUH/9063-14

SA Constant Voltage/Constant Current Regulator
MJ4502

r---~------~----~~~

RI
33

_.:;:::..,..J...----...- - - - - - i I - - -...- -....-~~~~~V

35V~.-~II\r...-t..
+ CI
rl~F

l IpFt+
C3

C5
75 pF

-8V

tSolid tantalum

R5
330.

+

R7
220

RI
VOLTAGE
ADJUST

TUH/9063-15

'lights in constant current mode

1-27

.... r-----------------------------------------------------------------------------,
~

CO)

........
~

~
....

Typical Applications (Continued)

1.2V-20V Regulator with
Minimum Program Current

1A Current Regulator

High Gain Amplifier

v'

CO)

:5
r::....
....
:::E

LMII7

VOUT"

R2

2.4

...
RI
10k
INPUT -W'Y--t--f

TLlH/9083-16

TLlH/9063-17
'Minimum load current :::: 4 mA

":"

TL/H/9063-18

Low Cost 3A Switching Regulator
III
2N3712.,..._ _ _ _ _ _~....~-~:!":~.....

IV-3IV ~"'~",,""'-I

-t----.. .

..

t-~"""

_I.IV TO 32V

+

DI
IN3110'

tSolid tantalum

TLlH/9063-19

'Core-Amold A-254168-2 60 tums

Precision Current Limiter

4A SWitching Regulator with OverloaclProtecUon

a.. I ..
RI

2NZ....,..._ _ _ _

~:::t::~'I.:..1\3,.".. .

*0.80:S; R1

_!oL
RI

:s; 1200

TL/H/9063-21
R2
&II

R4

LMII7

2.5

RI
Ilk

"'--....-""'...-.,.-...,-~___......_VOUT

LI ."H"

\.BVT032V

AI
Z40

+ C4

01

IOo,.Ft

IN31111

":"

tSolld tantalum

'Core-Amold A-254168-2 60 turns

TLlH/9063-20 )

1-28

r-

s:::
....
....
.....

Typical Applications (Continued)

.....
rs:::

Tracking Preregulator

....
;;:
.....
Co)

R2
120

r-

s:::
....
.....
Co)

Your
R3
120

TL/H/9063-22

Current Limited Voltage Regulator
VOUT = 1.25V (1

+ ~) + IAOJRz

OUT

r-----,
I
I

TRANSFORMERS.
RECTIFIERS.
AND
FILTER
CAPACITOR

I
I
I
1L ____ ..J
-Short circuil currenl is approXimatel~ 60~:V, or 120 mA

TLlH/9063-23

(Compared to LM117's higher currenllimlt)
- At 50 mA output o~ly % volt of drop occurs In R3 and R4

Adjusting Multiple On-Card Regulators with Single Control·

I--+-VOUT

I

""----+-------' - -- - ____ J
•All outputs wilhln ± 100 mV
tMinlmum load-l0 mA

1·29

TLlH/9063-24

Typical Applications (Continued)
AC Voltage Regulator

50 mA Constant Current Battery Charger

12Vp-p
24Vp-p

rv

lA
TL/H/9063-27

410

-Adjustable 4A Regulator

480r'-.J

120

TL/H/9063-25

..--

~,....IItA;,..,.

12V Battery Charger

4.SV TO 25V

5k

Sk
TL/H/9063-26

'Rs--sets output impedance of charger: ZOUT

= Rs ( I + ~)

Use of Rs allows low charging rates with fully charged battery.
TUH/9063-28

Current LImIted 6V Charger

240

'Sets peak current (0.6A for Ill)
"The 1000 ,.F is recommended to -filter out Input
transients

1*

TL/H/9063-29

1-30

r-

........==
.....

Connection Diagrams

......
r-

(TO-3)
Metal Can Package

(TO-39)
Metal Can Package

==
....
~
r==
....
.....
Co)

o--"""::O~--INPUT

Co)

o-....,,~-- OUTPUT

TL/H/9063-31

CASE IS OUTPUT

Bottom View
TL/H/9063-30

Order Number LM117H, LM117H/883,
LM317AH or LM317H
See NS Package Nl!mber H03A

Bottom View
Steel Package
Order Number LM117K STEEL
or LM317K STEEL
See NS Package Number K02A
Order Number LM117K/883
See NS Package Number K02C

(TO-220)
Plastic Package

il

(TD-263) Surface-Mount Package .

OUTPUT

I

lNPUT

TAB IS
GND

0

+0-

VOUT

.

OUTPUT

1

20

11

12

ADJ

TLlH/9063-35

Top View .
10

I

TL/H/9063-36

I
ADJ

-

INPUT
TL1H/9063-34

Side View

Top View

Order Number LM317S
See NS Package Number TS3B

Order Number LM117E/883
See NS Package Number E20A

I--VOUT
TLlH/9063-32

FrQntVlew
Order Number LM317AT or LM317T
See NS Package Number T03B

1-31

t!1National Semiconductor

LM 117HV/LM317HV 3~Terminal Adjustable Regulator
General Description
The LM117HVILM317HV are adjustable 3.terminal positive
voltage regulators capable of supplyIng in excess of 1.5A
over a 1.2V to 57V output range. They are exceptionally
easy to use and require only two external resistors to set the
output voltage. Further, both line and load regulation are
better than standard fixed regulators. Also, the LM117HV is
packaged in standard transistor packages which are easily
mounted and handled.
In addition to higher performance than fixed regulators, the
LM 117HV series offers full overload protection available
only in IC's. Included on the chip are current limit, thermal
overload protection and safe area protection. All overload
protection circuitry remains fully functional even if the ad·
justment terminal Is disconnected.

Also, it makes an especially simple adjustable switching reg.
ulator, a programmable output regulator, or by connecting a
fixed resistor between the adjustment and output, the
LM117HV can be used as a precision current regulator.
Supplies with .electronic shutdown can be achieved by
clamping the adjustment terminal to ground which programs
the output to ·1.2V where most loads draw little current.
The LM117HVK STEEL and LM317HVK STEEL are pack·
aged in standard TO-3 transistor packages, while the
LM117HVH and LM317HVH are packaged in a solid Kovar
base TO-39 transistor package. The LM317HVT uses a TO·
220 plastic package. The LM117HV is rated for operation
from -55"C to + 150"C, and the LM317HV from O"C to
+ 125"C.
.

Normally, no capacitors are needed unless the device is
situated more than 6 inches from the input filter capacitors
in which case an input bypass is needed. An optional output
• Adjustable output down to 1.2V
capacitor can be added to improve transient response.: The
• Guaranteed 1.5A output current
adjustment terminal can be bypassed to achieve very high
• Line regulation typically 0.01 %/V
ripple rejections ratios which are difficult to achieve with .
• Load regulation typically 0.1 %
standard 3-terminal regulators.
• Current limit constant with temperature
Besides replacing fixed regulators, the LM117HV is useful in
• 100% electrical burn·in
a wide variety of other applications. Since the regulator is
• Eliminates the need to stock many voltages
"floating" and sees only the input·to·output differential volt·
• Standard 3-lead transistor package
age, supplies of several hundred volts can be regulated as
• 80 dB ripple rejection
long as the maximum input to output differential is not ex·
• Output is short·circuit protected
ceeded, i.e. do not short the output to ground.
• P+ Product Enhancement tested

Features

Typical Applications
1.2V-4SV Adjustable Regulator

Digitally Selected Outputs

SV Logic Regulator with
Electronic Shutdown'

LM1tlHV

LM11lHV

t---P-v••r

v'o----I

....,

.VYOUl

TL/H/S082-1

Full output current not available
at high Input·output voltages
tOptional-irnproves transient responsa. Output
capacitors in the range 011 ,.F to 1000 ,.F of
aluminum or tantalum electrolytic are commonly
used to provide Improved output Impedance and
relection 01 transients.

TL/H/S062-3
INPUTS

TLlH/9062-2
'Sets maximum VOUT

'Needed H device is more than 6 inches from
Iilter capacitors.
ttVOUT = 1.25V (1

'Min. output

+~) +IADJ R2

1-32

= 1.2V

.-:s:::
....
....

Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
(Note 3)
Power'Dissipation
Internally limited
Input-Output Voltage Differential
+60V, -O.SV

......
:r:
~
.:s:::
Co)
....
......
:r:

Operating Junction Temperature Range
LM117HV
-55'Cto + 150'C
LM317HV
' O'C to + 125'C
-65'C to + 150'C
Storage Temperature
Lead Temperature (Soldering, 10 sec,)
SOO'C
ESD Tolerance (Note 4)
2000V

<

Electrical Characteristics (Note 1)
Parameter

Conditions

LM117HV

LM317HV

Typ

Max Min

Typ

Max

0.01

0.02

0.01

0.04 %IV

0.1

0.3

0.1

0.5

Min
Line Regulation
, Load Regulation
Thermal Regulation

TJ = 25'C, SV ~ VIN - VOUT ~ 60V
(Note 2) IL = 10 rnA
TJ
TJ

= 25'C,10 rnA ~ lOUT ~ IMAX
= 25'C, 20 ms Pulse

Adjustment Pin Current Change

10 rnA ~ IL ~ IMAX
3.0 V ~ (VIN - VOUT) ~ 60V

Reference Voltage

3.0 V ~ (VIN - VOUT) ~ 60V, (Note 3)
10 rnA ~ lOUT ~ IMAX' P ~ PMAX
~

(VIN - VOUT)

~

Line Regulation

S.OV

Load Regulation

10 rnA ~ lOUT ~ IMAX (Note 2)

60V, IL

Temperature Stability

TMIN ~ TJ ~ TMAX

Minimum Load Current

(VIN - VOUT)

Current Limit

(VIN - VOUT) ~ 15V
K, T Packages
H Package
(VIN - VOUT) ~ 60V
K, T Packages
H Package

= 25'C, 10Hz ~ f

RMS Output Noise, % of VOUT

TJ

VOUT = 10V, f
CADJ = 10/LF

Long-Term Stability

TJ

Thermal Resistance,
Junction to Case

H Package
TPackage
KPackage

100

50

100

/LA

0.2

5

0.2

5

/LA

0.02 0,07 %IV

0.3

1

0.3

7

3.5,
1.5
0.5

~

10kHz

= 120 Hz
66

= 125'C

Thermal Resistance,
H Package
Junction to Ambient (no heat sink) TPackage
KPackage

V

0.02 0.05

1

= 60V

Ripple Rejection Ratio

50

1.20 1.25 1.S0 1.20 1.25 1.S0

= 10 rnA, (Note 2)

%

0.04 0,07 %/W

O.OS 0.07

Adjustment Pin Current

Units

2.2
0.8

1.5

%

3.5

12

rnA

2.2
0.8

3.7
1.9

A
A

1

3.5 1.5
1.8 -0.5

%

0.3
0.03

0.3
0.03

0.003

0.003

%

65
80

65
80

dB
dB

66

A
A

O.S

1

0.3

1

%

12

15

2.3

3

12
4
2.3

15
5
3

'C/W
'C/W
'C/W

140
35

140
50
35

'C/W
'C/W
'C/W

Note 1: Unless otherwise specified, these specifications apply: - 55'C :s: TJ :s: + 15O'C for the LM117HV, and O'C :s: TJ :s: + 125'C forthe LM317HV; VIN - VOUT
= 5Vand lOUT = 'O,IA for the T0-39 package and lOUT = 0.5A for the T0-3 and TO-220 packages. Although power dissipation Is Internally limited, these
apecifications are applicable for power dissipations of 2W for the T0-39 and 20W for the T0-3 and T0-220, IMAX Is I ,5A for the T0-3 and T0-220 and 0.5A for the
T0-39 package.
Note 2: Regulation Is measured at constant junelion temperature. Changes in output voltage due to heating effects must be taken into account separately. Pulse
testing with low duty cycle is used.
Note 3: Refer to RETSI17HVH for LMI17HVH or RETSI17HVK for LMI17HVK military spacificatiolns.
Note 4: Human body model, 1.5 kfi in series with 100 pF,

,

1-33

Typical Performance Characteristics
Output capacitor = O",F unless C?the~ise noted."
Load Regulation

Current Limit

Adjustment Current·
60

0.2

~

..~~
..
.""
~

~

:'L1.0.!A I--

i!i

;:
:! -0,2

.

~ I--..
'L '1.5'A'-~

~

...
z

•a

> -0.6
~O.B

.. ; '

i5

-0.4

:~~~ ~5~OV-

-

I' "1

c

1

-1.0
-75 -50 -25 0 25 50 75 100 125 ·150

I

45

/

'0

ZO

30

40

50

40

35
-75 -50 -25 0 25 50 75 100 125 150

60

INPUT-OUTPUT DiffERENTIAL (v) .

TEMPERATURE II CI

Dropout Voltage

TEMPERATURE (·C)

Temperature Stability

3.0 ,......,.,...T"""T"""T"""T""...........- ,
.lVOUT" 100 mV

Mlnlmuni Operating Current
4.5

1.260

I I
_~ /'

4.0

50

~1.250

..

l' 3.0

~ 1.240

I-

..~

~

.\

i5
ffi

..

:t 1.230

I-

~

::l
5

.. ,.

2.5
2.0

Ripple Rejection
CADJ'l""F

..'"fi
.;;i

80

~ ~.~

z

~

60

~

;;;

20

o

!z

10

§..

I
I

40

~

V'N-VOUT·5V
lL'500mA
-'·120H.
Tj-25'C

I

"

/
II/'

10

10

15

20

25

30

40

10

100

OUTPUT VOLTAGE (VI

iE

VOUT'IIV

....

IL·~500mA.

~.

Tj'25'~

-

""

100.

I\YL ":CADJ-'

'1

"

1:1

-1.8

CADJ'l""F

......

68

'111.11
~ADJ'O

1M

40
VIN '15V
VDUT ·lDY

II:

;;;

20

to. 120Hz
Tj' 25 C

o
0.01

Load Transient Response

-I--

I
L
CL'O:CADJ'~
i I T _ ~

,;....
~~ :::i:L·M:CADJ·10.F
VIN '15V
Vour- 1DV

I"

Tj-ZS'C

-'CAOJ·l""F ....

........ .

~E

1111

FREQUENCY (H.I

lao.

1M

10

0.1
OUTPUT CURRENT (A)

INLz&OmA

TI· n ·c

-1.5

u

1\ 1 1

I

~=
z_ ..
.....
c 0.5

1.

~

c~ 'l~F:C~D}'l~F-

5~ ~0.5 . IL 'SOmA

>13
100

I

IA

VOUT~lav

5~

111"3
10

1.8
0..

>;:

-,.;

..

I"~\ f'oI..

10.

i-

;;i

Une Transient Response
1.5

VIN~1!iV

-CAOJ'~

..'"fi

1111111111

80

z

FREQUENCY (Nil

Output Impedance

-

1.

lit

~

ZO

35

100

I IL· 500mA
I
CADJ - l""F V,N' 15V
~ VOUT'10V
TI-25'C
...........CADJ·O ;~

-...,

40

3D

20

Ripple Rejection

o

o

I
o

INPUT-OUTPUT DIFFERENTIAL (VI

Ripple Rejection
lao

100

lit

o

. TEMPERATURE ( CI

TEMPERATURE ( CI

~

~ ~Tj'25'C

1.0

CI

1.220
-75 -51 -ZS 0 25 50 75 100 125'150

q:150'C

~

1.5
0.5

1.0 '-.l--'--..J......L._-'~~........
-75 '-50 C.25 0 25 50 75 100 125 150

~

Tjl •.

3.5

r-.. ~

~

-

,/

50

gj

I-

I!:

I-

55

I-

1\ I

II

0
10

20
TlME",~

30

10

20

30

40

TIME ",.1

TLlH/9062-4

1-34

,-----------------------------------------------------------------------------,
Application Hints
In operation, the LM117HV develops a nominal1.25V reference voltage, VREF, between the output and adjustment terminal. The reference voltage is impressed across program
resistor R 1 and, since the voltage is constant, a constant
current 11 then flows through the output set resistor R2, giving an output voltage of
VOUT = VREF (1

tance can cause excessive ringing. This occurs with values
between 500 pF and 5000 pF. A 1 ".F soiid tantalum (or 25
/LF aluminum electrolytic) on the output swamps this effect
and insures stability. Any increase of load capacitance larger than 10 /LF will merely improve the loop stability and
output impedance.

+ ~~) + IADJR2

Load Regulation
The LM117HV is capable of providing extremely good load
regulation but a few precautions are needed to obtain maximum performance. The current set resistor connected between the adjustment terminal and the output terminal (usually 2400) should be tied directly to the output of the regulator rather than near the load. This eliminates line drops from
appearing effectively in series with the reference and degrading regulation. For example, a 15V regulator with 0.050
resistance between the regulator and load will have a load
regulation due to line resistance of 0.050 x IL. If the set
resistor is connected near the load the effective line resistance will be 0.050 (1 + R2/Rl) or in this case, 11.5 times
worse.

LM117HV

Figure 2 shows the effect of resistance between the r!lgulator and 2400 set resistor.
TLfH/9062-5

LM117HV

FIGURE 1
Since the 100 /LA current from the adjustment terminal represents an error term, the LM117HV was designed to minimize IADJ and make it very constant with line and load
changes. To do this, all quiescent operating current is returned to the output establishing a minimum load current
requirement. If there' is insufficient load on the output, the
output will rise.

VIN

I
RS
VDUTLI-.A""'~0-4..... VDUT

ADJ

'I

: ~o
~

External Capacitors
An input bypass capacitor is recommended. A 0.1 /LF disc
or 1 /LF solid tantalum on the input is suitable input bypassing for almost all applications. The device is more sensitive
to the absence of input bypassing when adjustment or output capacitors are used but the above values will eliminate
the possiblity of problems.

TLfH/9062-6

FIGURE 2. Regulator with Line
Resistance In Output Lead
With the TO-3 package, it is easy to minimize the resistance
from the case to the set resistor, by using two separate
leads to the case. However, with the TO-5 package, care
should be taken to minimize the wire length of the output
lead. The ground of R2 can be returned near the ground of
the load to provide remote ground sensing and improve
load regulation.

The adjustment terminal can be bypassed to ground on the
LM117HV to improve ripple rejection. This bypass capacitor
prevents ripple from being amplified as the, output voltage is
increased. With a 10 /LF bypass capacitor 80 dB ripple rejection is obtainable at any output level. Increases over 10
/LF do not appreciably improve the ripple rejection at frequencies above 120 Hz. If the bypass capacitor is used, it is
sometimes necessary to include protection diodes to prevent the capacitor from discharging through internal low current paths and damaging the device.
In general, the best type of capacitors to use are solid tantalum. Solid tantalum capacitors have low impedance even at
high frequencies. Depending upon capacitor construction, it
takes about 25 /LF in aluminum electrolytic to equal 1 /LF
solid tantalum at high frequencies. Ceramic capacitors are
also good at high frequencies; but some types have a large
decrease in capacitance at frequencies around 0.5 MHz.
For this reason, 0.01 ".F disc may seem to work better than
a 0.1 ".F disc as a bypass.
Although the LM117HV is stable with no output capacitors,
like any feedback circuit, certain values of external capaci-

Protection Diodes
When external capacitors are used with any IC regulator it is
sometimes necessary to add protection diodes to prevent
the capaCitors from discharging through low current pOints
into the regulator. Most 10 ".F capaCitors have low enough
internal series resistance to deliver 20A spikes when shorted. Although the surge is short, there is enough energy to
damage parts of the IC.
When an output capaCitor is connected to a regulator and
the input is shorted, the output capaCitor will discharge into
the output of the regulator. The discharge current depends
on the value of the capacitor, the output voltage of the regulator, and the rate of decrease of VIN. In the LMI17HV, this
discharge path is through a large junction that is able to
sustain 15A surge with no problem. This is not true of other
types of positive regulators. For output capacitors of 25 ".F
or less, there is no need to use diodes.

1-35

~

......
==
......

.....

::J:

~
~

==
......
.....
::J:

Co)

<

>
::c
,...

....
CW)

:E
....I

:>
::c
,...
....
....

:E
....I

The bypass capacitor on the adjustment terminal can discharge through a low current junction. Discharge occurs
when either the input or output is shorted. Internal to the
LM117HV is a 50n resistor which limits the peak discharge
current. No protection is needed for output voltages of 25V
or less and 10 ,...F capacitance. Figure 3 shows an
LM117HV with protection diodes included for use with outputs greater than 25V and high values of output capacitance .

V,.

.....-+--....-VO"T

Current Limit

R2

Internal current limit will be activated whenever the output
currimt exceeds the limit indicated in the Typical Performance Characteristics. However, if during a short circuit condition the regulator's differential voltage exceeds the Absolute Maximum Rating of 60V (e.g. V,N ~ 60V, VOUT = OV),
internal junctions in the regulator may break down and the
device may be damaged or fail. Failure modes range from
an apparent open or short from input to output of the regulator, to a destroyed package (most common with the TO-220
package). To protect the regulator, the user is advised to be
aware of voltages that may be applied to the regulator during fault conditions, and to avoid violating the Absolute Maximum Ratings.

+C2

1'M
TUH/8062-7

FIGURE 3_ Regulator with Protection Diodes
VOUT

R2) + IADJR2
.
= 1.2SV ( 1 + Ai"

01 protects against Cl
02 protects against C2

Schematic Diagram

....---VI.

r----1~----t-----~-----t----_1~~----------------------------~--------~_

.

oz•

.

L.--~----~----~~~~--'--4-~--~-t::~~:::t::::~::~!:::::::::::::::::~~~:::~~
500,_

.'"

TlIH/8062-8

1-36

r-

Typical Applications (Continued)
Slow Turn-On 15V Regulator

Adjustable Regulator with Improved
Ripple Rejection

LMl17HV

s:::
....
....
......

:::J:

<
......
r-

s:::

~~---------t~~~T

....
......
Co)

"--"T''--",

:::J:

1.400Z

<

. TL/H/9062-9

TlIH/9062-10

tSolid tantalum
'Discharges Cl if output is shorted to ground

High Stability 10V Regulator

High Current Adjustable Regulator
3-LMI9S'S IN PARALLEL

LM111HV

VIN
15V

VOUT
10V
Al
Zk
5%

Cl

~O.1"F

RJ

2N29051_ _~""'_ _""II5",00I'lr-_ _"

AZ
1.5k
1%

LM329A

A3
281
1%

"""I'Ir-..-I

VIN_....

..

IN40D2

':'
TLlH/9062-11

oto 30V Regulator
LM111HV

VIN
35V

....P---P---~--t-VOUT

VOUT

A3
GBO
-10V
TL/H/9062-13

Full output current not available
at high input-output voltages

1-37

> ,-----------------------------------------------------------------------,
::c
..... Typical Applications (Continued)
....
CO)

:!l
~

::c
.....

....
....
::!!i

5A Constant Voltage/Constant Current Regulator
MJ45D2

r---~--------'-------~--~
CURRENT
ADJUST

..J

R3
0.2
5W·

R2
250k

t-~--------t-------t---+-----~~----~-~~~~~!V

~...::r=--'"

+

lO"Ftl
C3

C5
15 pF

tSolid tantalum
'Ughtsln constant current mode

-8V

R5
330k

R1
220

RI
5k
VOLTAGE
ADJUST

TL/H/9062-15

1A Current Regulator

1.2V-20V Regulator with
Minimum Program Current

TLlH/S062-16
TLlH/S062-17

'Minimum load current:::: 4 mA

1-38

r-

3i:
....
....
......

Typical Applications (Continued)
High Gain Amplifier

::c
~

Low Cost 3A Switching Regulator
Ql

V+

r-

2N3792-,.._ _ _ _ _ _ _ _-1~-;.~~~~~.....,

3i:

....
......

Co)

LM117HV
R2
2.4

8V-3SV ~J-'V'V'v""'H

::c

t-"""V'v-1I-t-----+--1.8V TO 32V

<

OUTPUT

+
Rl
10k

INPUT ...."",."....,.-t

LMI9S
01
lN388D

TLlH19062-18

tSolid tantalum

TLlH19062-19

'Core-Arnold A-254168-2 60 turns

4A Switching Regulator with Overload Protection

Precision Current Limiter

J-LM195IN PARALLEL

.,..--'........

.......

_-_-~11------..."I":0,,~1f_.
r _____....

.... ,o.. _v:.

"V""~

2N2905

TLlH19062-21

'0.80 ,; Rl ,; 1200

Y,N
8-35V

Rl
30

LM117HV
Y,N

R4
2.S

Your

Tracking Preregulator

AD.

+ Cl

RS
ISk

~'00/.lF;

C2
tllDpF

Ll

R2
720

---

Your

t.BV TO 3ZV

6Dfb,H*

R6
240

Y,N

VOUT
R3
120

+
01
1NJaiD

C4
10o,.Fl

R8
100

TLIH19062-22

tSolid tantalum

TLlH19062-20

'Core-Arnold A-25416B-2 60 turns

Adjustable Multiple On-Card Regulators
with Single Control'

Y,N

VOUT

I

' - - _......._ _ _ _ _.....1 _ _ _ _ _ _ _ J

• All outputs within ± 100 mV
tMinirnurn load-l0 rnA
TLlHI9062-23

1-39

•

>

::c

r-----------------------------------------------------------------------,

~

Typical Applications (Continued)

Cf)

::!!

AC Voltage Regulator

..J .

Adjustable 4A Regulator

:>
::c
.....
.....
.....

::!!
..J

·12Vp·p
·IA

24Vp.p

"v

480

4BD

r-S.
•

•

\;OJ
..........""',."..,.-- 4.5V TO 25V

5k

TL/H/9082-24

12V Ba~ery Charger
LM317HV

5k

1000 IIF~'

TL/H/9062-27

VIN
9V T06DV

TL/H/9062-2S

. . .
'Rs-oiels output impedanCe of

~harger

( R2)
ZOUT. = Rs 1 + R1

240

uSe of Rs allows low charging rates with fully charged battery.
"The 1000 p.F is recommended to filter oul input transienls

1.1k

50 mA Constant Current Battery Charger
LM317HV
1*

TUH/9062-28

'Sets peak currenl (0.6A for HI)
TL/H/9062-28

"The 1000 p.F is recommended

1-40

to filler out Inpullransienls

Connection Diagrams (See Physical Dimension section for further information)
(TO-3 Steel)
Metal Can Package

(TO-220)
Plastic Package

(T0-39)
Metal Can Package

0

--"",,--INPUT

+- Vour

o-......~- OUTPUT
TL/H/9062-30
TLlH/9062-29

Case Is Output
Bottom View
Order Number LM117HVKSTL/883,
or SMD #7703402
See NS Package Number K02C

I

Case Is Output
Bottom View
Order Number LM117HVH,
LM117HVH/883, SMD #7703402
orLM317HVH
See NS Package Number H03A

Order Number LM317HVK STEEL
See NS Package Number K02A

AOJ

---

I-YOUT
TLlH/9062-31

Front View
Order Number LM317HVT
See NS Package Number T03B

1-41

C)

N

r----------------------------------------------------------------------------,

CI)

='i tflNatio~al Semiconductor
~
....

:E
,;.J

LM120/LM320
Series. 3-Terminal Negative Regulators
General Description

Features

The LM120 series are three-terminal negative. regulators
with a fixed output voltage of - SV, -12V, and -1SV, and
up to 1.SA load current capability. Where other voltages are
required, the LM137 and LM137HV series provide an output
voltage range of -1.2V to -47V.

•
•
•
•

The LM120 need only· one external component-a compensation capacitor at the output, making them easy to apply.
Worst case guarantees ·on output voltage deviation due to
any combination of line, load or temperature variation assure satisfactory system operation.
Exceptional effort has been made to make the LM120 Series immune to overload conditions. The regulators have
current limiting which is independent of temperature, combined with thermal overload protection. Internal current limiting protects again~t m0rj1en1ary faults while thermal shutdown prevents junction temperatures from exceeding safe
limits during prolonged overloads.
Although primarily intended for fixed output voltage applications, the LM120 Series may be programmed for higher output voltages with a simple resistive divider. The low quiescent drain current of the devices allows this technique to be
used with good regulation.

Preset output voltage error less than ±3%
Preset current limit
Internal thermal shutdown
Oper.ates with input-output voltage differential down to

W·
III Excellent ripple rejection
• Low temperature drift
II Easily adjustable to higher output voltage
LM120 Series Packages a,!d "owe~ Capability
Device
LM120/LM320

Package

Design
Load
Current

Rated
Power
Dissipation

TO-3(K)

20W

1.5A

TO-39 (H)

2W

O.5A

LM320

TO-220 (T)

15W

1.5A

LM320M

TO-202(P)

7.5W

O.5A

Typical Applications
Dual Trimmed Supply

+ INPUT

Fixed Regulator

~-""'-""'----1>-O+5.DV
OUTPUT

....""',..,.....<1.

DI
IN4DDI

TL/H17767 -2

'Required if regulator Is separated from filter capacitor by more than 3" . For
value given, capaCitor must be solid tantalum. 25 ,.F aluminum electrolytic
may be substilUled.
tRequired for stability. For value given, capaCitor must be solid tantalum. 25
,.F aluminum electrolytic may substituted. Values given may be increased
without limit.
02

For output capacitance In excess of 100 ,.F, a high current diode from
input to output (1 N4001, etc.) will proteclthe regulator from momentary

IN4DDI

input shorts.
-INPUT

r--...- ....- ....--4I-<>-5.ZV
TL/H17767 -3

1-42

-5 Volt Regulators (Note 3)
Absolute Maximum Ratings

,

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sides
Office/Distributors for availability and specifications_
(Note 5)

Junction Temperatures

Input-Output Voltage Differential

Power Dissipation

Lead Temperature (Soldering, 10 sec.)
Plastic

-65°C to

Storage Temperature Range

Internally Limited

Input Voltage

25V
See Note 1

+ 150°C
300°C
260°C

-25V

!Electrical Characteristics
Power Plastic Package

Metal Can Package
Order Numbers

LM120K-5.0
(TO-S)

LMS201<-5.0
(TO-S)

LM120H-5.0
(TO-S9)

LMS20H-S.O
(TO-S9)

LMS20T-S.O
(TO-220)

Design Output Current (10) .
Device Dissipation (Po)

1.SA
20W

1.SA
20W

O.SA
2W

O.SA
2W

1.SA
lSW

Parameter

.j,.

""

Conditions (Note 1)

Output Voltage

TJ = 25°C, VIN = 10V,
ILOAD = 5mA

Line Regulation

TJ = 25°C, ILOAD = 5 mA,
VMIN s VIN s VMAX

Min

Typ

Mal(

Min

Typ

r,qa.)(

Min

Typ

Mal[

Min

Typ

Mal(

Min

Typ

Mal(

-5.1

-5

-4.9

-5.2

-5

-4.8

-S.l

-5

-4.9

-5.2

-5

-4.8

-5.2

-5

-4.8

V

40

mV

10

Ripple Rejection

f=120Hz

Load Regulation,
(Note 2)

T J = 25°C, VIN = 10V,
5 mA s ILOAD s ID

Output Voltage,
(Note 1)

- 7.5V s VIN s VMAX,
5 mA s ILOAD siD, P s PD

54

25
-7

-25

Input Voltage

64
50

-5.20

10

54
75
-4.80

40
-7

-25

54

64
100

60
-5.25

10

-4.75

25
-7

-25

54

64
30

40
-7

64

SO

50
-4.80

-5.20

10
--25

-5.25

10
-25

-7.5

54
50
-4.75

50
--:5.25

VMIN s VIN s VMAX

1

2

1

2

1

2

1

2

1

Quiescent Current
Change

- TJ = 25°C
VMIN s VIN s VMAX
5 mA s ILOAD s ID

0.1
0.1

0.4
0.4

0.1
0.1

0.4
0.4

0.05
0.04

0.4
0.4

0.05
0.04

0.4
0.4

0.1
0.1

TA = 25°C, CL = 1 p.F, IL = 5 mA,
VIN = 10V, 10 Hz s f s 100 kHz

Long Term Stability

1S0
5

Thermal Resistance
Junction to Case
Junction to Ambient

150

lS0
50

5

3
35

50
3
35

5

Note 4
Note 4

5

100

mV

-4.75

V
mA
mA
mA

0.4
0.4

150

p.V

50

10

mV

Note 4
Note 4

4
50

°C/W
°C/W

150
50

V
dB

64

Quiescent Current

Output Noise Voltage

Units

Note 1: This specification applies over -55'C ,; TJ ,; + 150'C for the LM120 and O'C ,; TJ ,; + 125'C for the LM320.
Note 2: Regulation is measured at constant junction temperature. Changes in output voltage due to heating effects must be taken into account separately. To ensure constant junction temperature, low duty cycle, pulse testing is
used. The LM120/LM320 series does have low thermal feedback, improving line and load regulation. On all other tests, even though power dissipation is internally limited, electrical specifications apply only up to Po-

Note 3: For -5V 3 amp regulators, see LM145 data sheet.
Note 4: Thermal resistance of typically 85'C/W (in 400 linear feet air flow), 224'C/W (in static air) junction to ambient, of typically 21'C/W junction to case.
Note 5: Refer to RETS120-5H drawing for LM120H-5.0 or RETS120·5K drawing for LM120-5K military specifications.
-

-

-

-

._-

-

-

-

---

o~£w,/o~~w,

II

LM120/LM320

-12 Volt Regulators
Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Offlce/Distributors for availability and specifications.
(Note 4)

Power Dissipation
Input Voltage

Internally Limited
-35V

Input-Output Voltage Differential
Junction Temperatures
Storage Temperature Range
Lead Temperature (Soldering, 10 sec.)

30V
See Note 1
-65'Cto + 150'C
300'C

Electrical Characteristics
Order Numbers

LM120K-12
(TO-3)

v

t

'C/W
'C/W
Note 1: This specification applies over - 55'C ,;; TJ ,;; + 150"'C for the LM120 and O"'C ,;; TJ ,;; + 125'C for the LM320.
Note 2: Regulation is measured at constant junction temperature. Changes in output voltage due to heating effects must be taken into account separately. To ensure constant junction temperature, low duty cycle, pulse testing is
used. The LM120/LM320 series does have low thermal feedback, improving line and load regulation. On all other tests, even though power dissipation is internally limited, electrical specifications apply only up to Po.
Note 3: Thermal resistance of typically 85'C/W On 400 linear feeVmin air flow), 224'C/W (in static air) junction to ambient, of typically 21'C/W junction to case.
Note 4: Refer to RETSI20H-12 drawing for LMt20H-12 or RETS120-12K drawing for LM120K-12 military specifications.

I

-15 Volt Regulators

I

Absolute Maximum Ratings
If Military/Aerospace'specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
(Note 4)
Power Dissipation

Internally Limited

Input Voltage
LM120/LM320
LM320T

-40V
-35V

30V

Input-Output Voltage Differential
Junction Temperatures

See Note 1

Storage Temperature Range

-65'C to

+ 150'C

Lead Temperature (Soldering, 10 sec.)

300'C

Electrical Characteristics
Power Plastic Package

Metal Can Package
Order Numbers

LM120K-15
(TO-3)

LM320K-15
(TO-3)

LM120H-15
(TO-39)

LM320H-15
(TO-39)

LM320T-15
(TO-220)

Design Output Current (10)
Device Dissipation (Po)

1A
20W

1A
20W

O.2A
2W

O.2A
2W

1A
15W

Parameter

.j,.

Conditions (Note 1)

Output Voltage

TJ = 25'C, VIN = 20V,
ILOAD = 5mA

Line Regulation

TJ = 25'C, ILOAD = 5 mA,
VMIN :0; VIN :0; VMAX

01

Min

Typ

5
-35

f= 120Hz

Load Regulation,
(Note 2)

TJ = 25'C, VIN = 20V,
5mA:O; ILOAD:O; ID

Output Voltage,
(Note 1)

17.5V:O; VIN :0; VMAX,
5 mA :0; ILOAD :0; ID' P

56

:0;

PD

Quiescent Current

VMIN

TJ = 25'C
VMIN :0; VIN :0; VMAX
5 mA :0; ILOAD :0; ID

Output Noise Voltage

T A = 25'C, CL = 1 ",F, IL = 5 mA,
VIN = 20V, 10 Hz:o; f:O; 100 kHz

VIN

:0;

VMAX

Long Term Stability

Typ

Max

Min

-15.5

20

5
-35
56

80
80

-17

Typ

5
-35
56

80
80

30

Max

Min

10
-17

Typ

10

5

Max

Min

25

20

-17

-35
56

80

-14.4 -15.5

-14.5 -15.6

80

10

-14.5 -15.6

Typ

Max

-15

-14.5

V

20

mV

5
-35

-17.5

56
40

30

-14.4 -15.7

V
dB

80
80

mV

-14.3

V

2

4

2

4

2

4

2

4

2

4

mA

0.1
0.1

0.4
0.4

0.1
0.1

0.4
0.4

0.05
0.03

0.4
0.4

0.05
0.03

0.4
0.4

0.1
0.1

0.4
0.4

mA
mA

400
15

Thermal Resistance
Junction to Case
Junction to Ambient

10
-17

30

Quiescent Current
Change

:0;

Min

-15.3 -15 -14.7 -15.4 -15 -14.6 -15.3 -15 -14.7 -15.4 -15 -14.6 -15.5

Input Voltage
Ripple Rejection

Max

Units

400

400
150

15

3
35

150
3
35

15

400

",V

150

30

mV

Note 3
Note 3

4
50

'C/W
'C/W

400
150
Note 3
Note 3

15

Note 1: This specification applies over -SS'C ,; TJ ,; + IS0'C for the LM120 and O'C ,; TJ ,; + 12S'C for the LM320,
Note 2: Regulation;s measured at constant junction temperature. Changes in output voltage due to heating effects must be taken into account separately. To ensure constant junction temperature,low duty cycle, pulse testing is
used. The LM120/LM320 series does have low thermal feedback, improving "line and load regulation. On all other tests, even though power dissipation is internally limited, electrical specifications apply only up to Po.

Note 3: Thermal resistance of typically 8S'C/W (in 400 linear feet/min air flow). 224'C/W (in static air) junction to ambient. of typically 21'C/W iunction to case.
Note 4: Refer to RETSI20-1SH drawing for LMI20H·1S or RETSI20·1SK drawing for LM120K·1S military specifications.
-

--_.-

O~&W'/OUW'

II

Typical Performance Characteri~tics
Output Voltage vs
Temperature
1.01

10.995

~ 0.990

.."

-

V~UT !I2VCANJ:;i ~

I--

i! 1.00
.....

,~

m

'"!I
ti

:;:a:

w

!::; 1.01
'~ 1.005

Output Impedance TO·3
and TO·220 Packages

100

I
1

~
1.00S
N

~ 1.00

Ripple Rejection
(All Types)

lOUT = lDO mA
~-=
VIN - VOUT' 5V
COUTs~:fo-==
Tj'Z5"C
-TANT~M-

=

10

COUT 1125~F

60

ALUMINUM

V

w

~

;c

1,,000 I"'"

F ~ r,\

I- Y
0.995
0.g90
-50 -25 0 25

-5,

I

I--

40

zo

10- 2
. 0.1.

0.01.

50 1& 100 125 150

I.

IDk

2.5

10'

g

Minimum Input-output
Differential T0-3 and
TO·220 Packages

~

..

1.1

,

~

1.7

lD"
0.01.

1.1
0.1

I.

0.1.

IDk

lOOk

C 1.Z5

i..

..•

1.2

-

,"

....

'Ia

1.1

V
T,'2!i"C-

~

~

0.1.

1.3

~~

...,..

C

..

US
0.1
5

T,' 1511"1:

10

IS 20

25

U

1.25

.!

....

ill
a:

1.2

a:

T"~

,r

I
T,'25"C

I..- I-'i

e....

1.1

~
a

1.0

T,' Jla'C

0.9

I

I

z

1.05
1.0

I

'~"

2.0
I.B
IS

1.4
IZ
1.0
0.8
0.5

1.5

~

,

3D 35 40

INPUT VOL1 AGE CV)

o

0.25

0.5

0.15

/
ib""

_ r - Ti ' 25"C

.1_ ....z i-"'

Ti.550C

" .-o

0.1

...yi· so"C'

0.2

I

J

0.3

0.4

0.5

OUTPUT CURRENT (AI

Quiescent Current vs
Load Current

LMI2o·5

--;~, ~55"J

a: 1.15

0.5

1M

z.z

0.4

021

lOOk

Minimum Input,Output
Differential TO·S and
TD-202 Packages

OUTPU1 CURRENT CAl

Quiescent Current vs
Input Voltage

.!

I

I
D

FREQUENCY CH.)

1.3

>

Ti' Z'-C-

'"

Ti' 1111"1:

Ol

1M'

w

/ q
/'//

1.3 I--Tj' -55 C

1.9

COUT • IIIjof SDLlo
TANTALUM

..~
..
..~

~

L

!;
1.5
>

i5

ZA

/

Z.I

10'

..

10k

FREQUENCY (H.I

2.3

:;

..

FREQUENCY CHz)

JUNCTION TEMPERATURE C'C)

ic

lDO

lOOk

Maximum Average Power
Dissipation (TO'3)
21

V

-

..-

t--

c::

19

Ii nIS
!I
;::

::

13
11

;;;

9

=
I
a:

To·3· '''C~~.t-"'...3j...'\~f--I
HEATSINK
I'-.... I'..

~

t-I-.l

o 1-1_D._3....
N_0_SI...
NK_........_........
I'---":L--I
1.0

OUTPUT CURRENT (AI

1.Z5 1.5

o

25

50

15

loD

IZ5

ISO

AMBIENT TEMPERATURE ('CI

TUH17767-4
'These ClINes for LM120.
Derate 2S'C further for LM320.

1-46

Typical Performance Characteristics
ID.D

Maximum Average Power
Dissipation (TO-S)

(Continued)

Maximum Average Power
Dissipation (TO-202)
ID

TO.s

I

Maximum Average Power
Dissipation (TO-220)
21
II

I

INFINITE
HEA~SlNK

INFINITE HUTSINK

-r-..

=r

;;;;;;;;I~n H[ATSINK .......

1\

r-

1.1

25

50

201
'
.OHEATSlNK"
......
J5

lID

"\.

1\\

125

a

ISO

I- 2fC" fEAT,SINK
D

MIIENT TEMPERATURE C'CI

ID

2D

3D

CD

SO

&D

"

15
13

iii

II

a

......

11

co

i

-.....

1"-1-

W:EKAE.f~~~~ V"'

i

.I

ffi

I

~

~

......

TO.z20.5·CIW
HEATSINK

.......

T~~~~:~~KSINK

D

10

o

A."BIENT TEMPERATURE rCI

I

..... ~O.22D III"CIW-

25
5D
15 IDD 125
AMBIENT TEMPERATURE rCI

15D

Short Circuit Current

ID152D253035411
VIN - VOUT CVI
TLlHln67-5

Typical Applications (Continued)
High Stability 1 Amp Regulator

----~----~~----. .----------~~----. .------------------_=~----VOUT(+}

+ C3
_ II'F

R2**

+

+

Cltt
_ 2.21&f

C2tt

_ lo,.F

R5
10k

3

II

R3**

......______...._ _ _ _ _ _ _ _ _ _ _ _. ._ _ VOUT

H

TL/H17767 -6

Lead and 'ine "'gulation -

0.01 % temperature stability -

0.2%

tDetermlnes Zener cUrlSn!.
ttSolid tantalum.
An LM120-12 or LM120-15 may be used to permR higher Input voltages. butlhe regulated output voltage must be alleast -15V when using the LM120-12 and
for the LMI20-15.

-lev

"Select resistora to set output vonage. 2 ppm/'C tracking suggested.

t-47

o

(\I'
e')

~

r---------------------------------------------------~----------------~--~~,

Typical Applications (Continued)
Wide Range Tracking Regulator

C;

Current Source

(\I

i...I
+

"!

1N40Ql

_~--~~===~:=t:=:Jt_--+_:"OCOMMON·
I '
.....i. 2,lpF ..
-,-'

.

-VON

,."

'"04

IN4DDI

:\

:;
'loUT =, I.mA

INPUT

"

(~~w.~=V~I"2'---....,....--+--+-o VOUT

5.0V

+ R1

, TLlH/7767-6

,'"

TUH/7767-7

± 15V, 1 Amp Tracking Regulators

'Reslslor tolerance of Rl and R2 determine matching of (+) and (-)
Inputs.

1""'-9----,...-.. . .--.-<>
....-

.,

"Necessary only If raw supply capacitors are more than 3" from regulators

' ..VIII 0-"'-""':'.'"

An LM3086N array may substitute for 01, 01 and 02 for better stability and '
tracking. In the array diode transistors 05 and 04 (In parallel) make up 02;
similarly, 01 and 02 beoome 01 and 03 replaces the 2N2222. ;

•

•
I.

... - .,

.'

. ' . C4••~

Variable Output

.

V0UT1+JIIV

10k

'''''.,-

1I14DOI

IG'

1
1

,I,
+----~p-~-+-----_+-;_-_+-o~.um

INPUT

o-...-..:.r

_VI,.

o-..._.....:I=f.

TLlH/7767-9

F"4-------4--6-<)VOUT HI&V
Performance (Typlc;al)

TLlH17767-12

lmV'"
Load Regulation ai ~I~ = A
•
10 niV
Output Ripple, CIN = 3000 "F, IL = lA
100 "Vrms
100 "Vrms
+50 mV
Temper.ture Stability
+50mV
Output Noise 10 Hz" f ,. 10 kHz
150'"Vrms 150 "Vrms
'Resistor tolerance of R4 and R5 determine matching of (+) and
(-) outputs.'
.

i

'Optional. Improves transient response and ripple rejection.

VOUT=VSET~
R2
SELECT R2 AS FOLLOWS:
-300n
LM12D-5
-7500
LM12D-12
-lk
LM120-15

"Necessary only If raw supply filter' capacitors are more than 2"
from regulators.
'

Light Controllers Using Silicon Photo Cells

I
I
I

C1,---1!
2s"F-r

I
I
I

BV-15V
B1ILB
1.16A
MAX TURN-ON
CIIIIII8IT

BV'...'5V
BULB :
USA
MAX TURN·pN
CURRENT

C2

2s"F

TL/H/7767-11

'Lamp brightnellS
, TL/H17767-10

increas~s

until il =iQ (1 rnA) +, ,5V1Rl.

tNecessary only if";;w supply filter capacitor is more than 2" from LM320.

'Lamp brightness increases until i, = 5V1Rl Q, can be set as low as 1 "A).
tNecessary only of raw supply filter capaCitor is more than 2" from
LM320MP.
"I.

";

1-48

,

Connection Diagrams

K

/':/

GND

(

U

•

.

OUTPUT

INPUT

(CASEI
INPUT

~ (CASEI

TLlH/7767-13
TL/H17767-14

Bottom View
Bottom View

Metal Can Package TO-39 (H)
Order Number LM120H-5.0, LM120H-12, LM120H-15,
LM120H-5.0/883, LM120H-12/883, LM120H-15/883,
LM320H-5.0, LM320H-12 or LM320H-15
See NS Package Number H03A

Steel Metal Can Package TO-3 (K)
Order Number LM120K-5.0/883, LM120K-12/883,
LM120K-15/883, LM320K-5.0, LM320K-12 or LM320K-15
See NS Package Number K02A

INPUT

rv

t

...

0

::l OUT
::l IN
::l GNO

....r-

TL/H/7767-17

Front View

en

Power Package TO-220
Order Number LM320T-5.0, LM320T-12 or LM320T-15
See NS Package Number T038

Schematic Diagrams
-5V

RIB

RIg

4k

5k

R17

. , - -...-_-oVOUT
J.-..<_-~~

03
6.2V

R20
20k

RZI Rl6
1500.05

V,Nc>-....-~....- -....-

.....-

------------I

....- -....- - - - - - - O - - - <.....

TL/H17767 -1 B

1·49

Schematic Diagrams (Continued)
-12Vand -15V

RIa
4k

RI9
51

R17

./'--"4-.....-0. VOUT
03
6.2V

R21 RI6

50 0.05

VINo-~...J-~-...J-~-~-~----"":""-~-"""-":'-----------I
TL/H/7767-19

1·50

rE:
.....

N

f}1National' Semiconductor

Co)

rE:

Co)

LM123/LM323A/LM3·23
3-Amp, 5~Volt Positive Regulator

N

Co)

»

rE:
Co)

General Description

N

power dissipation ensure that the LM123 will perform satisfactorily as a system element.
'

The LM123 is a three-terminal positive regulator with a preset 5V output and a load driving capability of 3 amps. New
circuit design and processing techniques are used to pro; vide the high output current without sacrificing the regulation
characteristics of lower current devices.

Co)

For applications requiring other voltages, see LM150 series
adjustable regulator data sheet.
Operation is guaranteed over the junction temperature
range ....:55·Cto +150'CforLM123, -40'Cto + 125'C for
LM323A, 'and O'C to + 125'C for LM323. A hermetic TO-3
package is used for high reliability and low thermal resistance.

The LM323A offers improved precision over the standard
LM323. Parameters 'with tightened specifications include
output voltage tolerance, line regulation, and load regulation.
The 3 amp regulator is virtually blowout proof. Current limiting, power limiting, and thermal shutdown provide the same
high level of reliability obtained with these techniques in the
LM1091 amp r~gulator.
No external components are required for operation of the
LM123. If the device is more than 4 inches from the filter
capacitor, however, a 1 }JoF solid tantalum capaCitor should
be used on the input. A 0.1 }JoF or larger capacitor may be
used on the output to reduce load transient spikes created
by fasl: switching digital logic, or to swamp out stray load
capaCitance.

Features'
II Guaranteed H'.
•
•
.•
•
•
.,

initial accuracy (A version)
3 amp output current
Internal curr~nt and thermal limiting
O.OHl typical output impedance
7.5V minimum input voltage
30W power dissipation
P+ Product Enhancement tested

An overall worst case specification for the combined effects
of input voltage, load currents, ambient temperature, and

Connection Diagram
Metal Can Package
GND
OUTPUT

~(CASE)

~

TUHI7771-2

Order Number LM123K STEEL, LM323AK STEEL or LM323K STEEL
See NS Package Number K02A

II

Order Number LM123K/883
See NS Package Number K02C

Typical Applications
Basic 3 Amp Regulator
+V'N

c;:; .:t.l
SOLID

TANTALUM

T

I
I

LM12l

..

'----

Jt--.--..
J...
T

",o vou,

+&v

lC L
D.l,.F

......

--

.!.
TUHI7771-3

'Required if LM123 is more than 4" from fllter capacitor.
tRegulator is stable with no load capacitor into resistive loads.

. .. 1-51

Absolute Maximum Ratings
If Mliltary/Aerospace specified devices are required,

Operating Junction Temperature Range
- 55·C to
LM123
-40"Cto
LM323A
LM323 ,
O·C to

please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
(Note 4)
Input Voltage
Power Dissipation

20V
Internally Limited

Storage Temperature Range
Lead Temperature (Soldering: 10 sec.)
ESD Tolerance (Note 5)

-

+ 150"C
+ 125·C
+ 125"C
65·C to + 150"C
300"C
2000V

LM 123 Electrical Characteristics (Note 1)
LM123
Parameter
Output Voltage

, Conditions
Tj = 25~C
VIN = 7.5V, lOUT

= OA

7.5V ~ VIN ~ 15V
OA ~ lOUT ~ 3A, P ~ 30W

Units

Min

Typ

Max

4.7

5

5.3

V

5.4

V

4.6

Line Regulation (Note 3)

Tj = 25·C
7.5V ~ VIN ~ 15V

5

25

mV

Load Regulation (Note 3)

Tj = 25·C, VIN = 7.5V,
OA ~ lOUT ~ 3A

25

100

mV

Quiescent Current

7.5V ~ VIN ~ 15V,
OA ~ IOUT~ 3A

12

20

mA

Output Noise Voltage

Tj = 25"C '
10Hz ~ f~ 100kHz,

40

Short Circuit Current Limit

Tj = 25·C
VIN = 15V
VIN = 7.5V

3
4

Long Term Stability
Thermal Resistance Junction
to Case (Note 2)

2

1·52

".Vrms

"

4.5
5

A
A

35

mV

·C/W

LM323A/LM323 Electrical Characteristics (Note 1)
LM323A
Parameter

Conditions
Tj = 25'C
VIN = 7.5V, lOUT

Output Voltage

= OA

7.5V,;; VIN';; 15V
OA ,;; lOUT';; 3A, P ,;; 30W
Line Regulation (Note 3)

TJ = 25'C
7.5V,;; VIN ,;; 15V

Load Regulation (Note 3)

LM323
Units

Min

Typ

Max

Min

Typ

Max

4.95

5

5.05

4.8

5

5.2

V

5.15

4.75

5.25

V

4.85
5

10

5

25

mV

TJ = 25'C, VIN = 7.5V,
OA,;; lOUT';; 3A

25

50

25

100

mV

Quiescent Current

7.5V ,;; VIN ,;; 15V,
OA,;; lOUT';; 3A

12

20

12

20

mA

Output Noise Voltage

TJ = 25'C
10Hz';; f,;; 100kHz

40

Short Circuit Current Limit

Tj = 25'C
VIN = 15V
VIN = 7.5V

40

3
4

4.5

3
4

6

Long Term Stability

35

Thermal Resistance Junction
to Case (Note 2)

JIoVrms

4.5
5

A
A

35

mV

2

2

'C/W

Note 1: Unless otherwise noted, specifications apply for -55'C';: Tj ,;: + 150'C for the LM123, -40'C';: Tj';: +125'Cforthe LM323A, and O'C ,;: Tj ,;: +125'C
for the LM323. Although power dissipation Is Internally limited, specifications apply only for P ,;: 30W.
Note 2: Wlthoul a heat sink, the thermal resistence of the TQ.3 packsge is about 35'C/W. With a heat sink, the effective thermal resistance can only approach the
specified values of 'Z'C/W, depending on the efficiency 01 the heat sink.
Note 3: Load and line regulation are specified at constant Junction temperature. Pulse testing is requirad with a pulse width,;: 1 ms and a duty cycle,;: 5%.
Note 4: Refer to RETSI23K drawing for LM123K military specifications.
Note 5: Human body model, 1.5 kG in series with 100 pF.

Typical Applications (Continued)
Adjustable Output 5V-10V 0.1 % Regulation
II

-+VIN

LMIZ3

RI
1211

:r
I-

I

h
I

3

,*.01

Y

DZ

LMI03
4.7V

1~5:

..... ,

I

CI

•

LMI05

1_

/

VOUT 15VI

- r- 5D ,F

R,

R3'
&.BK

5
RI
UK

4"1

2~mA

+ ....
c,_
,

? 5pF

V-'
UNREGULATED

'Select to Set Output Voltage
"Select to Draw 25 mA from V-

1-53

T

II
"::"

TUHI7771-4

Typical Performance Characteristics
Maximum Average Power
Dissipation for LM123

Maximum Average Power
DIssipation for LM323A, LM323

4D

5

Output Impedance
Ia"

4D

T,' 25'C
31

z

bITHERMAL EFFECT!

IL-I..

i

I

Peak Available Output Current

-:-

T,j~C

&0

~

I.

'I

r:-T~~~

--

15

10

i

~
2.0

::-- !'-o

1.5

Il.l+=
J

1.1

l:r

lA

f:::~

_i

5.n

~

2.5

i~
"''''

\

J

=~ -2.•

~

~~ -5.a
>~

...

1,0

!!!Ii'
e

~II:

/

T"21'oC~ ~
T, -125'C

II

tl

I
g

•I
o

....=
..'"Ii
!:i
>
....

VIN "11V
IL =20mA

I-

5.05

-I-

5.00

.1

TE"ERATUHE rC)

0.2

V.. -lOY
T,'25"C

~~

~i
.......
S ..

....S
..r:'"'"

Output Noise Voltage
I.D

I L 1\

'Co

~

-0.2

~ I'-- ~;I~~:'TALUII

~
t=

CL·t.I.F

f::

~

/

....

12
INPUT VOLTAGE IV)

I.

28

r---I-o.

4.15

Load Transient Response

e~,

12
,I'

~

5.1D

-15 -50 -25 0 25 58 15 100 125 158

...

T, --Ss·C ........

FREQUENCY 1Hz)

Output Voltage

TIIIEII'tJ

Quiescent Current

lDOK 1M

4.111

IUNCTION TEMP£RATUHE I'C)

14

11K

FREQUENCY IH,)'

5.15
IL "160mA
CL -D.I,.F T," 25'C _

u ..

~=,

•

IK

2D l--L_'---I.._.L.....--L-----l
I,
10 IDO IK 10K lDOK III

21

15

1.5

a'"
we

~

0.5

,j

I
lOll

~ .....

-15 -III -21 0 25 50 15 100 125 1&0

....

SOLID
TANTALUM

Ripple Rejection

Line Transient Response

IL-2~

S

I'

121

IN'UT VOLTAGE IV) ,

Dropout Voltage

2.5

1

~!iI;;F

T, -25'C

o

20

IN'UTVDLTAGE IV)

~

1,/

~ T"~I'C - ' - -

-....

"

•

lOll

Short Circuit Current

~TI"2,S'C

T"I~C

11

. 1. - AMBIENTTEMPERATURE rC)

T.- AMBIENT TEMPERATURE I'C)

~

I

I-v,. ·7.5V
21

e
~..

I"-

F~IN-15V

'&

ii5

CL - .\oF

I

..
...I I'
~

lOUT -1A

I-

'-

.G1

I'
TIME"'.)

101

IK

11K

FREQUENCY IH.)
TL/H/n71-5

1-54

Typical Applications (Continued)
10 Amp Regulator with Complete Overload Protection
RI

.In

zw

R4'

-20mA

R2

.In
2W

-RS'

20mA

VOUT
+5V

R3

.In
2W
+V'N

o-"'~\J\j""'''----------+--..:.t

C'N

I""
SOLID
TANTALUM

'Select for 20 rnA Current from Unregulated Negative Supply

TL/HI7771-6

Adjustable Regulator OV-10V @ 3A

,2V <; Y,N <; lOV

!..L..

•

- , - CI

CIN +
IpF
SOLID
TANTALUM -

V-

*R6=--

12mA

Al-LM10IA

v- H OV TO 20V)
NEED NOT BE REGULATED

C,--2 fLF Optional-Improves Ripple Rejection, Noise, and Transient Response

1-55

TLlH/7771-7

~.r--------------------------------------------------------------------------.

N

~

:l

Typical Applications (Continued)
Trimming Output to 5V

~

"':"-4'---...- - 0 -5V

~

:l
.....

..:tL.

_I_C,

C'N
I/l F - -

~

N
..-

:i

....

I

RI

I

120

-1-

1I&f

I
v-5V TO·-15V

REGULATED
TLf.HI7771-8

Schematic Diagram
INPUT

OUTPUT

"21
5.
R5
20

"22

10

DJ

6.2

RJ

R2J

ZOO

10

"24
10

L--"--~-4~"--"--~~-6-~----~~~------~~------~--------~~GND
TLIHI7771-1

1-56

r------------------------------------------------------------------,~

.....
==
N

f}1National Semiconductor

CI'I
......

!!i:
w
N
CI'I

LM125/LM325 Dual Voltage Regulators
General Description

Features

These dual polarity tracking regulators are designed to provide balanced positive and negative output voltages at current up to 100 mA, and are set for ± 15V outputs. Input
voltages up to ± 30V can be used and there is provision for
adjustable current limiting. These devices are available in
two package types to accommodate various power requirements and temperature ranges.

• ± 15V tracking outputs
•
•
•
•
•
•
•

Output current to 100 mA
Output voltage balanced to within 2%
Line and load regulation of 0.06%
Internal thermal overload protection
Standby current drain of 3 mA
I;xternally adjustable current limit
Internal current limit

Schematic and Connection Diagrams
Dual-llI-LIne Package
14 +SENS£

+lDGST

13 +CUfIRm

NC

UM"

12 ..

+Voo

'-----"'-r-o (!)

--v.

III

UMIT

]----"'----+--00'131
'---_~----r-o(!)

'14'

~k-.L_.Jc~-~=;::=+=:;:::;:=i:::;;:::::;:==+-o @

lUI

11 GNII

•

10 RmRENCE

i

-1lIIIE

lit
-BDOST

-VGuT

TL/H/7776-2

Top VIew

Order Number LM325N
See NS Package Number N14A

Metal Can Package

0

111

GIlD

-v,.
case connected to - V,N

TL/HI7776-3

Top VIew

Order Number
LM125H/883 or LM325H
See NS Package Number H10C

0

L-4-~-+-'_-<~t-+-~_4

111

__-_4_------_o(!) '01

(')"01
TLlHI7776-1

1-57

III

Absolute Maximum Ratings

Operating Conditions
" , Operating Free Temperature Range
LM125
LM325
Stor~ge Temperature Range , ,
c"L~d Temperatu(e:(Soldering, ,10 sec.)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
(Note 5)
"
Input Voltage
':!;30V"
"
-='0.5V
Forced Vo+ (Min)(Note 1)
Forced Vo - (Max) (Note 1)
+0.5V
.,:'.:,"
Power Dissipation (Note 2)
PMAX
Output Short-Circuit Duration (Note 3)
Continuous

-55°6to,,+'125°C
O°Cto +700C
-65°C to + 150°C
, ,
':'300°C

"

'

""
,,"

,

'"

,

,

"

,"

"

Electrical Characteristi~sLM~ 25/LM325 (Not~ 2)"
"

"

',,' Conditions
"

Output Voltage
LM125,
LM325

. 1'"i-'; ,

Tj

. ...

....

Input-Output Differential

14.8
14.5

15
15

"

"

. Units

Max
15.2 ,
15.5

V

V

"

V

VIN = 18Vt030V,IL = 20 rnA,
Tj=25°C'
"

,2.0

10

mV

VIN = 18Vt030V,IL =;20mA"

2.0

20

I')1V

3.0
5.0

10
:10

mV
mV

4.0
7.0.,

20
20

I')1V
mV

±150
±300

I]1V
I')1V

= Ot050mA, VIN ~
= 25°C,

Load Regulation
Vo+
Vo':'

IL
Tj

Load Regulation Over Temperature Range
Vo+
i' '
Vo-

IL = 0 to 50 rnA. VIN = ±3qV

Output Voltage Balance'
LM125
' ,

Tj == 25°C

±30V,

,

,

';'

.",

,

...

. ,'.

i

Output Voltage Over Temperature Range
LM125
LM325·

P ";;PMAX, 0 ,,;; 10 ,,;;,50 rnA;
18V,,;; IVINI ,,;; 30

,

;

:

i;

Positive Standby Current
Negative Stan~by Cumint ,

Tj = 25°C

Tj

260

Tj

150

Long Term Stability
Thermal Resistance Junction,to
Case (Note 4) "
LM125H.LM32~H ,
Junction ,to Ambient
Junctionto Ambie!)t , .

V

,

%

,

' 1.75

3.0

3.1

5.0

0.2

"

,

V

±0.3 ;

= 2~oC:
= 25°.C.BW=,100,-'-10kHz
Tj = 25°C,

"

Output Noise Voltage

15.35
15.73

14.65
14.27

I

Temperature Stability of Vo
Short Circujt Currerlt,Umit

Typ

2.0
,,'

Uf)e Regulation Over Temperature Range

LM32~

Min,

= 25°C

"

Une Regulation'

"

,.

.t'·.

..

"

Parameter

,

",

.'

rnA

:

jLVrms
rnA
rnA

:

%/kHr

'

,

20
215
82

(Still Air)
(400 LfImin Air Flow)

,

°C/W
°Q/W
°C/W

(Still Air)
Junction to Ambient
:
90
°C/W
'-'.
LM325N
,
I
"'
Note 1: That voltage to which the output may be forced witlioul datnage to the device.
"
Note 2: Unless othelWise specified these specifications apply for Tj ~ 55'C to + 151l"C on LM125. T/ '~ O'C 10 -I- 125'C on LM325A. Tj ~ O'C to + 125'C on
LM325. Y,N ~ ±20V. /L ~ 0 mA./MAX ~ 100 mAo PMAX ~ 2.0W for the Hl0 Package.IMAX ~ 100 mA.IMAX ~ 100 mAo PMAX ~ .1.0Wfor the DIP N Package.
Note 3: If the junction temperature exceeds 150"C. the output short circun duration is 60 seconds.
Note 4: Wrthout a heat sink, the thermal resistance jun,"'io~ to ambient of the Hl0 Package is about 155'C/W. With a heat sink. the effective thermal resistance
can only approach the junction to esse values specified, ilepending on the efficiency of the sink.
Note 5: Refer to RETS125X drawing for military specijication of LM125.
"

1-58

Typical Performance Characteristics
Load Regulation.
~

20

~

4.0

~

~

&.0

80
10

"'-

.

.~

NEG REG

12

~

"

~

'-

"

I

16

- - 1 - .,50·C
- - - r:;-5S·C'''7 r---,-

18

- - - 1,"'+25'C -

20

o

20

40

60

3.0 TA.::: +25·C

'"i:

2.0

.~

,~

-

;;
oS

1.0

TA
fA
TA

-!is'e

•

+2S·C
+1ZS'C

a

•

20

~

22

=>

V

L'

~

IL

26

24

-a',

'21

30

1.0

2.0 I--~-f--,:-~::-¥--t

;; 400

·55'C

.,..:.!!'~

~

48

;;

68

1111

IG

LOAD CURRENT (mAl

Peak Output
Currentvs
Junction Temperature
• 500

T,.,%

05

~
l!
z.

INPUT VOLTAGE ltV!

.--r--r--r-"-r......,.

U

~

-/

1.5

=>

/'

18

. 100

Regulator
Dropout Voltage for
Negative Regulator

iE

is

• SUPPLY

LOAD CURRENT ImAI

.

..~.

i

i

"

;: . 2.0

f ... +125·C

I80

~

- SUPPL Y

T.. .: -5S'e

~

.

~

POS REG

~

Regulator Dropout Voltage
for Positive Regulator

Standby Current Drain
4.0

LM125 Maximum Average
Power Dissipation vs
Ambient Temperature
10

~

~

.5~
is
=>

",:.
~

...oS

HHf-f-f-Hf-HHH

1.5

I--~-~-V-~-I

I

1.0

1--t--b''-t-7'f--;

~ 200 HI-I-I-I-F"'I~HHH

0.5

I-"""I->I<--::;O'"""i"""'-"=:---I

300

5
"

100

!

10

~

INFINITE HEAT SINK
HID

'-

I

~ ::;::NO HEAT~7~
I I

HI-I-I-I-I-

~

20

40

60

BO

100

150

_ O.BO

:

0.10

:;

l;1.0~~
NO HEAT SIN
DIP AND Hl0

0.1 L.._.J...._-'-_..:...L.._..1
75
100
25
50
T. - AMBIENT TEMPERATURE I'C!·

.!j:

IUD

=:~

0.50

",

!

OAO

!iii
~
g;

0.30

u

0.20

"-

,

r-"

.,1"..
.r.--

-50 -25

090

~ 0.80
.~

i::

0 25

50 15

.~DD

In 150

JUNCTION TEMPERATURE I;CI

"'25 ·50 ... n .100 +125

LM125 Current Limit Sense
Voltage VB Temperature
for Positive Regulator

iE

'r-...

0

' .. - AMBIENT TEMPERATURE "CI

LM125 Current Limit Sense
Voltage vs Temperature'
for Negative Regulator
l!

.e

-55 -25

. JUNCTION TEMPERATURE I'Cl

LM325 Maximum Average
Power Dissipation vs
Ambient Temperature
10

50

-50

100

LOAD CURRENT ImAI

"-

I

0.1

..~

r......

~

o.?O

II1:1

0.60

!
~a:

B:

1'0...

".

,
........

........
0.50
0.40

......
).

030
.. -50 '-25

'0 25 50 75 100 12S 150

JUNCTION TEMPERATURE I'C!
TL/Hl7nS-4

1·59

III

U)

'"

CO)

~

r---------------------------------------------------------------------------------,
Typical Performance Characteristics

(Continued)

U;
~

::::&

..I

I

I

..

Losd Transient Respon..·
for Negative Regulator

Load Tramdent Respon..
for Positive Regulator

AlL·.-I.':'"

-II

i
::
~ -II
i
=....
S

I

_ +'50

!
=+101
ii

t.1~

= ..
~

II

I"

~

~

.. ...

co

.&0
-IDO
TlMEI1,.IDIY,

TIME (I,.nIIVI

..

Line Transient Respon..
for PoaItlve Regulator
'YIN· .RY TO.m

I.:·'....

-

Line Transient Respon..
for Negative Regulator

,v"
•-M TO -DV
IL -11.

iII ••
it

,
;
i-'·
.

iI

I

+110

;:

TIME 11-..mIVI

nllll..,.IVI ,

I

I

.

Output Impedance
va Frequency

Ripple Rejection
II

I
i
..

zt
31

I!'l

41
II

i

II

I

II

~

5

1.1

c

I •
I.

-0 .. 10 mA

I."

,.. ''''

fREOUEIICY IHzI

.=

0.1

'"

0.01

,M

lDO

1.1.

'Ik

,11ft

,M

fREaUENCY 'H'I
TUHnne-5

Typical Applications
BasiC Regulatorttt

r--r--I

;:::::: C3"

GND -

-

.r-::-l

f'~=; ~

...L.
M-q'

I

'Clt

I
I

-

C4"

+Vo
}------+------~t_--o-vo

L __ _

~----..-o-V,N

TLlHI7776-6

2.0 Amp Boosted Regulator With Current Limit

r
...L.

TL/HI7776-7

Nole: Metal c,an (H) packages shown.
ICL = Current Limn Sense Voltage (See Curve)
RCL
tSolid tantalum
ttShort pins 6 and 7 on dip
tttRCL can be added to the basic regulator between pins 6 and 5, 1 and 2 to reduce
current limit.
'Required if regulator is located an appreciable distance from power supply filter.
"Although no capacitor is needed for stabilHy, it does help transient response. (If
needed use 1 ".F electrolytiC).
···Although no capacitor is needed for stability. it dOBS help transient response. (If

needed use 10 ".F electrolytic).

1-61

.."
C'\I

;
....;t;

Typical Applications (Continued)
Positive Current Dependent Simultaneous Current Limiting

C'\I
,...

:::i!5
....

...-o

}-+--+-~~-t-

-VOUT

C4f
~1-lIM

' - - - -...- ...-i,::---4II---oQ - V,N
·e2t
~11lF

TUH/7776-8
VSENSE NEG +

ICl +

VB~Q1

= _-"-2-:,.,--_ _
RI

R + = VSENSE+
Cl
I.IICl +

ICl + = VSENSE NEG + VOIOoE
RCl
ICl + Controls Both Sides of the Regulator.

Boosted Regulator With Foldback Current Umit
R3

Resistor Values
RI
R4
3ao

Positive Reg.
R5

,

200

IMAX = 2.0A
Isc+ = 750 mA
@TA=2S'C
+VIN =, +2SV

1
"1
.J

+VOUT

Negative Reg.
IMAX = 2.0A
Isc = 750 mA
@TA=2S'C
-VIN = -25V

Tl/HI7776-9

1-S2

Rl
R2
R3
RS
RCL

125

126

18
310
2.4k
300
0.7

20
180
1.35k
290
0.9

Typical Applications

ri:

....

(Continued)

N

.....
r(II

Electric Shutdown

i:
Co)
N

(II

3.0k.

v," ;, 2.0V Q-....IoI/IwIlor-+-.+-......
V,L $ O.8V

C4"

*"

}--+-I~~;;"-D-vouT

+VOUT

TLlHI7776-10
tSolid tal\talum
ttShort pins 6 and 7 on dip
·Required,if regulator is located an appreciable distance from power supply filter.
"Although no capacitor is needed for stability, it does help transient response. (If
needed use 1 p.F electrolytic).

1-63

IfI

Nat ion a I S e m i con d.u c to r

LM 133/LM333 3-Ampere Adjustable Negative Regulators
General Description

Features

The LM133/LM333 are adjustable 3·terminal nllgative volt·
age regulators capable of supplying'ln excess of -3.0A
over an output voltage range of -1.2V to -32V. These
regulators are exceptionally easY to apply, requiring only 2
external resistors to set the output voltage and 1 output
capacitor for frequency compensation. The circuit design
has been optimized for excellent regulation and low thermal
transients. Further, the LM133 series features internal cur·
rent limiting, thermal shutdown and safe·area compensa·
tion, making them substantially immune to failure from over·
loads.

•
•
•
•
•
•
•
•
•
•
•

The LM133/LM333 serve a wide variety of applications including local on-card regulation, programmable·output volt·
age regulation or precision current regulation. The LM133/
, LM333 are ideal complements to the LM150/LM350 adjustable positive regulators.

Connection Diagrams

Output voltage adjustable from -1.2V to -32V
3.0A output current guaranteed, - 55DC to + 150"C
Line regulation typically 0.01 %IV
Load regulation typically 0.2%
Excellent rejection of thermal transients
50 ppm/DC temperature coefficient
Temperature-independent current limit
Internal thermal overload protection
P + Product Enhancement tested
Standard 3-lead transistor package
Output is short circuit protected

Typical Applications

To-3
Metal Can Package

AdJustable Negative Voltage Regulator

CASE IS
-VIN

+ C2*

TL/H/9065-1

Bottom View
Steel To-3 Metal Can Package
(KSTEEL)
Order Number LM133K STEEL or
LM333K STEEL
See NS Package Number K02A

ADJUST

..........- -....--VOUT

-VOUT = -1.2SV (1 + ,::0) + ( -IADJ XR2)
= 1 "F solid tantalum or 10 "F aluminum electrolylic required for stabilily.
= 1 "F solid tantalum is required only il regulator Is more than 4' from power supply finer capscl.
tor.
Output capaCitors in the range of 1 "F to 1000 "F of aluminum or tantalum electrolyllc are commonly
used to provide lower output impedance and improved transient response.

TAB IS

I====f

...

TLlH/9065-3

tCl
'C2

TO·220
Plastic Package

o

-\\N-.....-

-VIN

VOUT

YIN
TL/H/9065-2

Front View
3·Lead TO·220 Plastic Package (T)
Order Number LM333T
See NS Package Number T03B

1-64

'

Absolute Maximum Ratings

(Note 1)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Power Dissipation

Lead Temperature (Soldering, 10 sec.)
TO-3 Package
TO-220 Package

Internally Limited

Input-Output Voltage Differential

- 65·C to

Storage Temperature

ESD Susceptibility

35V

+ 150·C
300·C
260·C
TBD

Operating Junction Temperature Range
TMINtoTMAX
LM133
- 55·C to + 150'C
lM333
- 40·C to + 125·C

Electrical Characteristics LM 133 Specifications with standard typeface are for TJ = 25·C, and those with
boldface type apply over the full operating temperature range. (Note 3)
Parameter
Reference Voltage

Conditions
IL

Typical

= 10mA

3V ~ iVlN - vOUTI ~ 35V
10 mA ~ IL ~ 3A, P ~ PMAX
Line Regulation
Load Regulation

3V ~ IVIN - vOUTI ~ 35V
lOUT = 50 mA (Note 4)
10 mA ~ lour ~ 3A, P ~ PMAX
(Notes 4, 5)

Thermal Regulation

10 ms Pulse

Temperature Stability

TMIN ~ TJ ~ TMAX

Long Term Stability

TJ

Min
(Note 2)

Max
(Note 2)

-1.250

-1.238

-1.262

V

-1.250

-1.225

-1.275

V

0.01

0.02

%IV

0.02

0.05

0.2

0.5

0.4

1.0

0.002

0.Q1

0.4

= 125·C,1000 Hours

90

70

100

2

8

10mA ~ IL ~ 3A
3.0V ~ IVIN - vOUTI ~ 35V

Minimum Load
Current

IVIN - vOUTI ~ 35V

2.5

5.0

IVIN - vourl ~ 10V

1.2

2.5

Current Limit
(Note 5)

3V ~ iVlN - vOUTI ~ 10V

IVIN - vourl

= 20V
= 30V

Output Noise
(%ofVOUT)

10 Hz to 10 kHz

Ripple Rejection

VOUT

Thermal Resistance
Junction-to-Case

= 10V, f = 120 Hz
CADJ = Op.F
CADJ = 10 p.F

%/W

%

65

Adjust Pin Current
Change

iVlN - vOUTI

%

%

0.15

Adjust Pin Current

Units

3.9

3.0

2.4

1.25

0.4

0.3

p.A
p.A

mA

A

0.003

% (rms)

60

dB

77

TO-3 Package (K STEEL)

1.2
1'63

Thermal Shutdown
Temperature

1-65

150

1.8

·C/W

190

'C

Electrical Characteristics LM333 Specifications with standard typeface are for TJ' ,;,. 25·C, and those with
boldface type apply over the full operating temperature range. (Note 3)

.-

Parameter
Reference Voltage

Conc!itlons

typical·

IL = 10mA

3V,;; IViN - vourl ,;; 35V
10 mA ,;; IL ,;; 3A, P ,;; PMAX
Line Regulation
Load Regulation

3V,;; IViN - vourl ,;; 35V
. lour = 50 mA (Note 4)

10 ms Pulse

Temperature Stability

TMIN ,;; TJ ,;; TMAX

Long Term Stability

Max
(Note 2)

Units

-1.250

-1.225

-.1.275

-1.250

-1.213

-1.287

V

0.04

%IV

0.01

0.02'

,.

10 mA,;; IL';; 3A, p,;; PMAX
(Notes 4 and 5)

Thermal Regulation

Min
(Note 2)

.0.07
"

0.2

1.0

%

1.5 .

0.4
0.002

0.02

%/W

0.5

. TJ = 125·C, 1000 Hours

%
%

0.2

Adjust Pin Current

65

95

70

100

2.5
,.

8

p.A

Adjust Pin Current
Change

10mA,;; IL';; 3A
3.0V ,;; IVIN - vourl ';;' 35V

Minimum Load
Current

IVIN - vourl ,;;' 35V

2.5

.10

IVIN - vourl ,;; 10V

.1.5

5.0

Current Limit
(Note5)

3V,;; IVIN -vourl ,;; 10V

3.9

3.0

"

IViN - vourl= 20V

2.4..

1.0

A

0.4

,IViN - vourl = 30V
Output Noise
(% ofVour)

10 Hz to 10 kHz

Ripple Rejection

Vour = 10V, f = 120 I;!z,
CAOJ 7" " 0 p.F
CADJ = 10jl.F

60
77

TO·3 Package (K STEEL)

1.2

Thermal Resistance
Junction to Case
rhermal Shutdown
Temperature
Thermal Resistance
Junction to Ambient
(No Heatsink)

3
163

..
KPackage

35

TPackage

50

mA-

. ,

I ~' ,

0.20

.. % (rms)

0.003

TO·220 Package (T)

p.A

dB'

'"

1.8
4

~C/W
•. !

·C

·C/W

Note 1: Absolute Maximum Ratings Indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when operating the device
outside of Us stated operating conditions.
Note 2: All limits are guaranteed at either room temperature (standard type face) or at temp.rature .......m•• (bold typ.f.ce) by production testing or
correlation techniques using standard Statistical Quality Control (SOC) methods.
Note 3: Unless otherwise specified: IVIN - vou-rl = 5V, lOUT = 0,5A. POISS S; 30W.
,
~
Note 4: Load and line regulation are measured at constant junction temperature. using low duty cycle pulse testing (output voltage changes due to heating effects
are covered by the Thermal Regulati,on specifocation). For the 'J:O-3 package, load regulation !s measured on the output pin, Yo' bel~ the base of the package.
Note 5: The output current of the LM333 is guaranteed to be ;" 3A in the range 3V S; IVIN - vOUTI s; tOY. For the range 10V s; IVIN - vOUTI s; 15V. the
guaranteed minimum output current is equal to: 301 (YIN - VOUT). Refer to graphs for guaranteed output currents at other voltages.

1-66

r-----------------------------------------------------------------------------~r

....
==

Guaranteed Performance Characteristics

Co)

LM133 Guaranteed Output Current

!e
r

LM333 Guaranteed Output Current

==

g

3.0 t-II.........-1~+-+--I--I

If!
i3

2.0

~

1.0 1-f-+-+-+---lI~+-~..d

_

5Y
lOY
15Y 20Y
25Y 30Y
35Y
(3.0A) (3.0A) (2.DA) (1.25A) (D.7A) (0.3A) (0.15A)
TESTED TESTED
TESTED
TESTED TESTED
(YIN-YOUT)

Co)
Co)
Co)

t-t+-+~[-f'IIkI--I---I

5Y
lOY 15Y
20Y 25V 30Y
35Y
13.0A) 13.0A) 12.DA) 11.0A) ID.4A) IO.2A) IO.DBA)
TESTED TESTED
TESTED
TESTED TESTED
IVIN-YOUT)

TL/H/9065-4

TLlH/9065-5

Typical Applications (Continued)
- 5.2V Regulator with Electronic Shutdown

TIL

CONTROL-------..,
-rON

7B7
1%

+

lpF
249
1%

-BVTO -2OV

----+--...--.. . .

TLlH/9065-6

Negative Regulator with Protection Diodes
03···
MR7520H
SIMIlAR

5A. SOY

'When CL is larger than 20 ,.F, 01 protects the
LM133 in case the input supply Is shorted.
"When C2 is larger than 10 ,.F and -VOUT is
larger than -25V, 02 protects the LM133 in
case the output is shorted.

·"'n case

t--4~-""'----"'----- :~~T
-YIN - - -....- - - - - - - '
TLIH/S065-7

1-67

VOUT

is shorted to a positive supply,

03 protects the LM133 from overvoHage, and
protects the load from reversed voltage.

~ r---------------------------------------------------------------------------------~
~
~

~

Typical Applications (Continued)
Hlgh·Performance 9-Ampere Adjustable Regulator

(;)

....

~

~

":'

+IIIIIE

I
I
I
I

HI
11101,.
HZ
VOLTAGE
C1
lDid'

+C3
1110,.,

AD.lUST
lk

+

YiN

-35V--+-+--I

(MAX)

~----.JII.D\II.I-----.....-

$

.....---....;~

:~u:a -2IV
OIA*-

*
'Wire Rl and R4 to the regulator that
provides the highest VOUT with a 3A
load.

0.1

"Full
output
current requires
5v,;lv,N-VOUTI,;10V. At higher Input-output vonages. load current will
be less (see guaranteed curves)

*
0.1

TL/H/9065-8

High Stability 10V Regulator

Current Regulator

287
LM329A

1%

+
+
lOUT

1.5k

,%

= VREF
111

t-...--~-....-

·0.4n ,; Rl ,; 120n

VoUT

-IOV

15 ppm/'C

TL/H/9065-9

-15V-"'---..I
TLlH/9065-10

1·68

Typical Applications (Continued)
High-Current Adjustable Regulator

+SENSE

I
I

VOLTAGE ADJUST
2k

+
10~

+

100 ~F

$

ADJ
\IN

lM333K
0.03
Vour
-35V-~~--1f--IVIN CONTROL Vourl'---~~~-IV-~~----O -1.2VTO -27V
(MAX)
. REGULATOR"
@ 9A"".
·Control regulator must have the larg-

est VREF

ADJ

"'-+--1 VIN

0.03
Vour t - - - -.........M ......

lM333K

.... Full
output
current
requires
SV,;IVIN-VOUTI ,;10V. At higher input~output voltages, load current will
be less (see guaranteed c~rves)

ADJ
0.03
Vour t - - - -.........M ......

1--_ _-1 VIN
lM333K

TLlH/9065-11

Adjustable Lab Voltage Regulator

Adjustable Current Regulator

+25V ---~~-_....,

1~

Rl'

III

lN4002
TLlH/9065-13

lN4002

l.SV)
lOUT = (
± 15% adjustable

A1

·O.SO ,; Rl ,; 240

-25V - - -......- _.......

TL/H/9065-12

·The 10 /-LF capacitors are optional to improve ripple rejection.

1-69

~.-------------------------------------------------~

CO)
CO)

::::E

.....

Typical Applications (Continued)

....I
CO)
CO)

....

::::E

....I

per watt, within the first 10 ms after a step of power is applied. The LM133's specification is 0.01%/W, max.

THERMAL REGULATION

When power is dissipated in an IC, a temperature gradient
occurs across the IC chip affecting the individual IC circuit
components. With an IC regulator, this gradient can be especially severe since the power dissipation is large. Thermal
regulation is the effect of these temperature gradients on
output voltage (in percentage output change) per watt of
power change in a specified time. Thermal regulation error
is independent of electrical regulation or temperature coefficient, and occurs within 5 ms to 50 ms after a change in
power dissipation. Thermal regulation depends on IC layout
as well as electrical design. The thermal regulation of a voltage regulator is defined as the percentage change of VOUT,

In Figure 1, a typical LM133's output drifts only 2 mV (or
0.02% of VOUT = -10V) when a 20W pulse is applied for
10ms. This performance is thus well inside the specification
limit of 0.Q1 %/WX 20W = 0.2% max. When the 20W pulse
is ended, the thermal regulation again shows a 2 mV step as
the LM133 chip cools off. Note that the load regulation error
of about 1 mV (0.01 %) is additional to the thermal regulation
error. In Figure 2, when the 20W pulse is applied for 100 ms,
the ou1put drifts only slightly beyond the drift in the first 10
ms, and the thermal error stays well within 0.1% (10 mY).

TL/H/9065-15

TUH/9065-14

FIGURE 2

FIGURE 1

1-70

,--------------------------------------------------------------------------------, r-

3:
.....
Co)

t!JNational Semiconductor

~
r3:
Co)

LM 137/LM337
3-Terminal Adjustable Negative Regulators

......

Co)

General Description
The LM137/LM337 are adjustable 3-terminal negative voltage regulators capable of supplying in excess of -1.5A
over an output voltage range of -1.2V to -37V. These
regulators are exceptionally easy to apply, requiring only 2
external resistors to set the output voltage and 1 output
capacitor for frequency compensation. The circuit design
has been optimized for excellent regulation and low thermal
transients. Further, the LM137 series features internal current limiting, thermal shutdown. and safe-area compensation, making them virtually blowout-proof against overloads.

•
•
•
•
•
•
•
•

77 dB ripple rejection
Excellent rejection of thermal transients
50 ppml'C temperature coefficient
Temperature-independent current limit
Internal thermal overload protection
P+ Product Enhancement tested
Standard 3-lead transistor package
Output is short circuit protected

LM137 Series Packages and Power Capability

The LM137/LM337 serve a wide variety of applications including local on-card regulation, programmable-output voltage regulation or precision current regulation. The LM1371
LM337 are ideal complements to the LM117/LM317 adjustable positive regulators.

Device

Package

Rated
Power
Dissipation

Design
Load
Current

LM137/337

TO-3 (K)
TO-39 (H)

20W
2W

1.5A
0.5A

LM337

TO-220m

15W

1.5A

Features
II Output voltage adjustable from -1.2V to - 37V

•
•
•
•

1.5A output current guaranteed, - 55'C to
Line regulation typically 0.01 %N
Load regulation typically 0.3%
Excellent thermal regulation, 0.002%/W

+ 150'C

Typical Applications
Adjustable Negative Voltage Regulator

+

;: :::C2*

::1200
LM137!
LM337

VOUT
.......-.....- - -. .---VOUT
TUH/9067-.1

Full output current not available at high input-output voltages

-VOUT

~

-1.25V (1 + 1::0) + ( -IADJ X R2)

tCl ~ 1 f'F solid tantalum or 10 f'F aluminum electrolytic required for stability
'C2 ~ 1 f'F solid tantalum is required only if regulator is more than 4" from power·supply filter capacitor
Output capacitors in the range of 1 f'F to 1000 f'F of aluminum or tantalum electrolytic are commonly used to provide Improved
output impedance and rejection of transients

1-71

•

Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
(Note 4)
Power Dissipation
Internally Limited
40V
Input-Output Voltage Differential

Operating Junction Temperature Range
LM137
- 55'C to
O'C to
LM337
Storage Temperature
- 65'C to
Lead Temperature (Soldering, 10 sec.)
Plastic Package (Soldering, 4 sec.)
ESDRating

+150'C
+ 125'C
+ 150'C
300'C
260'C
2kVoits

Electrical Characteristics (Note 1)
Parameter'

LM,137

Conditions
'Min

Line Regulation

Tj ~ 25'C,3V :s: IVIN - vOUTI :s: 40V
(Note 2) IL = 10 mA

Load Regulation

Tj = 25'C, 10 'mA :s: lOUT :s: IMAX

Thermal Regulation

Tj = 25'C, 10 ms Pulse

Adjustment Pin Current
~djustment

Pin Current Charge 10 mA :s: IL :s: IMAX
3.0V :s: IVIN - vou,TI :s: 40V,
TA = 25'C

LM337

Typ

Max

0.01

0.02

Min'

Units

Typ

Max

0.01

0.04

%N

0.3

0.5'

,0.3

1.0

%

0.002

0.02

0.003

0.04

%/W

65

100

65

100

p.A

2

5

2

5

p.A

-1.225 -1.250 -1.275 -1.213 -1.250 -1.287
-1.200 -1.250 -1.300 -1.200 -1.250 -1.300

Reference Voltage

Tj = 25'C (Note 3)
3V :s: iVJN - vOUTI :s: 40V, (Note 3)
10 mA:s: IOUT:S: IMAX' P :s: PMAX

Line Regulation

3V :s: iVJN ~ vOUTI :s: 40V, (Note 2)

0.02

0.05

0.02'

0.07

%N

1

0.3

1.5

%

Load Regulation

10 mA :s: lOUT :s: IMAX, (Note 2)

0.3

Temperature Stability

TMIN :s: Tj:S: TMAX

0.6

Minimum Load Current

iVJN - vOUTI :s: 40V
IVIN - vOUTI :s: 10V

Current Limit

IVIN - vOUTI :s: 15V
K and T Package
H Package
IVIN - vourl =40V, Tj = 25'C
K and T Package
H Package

0.6

' 2.5
1.2

5
3

1.5
0.5

2.2
0.8

3.5
1.8

0.24
0.15

0.4
0.17

RMS Output Noise, % of VOUT Tj = 25'C,:10 Hz:s: f:S: 10 kHz

V
V

%

2.5
1.5

10
6

mA
mA

1.5
0.5

2:2
0.8

3.7
1.9

A
A

0.15
0.10

0.4
0.17

A
A

0.003

0.003

%

60

60

dB
dB

Ripple Rejection Ratio

VOUT = -10V, f = 120 Hz
CADJ = 10 p.F

Long-Term Stability

Tj = 125'C, 1000 Hours

0.3

1

0.3

1

%

Thermal Resistance,
Junction to Case

H Package
KPackage
TPackage

12
2.3

15
3

12
2.3
4

15
3

'C/W
'C/W
'C/W

Thermal Resistance,
Junction to Ambient
(No Heat Sink)

H Package
KPackage
TPackage

140
35

66

77

66

77

140
35
50

'C/W
'C/W
'C/W

Note 1: Unless otherwise specified. these specHicaUons apply -55"C ,; TI ,; + 15

5

\

f- b3

VIN"~15V

-1.0

.

t: ~

'L -1.SA,.

:!
6,-0.•
VOUT-

S -1.2

HANOP
PACKAGED

-tov.

r1

1---

PACKAGED

~EVICES

"
~

"

.... ==-==

O· 25 50 75 100 125 150

10

. TEMPERATURE I'C)

Minimum Operating Current
1.1

,.-; ,lea

.!

1A
1.0

: 1.250

::!
il

25 50 75 .100 125 150

....

C

.....

Ii

i..

40

iii

2G

100

.~..
....

!

-

io..;

~

-

c~a)o- '-- -

K

i

o

-10

-30

-20

10

~

aD

1111

40

lui

!

20

o.a
1&1

004

>~

OJ

....

o

10-3
,.

10k

FREQUENCY IH,)

1l1iii0

1M

I I
I I

a.OJ

0

I- r-iLil.~ J

-0.2
-0.4

.

E! -1.0
i!!

10

20
TIME"")

0.'

10

1

Load Transient Response
D.6

0.4

0.2

~;' a

....

.1.

CAal- l

.
!a
c:=

~

jl,CADI=·

-

OUTPUT CURRENT IA)

I

HI

H
Dl O
-

-1~U

20

1M

Line Transient Response

~ ~ -CUi

..

\II

~

100

lOOk

10k

o. F
_lvOJT"~10V
IlL-SOmA
i- r- Tj"25'C

!~

.A"CAal-'D,.F

0.6

!~
~z

i!
....

~ ~CAal"D
-'!...

lk

40

V'N Vaur" -10V
'-'20 H, '
Tj "25~~1I11

FREQUENCY IH,)

-

VOUT--l0V
'L - SlOmA
CL -,,..F
Tj -25'C

'0

10 I-

..

40

100

30

lIltJ,W

lii

.~

10

20

100

:!!

-40

Output Impedance
VIN--1IV

10

Ripple Rejection

Ripple Rejection

10

OUTPUT VOLTAGE IV)

101

1

o

INPUT·OUTPUT DIFFERENTIAL IV)

0

o

"

--:- Tj -150'C

M
;; DA
--..-#
" 0.2 r-' .-: I

;;:

V,N-VOUT - 5V
IL"500mA .
'-120H,
TI ~ 25'C

o

I"'TI" 25'C

o.a

TEMPERATURE I'C)

CAt-,11JpF c-

aD

L/
.b'1

o.a

TEMPERATURE I'C)

1;

Til"-5b~

1.2

-75 -50 -25 0 25 50 75 '00 '25 150

Ripple Rejection

0 25 50 75 100 125 150

1.6

1.230

aD

.'
TEMP.ERATURE I'C)

..

~.

55
50
-75 -50 -25

ffi::; 1.240

0

..... 1'"

60

iii
c

1.270

!il

-...

15

40

30

..~

:!!

il
Ii

,..
i" i'.

Temperature Stability

Dropout Voltage

100

..

INPUT·OUTPUT DIFFERENTIAL IV)

3.5 r.7....:-T"":~.,.....,:-.--.-.,....,

0.5
•
-75 -50 -25

11
70

!,.

,;;,. ;.;;;

-

20

C

!5

~

T ;;.-;;: - 1"150' C

V CES

-1.4

-75 -so -25

10

--~"25"C
_._.- ~"-5&'C

I:{.J

-0.4

Adjustment Current

Current Limit

Load Regulation

0.2

==~ -0.2

I \Ii

Q

c -a.•

30

..9a

ff \T1 -_I
Cw- O

0
-0.5
-1.0
-1.&

1

I

'L CADI"I.,F

-,

1 1 1 I'"

-0.4

E
Ii

40

l-

~~

I-

~15J

VIIN =
VOUT o -l0V
'NL'SOmA

r2:;~
10

1
20

30

4.

TIME"'"
TL/H/9067-1S

1-76

f}1National Semiconductor

LM137HV/LM337HV 3-Terminal Adjustable Negative
Regulators (High Voltage)
General Description

Features

The LM137HV/LM337HV are adjustable 3-terminal negative voltage regulators capable of supplying in excess of
-1.5A over an output voltage range of -1.2V to -47V.
These regulators are exceptionally easy to apply, requiring
only 2 external resistors to set the output voltage and 1
output capacitor for frequency compensation. The circuit
design has been optimized for excellent regulation and low
thermal transients. Further, the LM137HV series features
internal current limiting, thermal shutdown and safe-area
compensation, making them virtually blowout-proof against
overloads.

g Output voltage adjustable from -1.2V to -47V

The LM137HV/LM337HV serve a wide variety of applications including local on-card regulation, programmable-output voltage regulation or precision current regulation. The
LM137HV/LM337HV are ideal complements to the
LM117HVILM317HV adjustable positive regulators.

• 1.5A output current guaranteed, - 55'C to
• Line regulation typically 0.01 %N
III Load regulation typically 0.3%
• Excellent thermal regulation, 0.002%/W
• 77 dB ripple rejection
• Excellent rejection of thermal transients
• 50 ppm/'C temperature coefficient
• Temperature-independent current limit
• Internal thermal overload protection
a P+ Product Enhancement tested
III Standard 3-lead transistor package
III Output short circuit protected

+ 150'C

Typical Applications
Adjustable Negative Voltage Regulator

+

;:~C2*
... 120
.~

LM137HVI
LM337HV

.

VOUT

~~e-------~----VOUT
-TlIH/9066-1

-VOUT
tCl

~

~

-1.2SV (1 + 1::0) + [ -IAdj (R2)

1 I'F solid tantalum or 10 I'F aluminum electrolytic
required for stability. Output capaCitors in the
range of 1 I'F to 1000 I'F of aluminum or tantalum
electrolytic are commonly used to provide im~
proved output impedance and rejection of
siants.

'C2

~

1.

tran~

1 I'F solid tantalum is required only if regulator is
more than 4' from power-supply filter capacitor.

1-77

•

Absolute Maximum Ratings
' Operating Junction Temperature Range
-55·Cto
LM137HV
O·C to
LM337HV
-65·Cto
Storage Temperature
Lead Temperature (Soldering, 10 sec.) ,
ESD rating is to be determined.

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
(Note 3)
Power Dissipation
Internally limited
Input-Output Voltage Differential
50V

+ 150"C
+ 125·C
+ 150"C
300·

Electrical Characteristics (Note 1)
Parameter

LM137HV

Conditions
Min

LM337HV

Typ

Max

Min

Units

Typ

Max

Line Regulation

TJ = 25·C,3V ;;;; IVIN-VOUTI ,.;; 50V,
(Note 2) IL, = 10 mA

0.01

0.02

0.01

0.04

%N

Load Regulation

TJ

= 25·C,10 mA,.;; lOUT";; IMAX

0.3

0.5

0.3

1.0

%

Thermal Regulation

TJ

=

0.002

0.02

0.003

0.04

%/w

65 '

100

65

100

p.A

2

5,

2

5

p.A

4

6

3

6

p.A

25·C, 10 in's Pulse

Adjustment Pin Current
Adjustment Pin Current Change 10mA,.;; IL";; IMAX
3.0V";; IVIN-VOUTI ,.;; 50V,
TJ = 25·
Reference Voltage

TJ = 25·C, (Note 3)
3V,.;; IVIN-VOUTI ,.;; 50V, (Note 3)
10 mA,.;; lOUT";; IMAX' P";; PMAX

Line Regulation

3V,.;; IVIN-VOUTI,.;; 50V, (Note 2)
IL = 10mA

0.02

0.05

0.02

0.07

%N

Load Regulation

10 mA ~ lOUT ~ IMAX' (Note 2)

0.3

1

0.3

1.5

%

Temperature Stability

TMIN ~ Tj ~ TMAX

0.6

Minimum Load Current

IVIN-VOUTI ~ 50V
IVIN-VOUTI ~ 10V

2.5
1.2

5
3

2.5
1.5

10
6

mA
mA

Current Limit

IVIN-VOUTI ~ 13V
KPackage
H Package
IVIN-VOUTI = 50V
KPackage
H Package

1.5
0.5

2.2
0.8

3.2
1.6

1.5
0.5

2.2
0.8

3.5
1.8

A
A

0.2
0.1

0.4
0.17

0.8
0.5

0.1
0.050

0.4
0.17

0.8
0.5

A
A

RMS Output Noise, % 'of VOUT TJ
Ripple Rejection Ratio

-1.225 -1.25.0 -1.275 -1.213 -1.250 -1.287
-1.200 -1.250 -1.300 -1.200 -1.250 -1.300

= 25·C, 10Hz ~ f~ 10kHz

VOUT = -10V, f
CADJ = 10 p.F

=

Long-Term Stability

TA

Thermal Resistance, Junction
to Case

H Package
KPackage

=

120 Hz
66

125·C, 1000 Hours

0.6

V
V

%

0.003

0.003

%

60

60

dB
dB

77

66

77

0.3

1

0.3

1

%

12
2.3

15
3

12
2.3

15
3

·C/W
·C/W

Thermal Resistance, Junction H Package
·C/W
140
140
·C/W
to Ambient
KPackage
35
35
Note 1: Unless otherwise specified,these specifications apply: -55'C ,,; Tj ,,; +15O"C for the LMI37HV. O"C ,,; Tj ,,; + 125'C for the LM337HV; VIN-VOUT =
5V; and lOUT = O.IA for the T0-39 package and lOUT = O.5A for the TO-3 package. Although power dissipation is internally limited. these speCifications are
apptlcable for power dissipations of 2W for the TO·39 and 20W for the TO·3. IMAX is I.SA for the T0-3 package and O.2A for the T0-39 package.
Note 2: Regulation is measured at constant junction temperature. using pulse testing with a low duty cycle. Changes in output voltage due to heating effects are

covered under the specHicatlon for thermal regulations. Load regulation is measured on the output pin at a point Ya" below the base of the T0-3 and TO·39
packages.
Note 3: Refer to RETS137HVH drawing for LM137HVH or RETS137HVK for LM137HVK military speclfica1ions.

1-78

R3

60
ADJ

en
n
J
CD

f
3

DJ

( ;'

E

1 •.

+" "' f1~ 1 P: I~

I M~ :!:~J

C

1

1 10'."

RIZ
ZZO

RZ7
100

~

.!.J
CD

R36

O.Z
R35

RI6
600

10

R34
150

RIB ...---il--~
4.Zk

R37
0.D4

RZO
4k

1 1 1 1 11 1

---I

t

1

i~~~

1

OVIN
TUH/9066-2

AHlf:f:W1'AHlf: ~ W1

II

>.-----------------------------------------------------------------------,

::c
.....
CO)
CO)

:i....
>
::c
.....

,..
CO)

:::ilil
-I

Thermal Regulation
In Figure 1, a typical LMI37HV's output drifts only 3 mV (or
0.03% of VOUT = -10V) when a lOW pulse is applied for
10 ms. This performance is thus well inside the specification
limit of 0.02%/W x lOW = 0.2% max. When the lOW pulse
is ended, the thermal regulation again shows a 3 mV step as
the LMI ;37HV chip cools off. Note that the load regulation
error of about 8 mV (0.08%) is additional to the thermal
regulation error. In Figure 2, when the lOW pulse is applied
for 100 ms, the output drifts only slightly beyond the drift in
the first 10 ms, and the thermal error stays well within 0.1 %
(10 mY).

When power is dissipated in an IC, a temperature gradient
occurs across the IC chip affecting the individual IC circuit
components. With an IC regulator, this gradient can be especially severe since power dissipation is large. Thermal
regulation is the effect of these temperature gradients on
output voltage (in percentage output change) per Watt of
power change in a specified time. Thermal regulation error
is independent of electrical regulation or temperature coefficient, and occurs within 5 ms to 50 ms after a change in
power dissipation. Thermal regulation depends on IC layout
as well as electrical deSign. The thermal regulation of a voltage regulator is defined as the percentage change of VOUT,
per Watt,' within the first 10 ms after a step of power is
applied. The LMI37HV's specification is 0.02%/W, max.

r

r

0.1% 1--l1/~~~*~=I:---1--I--_+__1

0.1 %I-----t--t---t--t---+--II---t----I--t-----l

L~~~~~~~~~
;.7

L~~~~~~~~~
\

--l

10ms

I---l00ms~

ITUH/9066-3

LM137HV, VOUT

~

TL/H/B066-4

-10V

LM137HV, VOUT

~

-10V

VIN-VOUT ~ -40V

VIN-VOUT ~ -40V

IL

IL

~

OA ..... O.25A ..... OA

Vertical sensitivity, 5 mV/div

OA ..... 0.25A ..... OA

FIGURE 2

FIGURE 1

Connection Diagram

~

Horizontal sensitivity, 20 ms/div

.

(See Physical Dimensions section for further information)

TO-3
Metal Can Package

TO-39
Metal Can Package
I-'~-- ADJUSTMENT

0-....,.......-

INPUT

CASE IS INPUT
TUH/9066-6

Bottom View

TL/H/B066-5

Order Number LM137HVH/883, SMD #7703404 or
LML337HVH
See NS Package Number H03A

BoHomVlew
Order Number LM137HVK/883 or SMD #7703404
See NS Package Number K02C
Order Number LM337HVK STEEL
See NS Package Number K02A

1-80

,-----------------------------------------------------------------------------'r

.........

i:

Typical Applications (Continued)

Co)

:::c
~

Adjustable High Voltage Regulator

r
i:
Co)

+50V--",--,

..- ...._-

~=

t.2V TO -t47V

Co)

......
:::c

<

r:;.::.:...__.-...- - -1.2V TO -47V
-50V-~""-""

TLiH/S066-7
Full output current not available
at high input-output voltages
'The 10 ,..F capacitors are optional to improve ripple rejection

Current Regulator

Adjustable Current Regulator

= VREF
Rl
, o.sn ,; Rl ,; 120n

lOUT

Rl
1
lOUT

1.5V)
= ( R1

.

± 15% adjustable

TLiH/9066-S
TLiH/9066-9

Negative Regulator with Protection Diodes

High Stability -40V Regulator
5.23k*
1%

+

1 ~F

1.5k*
1%

I:I-CI>---__.-__.- 35 ppmrc

.._ ..__-e___--VOUT

VOUT
-40V

~

~::p.;;..;..,j

, -32V

L........".....1
-46V,.....~....-....I

TLiH/9066-11

-V'N-~""---...I

, Use resistors with good tracking TC
TL/H/9066-10

'When CL is larger than, 20 ,..F, 01 protects the
LM137HV in case the input'supply is shorted
"When C21s larger than 10,..F and -VOUTis larger than
-25V, 02 protects the LM137HV is case the output is
shorted

1·81

< 25 ppm/'C

•

Typical Performance Characteristics (H and K·STEEL Package)
0.2

Load Regulation

!!

-

~
~ -0.2
c
~ -D.•
co
~

Current Limit

f-

I! -0'5A

-0.&

-t-

~

\

:ACKAG~

1 ;-'r

-1.2

o

-1.4
-15 -50 -25

a

25 50 15 100 125 150

o

10

C

15

z

10

ill

5
z

~ ~~
3D

20

~
c

55

4D

TEMPERATURE C"C)

Temperature Stability

Minimum Operating Current
3

~ 1.260
~ 1.250

'r--

~

,,..

::; 1.240

a:

1.230
-15 -50 -25 •

TEMPERATURE C"C)

Ripple Rejection

;0

'"co

Ripple Rejection

CAL.t

80

..~

i

~

60

-

C~D)O- ....;;-

4G

D

I--

'"co.
m

'--

o

fi

40

i

iO

.'"fi
..:5
a:

-20.

-3D

80

~

20

II

-4D

100

II1I11

40

lui

lk

10k

ll1Gk

, Output Impedance

20

Tj'2~:~""

0.11

0.8
..

0.&

>j;:

0.2

~~
~;; OA

i~

.

0

!;:!

I~

~ ~ -0.2
CI ,-U

=>"
S -0.6

~

CADJ -lo,.F

CI

=~ .0.4 I 0.2
>J:

II!

IJ\CAOJ'O

=>" -0.2

~'OV

-0.4 I - I-IVOJT'
IL "SOmA
I- Tj'25"C
~
CL
f~= -0.6
t-I
1·'1
I

.....

.

!iE

51-1.0
~u

r-

Load Transient Response

!i

i

i

10

20
TlMEr..)

D.•

S=

I

rIU ,

I.

-

0.1

OUTPUT CURRENT CAl

...

1,

ii"'"

-

f;:: 120Hz

Line Transient Response

101 F.:"'7"'ffil''';

50

-

-I~~

o

1M

WO

V,N'
VOUT' -10V

FREQUENCY CHz)

OUTPUT VOLTAGE CV)

40

3D

~tJ1UF

-

60

~

0
-10

20

Ripple Rejection

z

a:

~~~

~~

10

100

80
&0

.:5

:--

V,N-VDUT" 5V
IL"5D1mA
'-120Hz
Tj -25"C

20

o

Tj'25 C::::"

Tj"50"~

INPUT·OUTPUT DIFFERENTIAL CV)

lDO

z

i;

o

25 50 75 lDO 125 150

TEMPERATURE C"C)

IIIG

Tjl.J.~,

-r----r----

~co

0.5 L-J......J.......L.....I-..L.....J........L.....L..-I
-15 -50 -25 0 25 50 15 100 125 150

i--' ~

50
-15 -50 -2& 8 25 50 15 lDO 125 ISO

50

INPUT·OUTPUT DIFFERENTIAL CV)

1.218

....

. . . . r--..

85
80

a

~~

. fEV/CEf

TEMPERATURE C"C)

...,
..
.

PACKAGED I - rDEVICES

'It

~~

V,Ne -15V
UT

!; -1.0

5

-"-.-~ - -5I'C
i T - i - I 5D'C

~

... ~

IL'" l.SA

-0.•

>

Adjustment Current
80

t - 2I'C

-k

=
S

3

0
-0.5

~-1.0

3D

40

co
!-1.S

ft 1 T

CAOJ'O ,
I /.
~

'L

CAOJ =1000F "

/

/

/

l:- f- ViIN' ~15J

r-

II-

~

VOUTo-IOV
'NL'50mA
Tj-ZS"C
el '"'I'F
10

20

-'I

"
Ii
3D

40

TIME r.s)
TLlH/9066-12

1·82

,-------------------------------------------------------------------------.r
.....
==
Co)

IJ1National Semiconductor

co
......
r

==

Co)
Co)

LM138, LM338
S-Amp Adjustable Regulators

co

General Description
The LM138 series of adjustable 3-terminal positive voltage
regulators is capable of supplying in excess of 5A over a
1.2V to 32V output range. They are exceptionally easy to
use and require only 2 resistors to set the output voltage.
Careful circuit design has resulted in outstanding load and
line regulation-comparable to many commercial power
supplies. The LM138 family is supplied in a standard 3-lead
transistor package.
A un.ique feature of the LM138 family is time-dependent current limiting. The current limit circuitry allows peak currents
of up to 12A to be drawn from the regulator for short periods
of time. This allows the LM138 to be used with heavy transient loads and speeds start-up under full-load conditions.
Under sustained loading conditions, the current limit decreases to a safe value protecting the regulator. Also included on the chip are thermal overload protection and safe
area protection for the power transistor. Overload protection
remains functional even if the adjustment pin is accidentally
disconnected.
Normally, no capaCitors are needed unless the device is
situated more than 6 inches from the input filter capaCitors
in which case an input bypass is needed. An output capacitor can be added to improve transient response, while bypassing the adjustment pin will increase the regulator's ripple rejection.

the regulator is "floating" and sees only the input-to-output
differential voltage, supplies of several hundred volts can be
regulated as long as the maximum input to output differential is not exceeded, i.e., do not short-circuit output to
ground. The part numbers in the LM138 series which have a
K suffix are packaged in a standard Steel TO-3 package,
while those with a T suffix are packaged in a TO-220 plastic
package. The LM138 is rated for - 55'C :5: TJ :5: + 150'C,
and the LM338 is rated for O'C :5: TJ :5: + 125'C.

Features
•
•
•
•
•
•
•

Guaranteed 7A peak output current
Guaranteed 5A output current
Adjustable output down to 1.2V
Guaranteed thermal regulation
Current limit constant with temperature
P+ Product Enhancement tested
Output is short-circuit protected

Applications
• Adjustable power supplies
• Constant current regulators
• Battery chargers

Besides replacing fixed regulators or discrete designs, the
LM138 is useful in a wide variety of other applications. Since

Connection Diagrams (See Physical Dimension section for further information)
(TO-3 STEEL)
Metal Can Package

(TO-220)
Plastic Package

TLIH/S060-31

Front View
Order Number LM338T
See NS Package Number T03B
TL/H/S060-30

Bottom View
Order Number LM138K STEEL or LM338K STEEL
See NS Package Number K02A

1-83

II

Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
(Note 4)

Lead Temperature
Metal Package (Soldering, 10 seconds)
Plastic Package (Soldering, 4 seconds)

300"C
260"C
TBD

ESD Tolerance

Internally limited

Power Dissipation
Input/Output Voltage Differential

Operating Temperature Range

+40V, -0.3V

-55·C ~ TJ ~ +150"C
O"C ~ TJ ~ +125"C

LM138
LM338

-65·Cto + 150"C

Storage Temperature

Electrical Characteristics
Specifications with standard type face are for TJ :=25·C, andthose with boldface type apply over full Operating Temperature, Range. Unless otherwise specified, VIN - Your ,:,,' 5V; and lour = 10 mAo (Note 2)

SYll1 bol

LM138

Conditions

Parameter:

VREF

Reference Voltage

3V ~ (VIN - Your) ~ 35V, .
10mA ~ lour ~ 5A, P ~ 50W

VRLlNE

Line Regulation

3V ~ (VIN - Your) ~ 35V (Note 3)

VRLOAO

Load Regulation

10 mA ~ lour ,~ 5A (Note 3)

Thermal Regulation

'20msPuise

Typ

Max

,1.19

1.24,

1.29

"

0.005

0.01

%IV

0.04

%IV

0.1

0.3

%

0.3

0.6

%

0.002

0.01

%/W

45

100

/-LA

0.2

5

/-LA

5

mA

IADJ

Adjustment Pin Current
Adjustment Pin Current Change

10 mA,~ lour ~ 5A,
3V $ (VIN - Vour)' ~ 35'"

IlVR/r

Temperature Stability

TMIN ~ TJ ~ TMAX

1

ILOAO(Min)

Minimum Load Current

VIN - Your = 35V

3.5

ICL

Current Limit

VIN - VOUT ~ 10V
DC
0:5 ms Peak

5

7

f

RMS Output Noise, % 01 Vour

10Hz ~

Ripple Rejection Ratio

Your = 10V, f;' 120 Hz, CAOJ
O'/-LF
Your = 10V, 1 = 120 Hz, CADJ= 10 /-LF

Long·Term Stability

TJ = 125·C, 1000 Hrs

6JC

Thermal Resistance,
Junction to Case

KPackage

6JA

Thermal Resistance, Junction to
Ambient (No Heat Sink)

KPackage

IlVIN

~

10kHz

:=

"

60

A
A

1

A

0.003

%

60

dB
dB

75
0.3

35

1-84

%

B
12
1

VIN - Your = 30V

V

0.02

alAOJ

VN
aVR

Units

Min

1

%

1

·C/W
·C/W

Electrical Characteristics

(Continued)
Specifications with standard type face are for TJ = 25·C, and those with boldface type apply over full Operating Temperature Range. Unless otherwise specified, VIN - VOUT = 5V; and lOUT = 10 mA. (Note 2)
.
Symbol

Parameter.

LM338

Conditions

VREF

Reference Voltage

3V S; (VIN - VOUT) S; 35V,
10 mA S; lOUT S; 5A, P S; 50W

VRLlNE

Line Regulation

3V

Load Regulation

VRLOAD

(VIN - VOUT)

S;

10 mA

Thermal Regulation

S;

lOUT

S;

S;

Adjustment Pin Current Change

10 mA S; lOUT S; 5A,
3V :;; (VIN - VOUT) S; 35V

aVR/T

Temperature Stability

TMIN

ILOAD(Min)

Minimum Load Current

VIN - VOUT = 35V

ICL

Current Limit

VIN - VOUT S; 10V
DC
0.5 msPeak

Ripple Rejection Ratio

8JC

1.24

1.29

S;

TJ

S;

0.03

%N

0.02

0.06

%/V

0.1

0.5

%

0.3

1

%

0.002

0.02

%/W

45

100

}J-A

0.2

5

}J-A

10

mA

%

3.5

8
12

5
7

A
A
1

VOUT = 10V, f = 120 Hz, CADJ = O}J-F
VOUT = 10V, f = 120 Hz, CADJ = 10}J-F

Long-Term Stability

TJ ;= 125·C, 1000 hrs

Thermal Resistance
Junction to Case

KPackage
TPackage

60

V

0.005

1

TMAX

VIN - VOUT == 30V
10Hz S; f S; 10kHz

RMS Output Noise, % of VOUT

aVIN

1.19

20 ms Pulse

alADJ

~R

Max

5A (Note 3)

Adjustment Pin Current

VN

Typ

35V (Note 3)

IADJ

Units

Min

A

0.003

%

60
75

dB
dB

0.3

1

%

1

·C/W
·C/W
·C/W
·C/W

4

Thermal Resistance, Junction to
KPackage
35
Ambient (No Heat Sink)
TPackage
50
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but do not guarantee specHic performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: These specifications are applicable for power dissipetions up to 50W for the TO-3 (I<) package and 25W for the TCJ..220 (T) package, Power dissipation is
guaranteed at these values up to 15V input-output differential. Above 15V differential, power. dissipation will be limited by internal protection circuitry. All limits (i.e.,
the numbers In the Min. and Max. columns) are guaranteed to National's AOOL (Average Outgoing Quality Level).
Note 3: Regulation is measured at a constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating effects are
covered under the specifications for thermal regulation.
Note 4: Refer to RETS138K drawing for military specifications of LM138K.

8JA

Typical Performance Characteristics

I.
.

$

ifi

~
~
~

Current Limit

~

12
10

•

Current LImit

PRELOAO c:.~tffOO

"

T

12

iiliHt

~OUT-l~~11

I'

0

V,N-VOUr- l &V

I~\~VO~T~

• l2

Y'N-YOur - IOV

0

1IIIIIIIIIllW
0.1

10

1.6

TIME(...)

101

$

I
i
e>

== ~~CKU~~~:~~~:~T

-

_ TCASE - Wc
PRiLOAr - - ; ,

Fe

I

I

•

'"

' \ ,,-~RELrADi3~~_

'\

~

PRELOAO-&
I ~ I

I\. ~'IRELTAO i lA

20

10

3D

I.PUT.QUTPUT OIFFERENnAL IV)

ifi
co
co

12

I

4G

Jl

M~;h:OAD - ~ 111m
. . , PRELOAD-IA

10

• PRELOAD - &A

i IP"nt~Ii~A
il

•

Current Limit

6
4

V'N" 1Ill'
VOUT"6V
TCAS~~, ~~:C

2

I~
0

..

$

e>

~"j...l

I

I.

0
0.1

1

~
rr10

100

TIME (nn)
TL/H/9060-4

1-85

co
Cf)
Cf)

:E
-I
U)

r---------------------------------------------------------------------------------~

Typical Performance Characteristics

(Continued)
Adjustment
Current
'

Cf)

.....

Load Regulation

!i

z

0.1

~~
III

~

~

C

-0.2

, I

l;
~

---

r--- r--.

""

i

~

VOUT -10V
PRELOAD· &0 mA

i

§

..... i- l- f-

/

1/

w

~ 1.230

V'

~ 1.220

100

~

10-ti

'-;-

E.Ul

80

...

w

t
iC

40
20

o

Ti O-55°C

~

100

' lk

I I

e

~
VIII-VJBOJ
.... =ZA
I-121Hz
TJ - WC
o

5

10

15

80

,"

m

~.
Ul

80

, .....

"--

10k

110k

o

1M

w

t
iC

I
20

25

80

,.
iO

'\.,

V.. -IIV

Vour -IIV
lour - 2A
18

10a

~:
~~

~~

&0

It:

50

~

iC

til

10k

tOOk

VINOI~V

h
I!I

\.

TCASE'2S C
40

1M

',a

g

I

I I I

I I I
J I 1
20

30

'0

0,1

3
,2

,

,U='

[/'

-1,0 IGUT = IiD.A
TJ - 25'C

10

N.

VOUT' 'OV

t· 120 H.

Load Transient Response

1.8

I I
g= -D.5 VourI -!IV

......... CADJ"O

OUTPUT CURRENT (A)

1.5

'0

. f]if

I-J.

l

w

FREQUENCY (Hz)

'-~L=\"FkL'0~F
C~i 0; ,ADJ = 0
0.5 ~"'I

40

3D

Ripple Rejection

1-'

T.... - ZS'C
35

20

....... CAOJ"'0.F

§
ill

-28

30

10

70

~

CADJ'~

Line Transient Response
w

I I
o

III

40

20

~~25~C

INPUT,DUTPUT DIFFERENTIAL (VI

,C~DJ·1U.F

0:

I

s;

V

~

~""'Ti·25·C

L---IL---'-'''---'_~_--'

OUTPUr ~DLTAGE (V)

''',''

Minimum Operating
Current

Ripple Rejection '

,..

75' 100 12& '10

TEMPERATUREfc)

FREQUENCY'(Hz)

CAJ.,L

so

75 ' 50 -25 0 25

IDI

8.

I

30
25 50 75 100 125 150

....

)

II

35

r--'lF--if--i
10

Ripple Rejection

,.z
0:

"'

/

~

~-+-+-t---7I'~'"

TEMPERATURE (OC)

co

i';;

F-

10-3

, co'10-4

1.210
-75 -so -25 0 25' 10 7S '01 '25 ,&0

iO

40

I-

~

,00

z

~ ,r' ~--~--~~~~F--1
!I'D-2 r--if-~'-7"!-

,/

~

"

,I

I-

Output Impedance
101 .---'-r--r--;r--;r--;

1.260

S1.240

/'~

45

TEMPERATURE rC)

Temperature Stability

w

I

~

&A

~

TEMPERATURE ('C)

~1.250

lour -

r-!.our = 3A

1
-75 -&0 -2& 0

-75 -so -25 0 25 50 75 100 125 150

.

"

l-

VIN-15V

~ -0.3

50

3

f---I~url':' SA"

-0.1

55

.1VOUT -100 mV

~~-~

I-

-0,4

4

II

g

.

Dropout Voltage

I

40

TIME",,)

2
-3
B

r-r-t---t--t

t:::ta£E(j~
10

20

30

40

TIME",,,

TLlH/9060-5

1-86

Load Regulation

Application Hints

The LM138 is capable of providing extremely good load regulation but a few precautions are needed to obtain maximum performance. The current set resistor connected between the adjustment terminal and the output terminal (usually 2400) should be tied directly to the output of the regulator (case) rather than near the load. This eliminates line
drops from appearing effectively in series with the reference
and degrading regulation. For example, a 15V regulator with
0.0511 resistance between the regulator and load will have a
load regulation due to line resistance of 0.0511 x IL. If the
set resistor is connected near the load the effective line
resistance will be 0.0511 (1 + R2/R1) or in this case, 11.5
times worse.

In operation, the LM138 develops a nominal 1.25V reference voltage, VREF, between the output and adjustment terminal. The reference voltage is impressed across program
resistor R1 and, since the voltage is constant, a constant
current 11 then flows through the output set resistor R2, giving an output voltage of
VOUT = VREF (1

+ :~) + IADJR2.

Figure 2 shows the effect of resistance between the regulator and 24011 set resistor.
RS

I-"""---VOUT
R1"
120

TL/H/9060-6

FIGURE 1
Since the 50 poA current from the adjustment terminal represents an error term, the LM138 was designed to minimize
IADJ and make it very constant with line and load changes.
To do this, all quiescent operating current is returned to the
output establishing a minimum load current requirement:' If
there is insufficient load on the output, the output will rise.

TL/H/9060-7

FIGURE 2. Regulator with Line
Resistance in Output Lead
With the TO-3 package, it is easy to minimize the resistance
from the case to the set resistor, by using 2 separate leads
to the case. The ground of R2 can be returned near the
ground of the load to provide remote ground sensing and
improve load regulation.
.

External Capacitors
An input bypass capacitor is recommended: A 0.1 poF disc
or 1 poF solid tantalum on the input is suitable input bypassing for almost all applications. The device is more sensitive
to the absence of input bypassiing when adjustment or output capacitors are used but the above values will eliminate
the possiblity of problems.
The adjustment terminal can be bypassed to ground on the
LM138 to improve ripple rejection. This bypass capacitor
prevents ripple from being amplified as the output voltage is
increased. With a 10 poF bypass capacitor ,75 dB ripple rejection is obtainable at any output level. 'Increases over
20 poF do not appreciably improve the ripple rejection at
frequencies above 120 Hz. If the bypass capacitor is used, it
is sometimes necessary to include protection diodes to prevent the capacitor from discharging through internal low cur'
rent paths and damaging the deVice.

Protection Diodes
When external capaCitors are used with any IC regulator it is
sometimes necessary to add protection diodes to prevent
the capaCitors from discharging through low current points
into the regulator. Most 20 poF capacitors have low enough
internal series resistance to deliver 20A spikes when shorted. Although the surge is short, there is enough energy to
damage parts of the IC.
When an output capacitor is connected to a regulator and
the input is shorted, the output capacitor will discharge into
the output of the regulator. The discharge current depends
on the value of the capaCitor, the output voltage of the regulator, and the rate of decreas,e of VIN. In the LM138 this
discharge path is through a large junction that is able to
sustain 25A surge with no problem. This is not true of other
types of positive regulators. For output capaCitors of 100 poF
or less at output of 15V or less, there is no need to use
diodes.

In general, the best type of capacitors to use are solidtantalum. Solid tantalum capacitors have low impedance even at
high frequencies. Depending upon capacitor construction, it
takes about 25 poF in aluminum electrolytic 'to equal 1 poF
solid tantalum at high frequencies. Ceramic capacitors are
also good at high frequencies; but some types have a large
decrease in capacitance at frequencies around 0.5 MHz.
For this reason, 0.01 poF disc may seem to work better than
a 0.1 poF disc as a bypass.
Although the LM138 is stable with no output capacitors, like
any feedback circuit, certain values of external capacitance
can cause excessive ringing. This occurs with values between 500 pF and 5000 pF. A 1 poF solid tantalum (or 25 poF
aluminum electrolytic) on the output swamps this effect and
insures stability.

The bypass capacitor on'the adjustment terminal can discharge through a low current junction. Discharge occurs
when either the input or output is shorted. Internal to the
LM138 is a 5011 resistor which limits the peak discharge
current. No protection is needed for output voltages of 25V
or less and 10 poF capaCitance. Figure 3 shows an LM138
with protection diodes included for use with outputs greater
than 25V and high values of output capacitance.

1-87

•

co
C")
C")

:::!!i

r---------------------------------------------------------------------------------,
Application Hints (Continued)

..J

......
co

....
C")

:::!!i

..J

H ....- ...- -. .-VOUT

R2

C2

00F
1

+

T
TUH/9060CB

01 protec1s against Cl
02 protec1s against C2
VOUT = 1.25V (1

+~) +IADJR2

FIGURE 3. Regulator with Protection Diodes

Typical Applications
Regulator and Voltage .Reference

Temperature Controller

....-41-------....

Your

Rl
1.2k

HEATER

R2
80

TUH/9060-3

TL/H/9060-IO

Full output current not available
at high input·output voltages

1.2V-25V Adjustable Regulator

tOptional-improves translent·response. Output capecRors in the range of
1 p.F to 1000 p.F of aluminum or tantalum electrolytic are commonly used
to provide improved output impedance and rejection of transients.

......-.-Vourtt

'Needed

Rl"
120

+

ndevice is more than 6 inches from filter cspecltors.,

ttVOUT,- 1.25V (.1

+~) +IADJ «(12)

"AI = 2400 for'LMI38. AI. R2 as an assembly can be ordered from
Bourns:
MIL pari no. 7105A·AT2·502
COMM pert no. 7105A·AT7·502
TUH/9080-1

1-88

en
n
::r

..
CD

3

m

5"

I I~1 0

c

I~:o I~:o I~: r I

~

jii"

11

CQ
""I

VIN

m

3

OZ
6.3V

nl
R6

ZOOk

~I

RZZ

f"""I

a,

160

CD

I

I I

03
6.3V
01
•. lV

Cl
30pF

Rll 

~

IV

'VA
~n

!::1 ~

vour

A~

rUH/9D6D-9

8££W'/8£~W'

II

Typical Applications (Continued)
Precision Power Regulator with Low Temperature Coefficient

~--~t--------------'---Vmrr~~
1.2k

Rl

375

'Adj"stlor 3.75 across RI

TLlH/9060-12

Adjustable Regulator with Improved Ripple Rejection

Slow Turn-On 15V Regulator

Dl*
lN4002

TL/H/9060-14
TUH/9060-13

tSolid 1antalum
'Discharges CI H output is shorted to ground
"RI

= 2401} for LMI38

High Stability 10V Regulator

~Je-"'---4

..-.----4. . . ~fJlT

'--"';';;;--~

Cl

~D.,p.f

Digitally Selected Outputs

VIN

-----------1

t----,..-VDUT

Rl
2k
5%

R1··
121

R2
1.5k
1%

INPUTS

TLiH/9000-1S

TL/H/9060-16

'Sets maximum VOUT
"RI = 2401} for LM138

1·90

r-

s:::
.....
Co)

Typical Applications (Continued)

~

15A Regulator

r-

s:::

R5

0.1

Co)
Co)

co
R4
2k

RI
0.05

R6

0.1

R2
0.1

....

1--------~

+

CI
10ilF

-_4II_- VOUT*

C2
221lF

'Minimum load-lOa mA
TL/H/9060-17

oto 22V Regulator

5V Logic Regulator with Electronic Shutdown"
VIN
25V

VOUT
5V

VIN7V-35V

C2
O.II1F

TIL
lk

"Minimum output

= 1.2V

TLlH/9060-18

Light Controller
TL/H/9060-19

VIN

'AI

= 2400. A2 = 5k for LMI38
Full ,output curren! not available
at high Input·output voltages

TLlH/9060-11

1-91

co

CO)
CO)

:E

r---------------------------------------------------------------------------------~

Typical Applications (Continued)

..J

12V Battery Charger

;0

....
CO)

500

:E

RB

..J

0.2

+
LED

TO 12V
BATTERY

Rl
3k

+

0.1"" .

1""

TLlH/9060-20

Adjustable Current Regulator

Precision Current Limiter

RI
0.24

~~~~--~-~~~A

VRIF
'OUT"

R1

TL/H/9060-22
LMI17

Tracking Preregulator
R2

720

R3

120

V-

VOUT'

-5V TO -IOV

R3
120

TLlH/9060-21

5A Current Regulator

TL/H/9060-24

TLlH/9060-23

1-92

Typical Applications (Continued)
Adjusting Multiple On-Card Regulators with Single Control'

"""''''''-VOUT

VIN

tMinimum load-l 0 rnA
• All oulputs within ± 100 mV
TL/H/9060-25

Power Amplifier

r--------.---------------------.---4--35V
lOOk

0.1 IlF
Av~ I,RF~ 10k,CF~

Av

~

10, RF

Bandwidth

~

~

lOOk, CF

0.4

100pF
~

10 pF

100 kHz
TUH/9060-27

Distortion ,;; 0.1 %

Simple 12V Battery Charger

RI
240

-="12V

~

R2
2.4k

TL/H/9060-28

'Rs--sets output impedance of charger ZOUT

~ Rs ( 1 + *)

Use of Rs allows low charging rates with fully charged battery.
"The 1000 ,.F is recommended to filter out input transients

1-93

Typical Applications (Continued)
Current Limited 6V Charger

Adjustable l5A Regulator
V,N-_...._ ..

yiN

9Y TO lOY
240

+
I.1k

t-....""">h-4~- 4.SV TO 2SV
0.2*

Sk

TUH/9060-29

'Set max charge current to 3A
"The 1000 ".F Is recommended to filter out input transients.

Sk

, Tl/H/9060-26

lOA Regulator
R
0.1

R
0.1

Y,N

-+-...J\M,.--....---+---i

OUTPUT *
1.2VT02DV

'Minimum load-l00 mA
TL/H/9060-2

1-94

t(JNational Semiconductor

LM 140A/LM 140/LM340A/LM340/LM7800C
Series 3-Terminal Positive Regulators
General Description

Features

The LM140AlLM140/LM340AlLM340/LM7800C monolithic 3-terminal positive voltage regulators employ internal current-limiting, thermal shutdown and· safe-area compensation, making them essentially indestructible. If adequate
heat sinking is provided, they can deliver over 1.0A output
current They are intended as fixed voltage regulators in a
wide range of applications including local (on-card) regulation for elimination of noise and distribution problems associated with single-point regulation. In addition to use as fixed
voltage regulators, these devices can be used with external
components to obtain adjustable output voltages and currents.

Complete specifications at 1A load
• Output voltage tolerances of ±2% at Tj = 25·C and
±4% over the temperature range (LM140AlLM340A)
• Line regulation of 0.01 % of VourlV of aVIN at 1A load
(LM140AlLM340A)
• Load regulation of 0.3% of Vour/A (LM140AlLM340A)
• Internal thermal overload protection
• Internal short-circuit current limit
• Output transistor safe area protection
• P+ Product Enhancement tested
III

Considerable effort was expended to make the entire series
of regulators easy to use and minimize the number of external components. It is not. necessaly to bypass the output,
although this does improve transient response. Input bypassing is needed only if the regulator is located far from
the filter capacitor of the power supply., .
The 5V, 12V, and 15V regulator o'ptions are available in the
steel TO-3 power package. The LM340A/LM340/LM7800C
series is available in the TO-220 plastic power package, and
the LM7805 and LM7812 are also available in the surfacemount TO-263 package.

Device

Output Voltages

Packages

LM140AlLM140 5,12,15

TO-3(K)

LM340A/LM340 5,12;15

TO-3 (K), TO-220 (T)

5,6,8,12,15,
18,24

LM7800C

TO-220 (T), TO-263 (8)
(5Vand 12Vonly)

..

Typical Applications
Fixed Output Regulator

Adjustable Output Regulator

Current Regulator

INPUT

Rl

Rl

--

OUTPUT

R2

lOUT

TLlH/nBl-l

TL/HI77Bl-3

'Required If the regulator is located far from the
poWer supply filter.
"Although no output capacitor is n••ded for stability, it does help transient response. (If need·

ed, use 0.1 "F, ceramic disc).

.
lOUT
TLlH/77Bl-2

VOUT = 5V + (5V1Rl + loJ R2 5V1Rl > 3 10.
load regulation (Lr) :::: [(Rl + R2)/Rll (Lr of
LM340·5).
.

1-95

~Ia

VNI

= Rj+

10

= 1.3 rnA over lin. and load changes.

Operating Conditions (Note 1)

Absolute Maximum Ratings

(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
(Note 5)

Temperature Range (TAl (Note 2)
LM140A, LM140
LM340A, LM340, LM7805C,
LM7812C, LM7815C
LM7806C, LM7808C, LM7818C,
LM7824C

DC Input Voltage
35V
All Devices except LM7824/LM7824C .
40V
LM7824/LM7824C
Internal Power Dissipation (Note 2)
Internally Limited
Maximum Junction Temperature

-55°C to

+ 125°C

O°Cto +70"C
O°C to

+ 125°C

150"C

Storage Temperature Range
-65°C to + 150°C
Lead Temperature (Soldering, 10·sec.)
TO-3 Package (K)
300"C
TO-220 Package (T), TO-263 Package (S)
230"C
ESD Susceptibility (Note 3)

2kV

LM 140A/LM340A
Electrical Characteristics'
lOUT

Symbol

= 1A,

-55°C ~ TJ ~ + 150°C (LM140A), or O°C ~ TJ ~

l1VO

l1Vo

1~5°C (LM340A) unless otherwise specified (Note 4)

5V

Input Voltage (unless otherwise noted)

10V

Parameter
Va

+

Output Voltage

Output Voltage

Line Regulation

Load Regulation

I

I

12V

15V

19V

23V

I

I

Min Typ Max. Min Typ Ma~ Min
4.9
5 . 5.1 11.75 12 12.25 14.7

Conditions
TJ

..

= 25°C

Units

I Typ I Max

..

15 . 15.3

V

15.6
VIf.,j ~ 30)

V
V

Po ~ 15W,5mA ~ 10 ~ 1A
VMIN ~ VIN ~ VMAX

4.8
5.2 11.5
12.5 14.4
(7.5 ~ VIN ~ 20) (14.8 ~ VIN ~ 27) (17.9

10 = 500mA
l1VIN

10
18
22
(7.5 ~ VIN ~ 20) (14.8 ~ VIN ~ 27) (17.9 ~ VIN ~ 30)

mV
V

TJ = 25°C
l1VIN

18 .
3
10
4
4
22
(7.5 ~ VIN ~ 20) (14.5 ~ VIN ~ 27) (17.5 ~ VIN ~ 30)

mV
V

TJ = 25°C
Over Temperature
(8 ~ VIN ~
l1VIN
o
10
TJ = 25 cl.5mA ~ 10 ~1.5A
250 mA ~ 10 ~ 750 mA

S;

4
12
12)

9
30
(16 ~ VIN ~ 22)

10
30
(20 ~ VIN ~ 26)

mV
mV
V

25
15

12

12

35
21

mV
mV

32
19

Over Temperature,
5mA ~ 10 ~ 1A

25

60

75

mV

10

Quiescent Current

TJ = 25°C
Over Temperature

6
6.5

6
6.5

6
6.5

mA
mA

l1la

Quiescent Current
Change

5mA ~ 10 ~ 1A

0.5

0.5

0.5

mA

0.8
0.8
0.8
(7.5 ~ VIN ~ 20) (14.8 ~ VIN ~ 27) (17.9 ~ VIN ~ 30)

mA
V

TJ = 25°C,lo = 1A
VMIN ~ VIN ~ VMAX

10 = 500mA
VMIN ~ VIN ~ VMAX
VN

Output Noise Voltage TA

= 25°C,10 Hz s: f

0.8
(8 ~ VIN ~ 25)
~

100 kHz

Ripple Rejection

TJ = 25°C, f = 120 Hz, 10 = 1A
orf = 120 Hz, 10 = 500 mA,
Over Temperature,
VMIN ~ VIN ~ VMAX

Ro

Dropout Voltage
Output Resistance
Short-Circuit Current
Peak Output Current
Average TC of Va

TJ = 25°C,lo = 1A
f = 1 kHz
TJ = 25°C
TJ = 25°C
Min, TJ = O°C,lo = 5 mA

VIN

Input Voltage
TJ
Required to Maintain
Line Regulation

l1VIN
l1VOUT

0.8
(15 ~ VIN ~ 30)

40
68
68

80

(8 ~ VIN ~ 18)

0.8
(17.9 ~ VIN ~ 30)

mA
V

90

/LV

70

dB
' dB

75
61
61

72

60
60

(15 ~ VIN ~ 25) (18.5 ~ VIN ~ 28.5)

2.0
8
2.1
2.4
-0.6

2.0
18
1.5
2.4
-1.5

2.0
19
1.2
2.4
-1.8

V
V
mn
A
A
mVloC

= 25°C
7.5

1-96

14.5

17.5

V

LM140
Electrical Characteristics (Note 4) -55'C ~ TJ ~
Symbol

5V

12V

15V

Input Voltage (unless otherwise noted)

tOV

19V

23V

Parameter
Vo

!:.VO

Output Voltage

Line Regulation

Conditions

Load Regulation

Min

I Typ I Max

15.6

V

11.4
12.6
(15.5 ,;; VIN ,;; 27)

14.25
15.75
(18.5';; VIN ,;; 30)

V
V

aVIN

3
50
(7';; VIN';; 25)

4
120
(14.5';; VIN ,;; 30)

4
150
(17.5';; VIN ,;; 30)

mV
V

-55'C,;; TJ';; + 150'C
aVIN

50
(8';; VIN';; 20)

120
VIN';; 27)

150
(18.5';; VIN';; 30)

mV
V

120
(14.6';; VIN ,;; 27)

150
(17.7';; VIN ,;; 30)

mV
V

75
(20 ,;; VIN ,;; 26)

mV
V

12

150
75

mV
mV

TJ = 25'C

TJ = 25'C
aVIN

50
(7.5 ,;; VIN ,;; 20)

-55'C,;; TJ';; +150'C
aVIN

25
(8';; VIN';; 12)

5 rnA,;; 10';; 1.5A
250 rnA ,;; Ip ,;; 750 rnA

10

la

Quiescent Current

10';; 1A

ala

Quiescent Current
Change

SmA,;; 10';; 1A

TJ = 2S'C
-55'C,;; TJ ,;; + 150'C

~

50
25

60
VIN';; 22)
12

14.4

120
60

15

50

120

150

mV

6
7

6
7

6
7

rnA
rnA

O.S

0.5

0.5

rnA

0.8
(8,;; VIN';; 20)

0.8
(15,;; VIN';; 27)

0.8
(18.S ,;; VIN ,;; 30)

rnA
V

10 = 500 rnA, -55'C,;; TJ';; +150'C
VMIN ,;; VIN ,;; VMAX

0.8
(8';; VIN';; 2S)

(1S

0.8
VIN';; 30)

0.8
(18.5';; VIN';; 30)

rnA
V

Output Noise Voltage TA = 2S'C, 10 Hz';; f. ~ 100 kHz

40

{'o,;; 1A, TJ = 25'Cor
f= 120Hz
10 ~ 500 rnA,
-S5'C,;; TJ ';;+150'C
VMIN ,;; VIN ,;; VMAX

Ro

Dropout Voltage
Output Resistance
Short-Circuit Current
Peak Output Current
Average TC of VOUT

TJ = 25'C, 10 = 1A
f = 1 kHz
TJ = 25'C
TJ = 25'C
O'C,;; TJ';; + 150'C, 10 = 5 rnA

VIN

Input Voltage
TJ = 25'C, 10 ,;; 1A
Required to Maintain
Line Regulation

aVOUT

(16

~

12.5

TJ = 25'C, 10 ,;; 1A
VMIN ,;; VIN ,;; VMAX

Ripple Rejection

aVIN

(15

12

Units

I Typ I Max

4.8

5.2

11.5

Min

4.75
5.25
(8';; VIN';; 20)

-55'C ~ TJ';; +150'C,
SmA,;; 10';; 1A

VN

J Typ I Max

Po';; 15W,5mA,;; 10';; 1A
VMIN ,;; VIN ,;; VMAX
10 = 500 rnA TJ = 25'C

5

Min

TJ = 25'C,5mA';; 10';; tA

10.';; 1A

avo

+ 150'C unless otherwise specified

Output Voltage

68
68

80

75
·61
61

72

60
60

90

".V

70

dB
dB

(8.';; VIN ,;; 18)

(15,;; VIN ,;; 25)

(18.5';; VIN ,;; 28.5)

V

2.0
8
2.1
2.4
-0.6

2.0
18
1.5
2.4
-1.5

2.0
19
1.2
2.4
-1.8

V
mn
A
A
mV/,C

7.5

14.6

.'

1-97

~

17.7

V

LM340/LM7800C
Electrical Characteristics (Note 4) O'C :s; T J :s; + 125'C unless otherwise specified
Symbol

Output Voltage

5V

12V

l5V

Input Voltage (unless otherwise noted)

10V

19V

23V

Parameter
Vo

Output Voltage'

Conditions
TJ

= 25'C, 5 mA ,;; 10 ,;;

Min
lA

4.8

Po';; 15W,5mA,;; 10';; lA

Line Regulation

10

= 500mA TJ = 25'C
O'C,;; TJ ,;;

+ 125'C

dVIN
TJ

O'C,;; TJ ,;; + 125'C
dVIN
Load Regulation

dVo

TJ

= 25'C

Quiescent Current

dlO

Quiescent Current
Change

10';; lA

VMIN ,;; VIN ,;; VMfIOX.
Output Noise Voltage TA

VN
dVIN

Ripple Rejection

= 25'C,10 Hz,;; I,;; 100 kHz
{IO';; lA, TJ = 25'C

1 = 120Hz

dVOUT

Dropout Voltage

Ro

Output Resistance
Short-Circuit Current
Peak Output Current

or 10 ,;; 500 mA,
O'C,;; TJ ,;; + 125'C

V
V
V

(17.5 ,;; VIN ,;; 30)
4
150
(17.5 ,;; VIN ,;; 30) ,
150
(18.5 ,;; VIN ,;; 30)

mV
V
mV
V

120

150
(17.7 ,;; VIN ,;; 30)

mV

25
(8';; VIN';; 12)

60
(16 ,;; VIN ,;; 22)

75
(20 ,;; VIN ,;; 26)

mV

10

12

12

50

120

150

V

V

25

60

75

mV
mV

50

120

150

mV

8
8.5

8
8.5

!3
8.5

rnA
rnA

.0.5

0.5

0.5

inA

1.0
(7.5 ,;; VIN ,;; 20)

1.0
(14.8 ,;; VIN ,;; 27)

1.0
(17.9 ,;; VIN ,;; 30)

rnA

1.0
(7';; VIN';; 25)

1.0
(14.5';; VIN ,;; 30)

1.0
(17.5';; VIN';; 30)

rnA
V

90

".V

70

dB

40
62
62

80

75
55
55

72

54
54

V

dB

VMIN ,;; VIN ,;; VMfIOX.

(8';; VIN';; 18)

(15,;; VIN ,;; 25)

(18.5 ,;; VIN ,;; 28.5)

V

= 25'C, 10 = lA
1 = 1 kHz
TJ = 25'C
TJ = 25'C

2.0
8
2.1

2.0

2.0

18
1.5
2.4
-1.5

19
1.2

V
mO
A

2.4
-1.8

A
mV/'C

TJ

Average TC 01 VOUT O'C';; TJ';; +125'C,10
VIN

15.6
15.75

(14.6';; VIN ,;; 27)

=

10';; 500 mA, O'C ,;; TJ ,;; + 125'C

50

15

50

TJ
25'C
O'C';; TJ';; +125'C

VMIN ,;; VIN ,;; VMfIOX.

14.4
14.25

Units

I Typ I Max

(7.5 ,;; VIN ,;; 20)

5 rnA,;; 10';; 1.5A
250 rnA ,;; 10 ,;; 750 rnA

= 25'C,10';; lA

12.5

120
(15,;; VIN ,;; 27)

5mA,;; 10';; lA
TJ

12

,..In

11.4
12.6
(14.5 ,;; VIN ,,;; 27)

11.5

50
(8';; VIN';; 20)

5mA,;; 10';; lA,O'C';; TJ';; +125'C
10

:s; 20)

I Typ I Max

'4 '
120
(14.5 ,;; VIN ,;; 30)

= ,25°C

dVIN'

5.2
5.25

Min

(7';; VIN';; 25)

3

dVIN

10';; lA

5

4.75
(7.5 ,;; VIN

VMIN ,;; VIN ,;; VMfIOX.
I:,vo

I Typ I Max

Input Voltage
TJ
Required to Maintain

2.4
-0.6

= 5mA

= 25'C, 10 ,;; lA
7.5

14.6

17.7

V

Line Regulation
Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Conditions are conditions under which the device
functions but the specifications might not be guaranteed. For guaranteed specifications and test conditions see the Electrical Characteristics.
Note 2: The maximum allowable power dissipation at any arnbienttempemture is a function of the maximum junction tempemture for operation (TJMAX = 125"C or
150'C), the junction-to-ambientthermal resistance (8J,v, and the ambienttempemture (T,v. POMAX = (TJMAX - T,v18JA. If this dissipation is exceeded, the die
temperature will rise above TJMAX and the electrical specifications do not apply. If the die temperature rises above 150"C, the device will go into thermal shutdown.
For the TO-3 package (K, KC), the junction-to-ambient thermal resistance (8J,v is 39'C/W. When using a heatslnk, 8JA is the sum of the 4'C/W junction-to-case
thermal resistance (8Jcl of the TO-3 package and the case-Io-ambient thermal resistance of the heatsink. For the T0-220 package (1'), 8JA Is 54'CIW and 8JC is

4'C/W.
If the TO·263 package is used, the thermal resistance can be reduced by increasing the PC board copper area thermally connected to the package: USing 0.5
square inches of copper area, 8JA is SO"C/W; with 1 square Inch of copper area, 8JA is 37'G/W; and with 1.6 or more inches of copper area, 8JA is 3Z'C/W.
Note 3: ESD rating is based on the human body model, 100 pF discharged through I.S kn.
Note 4: All characteristics are measured with a 0.22 p.F capaCitor from input to ground and a 0.1 p.F capacitor from output to ground. All characteristics except
noise voltage and ripple rejection ratio are measured using pulse techniques (tw s: 10 ms, duty cycle::;;: 5%). Output voltage changes due to changes in intemal
temperature must be taken Into account separately.
Note 5: A military RETS specification is available on request. At the time of printing, the military RETS specifications for the LMI40AK·S.0/BB3, LMI40AK·12/BB3,
and LMt 40AK-15/BB3 complied with the min and max limits for the respective versions of the LMI40A. At the time of printing, the military RETS specifications for
the LMI40K-S.0/BB3, LM140K·12/BB3, and LMI40K-IS/BB3 complied with the min and max limHs for the respective versions of the LM140. The LM140H/BB3,
LM140K/BB3, and LM140AK/BB3 may also be procured as a Standard Military Drawing.

1-98

LM7806C
Electrical Characteristics

o'c

~ TJ ~ + 150'C, VI = 11V, 10 = 500 rnA, CI = 0.33 IJ.F, Co = 0.1 IJ.F, unless otherwise specified

Symbol

Parameter

Conditions (Note 4)

Vo

'Output Voltage

TJ

aVo

Une Regulation

TJ

Load Regulation

avo

= 25'C
= 25'C
= 25'C

TJ

Min

Typ

Max

Units

5.75

6.0

6.25

V

8.0V :s: VI :s: 25V

5.0

120

9.0V:S: VI :s: 13V

1.5

60

5.0 mA:S: 10:S: 1.5A

14

120

250 rnA :s: 10:S: 750mA

4.0

60
6.3

V

4.3

8.0

mA

Vo

Output Voltage

8.0V:s: VI :s: 21V, 5.0 mA:s: 10:S: 1.0A, P:S: 15W

la

Quiescent Current

TJ

ala

Quiescent Current
Change

VN

Noise

aVI/ aVo

Ripple Rejection

Voo

Dropout Voltage

Ro'

Output Resistance

I With Line

I With Load

5.7

= 25'C

8.0V :s: VI :s: 25V

1.3

5.0 rnA:i; 10:S: 1.0A

0.5

= 25'C,10 Hz:s: I:S: 100kHz
1 = 120 Hz, 10 = 350 rnA, TJ = 25'C
10 = 1.0A, TJ = 25'C
1 = 1.0 kHz
TJ = 25'C, VI = 35V
TJ = 2S'C
10 = S.O mA,O'C:s: TA:S: +12S'C
TA

los

Output Short Circuit Current

IpK

Peak Output Current

aVo/aT

Average Temperature
Coefficient 01 OutputVoltage

59

mV

mV

rnA

45

poV

7S

dB

2.0

V

9

mil

550

rnA

2.2

A

0.8

mV/,C

LM7808C
Electrical Characteristics
O'C ~ TJ ~ + 150'C, VI = 14V, 10
Symboi

=

500 rnA, CI = 0.33 poF, Co

Vo

Output Voltage

TJ

aVo

Une Regulation

TJ

Load Regl!lation

0.1 IJ.F, unless otherwise specified

TJ

= 2S'C
= 2S'C
= 25'C

8.3
160

11.0V:s: VI:S: 17V

2.0

80

5.0 rnA :s: 10:S: 1.5A

12

160

250 mA :s: 10 :s: 750 mA

4.0

80

11.5V:s: VI :s: 23V, 5.0 rnA :s: 10:S: 1.0A, P:s: 15W

Quiescent Current

TJ

ala

Quiescent
Current Change
Noise
Ripple Rejection
Dropout Voltage

Voo
RO

Output Resistance

--

los

Output Short Circuit Current

IpK

Peak Output Current

aVo/aT

Average Temperature
Coefficient 01 Output Voltage

"

7.7

Units
Max

6.0

Output Voltage

aVI/aVo'

Typ
8.0

la

VN

Min
10.SV:s: VI:S: 25V

Vo

I WithUne
I With,Load

LM7808C

Conditions (Note 4)

Parameter

aVo

=

7.6

= 25'C

4.3

V
mA

1.0
0.5

= 25'C, 10 Hz:s: I:S: 100 kHz
= 350 mA, TJ = 25'C
10 = 1.0A, TJ = 25'C
1 = 1.0 kHz
TJ = 25'C, VI = 35V
TJ = 25'C
10 = 5.0mA

52
56

72

mV

8.0

11.5V:s: VI:S: 25V
TA

rnV

8.4

5.0 rnA:S: 10:S: 1.0A
1 = 120 Hz, 10

V

rnA
po"
dB'

2.0

V

16

mil

0.45

A

2.2

A·

0.8

rnVl'C

Nole 4: All characteristics are measured with a 0.22 ,.F capaCitor from input to ground and a 0.1 ,.F capacitor from output to ground. All characteristics except
noise voltage and ripple reiection ratio are measured using pulse techniques (Iw :s;; 10 ms, duty cycle :s;; 5%). Output voltage changes due to changes in internal

temperature must be taken into account separately.

1·99

LM7818C
Electrical Characteristics
O"C :;;; TJ :;;;

+ 150°C, VI =

Symbol

27V, 10

=

500 mA, CI

0.33 IlF, Co

=

0.1 IlF, unless otherwise specified
LM7818C

Conditions (Note 4)

Parameter

Vo

Output Voltage

TJ

AVo

Line Regulation

TJ

AVo

=

Load Regulation

TJ

= 25°C
= 25°C
= 25°C

Typ

Max

17.3

18.0

18.7

21V:;;; VI:;;; 33V

15

360

24V:;;; VI:;;; 30V

5.0

180

5.0 mA :;;; 10 ,;; 1.5A

12

360

250mA,;; 10';; 750mA

4.0

180

Vo

Output Voltage

22V,;; VI ,;; 33V, 5.0 mA,;; 10';; 1.0A, p,;; 15W

IQ

Quiescent Current

TJ

Ala

Quiescent
Current Change

VN

Noise

AVI/AVo

Ripple Rejection

Voo

Dropout Voltage

Ro

Output Resistance

I With Line
I With Load

Min

17.1

= 25°C

4.5

22V,;; VI';; 33V

los

Output Short Circuit Current

IpK

Peak Output Current

AVo/AT

Average Temperature
Coefficient of Output Voltage

mV

mV
V

8.0

mA
'

,

mA

0.5

= 25°C, 10 Hz,;; f :;;; 100 kHz
f = 120 Hz, '10 = 350mA, TJ = 25°C
10 = 1.0A, TJ = 25'C
f = 1.0 kHz
TJ = 25'C, VI = 35V
TJ = 25'C
10 = 5.0mA
TA

,

V

18.9

1.0

5.0 mA:;;; 10';; 1.0A

Un"s

53

110

",V

69 '

dB

2.0

V

22

mO

0.20

A

2.1

A

1.0

' mVl'C

LM7824C
Electrical Characteristics
O'C :;;; TJ :;;;

+ 150'C, VI

Symbol

= 33V, 10 = 500 mA, CI = 0.33 ",F, Co = 0.1 ",F, unless otherw!se specified

Vo

Output Voltage

TJ

AVo

Line Regulation

TJ

AVo

Load Regulation

LM7824C

Conditions (Note 4)

Parameter

, TJ

= 25'C
= 25°C
= 25'C

Units

Min

Typ

Max

23.0

24.0

25.0

27V,;; VI';; 38V

18

480

30V,;; VI';; 36V

8.0

240

5.0 mA:;;; 10';; 1.5A

12

480

250 mA :;;; 10 ,;; 750 mA

4.0

,240

Vo

Output Voltage

28V,;; VI ';;'38V, 5.0mA,;; 10';; 1.0A, P:;;; 15W

10

Quiescent Current

TJ

Ala

Quiescent
Current Change

22.8

= 25'C

4.8

V
mA

28V,;; VI';; 3BV

1.0

5.0 mA,;; 10';; 1.0A

0.5

= 25'C, 10 Hz';; f,;; 100 kHz
= 120 Hz, 10 = 350 mA, TJ = 25°C
107' 1.0A, TJ = 25'C
f = 1.0 kHz
TJ = 25'C, VI = 35V
TJ = 25'C
10 = 5.0mA

Noise

TA

Ripple Rejection

f

Voo

Dropout Voltage

Ro

Output Resistance

los

Output Short Circuit Current

IpK

Peak Output Current

AVo/AT

Average Temperature
Coefficient of Output Voltage

"F

"F

50

mV

8.0

'- With Line

AVI/AVo

mV

25.2

I With Load

VN

V

mA

170

",V

66

dB

2.0

V

28

mO

0.15

A

2.1

A

1.5

mVl'C

Note 4: All characteristi~s a~e measured with a 0.22
capacHor from inpullo ground and a 0.1
capacHor from outpullo ground. All characteristics except
noise voltage and ripple rejection ratio are measured using pulse techniques (Iw ;;; 10 ms, duty cycle ;;; 5%). Outpul voltage changes due to changes in' internal
temperalure must be taken Into accounl separately.

1·100

Typical Performance Characteristics

2'

i

20

I.

1&

-

25

TO·3

INFINITE
HEATSINK

I\,

~

II~

-75 -50 -2&

0

1&

8 JA =3

1.1lT"t±--bW
IIIIIIII

NO HE ATSINK

a

50 15 100 125

a

2.

50

r--

~

73

J)

ic/Y- s:::;,

Ripple Rejection
90

I

tl

~
w

1--1-+-;';;

u
10

~ &.

U,I I--I-+--fi!j

: 0.915

8.

~

0.S90

~ 0.915

..'"

+f

10 20 30 40 50 60 70 80 90100

1.005 1---l--I--IiO

;: 0.995

i

,~

I

AMBIENT TEMPERATURE (Oe)

Ripple Rejection
1DO r-rnrn"'"T111m.-TT11nmr-rrmm

~ 1.010

i

o
a

75

AMBIENT TEMPERATURE ('C)

Output Voltage (Normalized
to 1V at T) = 25'C)

"C/Vi

~- ~~ :::'::s;

WITH tD"eM HEAT SINK

AMBIENT TEMPERATURE I'CI

~

8 JA

1' ......

10

2

to-:::

25

I I
=32°C/W
N
I
I"'!.. N

TO·UO

INFINI TE HEATSINK

lil

-

T-N-

~

..

\.

r--.. .......

NO HEAT SINK

~

20

~

~

lil

i

zQ

WITH lcrCNI HEAT SINK

10

Maximum Power
Dissipation (TO·263)
(See Note 2)

Maximum Average Power
Dissipation

Maximum Average Power
Dissipation

1-1-1-1!!!!

OJ70 1-1-1-.....-15 -60 -25 0 25 50 15 100 125 150

50
l'

1110

lOOk

10k

FREQUENCY 1Hz)

JUNCTION TEMPERATURE I'CI

f= '20 liz
rVIN-VOUT·' VOC t 3.5 Vnus-

-

f- IOUT-1A
Tj _ 25 C

•

10

15

20

25

OUTPUT VOLTAGE IVI

Note: Shaded area refers 10 LM340A/LM340,
LM7805C, LM7812C and LM7815C.

Output Impedance
§

.X!
~

~

!

~

./

0.111

5.5 .-,.....,.......,.,,""',.,.,...----,

LMI40K".0

1

Ti- ZSo C

1
'OUT'DA

=

1.1

I~

IAI ~UT"500mA

COUT-lp.F
TANTALUM

I.... ~

Q

I

O.oal
10

100

lk

10k

Quiescent Current

Dropout Characteristics

V1N 'IOY
~COUT=O!!;
VOUT' &V
IOUT·500mA
Tj'Z.'C

IDlk

II++-

'OrTjlA

1

1

3.& L...JL...J--I........
-75 -SO -25 0 25 50 7& 100 125 150

10

1M
'NPUT VOLTAGE (V)

FREQUENCY IHzl

JUNCT'ON TEMPERATURE rc)

Note: Shaded area refers to LM340AlLM340,
LM7805C, LM7812C and LM7815C.

Peak Output Current
3.5

4VOUT -lOG mV

.......

"- TIL.,~_
~2&~ .... "'.....

~ 2.5

;
~

~

1.5

i - TI'I&cr~

Q

0.&

'I 1

a
0

10

15

ZO

"-

~

2&

-

30

~

I

Quiescent Current

Z.5

&.5

..

oS

!;

!;

:::

35

l - I-

f-"

4.5

;;

0.&

"

!!!

INPUTTO OUTPUT DIFFERENTIAL (V)

5.5

I§ r

1.5

c;

~
e

VOUT- 5V
lOUT '" 10 ..A
Tj-25°C

C

-7' -50 -25 a

3.5
25 50 75 100 '25150

JUNCTION TEMPERATURE I'ci

Note: Shaded area refers to LM340AlLM340,
LM7805C, LM7812C and LM7815C.

1·101

S

10

15

20

25

30

35

'NPUTVOLTAGE (V)
TL/H/77BI-4

Typical Performance Characteristics

(Continued)

Load Regulation
140AK-5.0, VIN = 10V, TA = 25°C

Line Regulation
140AK-5.0,IOUT = 1A, TA = 25°C

~
z

~
z

C>

C>

fi

~~

fi

4.995

>-

4.995

wE!
> 4.990
;!!E

=

~~ 4.990
=>

~;

C>

=

~!!!
C>

1.5 ::;:

...>=
~

I

=
....

...>
:==
=
<>

~

:xl

0.5 ~
z

C>

~

C>

....=
....

20 <
C>

~
10 ".

g:

~

TIME (5 m,/DIV)

0
TIME (5 m,/DIV)

TL/H/7781-5

:s

TL/H/7781-6

Equivalent Schematic

r-..,...----....

......--_._VIN

--------1~--

RI
aOk

QI2
RI6
0.25
~------i_----+_~-oVOUT

R20

01

R21

2.61k

TUH/7781-7

1·102

,------------------------------------------------------------------------------,r
i:
....
Application Hints
".

The LM340/LM78XX series is designed with thermal protection, output short-circuit' protection and output transistor
safe area protection. However, as with any Ie regulator, it
becomes necessary to take precautions to assure that the
regulator is not inadvertently damaged. The following describes possible misapplications and methods to prevent
damage to the regulator.

Raising the Output Voltage above the Input Voltage:
Since the output of the device does not sink current, forcing
the output high can cause damage to internal low current
paths in a manner similar to that just described in the
"Shorting the Regulator Input" section.
Regulator Floating Ground (Figure 2): When the ground
pin alone becomes disconnected, the output approaches
the unregulated input, causing possible damage to other circuits connected to VOUT. If ground is reconnected with power "ON", damage may also occur to the regulator. This fault
is most likely to occur when plugging in regulators or modules with on card regulators into powered up sockets. Power
should be turned off first, thermal limit ceases operating, or
ground should be connected first if power must be left on.

Shorting the Regulator Input: When using large capacitors at the output of these regulators, a protection diode
connected input to output (Figure 1) may be required if the
input is shorted to ground. Without the protection diode, an
input short will cause the input to rapidly approach ground
potential, while the output remains near the initial VOUT because of the stored charge in the large output capacitor.
The capacitor will then discharge through a large internal
input to output diode and parasitic transistors. If the energy
released by the capacitor is large enough, this diode, low
current metal and the regulator will be destroyed. The fast
diode in Figure 1 will shunt most of the capacitors discharge
current around the regulator. Generally no protection diode
is required for values of output capacitance,,; 10 I-I-F.

Transient Voltages: If transients exceed the maximum rated input voltage of the device, or reach more than 0.8V
below ground and have sufficient energy, they will damage
the regulator. The solution is to use a large input capacitor,
a series input breakdown diode, a choke, a transient suppressor or a combination of these.

o
......
.......

VIN

IN4002

l

vIN-1
...........--t

340

JI--....- vDur

I

I

I

f

J

)1

340

II
J

o

l>
.......

r
i:
.....
".

o
.......
r
i:
CAl

".

~
.......
r

i:

CAl
".

o
......

r
i:

~
o
o

o

Your

TLlH/7781-9

FIGURE 2. Regulator Floating Ground
TLlH/7781-8

FIGURE I_Input Short

I
T-I __r----

VIN - - 4....-

..

340

Your

I

-L

~

I
I

..1.
TLlH/7781-10

FIGURE 3. Transients

1·103

•

Typical Applications
High Input Voltage Circuits

Fixed Output Regulator

v,---.....--t

t - -....---vo
0.1

0.22pF

pr

,(NOTE I) ,

Tl/H/7781-14

TLlH/7781-1a

Note 1: Bypass capacHer. are reccmmended for optimum stability and transient response. and should be located as close as possible tO,the regulator.

I-"--Vo

TL/H/7781-1S

High Current Voltage Regulator

-

101

RI

10

3.0n

MAX

---+-

P(Cl);;' 10 Max
IREGMax

.Vo

O.t pF .

Rl =~=
,P(Cl)VBE(Qll
IREG
IREG Max (.8 + 1) - 10 Max

Tl/H/7781-16

High Output Current, Short Circuit Protected
RSC

IN -

....- -.....".",.........'"

~",-<,--OUT

RI
3.0n

Rsc _ 0.8
ISC

Rl

=

PVBE(Qll
IREGMax(.8 + 1)

0.22pF

lOMax
TL/H/7781-17

Positive and Negative Regulator

t--1I----9-- + OUT

1.-...._ _ _...._ _ _...._ _ _...._

- OUT

Tl/H17781-18

1-104

.i:

....
~
......
.-i:
....
.a:a.

Connection Diagrams and Ordering Information
TO-3 Metal Can Package (K)

TO-220 Power Package (T)

o

......
.i:
Co)

TLfHf7781-11

TLfHf77Bl-12

Bottom View

Top View

Steel Package Order Numbers:
LM140K-S.O
LM140K-12
LM140K-1S
LM340AK-S.O
LM340K-12
LM340K-1S
LM340K-S.O
See Package Number K02A

Plastic Package Order Numbers:
LM340AT-S.O LM340T-S.O
LM340AT-12 LM340T-12
LM340AT-1S LM340T-1S
LM780SCT
LM7812CT
LM781SCT
LM7806CT
LM7808CT
LM7818CT
LM7824CT
See Package Number T03B

LM140AK-S.O/883 LM140AK-12/883 LM140AK-1S/883
LM140K-S.O/883 LM140K-12/883 LM140K-1S/883
See Package Number K02C

a

~
.i:
Co)

.co.

o
......

.i:
~
o
o

o

TO-263 Surface-Mount Package (S)

TO-39 Metal Can Package (H)

OUTPUT

TAB IS

GND

GND
INPUT
TUHf77Bl-20

Top View

TLfHf77Bl-19

TUHf77Bl-21

TopVlew.

Side View

Metal Can Order Numberst:
LM140H-S.O/883
LM140H-6.0/883
LM140H-12/883
LM140H-8.0/883
LM140H-1S/883
LM140H-24/883
See Package Number H03A

Surface-Mount Package Order Numbers:
LM780SS
LM7812S
See Package Number TS3B

tThe specifications for the LM 140H/883 devices are not contained In this datasheet. If specifications for these devices
are required, contact the National Semiconductor Sales Offlce/Dlstrlbutors.

1-105

.co.

~

~

,-------------------------------------------------------------------------,

~ ~National

Semiconductor'

::l
~

~

LM 140L/LM340L Series 3-Terminal Positive Regulators
General Description
The LM140L series of three terminal positive regulators is
available with several fixed outpul voltages making them
useful in a wide range of applications. The .LM140LA is an
improved version of the LM78LXx series with a tighter output voltage tolerance (specified over the full military temperature range), higher ripple rejection, better regulation and
lower quiesceni current The LM140LA regulators have
±2% VOUT specification, 0.04%1V line regulation, and
0.Q1 %/mA load regulation. When used as, a zener diode/resistor combination replacement, the LM140LA usually results in an effective output impedance improvement of two
orders of magnitude, and lower quiescent current. These
regulators can provide local on card regulation, eliminating
the distribution problems associated with single pOint regulation. The voltages available allow the LM140LA to be used
in logiC systems, instrumentation, Hi-Fi, and other solid state
electronic equipment. Although designed primarily as fixed
voltage regulators, these devices can be used with external
components to obi!lin adjustable voltages and currents.
The LMI40LA/LM340LA are available in the low profile
metal three lead TO-39 (H) and the LM340LA are also available in the plastic TO-92 (Z). With adequate heat sinking the
regulator can deliver 100 mA output current. Current limiting
is included to limit the peak output current to a safe value.
Safe area protection for the output transistor is provided to
limit internal power dissipation. If internal power dissipation

becomes too high for the heat sinking prOvided, the thermal
shut-down circuit takes over, preventing the IC from overheating.
For applications requiring other voltages, see LM 117L Data
Sheet.
"
' ,

Features
• Line regulation of 0.04%1V
• Load regulation of 0.01 %/rhA
• Output voltage tolerances of ± 2% at Tj = 25°C and
±4% over the temperature range (LMI40LA)
±3% over the temperature range (LM340LA)
• Output current of 1OC) mA ,
• Internal thermal overload protection
• Oulput transistor safe area protection'
• Internal short circuit current limit
• Available in metal T0-39 low profile package
(LMI40LA/LM340LA) and plastic TO-92 (LM340LA)

Output Voltage Options,
LMI40LA-5.0

5V
12V
15V

LM140LA-12
LM140LA"15

LM340LA-5.0
LM340LA-12
LM340LA-15

5V
12V
15V

Connection Diagrams
TO-39 Metal Can Package (H)

GND,

(CASE)

INPUT

TL/HI7782-2

BoHomVlew
Order Number LM140LAH-5.0, LM140LAH-5.0/883, LM140LAH-12,
LM140LAH-12/883, LM140LAH-15, LM140LAH-15/883, LM340LAH-5.0, LM340LAH-12 or LM340LAH-15
See NS Package Number H03A
TO-92 Plastic Package (Z)
OUTPUT

INPUT

TL/H/7782-3

BoHomVlew
Order Number LM340LAZ-5.0, LM340LAZ-12 or LM340LAZ-15
See NS Package Number Z03A
1-106 '

Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications. ,
(Note 4)

Operating Temperature Range
LM140LA
Ui.1340LA

Input Voltage

Storage Temperature Range
Metal Can (H package)
Molded TO·92

Maximum Junction Temperature

35V
Internally Limited

Internal Power Dissipation (Note 1)

-55'Cto +125'C
O'Cto +70'C
+ 150'C
- 65'C to + 150'C
- 55'C to + 150'C

Lead Temperature (Soldering, 10 sec.)
Metal Can
Plastic TO·92

+300'C
+ 230'C

Electrical Characteristics
Test conditions unless otherwise specified. TA = -55'C to + 125'C (LM140LA). TA = O'C to +70'C (LM340LA),10 = 40 rnA,
CIN = 0.33 /l-F, Co = 0.01 /l-F.

Symbol
Vo

Output Voltage Option

5.DV

12V

15V

Input Voltage (unless otherwise noted)

1DV

19V

23V

Paramet~r

Tj = 25'C

Output Voltage
Over Temp.
(Note 3)

LM140LA

Line Regulation

Min Typ Max
4,9

Tj = 25'C

Load Regulation Tj = 25'Q

10 = 1 - 100 rnA or
10=1-40mAand
VIN = ()V

4.85

VN
t.VIN

Tj = 25'C
Tj = 125'C

Quiescent
Current Change

Tj = 25"C

10 = 40 rnA
VIN = ()V

11.5

ITyp I Max
12

Min

12.25

14.7

12.5

14.4

(14.5-27)

5.15 11.65

30

18

65

30

30

15.3
15.6
V

15.45

(17.5-30)
37

(14.2-30)

(7.5-25)

15

12.35 14.55

30

(7-25)

ITyp I Max

(17.6-30)

(14.3-27)

18

10=1-40mA
10 = 1 -100mA

70

(17.3-30)
65

37

(14.5-30)

70

20

10

40

12

50

20

40

30

80

35

100

24
4.5

3

4.2

mV
1000 hrs

30
4.5

3.1

4.5

4.2

0.1

0:1'

0.1

t.Line
VIN = ()V

0.5

0.5

0.5

55

t.VOUT

(7.5-25)

(14.3-30)

(17.5-30)

40

80

90

62
(7.5-18)

Tj = 25'C, 10 = 40 rnA

7

47

,54
(14.5-25)

14.2

rnA

4.2

t.Load 10 = 1 - 40 rnA

Tj = 25'C (Note 2)
f = 10 Hz-10 kHz

mV

(17.5-30)

5

3

Ripple Rejection f = 120 Hz, VIN = ()V

Input Voltage
Required to
Maintain Line
Regulation

5.2

12

Quiescent
Current

Output Noise
Voltage

11.75

(7-20)

Long Term
Stability

t.la

Min

5.1

A.8

10 = 1 -100 rnA

10 = 100mA
VIN = ()V

10

5

(7.2-20)
LM340LA

t.VO

I I

Conditions

Output Voltage

Units

45

52

rnA

/l-V
dB

(17.5-28.5)

17.3

V

Note 1: Thermal resistance of H·package is typicalty 26'C/W BiC, 250'C/W BjA still air, and 94'C/W BiA 400 Itlmln of air. For the Z-package is 6fJ'C/W BiCo 232'CI
W BjA stilt air, and SS'C/W BjA at 400 Itlmin of air. The maximum junction temperature shall not exceed 125'C on electrical parameters.
Note 2: II is recommended that a minimum load capacitor of 0.Q1 ".F be used to limit the high frequency noise bandwidth.
Note 3: The temperature coefficient of VOUT is typically within 0.Q1 % VOI'C.
Note 4: A military RETS specification Is available upon request. At the time of printing, the LMI40LA-5.0, -12, and -15 RETS specifications complied with the Min
and Max "mils In this table. The LMI40LAH-5.0, LMI40LAH-12, and LM140LAH-15 may also be procured as Standard Military Drawings.

1-107

II

...o ,-----------------------------------------------------------------------------,
Typical Performance Characteristics
~

CO)

~

::.
~
.....
::E
~

MaxImum Average
Power DIssIpatIon
(Metal Can Package)

MaxImum Average Power
DIssIpatIon
10

i

,2

co

I.
III

r

,..r-...

-"",

1.0

0.2
0.1
-15 -50 -%5

'"co

:lIiii:

r

uu;

25 5= 75

III

•. 115" LEAD LENGTH
FROM PC BOARD
WITH 7Z"C/W HEAT SINK

51
t-

f

f

NO HEATSINK- ~

I.'

1.0

co

0.5

a.s

::c

1:~

.;;

6G

0.1

is

I

.. zoa
B

E

co~
CoUT' M TANTALUM

......

TI"'lO'e

........

•f

./

a

10

15

20

a L......I...-.l...-.l-.l-..J.......J.........I........I
. -71 -110 -21 a 21 .1 71 III 12&

3D

21

0.1
10

JUICYION TEMPERATURE rCI

RIpple RejectIon

QuIescent Current

i

::

..."

80

.

v" "IOV
Vour "IV

20

'r,"
o
la

100
It
IDle
FREOUEICY (H.I

Iii

3A
3.2
3.1

I

2J
2J
2A

co

lOUT -U ..A
21'C

C
.!

3.J

t-

....

'"
:!
I
V... "5V

louT " .. IlIA

2.2
2.0

T,"2rc
&

1011k

11k

It

lDDk

1M

QuIescent Current

3.J

10

100

FREOUENCY (H.]

• .1

100

I

75

V,. "IOV
VOUT"SV
lout "40mA
T."2IrC

.........l '

INPUT.QUTPUT DIFFERENTIAL IVI

...~

ID

4&

Output Impedance .

......

TI"II'C

3D

15

AMBIENT TEMPERATURE I'CI

TI" !&6'e

V

~co 1110

•

o

10

I-

I

I

AVOUT"'l1OmV
~

co

FROM PC BOARD
0.12&" LEAD LUGTH
FREE AIR
FROM PC IDARO
FREE AIR .

AMBIEITTEMPERATURE rCI

Peak Output Current
400

ii

D.4" LEAD LENGTH

f

AMBIENT TEMPERATURE ("el

o

LM34IILAZ

5.0

i

;:

!.

e

..
.iii
I!

INFINITE HEATSINK

i

~

WITH 3D"elW HEAT SINK....: ~

0.5

10

LM34IILAH

I.a

INFINITE HEAT SINK

10...

2.0

10

LUl'OLAH

-

5.D

MaxImum Average Power
DIssIpatIon (PlastIc Package)

I
;;

"

1015112&31

3.4
3.3
3.2
3.1
3.0

LM1"LA-&.0
V" "IOV

r.....

IL-4DmA

r.....
~

2.8

........

2.1

........

2.7

.......

Z.'
U
2.4
-7& -51 -Z5

a

25

50 7& 180 lZ5

JUNCTION TEMPERATURE rei

IIPUT VOLTAGE IVI

TlIH17782-4

Typical Applications
FIxed Output Regulator

Adjustable Output Regulator
INPUT ---4....--1

1----4.-- OUTPUT

Cl'
1.33,of

cz··

1----4....---4,...-OUTPUT

.

Rl

O.Dlpf

C2"
O.Olpf
R2

TlIHfn82-5

'Required H the regulator is located far from the power supply fiHer.
"See note 3 In the electrical characteristlcs·table.
TlIHI7782-6
VOUT = 5V + (5VfRl + 10) R2
5VfRI = 310 loed regulation (L,) I(RI + R2)fRl1 (L, of LMI40LA-5.0)

1-108

Equivalent Circuit

r--'--r---------------....,.---t-----+--o

09

R16
1004

RIO

H11

2.Sk4

1.94

. . .-------+. . . .~--~oo(l

VOUT

R12

Cl
SpF

R2
3.41 k4

V'N

R7

Dl

13k4

D2

RB
ISk4

Rl
3.89k4

013

Rl
7.Bk4

06

H13
2.23k4

H6

2.B4k4

~-+----~----~--~~------~~~----------------------l_~~D

TL/H17782-1

II

1-109

IfINational Semiconductor

LM 145/LM345 Negative Three Amp Regulator
General Description
The LM145 is a three-terminal negative regulator with a
fixed output voltage of - 5V and up to 3A load current capability. This device needs only one extemal component-a
compensation capacitor at the output, making it easy to apply. Worst case guarantees on output voltage deviation due
to any combination of line, load or temperature variation
aSSUi6 satisfactory system operation.
Exceptional effort has been made to make the LM145 immune to overload conditions. The regulator has current limiting which is independent of temperature, combined with
thermal overload protection. Intemal current limiting protects against momentary faults while thermal shutdown prevents junction temperatures from exceeding safe limits during prolonged overloads.
Although primarily intended for fixed output voltage applications, the LM145 may be programmed for higher output voltages with a simple resistive divider. The low quiescent drain

current of the device allows this technique to be used with
good regulation.
The LM145 comes in a hermetic TO-3 package rated at
25W. A reduced temperature range part LM345 is also available.

Features
•
•
•
•
•
•
•
•

Output voltage accurate to better than ±2%
Current limit constant with temperature
Intemal thermal shutdown protection
Operates with input-output voltage differential of 2.8V at
full rated load over full temperature range
Regulation guaranteed with 25W power dissipation
3A output current guaranteed
Only one extemal component needed
P+ PrQduct Enhancement tested

Schematic Diagram

RIB

RI9

4k

5k

,/"--t--1--o VOU1'
D3
6.ZV

R20
ZOk

Rli
0.05

V.o-~~~~~--~-~-~--~--------4--4-------------~
TL/H17785-1

1-110

Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
(Note 3)
Input Voltage
20V
Input-Output Differential
20V

Power Dissipation
Internally Limited
Operating Junction Temperature Range
LM145
- 55'C to + 150'C
LM345
O'C to + 125'C
Storage Temperature Range
Lead Temperature (Soldering, 10 sec.)

- 65'C to + 150'C
300'C

Electrical Characteristics (Note 1)
Limits
Parameter

Conditions

LM345

LM145

Output Voltage

Tj = 25'C, lOUT = 5 mA,
VIN = -7.5

Line Regulation (Note 2)

Tj = 25'C
-20V';: VIN ,;: -7.5V

Load Regulation (Note 2)

Tj = 25'C, VIN = - 7.5V
5 mA ,;: lOUT';: 3A

Output Voltage

-20V';: VIN';: -7.BV
5 mA ,;: lOUT';: 3A
p,;: 25W
TMIN ,;: Tj';: TMAX

Quiescent Current

-20V ,;: VIN ,;: -7.5V
5 mA ,;: lOUT:;;; 3A

Short Circuit Current

VIN = -7.5V, Tj = +25'C
VIN = -20V, Tj = +25'C

Output Noise Voltage

TA = 25'C, CL = 4.7]J.F
10Hz:;;;f;;; 100kHz

Units

Min

Typ

Max

Min

Typ

Max

-5.1

-5.0

-4.9

-5.2

-5.0

-4.B

V

5

15

5

25

mV

30

75

30

100

mV

-4.75

V

'-5.20

-4.BO

-5.25

1.0

3.0

1.0

3.0

mA

4
2

5.5
3.5

4
2

5.5
3.5

A
A

150

Long Term Stability

150

5

50

]J.V

5

50

mV

Thermal Resistance
2
2
'C/W
Junction to Case
Note 1: Unless otherwise specified, these specifications apply: -55'C ,;; TI ,;; + 150"C for the LM145 and O"C ,;; TI ,;; + 125'C for the LM345. VIN = 7.5Vand
lOUT = 5 mAo Although power dissipation is internally limited, electrical specifications apply only for power levels up to 25W. For calculations of junction
temperature rise due to power dissipation, use a thermal resistance of 35'C/W for the T0-3 with no heat sink. With a heat sink, use Z'C/W for junction to case
thermal resistance.

Note 2: Regulation is measured at constant junction temperature. Changes in output voltage dUB to heating effects must be taken into account separately. To

ensure constant junction temperature, pulse testing with a low duty cycle is used.

Note 3: Refer to RETSI45K·5V for LMI45K·5.0 military specifications.

Connection Diagram

Typical Applications

Metal Can Pacllage

Fixed Regulator
INPUT

C2t
-:b- ..L!". Cl' J ...L!:. 4.71'F

o
'":0'~'"

-

0

Tt21'F

INPUT

l

lM145

- SOLID TANTALUM
OUTPUT

0

TL/H/778S-3
tRequired for stability. For value given, capaCitor must be solid tantalum.
50 I'F aluminum electrolytic may be substituted. Values given may be in·

GND
TL/H/778S-2

creased without limit.

Bottom View
Order Number LM345K-5.0
See NS Package Number K02A

"Required if regulator is separated from filter capaCitor. For valUe given, ca-

pacitor must be solid tantulum. 50 I'F aluminum electrolytic may be substi·
tuted.

Order Number LM145K-5.0/883 or
SMD #5962-9064501
See NS Package Number 1(02C
1-111

•

Typical Performance Characteristics
Maximum Average Power
Dissipation for LM345

Maximum Average Power
Dissipation for LM145

3D

100

Ripple Rejection

CII,..--r---nr---,.------,

,411

VIN -

Ii;

I--+--If---+--I

80

:!!

60

~

40

- I'

SOLID TANTALUM

z

"t;
~

VOUT • IV

TJ - 2s-e
Co.rr - 4.1.F

~

w

\

.....

20
15

10

125

100

T... -AP!!!EP!TTEP:!P!:P.ATURE re}

I
w

Z

lOUT - lDO mA
V,N '-IOV
T,'2rC
:COUT .. 4.7#lF
SOLID TANTALUM

2.0

~

1/

"

J

1.4

I

,;

~

a
D.OI

~

1.2
1.0
D.8
0.6
0.4

10

100

Ik

10k

lOOk

1M

f----

+

T,'-5rc

~

T, -2 C _

'1
1 1 1
1 1 1

1M

10M

Output Voltage vs
Temperature

1

J

~ -S.D

~

>

-4.9
THERMAL
SHUTDOWN

... -4.•

~

"

1

-4.7

I I

-4.6
-4.4

I
-50

OUTPUT CURRENT (AMPS)

50

t

I

1

1

100

150

-4.2

IBM

I - FREQUENCY (Hz)

lOOk

>" -5.2
;:; -5.1

'-I . ¥
:..-J~

10k

,- FREQUENCY (H.I

-&.3

V

VI

lk

-SA

1
1

T,"'+15re

1.8
1.6

.

L

0.1

1
1

2.2

C

"

t:0

100

re}
Minimum Input-Output
Voltage Differential
2.4

~
::
~

u

i

125

TA - AMilENT TEMPERATURE

Output Impedance
10

lID

51

T - TEMPERATURE rCI

.TUHI7785-4

Typical Applications (Continued)
--.--~~--"-----'""4I---.---------~",--VOUT (+)

RZ·
C1"
4.7~F

+

SOLID
TANTALUM
Y'N - VOUT ~ 3V

R3·

LMt45

1-. .- - -. .----------..;;;:·--~~WT~-~tZV

TUH17785-5

'Select resistors to sel output voltage, 1 ppm/C tracking suggested.
"Cl Is not needed If power supply filter capscitor is within 3" of regulator.
tDetermines zener current. May be adjusted to minimize temperature drift.
ttSolid tantalum.
Load and line regulation

< o.ot %

Temperature drift < 0.001 %/C

1-112

Typical Applications (Continued)
High Stability Regulator
5V ;; V+ ;; 25V
(UNREGULATED)

C2

0.0471'F
01
IN457

':"

C3
200 pF

02*-

R2

LM113
1.2V

Ik

1%

+ C4t

+

;, 100 I'F/5V
R3
640
1%

-15V ;; VIN ;; -4.5V

RI
3.9k

o-.....-t

~----------------------------~~=-~
TUH/7785-6

"Cl is not needed if power supply filter capacitor is within 3" of regulator.
tKeep C4 within 2" of LM345.

"02 .ets Initial output voltage accuracy. The LM113 is available In -5, -2, and -1% tolerance.

-2V Eel Termination Regulator
Dual 3 Amp Trimmed Supply

+ INPUT o-~

Variable Output (-5.0V to -15V)

LM123

+5.0V
CI

150

1~F _..:.

SOL I~_~
TANTAlU

2.20F
SOLID

.:!:. .... 4. 7~F
OLIO
-~~ANTALUM

Ik

TANTALUM

22
INPUT

+&2

+

0-...--1

4.1.F

SOLID

R2
220

TANTALUM

1---"'---"-0

OUTPUT

COM

_':'4.S 7~F

+
2.~F
SOL 1 0 - -

..

TL/H/77B5-B

OLIO
TANTALUM

·Optional. Improves transient
response and ripple rejection.

330

TANTALU ~--

-INPUT O-~

__
_

22

lM145-5

Rl + R2)
VOUT= -5V ( ~

Ik

~

•

-5.0V

TL/HI77B5-7

1-113

~

~ ~National

~

Semiconductor.

~ LM 150, LM350A/LM350
~

3-Amp Adjustable Regulators

....

::&
.....

,

General Description
The LM150 series of adjustable 3-terminal positive voltage
regulators is capable of supplying in excess of 3A over a
1.2V to 33V output range. They are exceptionally easy to
use and require only 2 external reSistors to set the output
voltage. Further, both line and load regulation are comparable to discrata designs. Also. the LMi50 is packaged in.
standard transistor packages which are easily mounted and
handled.
In addition to higher performance than fixed regulators, the
LM150 series offers full overload protection available only in
IC's. Included on the chip are current limit, thermal overload
protection and safe area protection. All overload protection
circuitry remains fully functional even if the adjustment terminal is accidentally disconnected.
Normally, no capacitors are needed unless the device is
situated more than 6 inches from the input filter capacitors
in which case an input bypass is needed. An output capacitor can be added to improve transient response, while bypassing the adjustment pin will increase the regulator's ripple rejection.
Besides replacing fixed regulators or discrete designs, the
LM150 is useful in a wide variety of other applications. Since
the regulator is "floating" and sees only the input-to-output
differential voltage, supplies of several hundred volts can be
regulated as long as the maximum input to output differential is not exceeded, i.e., avoid short-circuiting the output.
By connecting a fixed resistor between the adjustment pin
and output, the LM 150 can be used as a precision current
regulator.· Supplies with electronic shutdown can be
achieved by clamping the adjustment terminal to ground

which programs the output to 1.2V where most loads draw
little current.
The part numbers in the LM150 series which have a K suffix
are packaged in a standard Steel TO-3 package, while
those with a T suffix are packaged in a T0-220 plastiC package. The LM150 is rated for - 55·C ,:;: TJ ,:;: + 150"C, while
the LM350A is rated for -40·C ,:;: TJ ,:;: + 125·C, and the
LM350 is rated for O"C ,:;: TJ ,:;: + 125·C.

Features
•
•
•
•
•
•
•
•
•
•

Adjustable output down to 1.2V·
Guaranteed 3A output current
Guaranteed thermal regulation
Output is short circuit protected
Current limit constant with temperature
P+ Product Enhancement tested
86 dB ripple rejection
Guaranteed 1% output voltage tolerance (LM350A)
Guaranteed max. 0.01 %IV line regulation (LM350A)
Guaranteed max. 0.3% load regulation (LM350A)

Applications
• Adjustable power supplies
• Constant current regulators
• Battery chargers

Connection Diagrams
(To-3 STEEL)
Metal Can Package

(TO·220)
PlastiC Package

TUH/9061-5

Front View
Order Number LM350AT or LM350T
See NS Package Number T03B

Bottom View
Order Number LM150K STEEL
or LM350K STEEL
See NS Package Number K02A
Order Number LM150K/883
See NS Package Number K02C

1·114

....
s:
....
en

Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National semiconductor Sales
Office/Distributors for availability and specifications.
(Note 4)

Lead Temperature
Metal Package (Soldering, 10 sec.)
Plastic Package (Soldering, 4 sec.)
ESD Tolerance

Internally Limited
+35V
-65'Cto + 150'C

Power Dissipation
Input·Output Voltage Differential
Storage Temperature

300'C
260'C
TBD

Operating Temperature Range
LM150
LM350A
LM350

-55'C s; TJ s; + 150'C
-40'C S; TJ S; + 125'C
O'C S; TJ S; +125'C

~
Ei:
Co)
en

....

....~....
s:
Co)

en
o

Electrical Characteristics
Specifications with standard type face are for TJ = 25'C, and those with boldface type apply over full Operating Tempera·
ture Range. Unless otherwise specified, VIN - VOUT = 5V, and lOUT = 10 mAo (Note 2)
Parameter
Reference Voltage

3V S; (VIN - VOUT) S; 35V,
10 mA S; lOUT S; 3A, P S; 30W

Line Regulation

3V ~ (VIN - VOUT)

Load Regulation

Thermal Regulation

LM150

Conditions

10 mA

S;

lOUT

S;

S;

Typ

Max

1.20

1.25

1.30

V

35V (Note 3)

3A (Note 3)

20 ms Pulse

Adjustment Pin Current
Adjustment Pin Current Change

10 mA

Temperature Stability

TMIN

S;

S;

lOUT

TJ

S;

S;

3A, 3V

VIN - VOUT

=

35V

Current Limit

VIN - VOUT
VIN - VOUT

S;

10V
30V

=

RMS Output Noise, % of VOUT

10 Hz s; f:S: 10kHz

Ripple Rejection Ratio

VOUT

=

=
=

(YIN - VOUT)

S;

35V

10V, f
10V, f

=
=

0.005

0.01

%IV

0.02

0.05

%IV

0.1

0.3

%

0.3

1

%

0.002

0.Q1

%/W

50

100

)LA

0.2

5

)LA

1

TMAX

Minimum Load Current

VOUT

S;

Units

Min

3.5

120 Hz, CADJ
120 Hz, CADJ

=
=

mA

3.0

4.5

0.3

1

A
A

0.001

%

85

dB

O)LF
10)LF

%

5

88

88

dB

0.3

1

%

KPackage

1.2

1.5

'C/W

KPackage

35

Long·Term Stability

TJ

Thermal Resistance, Junction
to Case
Thermal Resistance, Junction
to Ambient (No Heat Sink)

125'C, 1000 hrs

'C/W

II

1·115

Electrical Characteristics (Continued)
Specifications with standard type face are for TJ ,= 25"C, and those with boldface type apply over, full Operating Temperature Range. Unless otherwise specified, VIN - VOUT = 5V, and loUr = 10 mAo (Note'2) (Continued)

Reference Voltage

LM350A

Conditions

Parameter

LM350

Typ

Max

lOUT = 10 mA, TJ = 25·C

1.238

1.250

1.262

3V ,,; (VIN - VOUT) ,,; 35V,
10 mA ,,; lOUT"; 3A, P ,,; 30W

1.225 1.250 1.270 1.20 1.25 1.30

Line Regulation

3V ,,; (VIN - VOUT) ,,; 35V (Note 3)

Load Regulation

10 mA ,,; lOUT"; 3A (Note 3)

Min

Typ

Units

Min

Max
V
V

0.005

0.01

0.005 0.03 %IV

0.02

0.05

0.02 0.07 %IV

0.1

0.3

0.1

0.5

%

0.3

1

0.3

1.5

%

0.002

0.01

Adjustment Pin Current

50

100

50

100

/LA

Adjustment Pin Current Change 10 mA"; lOUT"; 3A, 3V,,; (VIN' - VOUT) ,,; 35V

0.2

5

0.2

5

/LA

10

mA

Thermal Regulation

20 ms Pulse

Temperature Stability

TMIN ,,; TJ ,,; TMAX

1

Minimum Load Current

VIN - VOUT = 35V

3.5

Current Limit

VIN - VOUT ,,; 10V
VIN - VOUT = 30V

Thermal Resistance" Junction
to Case

KPackage
TPackage

3.5

4.5

3.0

4.5

1

0.25

1

0.001

VOUT = 10V;f = 120 Hz, CADJ = 10 /LF
TJ = 125·C, 1000 hrs

10

0.3

85

VOUT = 10V, f = 120 Hz, CADJ = O/LF

Long-Term Stability

1

3.0

RMS Output Noise, % of VOUT 10 Hz,,; f,"; 10 kHz
Ripple Rejection Ratio

0.002 0.03 %/W

88 '

88
0.25
3

88

%

A
A

0.001

%

85'

dB

88

1

0.25

4

1.2
3

dB
1

%

1.5 ·C/W
4 ·C/W

Thermal Resistance, Junction KPackage
35
·C/W
to Ambient (No Heat'Sink)
TPackage
·C/W
50
50
Nole I: Absolute Maximum Ratings indicate limits beyond which damage to'the device may occur. Operating Ratings indicate conditions for which the device Is
intended to be functional, but do not guarantee specific performsnce limits. For guaranteed specifications and test conditions. see the Electrical Characteristics.
Nole 2: These specifications are applicable for poWer diSSipations up to 30W for the TO·3 (K) package and 25W,for the T0-220 package. Power dissipation Is
guaranteed at these values up to 15V input-output differential. Above 15V differential, power dissipation will be limited by internal protection circuitry. All limits (I.e"
the numbers in the Min. and Max. ccilumns) are guaranteed to National's AOQL (Average OutgOing Quality Level).
Note 3: Regulation Is measured at a constant junction temperature, using pulse testing with a low duty cYcle. Changes in output voltage due to heating effects are
covered under the specifications fo'therrnal regulation.
Note 4: Refer to RETSI50K drawing ,for military specifications of the LM150K.

m

,.

1-116

Typical Performance Characteristics

IlJaaL

15

,

I

I

iii

~

ITj '-15'C

I

VIN.JI)
VOUT"lav
-75

'"~

-25

71

25

125

10

TEMPERATURE rc)

15

~
'I

20

21

50

3D

~

40

"

35

a

--'-

3D

35

-75

-25

INPUT-OUTPUT DIFFERENTIAL IV)

25

tz5

75

TEMPERATURE I'CI

Minimum Operating Current

Temperature Stability

Dropout Voltage

~"

V

41

~

I

-I

55

!Z

Tj'2S'C

,....

60

~

3
d"::
- l..\

1r~

IauT-UA

Adjustment Current

Current Limit

Load Regulation
0.2

\.28

4.5
I

C

..s

r-.. ~

"

3.5

I-

~
I-

.
..

[\

Tjl'-5h,...

3

~

~

2.5

g

I-Tj"50'~
(.5

;;

~

~

.

~ ~ ~Tj"25'C

0.1

1.22
-75

-25

TEMPERATURE I'C)

10

'"is

60

fi

...it:;:
;;:

-

'r--...

~ADJ ~ 0
40

"-

I

10

!

50

fi

10

,

r--

20

20

16

'\ ~Ao}"0pf

4D

V. - VaUT'" IV
lour ~ SOha
1= IZOIll
TJ - WC

ZO

100

... v CADJ'~
1\\
...:;:
'\

r--

25

3a

35

I,... - SODonA
VII -16V
Yout - lOY
T, = WC

10

100

OUTPUT VOLTAGE IV)

§

60

'".z

.

1l1li

25

3D

35

~

lOOk

1

I""
I'

rililli10

40

~

g,
;;:

ClD~tIUI~

1

H

;;J

20

III
VIN"W
VOUT -10V
f= 12C1 Hz
Tj=2SoC,'LlJ

0.01

1M

0.1

10

OUTPUT CURRENT fA)

Load Transient Response

Line Transient Response
1.5

1.5

~~II-15V

VOUT - taV

Y,... -lOY

yo

!auT-SOD'""

CL'O,CADJ'O

TI-25'C _

F--I- CAOJ' 0 A
~

/

lour - lllooA
T,- WC

I

7'f

.~~
......

CADJ"Opf

~~

10k

FREClUENCY (Hz)

lOOk

1M

!!

i!

~

0.1
10

20
TIMEII4l

0.5

0

~~~~~~-f~~~

-1

-1.5

.. u

1k

gl

g"

I

-I

me:

U -0.5 1--I\,..-lI--l-4-

CL·1~D~'D~ rr

~

100

80

FREClUENCV (H.I

Output Impedance

10

;;;

o

Ik

20

Ripple Rejection

100
cJDJJ.pf

IS

INPUT-OUTPUT DIFFERENTIAL IVI

Ripple Rejection

Ripple Rejection
100
;;;

10

125

15

21

TEMPERATURE I'CI

3D

40

I

1.5 I--+r+-+~-+-I:--j-0.5

~-+--+----l­

o i-L-J--'_ _....L.,U,.-I-...j
10

20

3D

40

TIME ""I
TUH/9061-6

1·117

II

Q

11)
CO)

....

::!l

~
CO)

::!l

....

C;
11)
.-

....

::!l

r-------------------------------------------------------------------~

Application Hints
In operation, the LM150 develops a nominal 1.25V reference voltage, VREF, between the output and adjustment terminal. The reference voltage is impressed across program
resistor R1 and, since the voltage is constant, a constant
current 11 then flows through the output set resistor R2, giving an Ol,ltput voltage of
VOUT = VREF (1

LOAD REGULATION
The LM150 is capable of providing extremely good load regulation but a few precautions are needed to obtain maximum performance. The current set resistor connected between the adjustment terminal and the output terminal (usually 2400) should be tied directly to the output (case) of the
regulator rather than near the load. This eliminates line
drops from appearing effectively in series with the reference
and degrading regulation. For example, a 15V regulator with
0.050 resistance between the regulator and load will have a
load regulation due to line resistance of 0.050 x lOUT. If
the set resistor is connected near the load the effective line
resistance will be 0.050 (1 + R2/R1) or in this case, 11.5
times worse.

+ :~) + IADJ R2.

Figure 2 shows the effect of resistance between the regulator and 2400 set resistor.

TUH/9061-.7

FIGURE 1
Since the 50 p.A current from the adjustment terminal represents an error term, the LM150 was designed to minimize
IADJ and make it very constant with line and load changes.
To do this, all quiescent operating current is returned to the
output establishing a minimum load current requirement. If
there is insufficient load on the output, the output will rise.

TL/H/9061-8

FIGURE 2. Regulator with Line Resistance
In Output Lead
With the TO-3 package, it is easy to minimize the resistance
from the case to the set resistor, by using two separate
leads to the case. The ground of R2 can be returned near
the ground of the load to provide remote ground sensing
and improve load regulation.

EXTERNAL CAPACITORS
An input bypass capacitor is recommended. A 0.1 p.F disc
or 1 p.F solid tantalum on the input is suitable input bypassing for almost all applications. The device is more sensitive
to the absence of input bypassing when adjustment or output capacitors are used but the above values will eliminate
the possibility of problems.

PROTECTION DIODES
When external capacitors are used with any IC regulator it is
sometimes necessary to add protection diodes to prevent
the capacitors from discharging through low current points
into the regulator. Most 10 p.F capacitors have low enough
internal series resistance to deliver 20A spikes when shorted. Although the surge is short, there is enough energy to
damage parts of the IC.

The adjustment terminal can be bypassed to ground on tite
LM150 to improve ripple rejection. This bypass capacitor
prevents ripple from being amplified as the outpu1 voltage is
increased. With a 10 p.F bypass capacitor 86 dB ripple rejection is obtainable at any output level. Increases over
10 jJ.F do not appreciably improve the ripple rejection at
frequencies above 120 Hz. If the bypass capacitor is used, it
is sometimes necessary to include protection diodes to prevent the capacitor from discharging through internal low current paths and damaging the device.
In general, the best type of capacitors to use is solid tantalum. Solid tantalum capacitors have low impedance even at
high frequencies. Depending upon capacitor construction, it
takes about 25 p.F in aluminum electrolytic to equal 1 p.F
solid tantalum at high frequencies. Ceramic capacitors are
also good at high frequencies, but some types have a large·
decrease in capacitance at frequencies around 0.5 MHz.
For this reason, 0.01 p.F disc may seem to work· better than
a 0.1 p.F disc as a,bypass.
Although the LM 150 is stable with no ou1put capacitors, like
any feedback circuit, certain values of external capacitance
can cause excessive ringing. This occurs with values between 500 pF and 5000 pF. A 1 p.F solid tantalum (or 25 p.F
aluminum electrolytic) on the output swamps this effect and
insures stability.

When an output capacitor is connected to a regulator and
the input is shorted, the output capacitor will discharge into
the output of the regulator. The discharge current depends
on the value of the capacitor, the output voltage of the regulator, and the rate of decrease of VIN. In the LM150, this
discharge path is through a large junction. that is able to
sustain 25A surge with no problem. This is not true of other
types of positive regulators. For output capacitors of 25 p.F
or less, there is no need to use diodes.
The bypass capacitor on the adjustment terminal can discharge through a low current junction. Discharge occurs
when either the input or output is shorted. Internal to the
LM150 is a 500 resistor which limits the peak discharge
. current. No protection is needed for output voltages of 25V
or less and 10 p.F capacitance. Figure 3 shows an LM150
with protection diodes included for use with outputs greater
than 25V and high values of outpu1 capacitance.

1-118

r-

3:
.....

Application Hints (Continued)

U1

~
r3:
Co)

Dl
IN40D2

U1

~
......
r-

01 protects against Cl

H~-1~--t--VOUT

02 protects against C2

VOUT

= 1.25V (1

3:
Co)

+~) +IADJR2

U1

o

R2

TL/H/9061-9

FIGURE 3. Regulator with Protection Diodes

Schematic Diagram

L--4----'-------~~~~--~--'--4--1t::~:i~::::~::::~::::~::~~::::::::::::~::~:::
.on

IV

••

J

TL/H/9061-10

Typical Applications
Full output current not available
at high input·output voltages.

1.2V-25V Adjustable Regulator

tOptionaHmproves transient response. Output capacitors in the range of 1
,.F to 1000 ,.F of aluminum or tantalum electrolytic are commonly used to
provide improved output impedance and rejection of transients.

. .-VOUTtt

..........-

RI
240

+

'Needed If device Is more than 6 inches from fliter capacitors.

e2t

ttVOUT

hF

=

1.25V ( 1

Nate: Usually Rl

TUH/9061-1

1-119

+~)

+ IADJ (R2)

= 240n for LM150 and Rl = 120n for LM350.

•

C) r---------------------------------------------------------------------------------~

t.n

C")

:!!!

Typical Applications (Continued)

..J

......

~

Precision Power Regulator with
Low Temperature Coefficient

C")

Slow Turn·ON 15V Regulator

:!!!

,_

~f---_--e~~~T

..J
.....

~T-...I

....-~~~----~,...-VOUT~4V

C)

t.n
,....

1.211

:l

CI

RI

18D.F

376

TUH/9061-14

'Adjust for 3.75V across Rl

TUH/9061-13

Adjustable Regulator with Improved
Ripple Rejection

High Stability 10V Regulator
VIN
-IIV

VOUT
IDV

RI
Zk
6!1

ill *

lN48D2

RZ
1.611

,,,

LM1ZIA

R3

,,,

217

tSolid tantalum
'Discharges 01

TL/H/S061-15

noutput Is shorted to ground
TUH/9061-16

Digitally Selected Outputs

Regulator and Voltage Reference

~--~.... VOUT

VIN------I

RZ
Uk

VREF'U5V
DI
LMIZ9

TUH/9061-3

INPUTS
TL/H/S061-17

'Sets maximum VOUT

1-120

r-

3:
....
U1

Typical Applications (Continued)

Q

.......

10A Regulator

r-

3:
Co)

0.1

U1

Q

~
r-

3:
Co)

2k

0.05

U1

0.1

Q

0.1

~--------------"----~--VOUT*
120

IhF

+
22~F

'Minimum load current 50 mA

TL/H/9061-18

oto 30V Regulator

5V Logic Regulator with
Electronic Shutdown'
VIN

35V

H ....~~~9UT

.........;;::-......

C2
O.I~F

t-t-JVV\I-TIL
Ik

TL/H/9061-19

'Min output'" 1.2V

-IOV
TL/H/9061-20

Full output current not available at high input-output voltages

1·121

II

C)
II)
C")

:E

r---------------------------------------------------------------------------------,
Typical Applications (Continued)

..J

SA Constant Voltage/Constant Current Regulator

~
II)
C")

:E
..J
C;

R3
0.2
&W

II)

.....

:E
..J

RI
33

OUTPUT

35V

1.2V-30V
+CI

&3 +

IO~Ft1'

1'~F

C5
75 pF

t50lid tantalum

R5
330.

-&VTO -15V

'Lights in constant current mode

TLlHf9061-21

12V Battery Charger
500

RI
0.2

VIN~IBV

+

T01ZV

BATTERY
RI
3k

0.1 ~F

+

TlfHf9061-22

1-122

r-----------------------------------------------------------------------------'r

:s::
.....
CI'I

Typical Applications (Continued)

o
.......

Adjustable Current Regulator

r

t-"'JVV\~""IDUT= VREF,
Rt

TL/H/9061-24

:s::
Co)
CI'I

o

~
r

:s::
Co)
CI'I

o

LM111

V-5VTO -10V
TlIH/9061-23

1.2V -20V Regulator with
Minimum Program Current

3A Current Regulator

TlIH/9061-26
TL/H/9061-25
'Minimum oulpu! current ::: 4 mA

Tracking Preregulator
R2
720

•

VOUT

OUTPUT
ADJUST

TL/H/9061-27

1·123

Typical Applications (Continued)
Adjusting Multiple On-Card Regulators
with Single Control"

t-. . . .-YOUT

YIN

TL/H/9061-2B
tMinimum load-l0 rnA
'All oulputs wilhln ± 100 mY

AC Voltage Regulator

Simple 12V Battery Charger

RS*

0.2

RI
240

120
12 Vp-p

24 Vp-p

IODOjd'"" .

3A

f\J

480 r - \

•

--LJ

TL/H/90BI-30
'Rs-sets oulputlmpedance of charger. ZoUT = Rs ( 1

+ ~)

Use of Rs allows low charging rales wilh fully
charged battery.
"1000 ,..F is recommended 10 filter oul any input transients

TL/H/90BI-29

Temperature Controller

Light Controller

t--e------+- YOUT
RI
1.211

LAMP
HEATER

TUH/9061-12

TUH/9061-11

1-124

Typical Applications (Continued)
Adjustable 10A Regulator

...........""",."... .- - 4.5V TO 25V

5k

5k

TL/H/9061-31

Current Limited 6V Charger
VIN

IYTO lOY

TL/H/9061-32

'Sets peak current (2A lor 0.30)

··1000 JAoF is recommended to filter out any Input transients.

6A Regulator

III

RI

D.I

R2

0.1

VI.

-+--JVVY-"'---ii---f

CI

OUTPUT

+

hF

TL/H/9061-2

1-125

-I

.....

~

t!lNational Semiconductor
LM317L 3-Terminal Adjustable Regulator·
General Description
The LM317L is an adjustable 3-termlnal positive voltage
regulator capable of supplying 100 mA over a 1.2V to 37V
output range. It is exceptionally easy to use and requires
only two external resistors to set the output voltage. Further,
both line and load regulation are better than standard fixed
regulators. Also, the LM317L is available packaged in a
standard TO-92 iransistor package which is easy to use.
In addition to higher performance than fixed regulators, the
LM317L offers full overload protection. Included on the chip
are current limit, thermal overload protection and safe area
protection. All overload protection circuitry remains fully
functional even if the adjustment terminal is disconnected.

Features
• Adjustable output down to 1.2V
• Guaranteed 100 mA output current
• Une regulation typically O.OI%V
• Load regulation typically 0.1 %
• Current limit constant with temperature
• Eliminates the need to stock many voltages
• Standard 3-lead transistor package
• 80 dB ripple rejection
• Output is short circuit protected
Normally, no capacitors are needed unless the device is
situated more than 6 inches from the input filter capacitors
in which case an input bypass is needed. An optional output
capacitor can be added to improve transient response. The
adjustment terminal can be bypassed to achieve very high
ripple rejection ratios which are difficult to achieve with standard 3-terminal regulators.

Besides replacing fixed regulators, the LM317L is useful in a
wide variety of other applications. Since the regulator is
"floating" and sees only the input-to-output differential voltage, supplies of several hundred volts can be regulated as
long as the maximum input-to-output differential is not exceeded.
Also, it makes an especially simple adjustable switching regulator, a programmable output regulator, or by connecting a
fixed resistor between the adjustment and output, the
LM317L can be used as a precision current regulator. Supplies with electronic shutdown can be achieved by clamping
the adjustment terminal to ground which programs the output to 1.2V where most loads draw little current.
The LM317L is available in a standard TO-92 transistor
package and the SO-8 package. The LM317L is rated for
operation over a - 2SoC to 12SoC range.

Connection Diagram
w~..

vouKJ
VIEW

VINDs

VOUT

2

7

VOUT

3

6

ADJ4

NC

VOUT
VOUT

SNC

BOTTOM

TL/H/9064-5

TLlH/9064-4

Order Number LM317LZ
See NS Package
NumberZ03A

Order Number LM317LM
See NS Package
Number M08A

Typical Applications
1.2V-2SV Adjustable Regulator

Fully Protected (Bulletproof)
Lamp Driver

Lamp Flasher
LM317L

21V
HVlt4llmA
INCANDESCENT

TLlH/S064-2

I ..

TLlH/9064-1
Full output current not available at high Input·output vottages

TLlH/9064-3

Output rate-4llashes per second all0% duty
cycle

tOptionai-improves transient response
'Needed II device is more than 6 inches Irom
filter capacHors

ttVOUT

= 1.25V ( 1 + ~n + IADJ (R2l

1-126

Absolute Maximum Ratings
- 55·C to
Storage Temperature
Lead Temperature (Soldering, 4 seconds)
Output is Short Circuit Protected
ESD rating to be determined.

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Power Dissipation
Internally Limited
Input·Output Voltage Differential
40V
Operating Junction Temperature Range - 40·C to + 125·C

+ 150·C
260·C

Electrical Characteristics (Note 1)
Parameter

Conditions
Tj

=

25·C, 3V

Load Regulation

Tj

=

25·C, 5 mA

Thermal Regulation

Tj

=

25·C, 10 ms Pulse

Line Regulation

Min

s: (VIN - VOUT) s: 40V, IL s: 20 mA (Note 2)

s:

lOUT

s:

IMAX, (Note 2)

Adjustment Pin Current

0.5

%

0.2

%/W
p.A
/LA

1.25

1.30

V

0.02

0.07

%IV

5 mA

0.3

1.5

TMIN

0.65

Line Regulation

3V

Load Regulation

s: lOUT s: 100 mA, (Note 2)
s: Tj s: TMax
(VIN - VOUT) s: 40V
3V s: (VIN - VOUT) s: 15V
3V s: (VIN - VOUT) s: 13V
(VIN - VOUT) = 40V
Tj = 25·C, 10 Hz s: f s: 10 kHz

Ripple Rejection Ratio

0.1
0.04

5

3V s: (VIN - VOUT) s: 40V, (Note 3)
5 mA s: lOUT s: 100 mA, P s: 625 mW

Rms Output Noise, % of VOUT

%IV

100

Reference Voltage

Current Limit

Units

50
5 mA s: IL s: 100 mA
3V s: (VIN - VOUT) s: 40V, P s: 625 mW

Minimum Load Current

Max
0.04

0.2

Adjustment Pin Current Change

Temperature Stability

Typ
0.Q1

s:

(VIN - VOUT)

VOUT = 10V, f
CADJ = 10/LF

=

=

1.20

s: 40V, IL s: 20 mA (Note 2)

120 Hz, CADJ

=

100
25

0
66

%
%

3.5
1.5

5
2.5

mA

200
50

300
150

mA
mA

0.003

%

65
80

dB
dB

Long·Term Stability

Tj

125·C, 1000 Hours

0.3

Thermal Resistance
Junction to Ambient

Z Package 0.4· Leads
Z Package 0.125 Leads
SO·8 Package

180
160
165

1

%
·C/W
·C/W
·C/W

·C/W
Thermal Rating of SO Package
165
NDte 1: Unless otherwise noted, these specifications apply: -25'C ,;; TI ,;; 125'C for the LM317L; VIN - VOUT = 5V and lOUT = 40 rnA. Although power
dissipation is internally limited, tihese specifications are applicable for power dissipations up to 625 mW. IMAX is 100 rnA.
Note 2: Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating effects are
covered under the speCification for thermal regulation.
NDte 3: Thermal

resistance of the T0-92 package is 180'C/W junction to ambient witih 0.4' leads from a PC board and 16r:rC/W junction to ambient with 0.125'
lead lengtih to PC board.

1·127

•

~

.........

C')

r-----------------------------------------------------------------------Typical Performance Characteristics (Output capacitor =

0 ,...F unless otherwise noted.)

:E
~

~

..

--

-0.1

IL -O.IA

~

-0.3

~

t-...

..Ii~
..

VIDUr'i
-OA

...C

TJ- 15'C

--

o.z

::i

I-

1-~INoI5V

I-

~

5

I-

~ -0.2

~

10

0.3

l!i
!;i

ES

Adjustment Current

Current Limit

Load Regulation
0.1

0.1

i

"~

'-L

TJ'.-ZrC ....

-D••

I "

0
-75 -50 -25 0 15 50 75 100 115 1&0
TEMPERATURE rC)

0

IP~rUT·CU~UT

c

40

.

38

20

10

45

i

~~

&0

..
a:
~

'j-1Z&OC

55

1I
l

35
-7& -50 -2& 0 2& 50 7& 101 ,US 1&0

40

TEMPERATURE (::CI

DIFFERENTIAL fvl

Reference Voltage
Temperature Stability

Minimum Operating Current

1.270
~

4.U

~

~
z

~

..

,i'
I-

2.0

..

is

I-

Ii
~
!l

1.5

r-- ~

~
iiia:

.~

..

1-1-

CA~J",JoF

-

~

CADI =0
60

40

Il-

;;;

..
..is
i..
~

V,N-VDUT" 5V
lL =40mA

20 f..- TJ=2rC

10

I

16

20

I

z

80 J - -

40

30

t--

Y,N" \5Y

t--

IL 'COmA
Tl" 25'C

J - - VOUT-IOV
20

o
25

I--C~

35

1.5

~~

0.5

Line Transient Response
1.0

i~ -0.5

ga

CL =0
t;i:AoloO

I-

..

T +--

c;=IIF
CAW-IDOF _

1 I

t-

il

I- ;:'1,N o1,5V

..

!~
..,2

1.5

~;

O.S

100

-1.0 l- I- YOUT' lOY

-1.& I-

~=~

:;:

ii!= u.s I
!l c::I
0
>lj

I

I

rl
o

1-1- I-

.... ~

•

TIME "'~

ro

u " "

~L.l.

CADI= •
I

~~

1-1.5 I-t-

~=
....

I

248

-0.5
-1.0

Hi" I~'C I

1.0

1.0

100

so

\I

20

40

30

Output Impedance
'

"...... \
"",

-

Ik
10k IIIIIk
FREQUENCY (Hz)

I!:~

gD

IL =40mA

102

1M

Thermal Regulation

Load Transient Response

....

I

I
10

OUTPUT VOLTAGE IV)

.
~~

I

L I I
INPUT-oUTPUT DIFFERENTIAL (V)

t-- f--c1DI' ro~F- +--

80

".

f= 120 Hz

I

I
a

Ripple Rejection
!-- I--

-

'7 ~-12I'C-

Tj--2rC

I.a

TEMPERATURE rC)

100

TJ=25'C'II I

I-2.0

-7& -&0 -25 D Z& &0 75 100 IZ5 1&0

Ripple Rejection
80

1'-:"

10

0

1.230

TEMPERATURE rC)

'"z

l-

co

0.5 L.....L-...l-....L........-L.-L---L--II......J
-75 -50 -25 0 25 50 75 100 115 150

;;;

~
a:
a:

...
I..

1.0

100

J"I"

C

2.5

II
'I

I

30
VOUT=IOV
APDWER-IW

LA

t-..

1111

"

VIN.I,5J
Your"OV
INL - SOIA

i

yl~'CI

I

I

I

I

10

I

I-'"

CL-IoF
CADI" rooF

l!i

;::

1\

I

zo
nMEr.sl

30

40

i.

-3D
1.&

;;

'i

I
1

1.0 I

0.& I
0 L
10

zo

30

40

rIME !no,)
TL/H/9064-6

r-------------------------------~,-.--------------------------------------------,

Application Hints
In operation, the LM317L develops a nominal 1.25V reference voltage, VREF, between the output and adjustment terminal. The reference voltage is impressed across program
resistor R1 and, since the voltage is constant, a constant
current 11 then flows through the output set resistor R2, giving an output voltage of
VOUT = VREF (1

In general, the best type of capacitors to use is solid tantalum. Solid tantalum capacitors have low impedance even at
high frequencies. Depending upon capacitor construction, it
takes about 25 /-LF in aluminum electrolytic to equal 1 /-LF
solid timtalum at high frequencies. Ceramic capacitors are
also good at high frequencies; but some types have a large
decrease in capacitance at frequencies around 0.5 MHz.
For this reason, a 0.01 /-LF disc may seem to work better
than a 0.1 /-LF disc as a bypass.

+ :~) + IADJ(R2)

Since the 100 /-LA current from the adjustment terminal represents an error term, the LM317L was designed to minimize IADJ and make it very constant with line and load
changes. To do this; all quiescent operating current is returned to the output establishing a minimum load current
requirement. If there is insufficient load on the output, the
output will rise.

r
3:

w
....
.....
r

Although the LM317L is stable with no output capacitors,
like any feedback circuit, certain values of external capacitance can cause excessive ringing. This occurs with values
between 500 pF and 5000 pF. A 1 /-LF solid tantalum (or 25
/-LF aluminum electrolytic) on the output swamps this effect
and insures stability.
Load Regulation
The LM317L is capable of providing extremely good load
regulation but a few precautions are needed to obtain maximum performance. The current set resistor connected between the adjustment terminal and the output terminal (usually 2400) should be tied directly to the output of the regulator rather than near the load. This eliminates line drops from
appearing effectively in series with the reference and degrading regulation. For example, a 15V regulator with 0.050
reSistance between the regulator and load will have a load
regulation due to line resistance of 0.050 x IL. If the set
resistor is connected near the load the effective line resistance will be 0.050 (1 + R2/R 1) or in this case, 11.5 times
worse.
Figure 2 shows the effect of resistance between the regulator and 2400 set resistor.

lM317l

TL/H/9064-7

FIGURE 1

With the TO-92 package, it is easy to minimize the resistance from the case to the set resistor, by using two separate leads to the output pin. The ground of R2 can be returned near the ground of the load to provide remote ground
sensing and improve load regulation.

External Capacitors
An input bypass capacitor is recommended in case the regulator is more than 6 inches away from the usual large filter
capacitor. A 0.1 /-LF disc or 1 /-LF solid tantalum on the input
is suitable input bypassing for almost all applications. The
device is more sensitive to the absence of input bypassing
when adjustment or output capacitors are used, but the
above values will eliminate the possiblity of problems.

LM317l

v,N

The adjustment terminal can be bypassed to ground on the
LM317L to improve ripple rejection and noise. This bypass
capacitor prevents ripple and noise from being amplified as
the output voltage is increased. With a 10 /-LF bypass capacitor 80 dB ripple rejection is obtainable at any output level.
Increases over 10 /-LF do not appreciably improve the ripple
rejection at frequencies above 120 Hz. If the bypass capacitor is used, it is sometimes necessary to include protection
diodes to prevent the capacitor from discharging through
internal low current paths and damaging the device.

V,N

.L .... RS...

vour

ADJ

'I

VOUT

Y

~Rl

'.240

TLiH/9064-B

FIGURE 2. Regulator with Line Resistance
in Output Lead

1-129

II

~r-------------------------------~------------------~~~--~

....
....
C")

:::IE
,~

Application Hints (Continued)
vent the capacitors from discharging through low current
points into the regulator. Most 10 ,...F capacitors have low
e'nough internal series resistance 'to deliver 20A spikes
when shOrted. Although the surge is short, there is enough
energy to aamage parts of the IC.
' '

Thermal Regulation"
When power is dissipated in an IC, a temperature gradient
occurs across the IC chip affecting the individual IC circuit
components. With an IC regulator, this gradient can be especially severe since power dissipation is large. Thermal
regulation is the effect of these temp,erature gradients on
output voltage (in percentage output change) per watt of
power change in a specified time. Thermal regulation error
is independent of electrical regulation or temperature coefficient, and ()ccurs within 5 ms to 50 ms after a change in
power dissipation. Thermal regulation depends on IC layout
as well as electrical design. The thermal regulation 01. a voltage regulator is defined as the percentage change,of VOUT,
per watt, within the first 10 rns after a step of power is applied. The LM317L specification is 0.2%/W, maximum.
In the Thermal Regulation curve at the bottom of the Typical
Performance Charecteristics page, a typical LM317L~s output changes only 7 mV (or 0.07% of VOUT = -10V)when
a 1W pulse is applied for 10 ms. This performance is thus
well inside the specification limit of 0.2%/W X 1W = 0.2%
maximum. When the 1W pulse is ended, the thermal regulation again shows a 7 mV change as the gradients across the
LM317L chip die out: Note that the load regulation error of
about 14 mV (0.14%) is additional to the therrnal regulation
error.

When an output capacitor is connected to a regulator and
the input is shorted, the output capacitor will discharge Into
the output of the regulator. The discharge current depends
on the value of the capacitor, the output voltage of the regulator, and the rate of decrease of VIN. In ,the LM317L,this
discharge path is through a large junction that is able to
sustain a 2A surge with no problem. This is not true of other
types of positive regulators. For output capacitors of 25 ,...F
or less. the LM317L's ballast resistors and Olltnllt strur.tIl'A
limit the peak current to a low enough I~vel s~that th';r;'i;
no need to use a protection diode.
'
The bypass capacitor on the adjustment terminal can discharge through a low current junction. Discharge occurs
when either the input or output is shorted. Internal to the
LM317L is a 50n resistor which limits the peak discharge
current. No protection is needed for output voltages of 25V
or less and 10 ,...F capacitance. F/fJure 3 shows an LM317L
with protection diodes included for use with outputs greater
than 25V and high values of output capacitance.

Protection Diodes
When external capacitors are used with any IC regulator it is
sometimes necessary to add protection diodes to pre-

,I~,

, LM317L

VIN -

~VIN ADJvOUT:H....02 - ~
1N4002 ~ ~

. .L
....-VOUT

....- - -

RI
... 240

'

"l'

CI,

rUH/9064-9

FIGURE 3. Regulator with Protection Diodes

.Your = 1.25V ( 1 +

R2)
,
Ai
IAOJ R2

01 protects against C1

02 protects against C2

1-130

W

:::r
CD

3

a

n'
c

I

IN

AI
3
DIB
&.2V

·

~

RI2
0.3

~

019
&.2V

RI4
15k

OUT

TLIH/9064-10

1.H£W1

Typical Applications (Continued)
Digitally Selected Outputs

HlghGaln Amplifier
v'

I---'---<..... VOUT
LM317L

RI
240

H2
12

R2*
RI
10k
'NPUT ~M""""f-I

i

'NPUTS

TUH/9064-12

TLlH/9064-11

·Sets maximum VOUT

Adjustable Current Limiter
VIN

Precision Current Limiter

-1.2

I-<....M""'_-IOUT= AI

'---T----'
TLlH/9064-13

12';; Rl ,;; 240

TLlH/9064-14

Slow Turn·On 15V Regulator
V,N

Adjusta,ble Regulator with
Impr9ved Ripple Rejection

t-4,...----...-~l'JlT

.........:;:-...1

V'N

RI
Z4U

01*

IN4aaZ

INcaaz

CI
25,.F

TLlH/9064-15

TLlH/9064-16

tSolid tantalum
, '
'Discharges Cl if o",put'is shorted to ground

Adjusta~le Regulator with Current Limiter

High Stability 10V Regillator

r----.,+

VIN
15V

I
I
I
I

I

I
I
I

I
I
I
.
I TRANSFORMER.I

LM329

:~~T:r~~~= I
CAPACITOR

R2
2k

I

I

R3
217
1%

I

I

'='

R4=2R3'22

I
I

L
--------..1

TLlH/9064-17

TL/H/9064-16
Short circuil current is approximately 600 mVlR3. or 60
LM317LZ's 200 mA cUlTent limtt). '
AI 25 mA output only 3/4V of drop occurs in R3 and R4.

1·132

rnA (compared to

r-

s::

Typical Applications (Continued)
OV-30V Regulator

.....
Co)

Regulator With 15 mA Short Circuit
Current

.....

r-

Power Follower
10V-40V

T
INPUT

C1

O.I~r-F_t--'I

-'VI""'. . . . . .
R1
10k

120k

LM311L
R2
12

-10V
TLlH/9064-20

TUH/9064-19

TL/H/9064-21

Full oUlput current not available at high input-output voltages

Adjusting Multiple On-Card Regulators with Single Control'

I-+-VDUT

_ _ _ _ _ _ JI

'All oUlputs within ± 100 mV
tMinimum load - 5mA
TLlH/9064-22

100 mA Current Regulator
LM317L

1.2V-12V Regulator with Minimum
Program Current
LM311L
15V

50 mA Constant Current Battery
Charger for Nickel-Cadmium
Batteries

VDUT*

TL/H/9064-25

-

TUH/9064-23

'Minimum load current:::: 2 mA

1-133

TLlH/9064-24

,-----------------------------------------------------------------------------,
....
.... Typical Applications (Continued)

~

C")

:::::IE
~

5V Logic Regulator with Electronic Shutdown'

Current Limited 6V Charger
V,N

........_·_~9UT

BVTO 30V

L...-.;:::........

240

.T

10001'F**

l-t-oIVV\o-TTL
lk

+

1.1k
100

2N2222

. .1. . ---41----...f ~~.

TL/H/9064-26

'Minimum output'" 1.2V

TL/H/9064-27
'Sets peak current, ipEAK

~

O.6V1R1

··1000 /AoF is recommended to filter out any input transients.

Short Circuit Protected SOV Supply

115~~II~

1118 AMP, TYPE BAG
I
I

BLACK·YELLOW

FUSE OR CIRCUIT BREAKER

.I

LM317L

TL/H/9064-28

1-134

r-----------------------------------------------------------------------------~r

Typical Applications (Continued)

==
.....
.....
Co)

r

Basic High Voltage Regulator
VIN2 170V_....- - - - -..._-,

R3
100

1/2W

VOUT

LM317L

VOUT

t - -...- - -...._l.2V TO

160VIIil25mA

AOJ

-=!="

C2
1.0 IlF

02
lN4001
R6
20k
5W
01, 02: NSD134 or similar
Cl, C2: 1 "F, 200V mylar"
·Heat sink

TUH/9064-29

Precision High Voltage Regulator

Y,N Z170V

-t------...--,

LM317L

VOUT .....t - -...-

AOJ

160VIIil25 mA

RI
2.7
R5
1.5k

02
lN4001

01, 02: NSD134 or similar
Cl, C2: 1 "F, 200V mylar"

VOUT

. .- . .-IV TO

T

R7
20k
5W

Cl
1.0 IJf

':"

·Heat sink
"Mylar is a registered trademark of DuPont Co.

1·135

TL/H/9064-30

•

-l
.....
.,...
C')

:::IE
-l

r-------------------------------------------------------------------------------------~

Typical Applications (Continued)
Tracking Regulator

Regulator With Trimmable Output Voltage

VIN

VIN (25V TO 4oVI·

.........--......-VOUT

VOUT (2ZV ±1%1

RI
10k*

16k

5%

5%

R5

1

R2~GNO.
10k'

R4
8.2k

3.9Zk
RZ
,%

I pF TANTALUM

TLlH/9064-32

Trim Procedure:
-

If VOUT is 23.0BV or higher;' cut out R3 (if lower, don't cut it outl.

-

Then if Vour is 22.47V or higher, cut out R4 (if lower, don'tl.

-

Then if VOUT is 22.16V or higher, cut out RS (if lower, don'tl.

This will trim the output to well within ± I % of 22.00 Voc, without any of Ihe
expense or uncertainty of a trim pot (see LB·46). Of course, this technique
can be used at any output voltage level.

TL/H/S064-31
AI = LM30IA, LM307, or LFI3741 only
RI, R2 = matched resistors with good Te tracking

Precision Reference with Short-Circuit Proof Output
15V----~----------------------~----_,

IO.OOOV OUTPUT

, PpmfC\llA.X

r

I
I

I
I

I

L
OUTPUT

POWER

~~------~--------------~~----------'

RETURN

COMMON----. .

TL/H/9064-33

I,.

-R1-R4 from thin-film network,
Beckman 694-3-R2K-D or similar

1-136

,-------------------------------------------------------------------------, r

i:
w

~

tflNational Semiconductor

.r
~
~

LM320L, LM79LXXAC Series
3-Terminal Negative Regulators

~

><

~

General Description
The LM320LlLM79LXXAC series of 3-terminal negative
voltage regulators features fixed output voltages of - 5V,
-12V, and -15V with output current capabilities in excess
of 100 mA. These devices were designed using the latest
computer techniques for optimizing the packaged IC thermal/electrical performance. The LM79LXXAC series, even
when combined with a minimum output compensation capacitor of 0.1 p.F, exhibits an excellent transient response, a
maximum line regulation of 0.07% VOIV, and a maximum
load regulation of 0.01 % Yo/mAo
The LM320L/LM79LXXAC series also includes, as self-protection circuitry: safe operating area circuitry for output transistor power dissipation limiting, a temperature independent
short circuit current limit for peak output current limiting, and
a thermal shutdown circuit to prevent excessive junction
temperature. Although designed primarily as fixed voltage
regulators, these devices may be combined with simple external circuitry for boosted and/or adjustable voltages and
currents. The LM79LXXAC series is available in the 3-lead
TO-92 package, and SO-8; 8 lead package. The LM320L
series is available in the 3-lead TO-92 package.

Typical Applications

For output voltage other than -5V, -12V and -15V the
LM137L series provides an output voltage range from 1.2V
to 47V.

Features
• Preset output voltage error is less than ± 5% overload,
line and temperature
• Specified at an output current of 100 mA
• Easily compensated with a small 0.1 p.F output
capacitor
• Internal short-circuit, thermal and safe operating area
protection
• Easily adjustable to higher output voltages
• Maximum line regulation less than 0.07% VOUTIV
• Maximum load regulation less than 0.01% VOUT/mA

Connection Diagrams

Fixed Output Regulator

SO-S Plastic (Narrow Body)

our

NC

-V

-VIN
LM3ZDLZ
LM79LXXACZ

--I

-VINo--......

-VIN

-VIN

3

6

-VIN

NC

4

5

GND
TL/H17748-4

TUH17748-1

Top View

'Required if the regulalor is located far from the power supply filter. A 1 ,..F
aluminum electrolytic may be substituted.
':'Requlred for stability. A 1 ,..F aluminum electrolytic may be substituted.

Order Number LM79L05ACM,
LM79L 12ACM or LM79L 15ACM
See NS Package Number MOSA

Adjustable Output Regulator

TO-92 Plastic Package (Z)

CI
UhF

+
TUH/7748-2

Bottom View
TL/H/7748-3

-Yo

~

-5V - (5V/RI + lal e R2,
5V/RI > 310

1-137

Order Number LM320LZ·5.0, LM79L05ACZ,
LM320LZ·12, LM79L 12ACZ, LM320LZ·15 or
LM79L15ACZ
See NS Package Number Z03A

Absolute Maximum Ratings

Electrical Characteristics (Note 2) TA =

,"

' Output Voltage

-5V

Input Voltage (unless otherwise noted)

-10V

Symbo
Vo

Parameter

Conditions

1 mA s: 10 s: 100 mA
VMIN s: VIN s: VMAX

Tj ;= 25·C, 10 = 40 mA
VMIN s: VIN s: VMAX
aVO

Load Regulation

Tj = 25'C
1 mA s: 10

(-20

s: VII~

'.1'

-12

Min

.
Units

I Typ I Max

-11.5 -15.6' -15 -14.4

s: VIN s:

45
-'14.6) (-30 OS; VIN

45
-17.7)

mV
V

60
-7) (-27

s: VIN s:

45
45
-14.5) (-30 S:VIN S:-17.5)

mV
V

s: VIN s:

50

aVO

Long Term Stability

10 = 100mA

20

la

Quiescent Current

10=100mA

2

ala

Quiescent Current'
Change

1 mA

s: 10 s: 100mA
1 mA s: 10 s: 40 mA
s: VMAX

Vn

Output Noise Voltage Tj = 25'C, 10 = 100 mA
f = 10Hz-10kHz

aVIN
aVo

Ripple Rejection

Tj = 25·C,IO = 100 mA
f = 120Hz

Input Voltage
Required to
Maintain Line
Regulation

Tj = 25·C,lo = 100 mA
lo=40mA'

V

60
s: -7.3) (-27

,10 = 100mA

".

-20V

I Typ 1Max

Min

-5' -4.8 ....:12.5

s: 100 mA

VMIN s: VIN

-15V

-'-17V:

-12.6 -11.4 -15.75
-5.25
-4.75
-14.2f
(-20 s: VIN s:. -7) (-:-27 s: VIN s: -14.5) (-30 s: VIN s: -17.5)

Tj = 25·C,10 = 100 mA
(-20
VMIN s: VIN s: VW,AX

Line Regulation ,

,-12V

-5.25
-11.4 -15.75
-14.25
-4;.75 -12.6,
,(-20 s: VIN s: -7.5) (-27 s: VIN s: -14.8) (-30 s: VIN s: -18)

1 mAs: 10 s:40mA: '
VMIN s: VIN s: VMAX
avo

>

>

I Typ i Max

Min

Tj = 25·C,lo = 100 mA -5.2

Output Voltage

+70·C
+ 125·C
- 55·C to + 150·C
260·C

O·C to + 70·C unless otherwise noted.

"

.' ;,

O~Cto

Operating Temperature Range
Maximum Junction Temperature
Storage Temperature Range
Lead Temperature (Soldering, 10 sec.)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Input Voltage
Vo = -5V, -12V, -15V
-35V
Internal Power Dissipation (Note 1)
Internally Lir,nited

s:

100

125

' 48
6

2

60
6

2

mV
mV/khrs

6

mA

0.3

0.3

0.3

0.1

0.1

0.1

mA

0.25

0.25

0.25

mA

(-20 s: VIN,s: -7.5) (-27
40

s: VIN s:

-14.8) (-30

52
-7.3
-7.0

V

120

96·

50

s: VIN s: -18)

/LV

50
-14.6
-14.5

dB
-17.7
-17.5

'V
V

Note 1: Thermal resistance of Z package is 60'C/W 8iC' 23Z'C/W 8ia at still air, and 8fr'C/W at 400 It/min of air. The M package 8ia is 180'C/W In still air.
The maximum junction temperature shall not exceed 125"C on electrical parameters,
Note 2: To ensure c;,~su.~t jUnction\empe;ature, low duty cycle pulse testing Is used.

..

:

1-138

Typical Performance Characteristics
Maximum Average Power
Dissipation (TO-92)
a.12S·· LEAD LENGTH
FROM PC BOARD
FREE AIR

-- =-

•.1

..'"
i....
!

~

~""
GA" LEAD LENGTH

GA
I---

FROM PC BOARO_
FREE AIR

Tj-~C

5t-

~

ill
0:

0.15

t-

0.1

....~

Tj

45

sa

"2~'C

.......

0.05

o

0.1
3D

15

t-

0.15

1;

0.1

".

~

..
~

10

15

20

25

...

~

§

:;:

t
a:
sa

15

100

~

125

80

fil

~ 0.99a

1--1--1--1--1-----1

~

40

~ 1.0to I--I--j-'-I--I-----I

,.

iiii

20

t-

VIN - VOUT:
6VIN-7Vp-p
1

~ 1.aoa r::::~~~~~~~~
is
~

lour- 50Ti:
o TA=~ 1I111m
10

Tj - JUNCTION TEMPfRATURE I'C)

3

~::l 1.000 r=-t-OIII!I:l:mflZ

VOUl--5V

0:

25

-5 -10 -15 -20 -25 -3D -35
INPUT VOLTAGE IV)

VOUT- -1ZV

a

o

Output Voltage vs,
. Temperature (Normalized
to 1V@
1.010 ,-r--'-r-'--r--r--,

Ripple Rejection

__L--L__

"

O.OS

3D

80

~

Tj"2S'C

INPUT-OUTPUT OIFFERENTIAL IVI

Dropout Voltage

vOUT"av

,- ~ ~ ~
Tj-125'C
r---.. i'... ~

5
ill
0:
§

a

o

TA - AMBIENTTEMPERATURE I'C)

_1L--L__

lj-a'C

=::::t.....

02

~~

Tj -125'C

~

15

0.25

AVOUT -100 mY

0.2

D.2

D

Short Circuit Output
Current

Peak Output Current

025

100

lk

UBa
10k..

'-_J......;_1-_1-_=~

o

lOOk

25

50

15

loa

125

Tj - JUNCnON TEMPERATURE I'CI

FREQUENCY IHzI

Quiescent Current

I

-

TjJc

-.:::::: ~"2S'C
1
~
1

-5

-la

Tj"12S'C
VOUT"-SV :-

I
I
-15

IOUt- 4D jA_

0.01
-20

-25

-3a

-35

'-_'-....J'----'_--'_--'
10

100·

lk

ll1k

lOOk

1M

FREQUENCY IH.I

INPUT VOLTAGE IV)

Tl/H/7748-5

Typical Applications (Continued)
± 15V, 100 mA Dual Power Supply
....--e--oVOUT = 15V@100rnA

C2
0.1 ~F
GNDo-~-------4~----~'-O

C4

D.1 ~F
-V1No-+_-I
20V
TUH/7748-6

1-139

•

Schematic Diagrams
-5V
OND

TLlHI774B-9

-12Vand -15V
GND

DI

R21
4.Uk

IV

RU

R23

OJ
(l.41

-v,"

TL/H/n4B-l0

1-140

f}1National Semiconductor

LM337l 3-Terminal Adjustable Regulator
General Description
The LM337L is an adjustable 3-terminal negative voltage
regulator capable of supplying 100 mA over a 1.2V to 37V
output range. It is exceptionally easy to use and requires
only two external resistors to set the output voltage. Furthermore, both line and load regulation are better than standard fixed regulators. Also, the LM337L is packaged in a
standard TO-92 transistor package which is easy to use.
In addition to higher performance than fixed regulators, the
LM337L offers full overload protection. Included on the chip
are current limit, thermal overload protection and safe area
protection. All overload protection circuitry remains fully
functional even if the adjustment terminal is disconnected.
Normally, only a single 1 JLF solid tantalum output capacitor
is needed unless the device is situated more than 6 inches
from the input filter capacitors, in which case an input. bypass is needed. A larger output capacitor can be added to
improve transient response. The adjustment terminal can be
bypassed to achieve very high ripple rejection ratios which.
are difficult to achieve with standard 3-terminal regulators.
Besides replacing fixed regulators, the LM337L is useful in a
wide variety of other applications. Since the regulator is
"floating" and sees only the input-to-output differential voltage, supplies of several hundred volts can be regulated as
long as the maximum input-to-output differential is not exceeded.
Also, it makes an especially simple adjustable switching regulator, a programmable output regulator, or by connecting a
fixed resistor between tile adjustment a~d output,. the
LM337L can be used as a preCision current regulator. Supplies with electronic shutdown can be achieved by clamping
the adjustment terminal to ground which programs the output to 1.2V where most loads draw little current.

The LM337L is available in a standard TO-92 transistor
package and a SO-8 surface mount package. The LM337L
is rated for operation over a - 25'C to + 125'C range.
For applications requiring greater output current in excess
of 0.5A and 1.5A, see LM137 series data sheets. For the
positive complement, see series LM117 and LM317L data
sheets.

Features
•
•
•
•
•
•
•
•
•

Adjustable output down to 1.2V
Guaranteed 100 mA output current
Line regulation typically 0.01 %IV'
load regulation typically 0.1 %
Current limit constant with temperature
Eliminates the need to stock many voltages
Standard 3-lead transistor package
80 dB ripple rejection
Output is short circuit protected

Connecti,on Diagram

TUH/9134-1

Bottom View

TLiH/9134-2

Top View
Order Number LM337LMor LM337LZ
See NS Package Number M08A or Z03A

Typical Applications
1,2V-25V Adjustable Regulator

Regulator with Trimmable.Output Voltage

R2
3.9:ul
:1:1%
R5
16kD.
5%
~:;';"'~--------~1--22V

TUH/9134-3
Full output current not available at high input-output voltages
-VOUT

=

-1.25V (1

+~)
2400

tCI = 1 "F solid tantalum or 10 "F aluminum electrolytic
required for stability
'C2 = 1 "F solid tantalum is required only if regulator is more
than 4' from power supply filter capacitor

TUH/9134-4

Trim Procedure:
-If VOUT is -23.08V or bigger, cut out A3 (if smaller, don't cut it out).
-Then if VOUT is -22.47V or bigger, cut out A4 (il smaller, don't).
-Then if VOUT is -22.16V or bigger, cut out AS (if smaller, don't).
This will trim the output to well within 1% of -22.00 Voe, without any of the
expense or trouble of a trim pot (sse LB-46). Of course, this technique can
be used at any output voltage level.

1-141

•

Absolute Maximum Ratings
Operating Junction Temperature Range -25·Cto
- 55·C to
Storage Temperature
Lead Temperature (Soldering, 10 sec.)
Plastic Package (Soldering 4 sec.)
ESD rating to be determined.

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Power Dissipation
Internally Limited
Input-Output Voltage Differential
40V

+ 125·C
+ 150·C
300·C
260·C

Electrical Characteristics (Note 1)
Parameter

Conditions

Min

Typ

Max

Units

Line Regulation

TA = 25·C, 3V ,;; iVlN - .vourl ,;; 40V,
(Note 2)

0.01

0.04

%IV

Load Regulation

TA = 25·C, 5 mA·';; lour';; IMAx' (Note 2)

0.1

0.5

%

Thermal Regulation

TA = 25·C, 10 ms Pulse.

0.04

0.2

%/W

50

100

",A

0.2

5

",A

1.25

1.30

V

Adjustment Pin Current
Adjustment Pin Current Change

5 mA,;; IL ,;; 100 rnA
3V ,;; IVIN - vourl ,;; 40V

Reference Voltage

3V ,;; iVlN - vourl ,;; 40V, (Note 3)
10 mA,;; lour';; 100 mA, p,;; 625 mW

Line Regulation

3V ,;; IVIN - vourl ,;; 40V, (Note 2)

0.02

0.07

%IV

Load Regulation

5 mA ,;; lour';; 100 rnA, (Note 2)

0.3

1.5

.%

Temperature Stability

TMIN';; Tj';; TMAX

0.65

Minimum Load Current

IYIN - vourl ,;; 40V
3V,;; IVIN - vourl ,;; 15V

3.5
2.2

5
.3.5

rnA
mA

Current Limit

3V,;; IVIN - vourl ,;; 13V
iVlN - vourl = 40V

200
50

320
120

mA
mA

Rms Output Noise, % of Your

TA = 25·C,10Hz,;; f,;; 10kHz

Ripple Rejection Ratio

Your = -10V, F = 120 Hz, CADJ = 0
CADJ = 10",F

1.20

100
25

66

%

0.003,

%

65
80

dB
dB

TA = 125·C
0.3
1
%
these specilicationsapply -25'C:S; rj :s; + 125'C lor the LM337L; IVIN - vOUTI ~ 5Vand lOUT ~ 40 mAo Although power
diSSipation is Internally limned, these specifications are applicable lor power dissipations up to 625 mW. IMAX Is 100 mAo
Note 2: Regulation Is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating effects are
covered under the specification lor thermal regulation.
Note 3: Thermal resistance of the TO·92 package Is 180'C/W lunclion to ambient with 0.4" leads Irom a PC board and 160'C/W lunction to ambient with 0.125"
lead length to PC board. The M package 8JA Is 180'C/W in still air.
Long-Term Stability

Note 1: Unless otherwise specilied,

1-142

r-------------------------------------------------------------------------, r
3:
w
....
tfJNational Semiconductor
~

en
CD
:::!!.

m

LM341, LM78MXX Series
3-Terminal Positive Voltage Regulators
General Description

Features

The LM341 and LM78MXX series of three-terminal positive
voltage regulators employ built-in current limiting, thermal
shutdown, and safe-operating area protection which makes
them virtually immune to damage from output overloads.

•
•
•
•
•
•
•

With adequate heatsinking, they can deliver in excess of
O.5A output current. Typical applications would include local
(on-card) regulators which can eliminate the noise and degraded performance associated with single-point regulation.

Output current in excess of O.5A
No external components
Internal thermal overload protection
Internal short circuit current-limiting
Output transistor safe-area compensation
Available in TO-220 and TO-39 packages
Output voltages of 5V, 12V, and 15V

Connection Diagrams
TO-39 Metal Can Package (H)

INPUT

TL/H/l0484-5

Bottom View
Order Number LM78M05CH, LM78M12CH or LM78M15CH
See NS Pac!-

o H4~.-I-;;";;"';';""~",,*,++-I 0

VI = 10V
.LL
I I
3.0 Vo = s.OV
LOAD CURRENT

is

2.0

I

1.0
0

=25°C

~

,i-t-HHY-+4-1

o

-20 Vo= s.OV

o

2

4

8

10

0

Ii

"<

.§.

...z
l-

'"
'":::>

OUTPUT VOLTAGE

l- I- r- DEVIATION

:::>

10 = 500 mAt-H-t-t-t-+-H

0.5

Ll
I I
I I

. I-

-10 TJ

1.0

LM78M05

0

I"

Q

9

-1.0 HH-t-t-t++++--t-H
-2.0 .............-..L.-'--'--'-.L-........................
o 10 20 30 40 50 60

12

TIME (}'s)

TIME (}'s)
TL/HI10484-8

TL/H/10484-7

Typical Application

Design Considerations
The LM78MXX/LM341 XX fixed voltage regulator series has
built-in thermal overload protection which prevents the device from being damaged due to excessive junction temperature.
The regulators also contain internal short-circuit protection
which limits the maximum output current, and safe·area protection for the pass transistor which reduces the short-circuit current as the voltage across the pass transistor is increased.'
.

VIN +---t--I IN

.~

0.33 }'F

OUTt--t--+. VOUT
LM78MXX
Lt.t341T-XX

=k..

0.1 },F

GND

Although the internal power dissipation Is automatically limited, the maximum junction temperature of the device must
be kept below + 125'C in order to meet data sheet specifications. An adequate heatsink should be provided to assure
this limit is not exceeded under worst·case operating conditions (maximum input voltage and load current) if reliable
performance is to be obtained.
.

1
TLlH/10484-9

'Required if regulator input is more than 4 inches from Input filter capacitor
(or If no input filter capacHor Is used).
"Optional for improved transient response.

1:-148

r

s::
......
N

t!lNational Semiconductor

Co)

.......
r

s::
......

N

LM723/LM723C Voltage Regulator

Co)

o

General Description

Features

The LM723/LM723C is a voltage regulator designed primar.
ily for series regulator applications. By itself, it will supply
output currents up to 150 mA; but external transistors can
be added to provide any desired load current. The circuit
features extremely low standby current drain, and provision
is made for either linear or foldback current limiting.
The LM723/LM723C is also useful in a wide range of other
-application's such as a shunt regulator, a current regulator or
a temperature controller.
The LM723C is identical tei the LM723 except that the
LM723C has its performance guaranteed over a O°C to
+ 70°C temperature range, instead of - 55°C to + 125°C.

• 150 mA output current without external pass transistor
• Output currents in excess of 10A possible by adding
external transistors
• Input voltage 40V max
• Output voltage adjustable from 2V to 37V
• Can be used as either a linear, or a switching regulator

Connection Diagrams
Dual-In-Llne Package
NC

14

Metal Can Package

CURRENT LIMIT

2

13

CURRENT SENSE

3

12

NC
FREQUENCY
COMPENSATION
y+

INVERTING INPUT
NON-INVERTING
INPUT
YREF

4

11

Yc

5

10

VOUT

Y-

7

CURRENT
LIMIT

INVERTING
INPUT
NON-INVERTING
INPUT

Vz
NC
VTUH/8563-3

TUH/8563-2

Note: Pin 5 connected to case.

Top View

Top View

Order Number LM723J/883 or LM723CN
See NS Package J14A or N14A

Order Number LM723H, LM723H/883 or LM723CH
See NS Package H10C

Equivalent Circuit*
V'

FREOUENCY
COMPENSATION
9

CURRENT

FREQ COWP

LlWIT

Vc

CURRENT
SENSE

•

2 111 20 19
18
"

5

17

8

14
10 11 12 13

3

16

·1N

V+
Vc

15

TEMPERATURE
COMPENSATED
ZENER

+1N

•

VREF
V·

OUT

Vz

TLlH/6563-20

Top View

5

v-

1
CURRENT
SENSE

Vz

TLlH/8563-4

·Pin numbers refer to metal can package.

1·149

Order Number LM723E/883
See NS Package E20A

II

Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
(Note 9)
Pulse Voltage from V+ to V- (50 ms)
50V
Continuous Voltage from V+ to V40V
Input-Output Voltage Differential
40V
Maximum Amplifier Input Voltage (Either Input)
8.5V
Maximum Amplifier Input Voltage (Differential)
5V
Current from Vz
25mA
15mA
Current from VREF

Internal Power Dissipation Metal Can (Note 1)
800mW
Cavity DIP (Note 1)
900mW
Molded DIP (Note 1)
660mW
Operating Temperature Range LM723
- 55·C to + 150·C
O·Cto +70"C
LM723C
Storage Temperature Range Metal Can -65·C to + 150·C
Molded DIP :- 55·C to + 150·C
Lead Temperature (Soldering. 4 sec. max.)
,300"C
Hermetic Package
'.
Plastic Package
260"C
,
ESD Tolerance
1200V
(Human body model, 1.5 kO in series with 100 pF)

Electrical Characteristics (Notes 2, 9)
Parameter
Line Regulation

IL = 1 mA to IL = 50 mA
-55·C";; TA";; +125·C
O·C,,;; TA";; +70·C

Ripple Rejection

f
f

Average Temperature Coefficient of Output Voltage (Note 8)

-55·C";; TA";; + 125·C
O·C,,;; TA";; +70"C

Short Circuit Current Limit

Rsc

Max

0.01

,0.1 '
0.3

0.01

0.1

0.02

0.2

0.1

0.3
0.5

0.03

0.2
0.6

= 50 Hz to 10 kHz, CREF = 0
= 50 Hz to 10 kHz, CREF = 5/LF

74
86

74
86
0.003 0.015

= 100, VOUT = 0

65

65

= 100 Hz to 10 kHz. CREF = 0

86
2.5

86
2.5

= 100 Hz to 10 kHz, CREF = 5/LF

0.05
IL

= 0, VIN = 30V

1.7

1.7

%VOUT
%VOUT
%VOUT

%rC
%rC

V
/LVrms
/LVrms
%/1000 hrs

0.05
3.5

%VOUT
%VOUT
%VOUT
%VOUT

mA

6.95 7.15 7.35 6.80 7.15 7.50
BW
BW

Units

dB
dB

0.002 0.015

Long Term Stability
Standby Current Drain

Max Min Typ

0.03 0.15
0.6

Reference Voltage
Output Noise Voltage

Min Typ

VIN = 12VtoVIN = 15V
-55·C";; TA";; +125·C
O·C,,;; TA";; +70·C
VIN = 12VtoVIN = 40V

Load Regulation

' LM723C

LM723

Conditions

4.0

rnA

Input Voltage Range

9.5

40

9.5

40

V

Output Voltage Range

2.0

37

2.0

37

V

Input-Output Voltage Differential

3.0

38

3.0

38
105

V
·C/W

OJA

Molded DIP

OJA

Cavity DIP

150

OJA

Hl0C Board Mount in Still Air

165

165

·C/W

OJA

Hl0C Board Mount in 400 LF/Min Air Flow

'66

66

·C/W

22

22

·C/W

OJC

·C/W

Note 1: See derating curves for maximum power rating above 25°C.

Note 2: Unless otherwise specified, TA = 25'C, VIN = V+ = Ye = 12V, Y- = 0, VOUT = 5V, IL = 1 mA, Rse = 0, Cl ,= 100 pF, CREF = 0 and divider
Impedance as seen by error amplifier,; 10 kO connacted as shown in FigUre 1. Une and load regulation speCifications are given for the condition of constant chip
temperature. Temperature drifts must be taken into account separately for high dissipation conditions.

Nole 3: Ll is 40 turns of No, 20 enameled copper wire wound on Ferroxcube P36/22-387 pol core or equivalent wilh 0.009 in. air gap.
Note 4: Figures in parentheses may be used if Rl/R2 divider is placed on ,opposile input of error amp.
Note 5: Replace Rl/R2 in figures wilh divider shown in Figure 13.
Nole 6: V+ and Vee musl be connected to a +3Y or grealer supply.
Nole 7: For metal can applications where Yz is required, an external6.2V zener diode should be connacted in series with YOUT.
Nole 8: Guarenteed by correlalion to other lests.
Note 9: A milnary RETS specification is available on request. At the lime of printing, the LM723 RETS specification complied wilh the Min and Max limns in this
table. The LM723E, H, and J may also be procured as a Standard Military Drewing.

1-150

r

:s::
......

Typical Performance Characteristics

N

(0)

Load Regulation
Characteristics with
Current LImiting
0.1

g
I

~

Ii

lise -lOll

o

-0.2

~

VOUT· +5V. VIN· +lZV

-0.25

:5

z
;::

T.-m'c ~

-0.2

-0.1

I

"N...-r--

~ -0.15
~

'"

.
..

1

20

25

30

o

20

"'"~

"5>

~
~

>
;::

~

'"

VOUT " SV. VIN = +lZV
lise-Ion

r

a

0.&

'"c~

0.1

~

D.6

~

D.4 r---~~URRENT
Rse -,Ou

">

0.6

- r - ~.-~5'~OA T.--55'C

!

....

0.2

~'"
20

40

60

10

"

~

-rT.-ln'c

o

0.5

......

4.0

;;

5... z

2.0

"
" Iiill

2.0

i"'" r!U!UT VOLTAGE-2.•

VIt... +1ZV
VOUT +5V

"....>

=

S

-4.0

-4.0
-&.0

15

-5

25

35

=
c

~

1--0

"

ill

" ..
10

~

40 !:

....z

::!

~

::::i

t;

1

50

12

100

45

T"~5·J- -

1.4
I.Z

T~-1~5·J-

1.0
D.8

0.6
0.4
0.2

VQUT'"VREF

IL ·0

10

150

1.0

..
'"
• .."
S S
..
..~
~

10

i 5

45

..:;:
,. ..
...." I!;
..

,.::; g
~

4.0
-10

OUTPUT VOLTAGE"

-~
-4.0

\

-1.0

-5

15

TIME"'~

VIN -+12V
VOUT=+SV

-20

IL=4DmA
TA -25 C
1Ise-0

-30

25

TIME

35

40

VOUT "·5V
VIN ·+1ZV

10

u

~

30

50

Outputlmpedence va
Frequency

\

~

20

INPUT VOLTAGE IVI

LOAD CURRENl

::! >

IL -lmA
TA .. ZSoc
1Ise-0

=> -2.0

"

3

I'...t'

<

1/

35

25

T~-J5·J- -

1.8

C
.! 1.&

Load Transient Response

4.0

~

~

120

~

~

.

JUNCTION TEMPERATURE I'CI

INPUT VOLTAGE

~

2.0

160

'I..

-50

Ii

~

15

Standby Current Drain va
Input Voltage

SENSE VOLTAGE

~-i'
'N-I.

r--

100

~

~

r--

1
IL -lmAtoll-SDmA

-5

100

1

I'

D.3

Line Transient Response
&.0

~::2:'C

-0.2
80

200

LlM;.J~R~

OUTPUT CURRENT (mAl

;;

60

,;'

VDY'-~~~

-0.1

JuncUon Temperature

0.8

o

'"

\l

1

LINE

"'-

Current LImiting
Characteristics vs

Characteristics

1.0

0.1

~~

1

40

TA "+2So C
l:J.V-+JV
I.. " t mA

0.2

~

~rj55'IC

(0)

o

OUTPUT CURRENT ImAI

Current Limiting

~

.,

~

1

OUTPUT CURRENT ImAI

a

I

T.-25'C~

-0.3
-0.4

15

I.Z

~

\ 'i

N

Rsc- O

J.

r---T.;12~'C

JI

10

~

:s::
......

Vou,-+SV

r

>

~

T.-25'C-

-D.1

0.3

VOUT • SV, VIN .. +lZV
Asc-IOI1
r-

g

T,," -!SoC

.......... l

;; -0.05

Load & Line Regulation vs
Input-Output Vollage
Differential

Load Regulation
Characteristics with
Current LImiting

0.05

......
r

S

::!

z
c

....
=>

CL-D

Asc=·
TA = 25°C

1.0

IA'1

_.. -SamA

C.. -lpF

'.1

!:

.01
45

110

lili

lk

"'.1

10IIi

1M

FREQUENCY!H,I
TL/H/8563-6

II

Maximum Power Ratings
Noise vs Filter Capacitor
(CREF In Circuit of Figure t)
(Bandwidth 100 Hz to 10 kHz)

LM723
Power Dissipation va
Ambient Temperature

100
50

1000
90D
BOD
700

I'...

......

.....

HIOC

I'

o

.DOl

.01

.1

Cm-CPF)

10

~BOD

..5.500
.e'400

~

-55 -25 0

1
HIOC

700

~
~

.lOU TJIIAl( = 150"1:
20D RTH= I 65"1:/W (HIOC)
100 RTH = 15O"C/W (DIP)
NO HEAT SINK
1

1"\
o

I"-

'"

..5.500
.e'400

o

1000
90D
BOD

DIP

~BOD

20

LM723C
Power Dissipation va
Ambient Temperature

"-

25 50 75 100 125 150

TA AMBIENT 1IIIPERATURE ("1:)

- -

~

.,"\1\.

\.

I"\:

.lOU rI'lAX=15O"C
20D RIH =I65"C/W (HIOC)
100 RTH = I5O"C/W (DIP)
NO HEAT SINK
1

o

-55 -25 0 25 50 75 100 125 150
TA AMBIENT 1IIIPERATURE ('C)
TL/H/8563-7

1-151

TABLE I. Resistor Values (kO) for Standard ,Output Voltage
Fixed
Output
±5%

. Applicable
Figures

Positive
Output
Voltage

Output
Adjustable
± 10% (Note 5) .

Negative
Output
Voltage

Applicable
Figures

5% Output
Adjustable
±10%

Fixed
Output
±5%
. R2

R1

" P1

3.57

102

2.2

10

91

7,

3.57

255

2.2

10

240

-6 (Note 6)

3, (10)

3.57

2:43 : 1.2

0.5

0.75

-9

3,10:

3.48

5.36

1.2

0~5

2.0

. -12

3,10

3.57

8.45

1.2

0:5

3.3

3.0

-15

3,10

3.65

1'1.5

1.2

0.5

4.3

3.0

-28

3,10

3.57

24.3

1.2

0.5

10
33

(Note 4)

R1

R2

R1

P1

R2

+3.0

1, 5, 6, 9, 12 (4)

4.12

3.01

1.8

0.5

1.2

+100,

7

+3.6

1,5,6,9,12 (4)

3.57

3.65

1.5

0.5

1.5

+250

+5.0

1,5,6,9,12 (4)

2.15

4.99

0.75

0.5

2.2

+6.0

1,5,6,9,12 (4)

1.15

6.04

0.5

0.5

2.7

+9.0

2,4, (5, 6, 9,12)

1.87

7.15

0.75

1.0

2.7

+12

2,4, (5, 6, 9,12)

4.87

7.15

2.0

.. 1.0

+15

2,4, (5, 6, 9,12)

7.87

7.15

:H

1.0

R1

R2

+28

2,4, (5, 6, 9,12)

21.0

7.15

5.6

1.0

2.0

-45

8

3.57

41.2

2.2

10

+45

7

3.57

48.7

2.2

10

'39

-100

8

3.57

97>.6

2.2

10

91

+75

7

3.57

78.7

2.2

10

68

-250

8

3.57

,249

2.2

10

240

. TABLE II. Formulae for Intermeifiat~ Output Voltages
Outputs from + 2 to + 7 volts
(Figures 1, 5, 6, 9, 12, l4})
(

VOUT =

Outputs from + 4 to + 250 volts
(Figure 7)
.
(VREF
R2 "'- R1 )
,
VOUT"" · - - X - - - 'R3=A4
.
2
R1",

~REF ,x R1 R2)
;t- R2

Outputs from -6 to - 250 volts,
(Figures 3, 8, 10)

Outputs from + 7 to + 37 volts
(Figures2, 4, (5, 6, 9,12])
(

VOUT =

VREF X

Current Limiting
VSENSE
.ILlMIT = - - Rse
Foldback Current'Limiting
I
- (VOUT R3
KNEE -. Rse A4

(VREF
R1 + A2)
VOUT = -2- X -R-1- ; R3 = R4

R1 + R2)

R2

ISHORTeKT =

+

VSENSE (R3 + R4»)
Ase R4

(VSENSE
R3 + R4)
--- X --Rse
R4

Typical,Applications

"
"

.h.
VO" ,

V'

-

LM7Z3

CL

LM123C

r-:-;...

...

VAEF

.,

~'i

,.

'.

REGULATED

OUTl'UT

lise

R3

LM723
LM723C

f·
"::"

Note: R3

~

=

Vl

Rl R2
Rl + R2

for minimum temperature drift.

.3
INV.
COMP

-:l-

,

-

N.I.
"

INV.

y-

R1R2
Fi1+"R2

;

for minimum temperature drift.
Ril ,may be 'eliminated foi

"

.. '

lct

-=F

~
=

Rt

TtOOP~ ~ R2

,

Note: R3

II

ICOMP

"

FIGURE 1. Basic Low Voltage Regulator
(VOUT = . 2 t07 Volts)
,;

REGULATED
OUTPUT

CL
CS

C11DO pF

TL/H/8563-8
Typical Performance
Regulated Output Voltage
SV
Line Regulation (.1Villi = 3V)
O.SmV
Load Regulation (.1IL = SO mAl 1.SmV

"

VOUT ~

VREF

CS

N.r.

IVee

TL/H/B563-9
Typical Performance
Regulated Output Voltage
tSV
Line Regulation (.1VIN = 3V)
1.5mV
Load Regulation (.1IL ,= SO mAl 4.SmV

minlmufTl component count.
"

1-152

; FIGURE 2. Basic High Voltage Regulator
(VOUT = 7 to 37 Volts)

Typical Applications

(Continued)

LM723
LM723C
CI
1DOpF

L..._ _..._ _..._ _ _ _ _ _~~~_:~~TED

HZ
TlfHf8583-10

Typical Performance
Regulated Output Voltage
-15V
line Regulation (a Y,N = 3V)
1 mV
Load Regulation (all = 100 mAl 2 mV

TlfHf8563-11

Typical Performance
Regulated Output Voltage
+ 15V
Une Regulation (aV'N = 3V) 1.5 mV
Load Regulation (all = lA)
15 mV

FIGURE 3. Negative Voltage Regulator

FIGURE 4. Positive Voltage Regulator
(External NPN Pass Transistor)

Vee

lise
3D

y+

REGULATED
OUTPUT

VOUT

VREF

H3

UK

VOUT
RI

LM123
LM123C

CL
R4

LM723
LMl23C

Rl

UK

CS
CL

CS

-=

Hsc
H2

N.I.

REGULATED
OUTPUT

INV.

R2

TLfH/8563-13

Typical Performance
Regulated Output Voltage
+ 5V
Line Regulation (a Y,N = 3V)
0.5 mV
Load Regulation (all = 10 mAl 1 mV
Short Circuit Current
20 mA

TLfHf8563-12

Typical Performance
Regulated Output Voltage
+ 5V
Une Regulation (aV,N = 3V) 0.5 mV
Load Regulation (all = lA)
5 mV

FIGURE 6. Foldback Current Limiting

FIGURE 5. Positive Voltage Regulator
(External PNP Pass Transistor)

1·153

III

Typical Applications

(Continued)

R52DD

Tvee

wT
VREF

VOUT

~N3234

Vz
D136V~

INI364 ..

~

R4
3.0K

LM723
LM723C

RI

CL

~R5

cSIl
INV.

N.I.

---4

~1

R3
3.0K

R2

"

ICOMP

In

,

~ICI

500pF
REGULATED
OUTPUT

-'TLlH/8563-14

Typical Performance
Regulated 0utput Voltage
Une Regulation (liNIN ~ 20V)
Load Regulation (<

~d
~

pNational Semiconductor

LM78LXX Series 3-Terminal Positive Regulators
General Description

Features

The LM7SLXX series of three terminal positive regulators is
available with several fixed output voltages making them
useful in a wide range of applications. When used as a zener diode/resistor combination replacement, the LM7SLXX
usually results in an effective output impedance improvement of two orders of magnitude, and lower quiescent current. These regulators can provide local on card regulation,
eliminating the distribution problems associated with single
point regulation. The voltages available allow the LM7SLXX
to be used in logic systems, instrumentation, HiFi, and other
solid state electronic equipment.

• Output voltage tolerances of
the temperature range
•
•
•
•
•

± 5% (LM7SLXXAC) over

Output current of 100 mA
Internal thermal overload protection
Output transistor safe area protection
Internal short circuit current limit
Available in plastic TO-92 and metal TO-39 and plastic
SO-S low profile packages

• No external components
• Output voltages of 5.0V, 6.2V, S.2V, 9.0V, 12V, 15V

The LM7SLXX is available in the metal three-lead TO-39(H)
package, the plastiC TO-92 (2) package, and the plastic
SO-S (M) package. With adequate heat sinking the regulator
can deliver 100 mA output current. Current limiting is included to limit the peak output current to a safe value. Safe area
protection for the output transistors is provided to limit. internal power dissipation. If internal power disSipation becomes
too high for the heat sinking provided, the thermal shutdown
circuit takes over preventing the IC from overheating.

Connection Diagrams
(TO-39)
Metal Can Package (H)

SO-S Plastic (M)
(Narrow Body)

(T0-92)
Plastic Package (Z)

OUTPUT

INPUT

(?

GND
(CASEI

VDUT -

t· ' - ' 8

-VIN

GND- 2

7 -GND

GND- 3

6 -GND

NC- 4

5 !"'"NC

"B~
GND

../'-

TLlHI7744-3
TL/H/7744-2

TL/H/7744-1

Bottom View

Top View

Order Number LM7SL05ACH,
LM7SL 12ACH or LM7SL 15ACH
See NS Package Number H03A

Order Number LM7SL05ACM,
LM7SL 12ACM or LM7SL 15ACM
SeeNS Package Number MOSA

1-158

BoHomView
Order Number
LM7SL05ACZ, LM7SL09ACZ,
LM7SL 12ACZ, LM7SL15ACZ,
LM7SL62ACZ or LM7SL82ACZ
See NS Package Number Z03A

r-

rs::
......

Absolute Maximum Ratings

(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Power Dissipation (Note 5)
Internally Limited
Input Voltage

-65·C to

Storage Temperature

O·C to

Operating Junction Temperature

+ 150·C
+ 125·C
265·C

Lead Temperature (Soldering, 10 seconds)
ESD Susceptibility (Note 2)

2kV

S5V

LM78LXXAC Electrical Characteristics

Limits in standard typeface are for TJ = 25·C, bold typeface applies over the O·C to + 125·C temperature range. Limits are
guaranteed by production testing or correlation techniques using standard Statistical Quality Control (SQC) methods. Unless
otherwise specified: 10 = 40 mA, CI = O.SS ,..F, Co = 0.1 ,..F.

LM78L05AC Unless otherwise specified, VIN =
Symbol
Vo

tNo

Parameter

10V
Conditions

Output Voltage

Line Regulation

Min

Typ

Max

4.B

5

5.2

7V,,; VIN"; 20V
1 mA:,,;10:O':40mA
(NoteS)

4.75

5.25

1 mA:,,;10:,,;70mA
(NoteS)

4.75

5.25

7V:,,; VIN:"; 20V

1B

75

BV:,,; VIN:"; 20V

10

54

1 mA:,,; 10"; 100 mA

20

60

5

SO

tNo

Load Regulation

10

Quiescent Current

Alo

Quiescent Current Change

BV:,,; VIN:"; 20V

1.0

1 mA :,,; 10 :,,; 40 mA

0.1

Vn

Output Noise Voltage

f = 10 Hz to 100 kHz
(Note 4)

Ripple Rejection

f=120Hz
BV:,,; VIN:"; 16V

1mA:,,;IO,,;40mA

AVIN
AVOUT
IpK

Peak Output Current

AVo
AT

Average Output Voltage Tempco

VIN
(Min)

Minimum Value of Input Voltage
Required to Maintain Line Regulation

S

10 = 5mA

47

V

mV

5
mA

40

,..V

62

dB

140

mA

-0.65

mV/·C

6.7

1-159

Units

7

V

Q)

r-

><
><

LM78LXXAC Electrical Characteristics

Limits in standard typeface are for TJ = 25'C. bold typeface applies over the O'C .to + 125'C temperature range. Limit!; are
guaranteed by production testing or correlation, techniques, using standard Statistical.. Quality Control (SQC) methods. Unless
otherwise specified; Ip = 40 mAo CI = 0.33 p.F •. ~a= 0.1 p.F. (Continued)
"

LM78L62AC Unless otherwise specified. VII'; =
Symbol
Va

12V
Conditions

Parameter
Output Voltage

B.5V :S:' VIN :S: 20V
1mA:S:lo:S:40mA
(Note 3)
1 mA :S: 10 :S: 70 mA
(Note 3)
aVo

Line Regulation

aVo

Load Regulation

10

Quiescent Current

ala

Quiescent Current Change

Vn
aVIN

Output Noise Voltage

"

Ripple Rejection

aVOUT
IpK

Peak Output Current

aVo
aT

Average Output Voltage Tempco

VIN
(Min)

Minimum Value of Input Voltage
Required to Maintain Line Regulation

..

Min

Typ

Max

5.95 '

6.2

6.45

5.9

6.5

5.9

6.5

B.5V :S: VIN :S: 20V

65

175

9V:S: VIN:S: 20V

55

125

1 mA:S: 10:S: 1()OmA

13

BO

1 mA:S: lo:S: 40mA

6

40

2

5.5

BV:s: VIN:S: 20V

1.5

1 mA.:S: 10:S: 40mA

0.1

.1'= 10 Hz to 100 kHz
(Note 4)
f = 120Hz
10V:S: VIN:S: 20V

40

10=5mA

I

Units

V

,
mV

mA

50

p.V

46

dB

140

mA

-0.75

mVl'C

7.9

V

......

!!:

LM78LXXAC Electrical Characteristics

Limits in standard typeface are forTJ = 25·C, bold typeface applies over the O·C to + 125·C temperature range. Limits are
guaranteed by production testing or correlation techniques using standard Statistical Quality Control (SQC) methods. Unless
otherwise specified: 10 = 40 mA, CI = 0.33 /loF, Co = 0.1 /loF. (Continued)

LM78L82AC Unless otherwise specified, VIN =
Symbol
Vo

!:>.vo

Parameter

Line Regulation

Load Regulation

IQ

Quiescent Current

Il.lci

Quiescent Current Change

Il.VIN

Conditions

Output Voltage

Il.Vo

Vn

14V

1 mA,;;10';;70mA
(Note 3)

7.8

8.6

11V';; VIN';; 23V

80

175

12V,;; VIN ,;; 23V

70

125

1 mA,;; 10';; 100mA

15

80

1 mA,;;10';;40mA

8

40

2

5.5

12V ,;; VIN ,;; 23V

1.5

1mA,;;IO';;40mA

0.1

f = 120 Hz
12V,;; VIN ,;; 22V

Peak Output Current
Average Output Voltage Tempco

VIN
(Min)

Minimum Value of Input Voltage
Required to Maintain Line Regulation

8.53

8.6

Ripple Rejection

IpK

Max

8.2

7.8

f = 10 Hz to 100 kHz
(Note 4)

Il.Vo
Il.T

. Typ

l1V,;; VIN';; 23V
1 mA,;; 10';; 40mA
(Note3) .

Output Noise Voltage

Il.VOUT

Min
7.87

10

=

5mA

1·161

39

Units

V

mV

mA

60

/loV

45

dB

.140

mA

-0.8

mVI"C

9.9

V

......
co
......

><
><

LM78LXXAC Electrical Characteristics

Limits in standard typeface are .for TJ = 25'C. bold typeface applies over the O'C to + 125'C.temperatu~ range. Limits are
guaranteed by production testing or correlation techniques using standard Statistical Quality .Control (SOC) methods. Unless
.otherwise specified: 10 = 40 mAo CI = 0.33 ""F. Co = 0.1 ""F. (Continuedl

LM78L09AC Unless otherwise specified, VIN = 15V
Symbol
Vo

,Parameter

..
. Conditions

Output:Voltage
11.5V s: VIN s: 24V
1mAS:loS:40mA
(Note3l

I

1 mA S:·lo
(Note3l

!NO

AVo

Line Regulation

Load Regulation

.-

s: 70 mA

Min'

Typ

Max

8.64

9.0

9.36

8.55

••45

8.55

••45

11.5V

s: VIN s: 24V

100

200

13V

VIN

90

150

20

90

10

45

S;

1 mA

S;

S;

24V

10 S; 100mA

1 mAs; 10 s;40mA

10

Quiescent Current

Ala

Quiescent Current Change

2

I

Vn

Output Noise Voltage

AVIN
AVOUT

Ripple Rejection

IpK

Peak Output Current.

AVO
AT

Average Output Voltage Tempco

VIN
(Min)

Minimum Value of Input Voltage
Required to Maintain Line Regulation

'1.1

1 mA s; 10 s; 40mA

0.1

10

mV

mA

" '70

""V

44

dB

14.0

mA

-0.9
' ,

mVl'C

10.7

V

..

..

38

= 5mA

,

1·162

V

5.5

11.5V s; VIN s; 24V

f = 120Hz
15V S;, VIN s; 25V

' Units

LM78LXXAC Electrical Characteristics

Umits in standard typeface are for TJ = 25'C, bold typeface applies over the O'C to + 125'C temperature range. Limits are
guaranteed by production testing or correlation techniques using standard Statistical Quality Control (SQC) methods. Unless
otherwise specified: 10 = 40 mA, CI = 0.33 ""F, Co = 0.1 ""F. (Continued)

LM78L 12AC Unless otherwise specified, VIN = 19V
Symbol
Vo

Parameter

Conditions

Output Voltage

AVo

Une Regulation

AVo

Load Regulation

la

Quiescent Current

Ala

Quiescent Current Change

Vn

Output Noise Voltage

AVIN
AVOUT

Ripple Rejection

Min

Typ

Max

11.5

12

12.5

14.5V!5': VIN !5': 27V
1 mA!5': 10 !5':40mA
(Note 3)

11.4

12.6

1 mA!5':10!5':70mA
(Note 3)

11.4

12.6

14.5V!5': VIN !5': 27V

30

180

16V !5': VIN !5': 27V

20

110

1 mA!5': 10!5': 100 mA

30

100

1 mA !5': 10 !5': 40 mA

10

50

3

5

16V !5': VIN !5': 27V

1

1 mA!5':10!5':40mA

f = 120Hz

15V!5': VIN !5': 25V

IpK

Peak Output Current

AVo
AT

Average Output Voltage Tempeo

VIN
(Min)

Minimum Value. of Input Voltage
Required to Maintain Line Regulation

10 = 5mA

Units

V

mV

mA

0.1

40

80

""V

54

dB

140

mA

-1.0

mVl'C

13.7

14.5

V

•
1-163

LM78LXXAC Electrical Characteristics

Limits in standard typeface are for TJ = 25·C, bold typeface applies over the O·C to + 125·C temperature range. Limits are
guaranteed by production testing or correlation techniques using standard Statistical Quality Control (SQC) methods. Unless
otherwise specified: 10 = 40 mA, CI = 0.33 p.F, Co = 0.1 p.F. (Continued)

LM78L 15AC Unless otherwise specified, VIN =
Symbol
Vo

23V

Parameter

Conditions

Output Voltage

AVo

Une Regulation

AVo

Load Regulation

la

Quiescent Current

Ala

Quiescent Current Change

Min

Typ

Max

14.4

15.0

15.6

17.5V :5: VIN :5: 30V
1mA:5:lo:5:40mA
(Note 3)

14.25

15.75

1mA:5:IO:5:70mA
(Note 3)

14.25

15.75 .

17.5V :5: VIN :5: 30V
20V

~

1 mA

VIN :5: 30V

~

10:5: 100 mA

1mA~lo~40mA

20V.~

1 mA
Vn

Output Noise Voltage

AVIN
AVOUT

Ripple Rejection

IpK

Peak Output Current

AVo
AT

Average Output Voltage Tempco

VIN
(Min)

Minimum Value of Input Voltage
Required to Maintain Line Regulation

VIN

~

~

37

250

25

140

35

150

12

75

3

5

30V

1

10 :5: 40 mA

f = 120Hz
18.5V ~ VIN

~

28.5V

10=5mA,

Units

V

mV

mA

0.1

37

90

p.V,

51

'dB

140

mA

':"1.3

mVl·C

16.7

17.5

V

Note 1: Absolute Maximum Ratings Indicate limits beyond which damage to the device may occur, Electrical specllicatlons do not apply when operating the devloe
outside 01 Its stated operating conditions,
Note 2: Human body model, 1.5 kll In series with 100 pF.
Note 3: Power dissipetion :s; 0.7SW.
Note 4: Recommended minimum load capecltance 01 0.Q1 ".F to limit high Irequency noise.
Note 5: Typical thermal resistance values lor the packages are:
H Package: Rth(J·C) = 26 'C/W, Rth(J-A) = 120 'C/W
Z Package: Rth(J-C) = 60 'C/W, Rth(J-A) = 230 'C/W
M Package: Rth(J-A) = 180 'C/W

1-164

r

.....
==
co

Typical Performance Characteristics

10

Maximum Average Power
Dissipation (Z Package)

5.0

z

0:

~NF1N1TE HEATSINK=

5.0

~

1.0

co
;::

::!

ti

is
a:

D••" LEAD LENGT
FROM PC BOARD
FREE AIR
0.125" LEAD LENGTH
FROM PC BOARD
FREE AIR

0.5

Ii!

3:

I -I--

I

z

0.125" LEAD LENGTH
FROM PC BOARD
WITH 7ZOCIW HEAT SINK

co

is
a:

Peak Output Current
400

10

g

iti

~
><

Maximum Average Power
Dissipation (H Package)

T- t;-

1.0

NO HEAT SINK

==

0.5

Ii!

0

15

30

45

60

0

-=

I

I

I

30

45

60

I

75

==

oS
0ill
a:

~
0-

"~

WITH 30'CIW HEAT SINK

0.1

0.1

.

15

co

75

300

I
r-- -T)O'C

II

Tj-25·C

200

If

Tj'150'C

I ••

0

...;:::: ~

1

........... r-..."""'"

I
I
5

AMBIENT TEMPERATURE rCI

AMBIENT TEMPERATURE rCI

dVQUT·10DmV

10

15

20

25

30

INPUT·OUTPUT DIFFERENTIAL (VI

TL/H/7744-4

Dropout Voltage
2.5

~

~

2.0

i

1.5

0-

1.0

is

"I!:
:!"
Ii!

0.5

1-;;;;

IO~T270~~

-

-~

--

m
:!!

ill

lOUT -40mA

IOyT '."0 rA

r

§

f=

;;:
a:

w

I I I

DROPOUT

"I ViT

i!!

Ripple Rejection

CD~D'~'D~S

=t' if

VI"T 1

50

75

10

§

BO

f- f-

25

VIN =10V
Vour " 5V

20

125

TA • 25°C
COUT

~

1.0

!;

0.5

~

40

I!:

'"

l~F TANTALUM'

"co

lOUT -40 rnA
TA =25"C

r-r100

CO,~~

w

~

a:

VIN = 10V
Vour = 5V
lOUT =40 rnA

5.0

u
z

60

0
0

Output Impedance

100

I I I

./
0.1

10

JUNCTION TEMPERATURE rCI

100

lk

10k

10

lOOk

100

lk

10k

lOOk

1M

FREQUENCY (Hzl

FREOUENCY (Hoi

TL/H17744-5

4.0

..
~

2.•
2.6

5

2.4

'"

..

1.6
3.4

fil

Quiescent Current

3.B

oS
0ill
a:

~
0-

Quiescent Current

oS
0ill
a:

3.2
1.0

IL

2.2

!ii

2••

10

15

20

25

I""-..

"- I.........
i"'-..

2.7
2••

2.'

3D

INPUT VOLTAGE (VI

_

Your = 5V

tOUT =40mA-

I""-..

J"'o...

2.5

Z.O
5

3.1
3.0
2.8

~
:l

Vour " 5V
lOUT .. co rnA
T.-2!i"C

VIN =10V

13

3.2

a:
u

"

II

3.4

a

25

50

75

100

125

150

JUNCTlQN TEMPERATURE ("CI

TLlHI7744-6

1-165

•

Equivalent Circuit
LM78LXX

..

r-----~------_e------------------------------------ ------~--~----_1~OVIN

09

Rn
1.9

L.....----------+---...--+-o Vou,

CI
5 pF

RI2

RS
15k

R7
13k

01

02

RI

R5

3.89k

7.8k

RI3
22Jk

L-~~----6_------~--~--~-------~~~----------------------------~~GND
TL/H/7744-7

Typical Applications
Fixed Output Regulator
INPUT --4~--1

Adjustable Output Regulator

1---"---

CI'
D.3J,.F

I-~"'--"'-DUTPUT

INPUT --~""--1

OUTPUT

RI

C2**
D.DII'F

C2

D.DII'F
R2

TL/HI7744-B

'Required H Ihe regulalor is localed more than 3" from the power supply
filter.

TL/H17744-9

.. See NOle 4 in the electrical characteristics table.

VOUT
SVlRt

1-166

= SV +

(SVlRt

+

lal R2

> 3 la. load regulation

(Lr) '" «Rt

+

R2)/Rt) (Lr of LM78LOS)

Typical Applications (Continued)
Current Regulator

--"--4

INPUT

Rl

-

.....- - - - . - - OUTPUT
lOUT

= (Vour/RI) + 10
> 10 = 1.5 mA over line and load changes

lOUT

TUH/7744-10

5V, 500 rnA Regulator with Short Circuit Protection
1.1

VOUT = SV AT SOD mA

4.4

·Solid tantalum.

TL/HI7744-11

"Heat slnk Q1.

···Optional: Improves ripple rejection and transient response.
Load Regulation: 0.6% 0 ,;; IL ,;; 250 rnA pulsed with taN = 50 ms.

± 15V, 100 rnA Dual Power Supply
+V'N -20V

0---4.....

-V'N • -2oV o--~I-f

1----....-o+VOUT =ISVAT100mA

.........- -...-0

-VOUT

=-ISV AT 100 mA
TL/HI7744-12

Variable Output Regulator 0.5V·18V

~-~---+---------~--~--oVOUT

+

II

TI"F

C3-

30 pF
TUH/7744-13

'Solid tantalum.

= VG + 5V, RI = (-VIN"O LM78LOsl
VOUT = 5V (R2/R4) lor (R2 + R3) = (R4 + R5)
A 0.5V output will correspond to (R2/R4) = 0.1 (R3/R4) = 0.9
VOUT

1·167

:5~d
pNa'tional

Semiconductor

LM78XX Series Voltage Regulators
General Description
The LM78XX series of three terminal regulators is available
with several fixed output voltages making them useful in a
wide range of applications. One of these is local on card
regulation, eliminating the distribution problems associated
with single point regulation. The voltages available .allow
these regulators to be used in logic systems, instrumentation, HiFi, and other solid state electronic equipment. Although designed primarily as fixed voltage regulators these
devices can be used with external components' to obtain
adjustable voltages and currents"
The LM78XX series is available in an aluminum TO-3 package which will allow over 1.0A load current if adequate'heat
sinking is provided. Current limiting is included to limit the
peak output current to a safe value. Safe area protection for
the output transistor is provided to limit internal power dissipation. If internal power diSSipation becomes too high for
the heat· sinking provided, the thermal shutdown circuit
takes over preventing the IC from overheating.

of external components. It is not necessary to bypass the
output, although this does improve transient response. Input
bypassing is needed only if the regulator is located far from
the filter capacitor of the power supply.
'For output voltage other than 5V, 12V and 15V the LM117
series provides an output voltage range from 1.2V to 57V.

Features
•
•
•
.•
•
•

Output current in excess of 1A
Internal thermal overload protection
No external components required
Output transistor safe area protection
Internal short circuit current limit
Available in the aluminum TO-3 package

Voltage Range

Considerable effort was expanded to make the' LM78XX series of regulators easy to use and mininize the number

LM7805C

5V

LM7812C

12V
15V

LM7815C

Schematic and Connection Diagrams
r - -.....- - - -.....- - - -......- - t - 'NPUT

Metal Can Package
TO-3(K)
Aluminum

OUTPUTDD

o

0

INPUT
"1&

TL/H/7746-2

D.l

...---+--....- ................----+----+-DUTtUT
"U

"'

l"

BoHomVlew
Order Number LM7805CK,
LM7812CK or LM7815CK
See NS Package Number KC02A
Plastic Package
TO-220m

,""...
TL/HI7746-3

Top View
Order Number LM7805CT,
LM7812CTor LM7815CT
See NS Package Number T03B

"'

1.n

TL/H/77~6-1

1-168

r-

!:

Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.

Maximum Junction Temperature
(KPackage)
(T Package)

Input Voltage (VA = 5V,12Vand 15V)

Storage Temperature Range

35V

Internal Power Dissipation (Note 1)

Internally Limited

(TAl

O'Cto +70'C

Operating Temperature Range

~

150'C
150'C

><
><

-65'Cto + 150'C

Lead Temperature (Soldering, 10 sec.)
TO·3 Package K
TO·220 Package T

300'C
230'C

Electrical Characteristics lM78XXC (Note 2) O'C,;; Tj ,;; 125'C unless otherwise noted.

Symbol
Va

Output Voltage

5V

12V

l5V

Input Voltage (unless otherwise noted)

10V

19V

23V

Parameter
Output Voltage

Conditions'

Min

. Line Regulation

V

Po';; 15W,5mA,;; 10';; lA

4.75
5.25 11.4
12.6 14.25
15.75
(7.5 ,;; VIN ,;; 20) (14.5 ,;; VIN ,;; 27) (17.5';; VIN ,;; 30)

V
V

10 = 500mA Tj = 25'C

.6.VIN
10';; lA

Tj = 25'C
AVIN
O'C';; Tj ,;; + 125'C
AVIN

la

Quiescent Current

Ala

Quiescent Current
Change

Tj = 25'C

12

12.5

14.4

15

4
120
14.5';; VIN ,;; 30)

4
150
(17.5 ,;; VIN ,;; 30)

mV
V

50
(8';; VIN';; 20)

120
(15,;; VIN ,;; 27)

150
(18.5 ,;; VIN ,;; 30)

mV
V

50
120
(7.5 ,;; VIN ,;; 20) (14.6 ,;; VIN ,;; 27)

150
(17.7 ,;; VIN ,;; 30)

mV
V

25
(8';; VIN ,;; 12)

60
(16,;; VIN ,;; 22)

75
(20 ,;; VIN ,;; 26)

mV
V

10

12

12

150
75

mV
mV

50
25

120
60
120

150

mV

10';; lA

8
8.5

8
8.5

8
8.5

mA
mA

0.5

0.5

0.5

mA

1.0
(7.5 ,;; VIN ,;; 20)

1.0
(14.8 ,;; VIN';; 27)

1.0
(17.9 ,;; VIN ,;; 30)

mA
V

1.0
(7';; VIN';; 25)

1.0
(14.S';; VIN';; 30)

1.0
(17.5 ,;; VIN ,;; 30)

mA
V

Tj = 25'C
O'C';; T/ ,;; + 125'C

5 mA,;; 10';; lA
Tj = 25'C, 10 ,;; lA

Output Noise Voltage TA =25'C, 10 Hz,;; I,;; 100 kHz

AVOUT

11.5

50

10';; 500 mA, O'C ,;; Tj ,;; + 125'C

Ripple Rejection

5.2

5mA,;; 10';; lA,O'C ,;;Tj,;; + 125'C

VMIN ,;; VIN ,;; VMAX

AVIN

5

3
50
(7';; VIN';; 25)

5mA,;; 10';; 1.5A
250 mA ,;; 10 ,;; 750 mA

VMIN ,;; VIN ,;; VMAX

VN

Units

I Typ I Max
15.6

O'C';; Tj,;; +125'C

Load Regulation

Min

4.8

AVIN

AVo

I I Max

Min Typ

Tj = 25'C, 5 mA,;; 10';; lA

VMIN ,;; VIN ,;; VMAX
AVo

1Typ IMax

{
1= 120Hz

40

10';; lA, Tj = 2S'Cor
10';; SOOmA
O'C';; Tj,;; +12S'C

62
62

80

75
5S
55

72

54
54

90

".V

70

dB
dB

(8';; VIN ,;; 18)

(15';; VIN ,;; 25)

(18.5 ,;; VIN ,;; 28.5)

V

Ro

Tj = 2S'C, lOUT = 1A
1 = 1 kHz
Tj = 2S'C
Tj = 2S'C
Average TC 01 VOUT O'C';; Tj,;; +125'C,10 = SmA

2.0
8
2.1
2.4
0.6

2.0
18
l.S
2.4
1.5

2.0
19
1.2
2.4
1.8

V
mil
A
A
mV/'C

VIN

Input Voltage
Required to Maintain Tj = 25'C, 10 ,;; lA
Line Regulation

7.S

VMIN ,;; VIN ,;; VMAX
Dropout Voltage
Output Resistance
Short-Circuit Current
Peak Output Current

14.6

17.7

V

Note 1: Thermal resistance of the TO·3 package (K, KC) is typically 4'C/W junction to case and 3S'C/W case to ambient. Thermal resistance of the TO-220
package (T) is typically 4'C/W junction to case and Sf1'C/W case to ambient.
Note 2: All characteristics are measured with capaCitor across the input of 0.22 ,.F, and a capaCitor across the output of 0.1 ,.F. All characteristics except noise
voltage and ripple rejection ratio are measured using pulse techniques (Iw ,; 10 ms, duty cycle,; S%). Output voltage changes due to changes In internal
temperature must be taken into account separately.
1-169

•

Typical Performance Characteristics
Maximum Average Power
Dissipation
Zi

-

..

~

20

i

15

!..

Maximum Average Power
Dissipation
.25

TO·3

INFINITE
HEATSINK

I I

.E

WITH 10 C/W HEAT SINK'

18

!i

...... .......

NO HUTSINK

~

-t-I.

$

!.

"
\

0

10

2

15

50

.......

Ripple Rejection

Etun

~ 0.110

iD

.80

..

iD

5

BO

40

!

10

20

ir

60

~
tir

0.115

~

~

~ 0.110

:; 0.175
0.970
~15 -50 ~25 0

25 50 '75 10D 125 ISO

10

JUNCTION TEMPERATURE ( CI

...
i.
..~

V,N -IOV
VOUT" IV
'OUT' 500mA
Ti' 2rC

<

Electrical Characteristics LM79M12C, LM79M15C
Conditions unless otherwise noted: lOUT

=

350 mA, CIN

=

2.2

,...F, COUT = 1 ,...F, O°C :S: TJ :S: + 125°C
LM79M12C

LM79M15C'

Output Voltage

-12V

-15V

Input Voltage (Unless Otherwise Specified)

-19V

-23V

Part Number

Symbol
Vo

Parameter
Output Voltage

Conditions
TJ

= 25°C
s: lOUT s: 350 mA

5 mA

I:.vo

Line Regulation

TJ

Load Regulation

TJ = 25°C, (Note 3)
5 rnA s: lOUT s: 0.5A

10

Quiescent Current

TJ

1110

Quiescent Current
Change

With Input Voltage

lOMAX

f = 120Hz

Typ,

Max

-14.4

-15.0

-15.6

V
V

s: VIN s:

-15.75
-10.5),

,-12.5

s: VIN s:

-12.6
-14.5)

(-30

s: VIN s:

(-30

s: VIN s: -17.5)

(-25

s:

(-26

s: VIN ~

80
-14.5)
3
50
VIN s: - 15)

-14.25 '
(-30

5,

5

30

30

3

1.5

s: VIN s:

0.4
-14.5)

(-30

s: VIN s:

0.4
400
54
(-25

= 25°C, lOUT = 0.5A
TJ = 25°C
lOUT = 5mA,
O'C s: TJ s: 100'C
TJ

-15)

54
(-30

50

rnV

240

mV

3

rnA

0.4
-27)

mA

0.4

rnA
p.V

70

s: VIN s:

mV

-18)

400

70

s: VIN s:

80

3

240

...CD'
til

Min

-12.0

s: 350 mA

Ripple Rejection

Units

-11.4
(-27

(-30

TA = 25°C,
10HzS:fS:l00Hz

Peak Output Current

-11.5

1.5

Output Noise Voltage

Average Temperature
Coefficient of
Output Voltage

Max

= 25°C

With Load,
5 mA s: lOUT

Dropout Voltage

Typ

= 25°C (Note 3)

I1Vo

Vn

Min

><

en
CD

dB
-17.5)

1.1

1.1

V

800

800

mA

-0.8

-1.0

mV/,C

Note 1: Absolute Maximum Ratings Indicate limits beyond which damage to the device may occur. Operating Ratings Indicate condHlons for which the device is
intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: Refer to Typical Performance Characteristics and Design Considerations for details,
Note 3: Regulation is measued at a constant junction temperature by pulse testing with a low duty cycle. Changes in outPut voHage due to heating effects must be
taken into account.

II

1·173

Typical Performance Characteristics
Output Voltage vs
Temperature
1.0 I
.~ 1.005

~

I
~

I

1.00

0.995

Ripple Rejection

I

I

I

T-

VOUT '-12V,-15V

0.990

-

1.0 I
1.005

I-

1.00

Your = -5V

0.995
0.990
-50 -25

I
0

25

W-2 '-_L-_L-_'-_'----J

20
O.Olk

50 75 100 125 150

O.lk

JUNCTION T,EMPERATURE (OC)

LM79M05

~

~

1.4

~

~

1,6

1.0
0.8

f""':

0.6
0.4

-

Tj = DoC

o

0.1

1.2

~

1.15

/

TJ= 2S D C

1.2

.!'.
~

... l-t:Zo f-'"
:;;;.or

Tj ,I250C

B

1.1

i

1.05

0.3

0.95
0.9
0.4

Tl = t250C

0.5

5

10

IS

20

25

35

i

0.50

Tj 'I125 0 C

-=~ ~

!;!

Tj ' 25°C

~

=

TJ DoC

O. I

0.25

t .... ~

~ V5~C/W

14
12

is

8

10

..........

~

~

C

o
5

10

15

20

25

30

35

o

40

"

r--...

0.3

0.4

0.5

NO HEAT SINK 25

JEAT SIJK-

'" ............:

~H{.;T~

:c

o

o

0.2

I

J
I

16

~

2i

~

Tj ' I2

I--

I

40

18

"g

1.0

r---:=

1.0
0.9
0.8

20

1.25

5

Tji250C I -

Maximum Average Power
Dissipation (TO-220)

1.50

0.75

Tjl,OOC

1.1

OUTPUT CURRENT (A)

Short-Circuit Current

I

1M

1.2

INPUT VOLTAGE (V)

OUTPUT CURRENT (A)

:5

~
§

l..-'

30

1.3

iB

V

Tji25jC- I"-

..

<7

I
I

0.2

.!'.

1.0

:;

lOOk

I
I

LM79Y05
1.4

-;;:

,

10k

Quiescent Current vs
Load Current

1.25

-;;:

2.0
1.8

Ik

FREOUENCY (Hz)

1,3

2.2

~

O.Olk O.lk

lOOk

Quiescent Current vs
Input Voltage

2.4

!i!

10k

Ik

FREQUENCY (Hz)

Minimum Input-Output
Differential

:E

Output Impedance

100 """""nmr..,-;mn",,,,--.,-=m

50

-"

75

~

100

125

AMBIENT TEMPERATURE (OC)

IVIN-VOUTI (V)

TL/H/I0483-IO

1-174

r-

s:::
.....
s:::

Schematic Diagrams

CD

-5V

><
><

en
CD

-=

~

A18
4k

ii'

A19
5k

til

R17
5.4k

./--+--....--0 VaUT
03
6.2V

A2l A16

150 0.05

V,No-~-~-~--~--O-~~--4---------~-~------------~
TL/H/l0483-8

-12Vand -15V

A18
4k

A19
5k

R17
l1.7k (8V)
20.1k (12V)
26.4k (15V)
o/--~"""-OVOUT

03
6.2V

A20
20k

A2l A16
50 0.05

V'No-~-~~~--4--4--4---~-------~~-~-----------~
TUH/l0483-9

1·175

•

o

II)

r------------------------------------------------------------------------------------------,

"C

Design Considerations

Typical Applications

(/)

The LM79MXX fixed voltage regulator series have thermaloverload protectiol'1 from excessive power, Internal short-circuit protection which limits the circuit's maximum current,
and output transistor safe-area compensation for reducing
the output current as the voltage across the pass transistor
is increased.
Although the internal power dissipation is limited, the junction temperature must be kept below the maximum specified temperature in order to meet data sheet specifications.
To calculate the maximum junction temperature or heat sink
required, the following thermal resistance values should be
used:

Bypass capacitors are necessary for stable operation of the
LM79MXX series. of regulators over the input voltage and
output current ranges. Output bypass capacitors will improve the transient response of the regulator.
The bypass capacitors (2.2 p.F on the input, 1.0 p.F on the
output), should be ceramic or solid tantalum which have
good high frequency characteristics. If aluminum electroiytics are used, their values should be 10 p.F or larger. The
bypass capacitors should be mounted with the, shortest
leads, and if possible, directly across the regulator terminals.
Fixed Regulator

G)

><
><

:E

~

:i

Package
TO-220

9JC

9JA

('C/W)

(,C/W)

3

40

1-.....-0 OUTPUT
P
_ TJMax-TA
OMAX - 9JC + 9CA or

(1)

TL/HI10483-2

'Required if regulator Is separated from fiRer capacRor by more than 3'.
For value given. capaCitor must be solid tantalum. 25 ,.F aluminum electrolytiC may be substituted.
tRoquired for stability. For value given. capacitor must be solid tantalum,
25 ,.F aluminum electrolytic may be substituted. Values gillen may be
Increased without limit.
'
For output capacitance in excess of 100 ,.F, a high cunrent diode from
Input to output (I N400l, etc,) will protect the regulator from momentary
Input shorts.

TJMax - TA (Without a Hailt Sink)
9JA
9CA = 9cs + 9SA
Solving for TJ:
TJ = TA -l; Po (9JC + 9CA) or
= TA = + P09JA (Without a Heat Sink)
Where
TJ
= Junction Temperature
TA = Ambient Temper~ture
Po = Power Dissipation
9JC = Junction-to-Case Thermal Resistance
9CA = Case-to-Ambient Thermal Resistance
9cs = Case-to-Heat Sink Thermal Resistance
9SA = Heat Sink-to-Ambient Thermal Resistance,
9JA = Junction-to-Ambient Thermal Resistance

Variable Output .

Cl
2.2#r
SOLID
TANTALUM
INPUT 0-.....--1

1--...- -....-0 OUTPUT
TLIH/I0483-3

'Improves transient response and ripple rejection.
Do not increase beyond 50 ,.F.
.

VOUT=VSET

+ R2)
~

(RI

Select R2 as follows:
LM79M05C
300n
LM79MI2C
750n
LM79MI5C
Ik

1-176

r-----------------------------------------------------------------------------, r

!i:

Typical Applications (Continued)

~

!i:

± 15V, 1 Amp Tracking Regulators
+VIN

I
I
I
I
I
I

RS·
10k
1%

T

I
I
I
I

m
01
lN4001

COMMON

I
I

CS··
2SJ.lF

~

:::!"

R4·
10k
1%

ct· ..J.!
2SJ.lF

~

VOUT +ISV

..J.!

Rl
SO

R3
Sk
OUTPUT TRIM
TO -IS.0V

T

02
lN4001
VOUT -ISV

-VIN

TUH/l0483-1

Load Regulation at 0.5A
Output Ripple, CIN = 3000 /LF, IL = 0.5A
Temperature Stability
Output Noise 10 Hz ~ f ~ 10 kHz

Performance (Typical)
(-15)
(+15)
40mV
2mV
100/LVrms
100/LVrms
50mV
50mV
150/LVrms
150/LVrms

"Resistor tolerance of R4 and R5 determine
matching of (+) and (-) outputs.
""Necessary only if raw supply flIter capacitors
are more than 3 H from ~~gulators.

Dual Trimmed Supply
+INPUT

....-~'"""~'"""------4~-o +S.OV

o----4~

Ik
0.22 ).IF

01
lN4001

---+-+-.....--+--<:I COM

0----4.....----4.....

02

2.2 ).IF

INPUT

o---4H

lN4001

....- .....- .....- ....- -....- 0 -S.OV
TL/H/l0483-4

II

1-177

-~= tflNational Semiconduc~or
LM79XX Series 3·Terminal Negative Regulators
General Description
The LM79XX series of 3-terminal regulators is 'available with
fixed output voltages of -5V, -8V, -12V, and -15V.
These devices need only one external component-a compensation capacitor at the output. The LM79XX series is
packaged in the TO-220 power package and is -capable of
supplying 1.5A of output current.
These regulators employ internal current limiting SlIfe area
protection and thermal shutdown for protection against virtually all overload conditions.
Low ground pin current of the LM79XX series allows output
voltage to be easily boosted above the preset value with a
resistor divider. The low quiescent current drain of

Connection Diagrams

these devices with a specified maximum change with line
and load ensures good regulation in the voltage boosted
mode.
For applications requiring other voltages, see LM137 data
sheet. -

Features
•
•
•
•

Thermal, short circuit and safe area protection
High ripple rejection
1.5A output current
4% tolerance on preset output voltage

Typical Applications

TO·220 Package

Fixed Regulator

.J:. ...l!:.
el* -I
~IZ_2pF
-

OUTPUT,

o

1:::::===:::>
o

INPUT

-

...l!:. ezt

GND

IN LM19XXeT OUT

- I.F
OUTPUT

INPUT
TUHI7340-3

GROUND
TUH/7340-14

FrontVle~

Order Number LM7905CT. LM7912CT or LM7915CT
See NS Package Number T03B

"Required if regulator is separated from filter capacitor by
more than S". For value given, capacitor must be solid
tantalum. 25 p.F aluminum electrolytic may be substituted.
tRequired for stability. For value given, capacitor must be
solid tantalum. 25 p.F aluminum electrolytic may be substituted. Values given may be increased without limit.
For output capacitance In excess of 100 p.F, a high current
diode from input to output (1 N4001, etc.) will protect the
regulator from momentary input shorts.

1-178

r-

s::
......

Absolute Maximum Ratings (Note 1)

CO

If Military/Aerospace specified devices are required,
please contact the National 'Semiconductor Sales
Office/Distributors for availability and specifications.

Input·Output Differential
(VO = -5V)
(VO = -12Vand -15V)

Input Voltage
(Vo = -5V)
(Vo = -12Vand -15V)

Power Dissipation (Note 2)
Internally Limited
Operating Junction Temperature Range
O"Cto +125'C
Storage Temperature Range
-65'C to + 150'C

-25V
-35V

25V
30V

Lead Temperature (Soldering, 10 sec.)

Electrical Characteristics Conditions unless otherwise noted: lOUT =
O'C

~

TJ

~

+ 125'C, Power DiSSipation

~

500 mA, CIN = 2.2 p.F, COUT = 1 p.F,

1.5W.

Part Number

Symbol

LM790SC

Output Voltage

..:sv

Input Voltage (unless otherwise specHled)

-10V

Parameter

Conditions

Vo

Output Voltage

TJ = 25'C
5 mA ~ lOUT ~ 1A,
P ~ 15W

AVO

Line Regulation

TJ = 25'C, (Note 3)

AVO

Load Regulation

I

Min
-4.8
-4.75

(-20

TJ = 25'C

Quiescent Current
Change

With Line

(-25

~

(-12

~

(-25
With Load, 5 mA

~

Output Noise Voltage

TA = 25'C, 10Hz

Ripple Rejection

1 = 120Hz

~

lOUT

VIN
8
VIN
2
VIN

~

~

VIN

~

-7)

~

-7)

~

-8)

1 ~ 100Hz

~

VIN

mV
V
mV
V

100
50

mV
mV

2

mA

0.5

mA

0.5

mA

V

dB
~

-8)

V

Dropout Voltage

TJ = 25'C,IOUT = 1A

1.1

V

Peak Output Current

TJ = 25'C

2.2

A

Average Temperature
Coefficient 01
Output Voltage

lOUT = 5mA,
OC ~TJ ~ 100"C

0.4

mVl'C

Typical Applications (Continued)
Variable Output

Cl

+

SOLID

-

L;

.ltC3*
Z5"F

- -=

~

Rl

TANTALUM

-.!.M

RZ

GND
INPUT

IN

~
cz

Z,hF- ....

LM19XXCT

loUT

I

- TANTALUM
I~sOLID
OUTPUT

TLlH/7340-2

'Improves transient response and ripple rejection. Do not increase beyond 50 ,.F.
VOUT=VSET

50

p.V

66
~

V
V
V

-7)

125
54

Max
-5.2
-5.25

15

1A

(-18

lOMAX

~

1

Quiescent Current

I

Typ

15
5

la

Units

-5.0

TJ = 25'C, (Note 3)
5 mA ~ lOUT ~ 1.5A
250 mA ~ lOUT ~ 750 mA

Ala

Vn

230'C

(Rl
+ R2)
~

Select R2 as follows:
LM7905CT
3000
LM7912CT
7500
LM7915CT
lk

1·179

><
><

Electrical Characteristics (Continued) Conditions unless otherwise noted:
= 1 p.F,O°C ::;: TJ ::;: + 125°C, Power Dissipation = 1.5W.

lOUT = 500 mA, CIN = 2.2 /LF,

COUT

Symbol

Part Number

LM7912C

LM7915C

Output Voltage

-12V

-15V

Input Voltage (unless otherwise specified)

-19V

-23V

Parameter

'Conditions

Min

Va

Output Voltage

TJ = 25°C
5mA::;: lOUT::;: 1A,
P::;: 15W

aVo

Line Regulation

TJ

aVO

Load Regulation

TJ = 25°C, (Note 3)
5mA::;: lOUT::;: 1.5A
250 mA ::;: lOUT::;: 750 mA

-11.5
-11.4
(-27

= 25°C, (Note 3)

Quiescent Current

TJ

ala

Quiescent Current
Change

With Line

Vn

Output Noise Voltage

TA

Ripple Rejection

1 = 120Hz

Dropout Voltage

TJ

Peak Output Current

TJ

I

Max

I

Min

Typ

I

Max

-14.4 -15.0 -15.6
-14.25
-15.75
(-30::;: VIN ::;: -17.5)

V
V
V

5
80
(-30::;: VIN ::;: -14.5)
3
30
(-22::;: VIN ::;: -16)

5
100
(-30::;: VIN::;: -17.5)
3
50
(-26::;: VIN ::;: -20)

mV
V
mV
V

15
5

200
75

15
5

200
75

mV
mV

1.5

3

1.5

3

mA

s:

-12.5
-12.6
VIN::;: -14.5)

0.5
(-30::;: VIN::;: -14.5)
0.5

With Load, 5 mA ::;: lOUT::;: 1A

= 25°C,10Hz::;: f::;:

Typ
-12.0

= 25°C

IQ

lOMAX

I

'Units

0.5
(-30 ::;:VIN ::;: -17.5)
0.5

mA
V
mA

300

375

/LV

54
70
(-25::;: VIN ::;: -15)

54
70
(-30::;: VIN::;: -17.5)

dB
V

1.1

1.1

V

2:2

2;2

A

100Hz

= 25°C, lOUT ':= ,1A
= 25°C
lOUT = 5mA,

mVloC
-1.0
-0.8
Average Temperature
Coefficient 01
OC::;: TJ ::;: 1000C
OutputVoltage
Nate 1: Absolute Maximum Ratings indicate limits beyond which damage'to the device may occur. Operating Ratings Indicate conditions for which the device Is
Intended to be functional, but do not guarantee Specific Performance limits. For guaranteed specHications and test conditions, see the, Electrical Characteristics. Nate 2: Refer to Typical Performance Characteristics lind Design: Considerations for details.
Nate 3: Regulation Is measured at a'constantjunction temperature by pulse testing with a low duty cycle. Changes In output voltage due to heating effects must be
taken Into account.
"

Typical Applications (Continued)
Dual Trimmed Supply
+INPUT 0---

~

;

+5.0V

LM340-5 ;OUT
GND
240

0.22 j'F::

• r' Dl

1k

~ .. lN4001

33
COM
+
2.2 j'F::=

33

:
470

5k' ,

+
;1 j'F _
'

D2
. to-~ lN4001

GND
-INPUT 0---

~

LM7905

IlOUT

-5.0V
TL/HI7S40-4

1-180

rs:
......

Design Considerations

CD

The LM79XX fixed voltage regulator series has thermal
overload protection from excessive power dissipation, internal short circuit protection which limits the circuit's maximum current, and output transistor safe-area compensation
for reducing the output current as the voltage across the
pass transistor is increased.

TJ

.;= Junction Temperature
T A = Ambient Temperature
= Power Dissipation
= Junction-to-Ambient Thermal Resistance
9JC = Junction-to-Case Thermal Resistance

Po

9JA

Although the internal power dissipation is limited, the junction temperature must be kept below the maximum specified temperature (125·C) in order to meet data sheet specifications. To calculate the maximum junction temperature or
heat sink required, the following thermal resistance values
should be used:

Package
TO-220

Typ

Max

Typ

tlJC

tlJC

tlJA

tlJA'

'C/W

·C/W

'C/W

'C/W

3.0

5.0

60

40

9CA = Case-to-Ambient Thermal Resistance
9cs = Case-to-Heat Sink Thermal Resistance
9SA = Heat Sink-to-Ambient Thermal Resistance

Typical Applications (Continued)
Bypass capacitors are necessary for stable operation of the
LM79XX series of regulators over the input voltage and output current ranges. Output bypass capacitors will improve
the transient response by the regulator.

Max

The bypass capacitors, (2.2 ,...F on the input, 1.0 ,...F on the
output) should be ceramic or solid tantalum which have
good high frequency characteristics. If aluminum electrolytics are used, their values should be 10 ,...F or larger. The
bypass capacitors should be mounted with the shortest
leads, and if possible, directly across the regulator terminals.

P
TJMax-TA TJMaxTA
o MAX = tlJC + tlCA or~
tlCA = tics

+ tlSA (without heat sink)

Solving for T J:
TJ = TA
= TA

><
><

Where:

+ Po (tlJC + ticAl or
+ P09JA (without heat sink)

High Stability 1 Amp Regulator

- ...--....--...----...

...-

-~P-------_=

+ C3

VOUT (+)

Dl
LM320

-1 pF

7V
R2·

+ Cl tt
- 2.2 pF

+ C2tt

2N40~

IN

- 10 pF

1=;+--...- - - - - - - -..........-

VOUT (-)
TL/H17340-5

Load and line regulation < 0.01 % temperature stability ,;; 0.2%

II

tDeterrnlne Zener current
ttSolid tantalum
'Select resistors to set output voltage. 2 ppmrC tracking suggested

1-181

Typical Applications (Continued)

e

Current Sour..

2.21'F

O.,II'F

+

SOLID
TANTALUM

Rl·
INPUT
'lOUT

~

1 rnA

+~

TL/H17340-7

R1

Light Controller Using Silicon Photo Cell
I
I
I
I

SV- ISV
BULB
1.7SA
MAX TURN-ON
CURRENT

CIt ...J!

2SI'F""r
I
I
I
I

TLlHI7340-8
'Lamp brightness increase until II

~

ie (:::: 1 rnA)

+

SVlR1. '

tNecessary only if raw supply filler capacilOr is more than 2" from LM790SCT

1-182

ri:

Typical Applications (Continued)

~

><

Hlgh·Sensltlvlty Light Controller
I
I
I

av- 15V
BULB
1.7SA
MAX TURN-ON
CURRENT

I
CIt ...J.!.

2SJ.lF""r
I
I
I
I

TL/H17340-9
'lamp brightness increases until i, = 5V1Rl (I, can be sat as low as I pA)
tNecessary only If raw supply lilter capacitor is more than 2" lrom LM7905

± 15V, 1 Amp Tracking Regulators
+VIN

o-....___:;.;IN..

-.:O;.;;U;.;.T-4~_ _ _ _ _" "_ _ _~_ _""-O VOUT

(+) ISV

R4'
10k

1%

7

C4"

...!!.

RS'
10k

6

25J.1F -;-

Dl
lN4001

1%
I
I
I
I

Cl
25 J.lF

...-----....- ....--+-------t--+--....-o COMMON
cs"

Rl
SO

...!!.

25J.1F -;-

R2
lk

C2
2SJ.lF

R3
5k

+
D2
IN4001

"'-".IYv-lK OUTPUT

TRIM
TO -IS.OV

I
I
I
-VIN O-"---":lIN~

t:O~U':"T...- - - - - - - - -....- -....--0 VOUT (-) 15V
TUH17340-1
(-15)

(+15)

2mV
Load Regulation at ~IL = lA
40mV
Output Ripple. C'N = 3000 "F, IL = IA
100 "Vrms
100 "Vrms
Temperature Stability
50mV
50mV
Output Noise 10 Hz,; I,; 10 kHz
150 "Vrms
150 "Vrms
'Resistor tolerance 01 R4 and R5 determine matching of (+) and (-)
outputs.
"Necessary only il raw supply filter capacitors are more than 3" Irom regulators.

1-183

LM19XX

W
:::r
CD

-~

-~

( ;'

C

':'

01

_.&.

U,

~
.

02:

RIB
4k

iii'

~

fR 19

S»

"

3

.
R6

fI)

7k

R5

~

'"I

I "r

" ..~ to'"~' d'" r

~"."I

I Fi h

OVM

~.,'•
~R20

R4
20k

20 pF

RB

20k

Y'N

R9

20k

Y 20.

R 13

R21

5.

150

RIB
0.2
TLlH17340-12

I

en
n
:::r
CD

3
I»
c;"

-12Vand -15V

c

iii"

":'

R18
4k

ea

iil

R19
5k

3(I)
g>

a

1'"
R17

'1 ra J r

~

0>

01

I,

OVOUT

OJ
6.2V

012
R20
20k
R4
20k

1 1I i i 1 1
RJ
6k

V'NO

11

_n

~~1 i

R16
0.2

TLlH17340-13

XX6lW1

II

Section 2
Low Dropout
Voltage Regulators

•

Section 2 Contents
Low Dropout Voltage Regulators-Definition ofTerms .................•................
Low Dropout Regulators-Selection Guide .......•.......•..................•.........
LM330 3-Terminal Positive Regulator........ .....•.... .............. ......... ........
LM2925 Low Dropout Regulator with Delayed Reset • . . . . . . . . . . . . . . . . . • . . . . . . . . . . . • . . . . .
LM29261 LM2927 Low Dropout Regulators with Delayed Reset. . . . . . . . . . . . . . . . . . . . . . . . . . .
LM2930 3-Terminal Positive Regulator ......................................... '" ....
LM2931 Series Low Dropout Regulators. . . . . . . . . . . . . . . . . .. . . . . . . . ... . . •. .. .•. . . .. . . . ..
LM2935 Low Dropout Dual Regulator ......... . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . .
LM2936 Ultra-Low Quiescent Current 5V Regulator. . . . . . . • . . . . . . • . . . • . . . . . . . . • . . . • . . . • .
LM2937 500 mA Low Dropout Regulator ..............................................
LM2940/LM2940C 1A Low Dropout Regulators..................................... ...
LM2941/LM2941C 1A Low Dropout Adjustable Regulators..............................
LM2984 Microprocessor Power Supply System. . . . . . . .. . . . .. .. . . . . . . .. . . . .. . . . . . . . . . . . .
LM2990 Negative Low Dropout Regulator .............................................
LM2991 Negative Low Dropout Adjustable Regulator .•...•..•........•.................
LM3420-4.2, -8.4, -12.6 Lithium-Ion Battery Charge Controller . • . . . • . . . • . . . • . . . . . . • . . . . . . .
LM3940 1A Low Dropout Regulator for 5V to 3.3V Conversion. . . . . . . . . . . . . . . . . . . • . . . . . . . .
LP29501 A-XX and LP2951 I A-XX Series of Adjustable Micropower Voltage Regulators.. • . . .
LP2952/LP2952A1LP2953/LP2953A Adjustable Micropower Low-Dropout Voltage
Regulators... ..... ......... ...... ... ......•..........•.......... ....... .... ... ..
LP2954/LP2954A 5V Micropower Low-Dropout Voltage Regulators. . . . . .. . .. . . . . .. . . .. . . .
LP2956/LP2956A Dual Micropower Low-Dropout Voltage Regulators.....................
LP2957 ILP2957A 5V Low-Dropout Regulator for ,...p Applications. . . . . . . . • . . . . . . . . . . . . . . . .
LP2980 Micropower SOT, 50 mA Ultra Low-Dropout Regulator. . . . . . . . . . . . . . . • . . . . . . . . . . .

2-2

2-3
2-4
2-5
2-9
2-15
2-23
2-29
2-37
2-45
2-50
2-55
2-65
2-72
2-85
2-92
2-99
2-111
2-116
2-131
2-146
2-153
2-166
2-177

f}1National Semiconductor

~c

a

-

"0

o
C

. Low-Dropout Voltage Regulators
Definition of Terms

<
o

iif

CQ

CD

:::D
CD

CQ
C

Dropout Voltage: The input-voltage differential at which
the circuit ceases to regulate against further reduction in
input voltage. Measured when the output voltage has
dropped 100 mV from the nominal value obtained at (VOUT
+ 5V) input, dropout voltage is dependent upon load current and junction temperature.

Load Regulation: The change in output voltage ·for a
change in load current at constant chip temperature.

~

Long Term Stability: Output voltage stability under accelerated life-test conditions after 1000. hours with maximum
rated voltag·e and junction ·temperatiJre.

-

Output Nolil~ Voltage: The rms AC voltage at the output,
with constant load and no input ripple; measured over a
specified frequency range.

Input Voltage: The DC voltage applied to the input terminals with respect to ground.
Input-Output Differential: The voltage difference between
the unregulated input voltage and the regulated output voltage for which the regulator will operate.

Quiescent Current: That part of the p~sitiye input current
that does not contribute to the positive load current. The
regulator' ground lead current.

Line Regulation: The change in output voltage for a
change in the input voltage. The measurement is made under conditions of low dissipation or by using pulse techniques such that the average chip temperature is not significantly affected.

Ripple Rejection: The ratio of the peak-to-peak input ripple
voltage to the peak-to-peak output ripple voltage.
.

Temperatu~e Stability of Vo: The percentage change in
output voltage for a thermal variation from room tempera. ture to either temperature extreme.

2-3

UI

cCD

:::;:i"

o·
:::::II

9.
';;}
~

3
o

Low Dropout Regulators Selection Guide

Output
Current
(A)
1.0
0.75
0.5

0.1

I\J

.j,.

0.05

Device

Output
Voltage
(V)

LM2940
LM2940C
LM2925
LM2935
LM2926
LM2927
LM2937
LM2984
LM2931
LM2931C
LP2950C
LP2950AC
LP2951
LP2951C
LP2951AC
LM2936

5,8,12,15
5,9,12,15
5
Two 5V Oulpuls
5
5
5,8,10,12,15
Three 5V Outputs
5
Adj. (3 10 29)
5
5
5, Adj. (1.24V 10 29)
3.0, 3.3, 5, Adj. (1.24V to 29)
3.0, 3.3, 5, Adj. (1.24V to 29)
5

Typical
Dropout
Voltage
(V)'
0.50
0.50
0.82
0.82
0.35
0.35
0.50
0.53
0.30
0.30
0.38
0.38
0.38
0.38
0.38
0.4

Maximum
Input
Voltage
(V)
26
26
26
26
26
26
26
26
24
24
30
30
30
30
30
40

*Guaranteed maximum dropout voltage at full load over temperature.
··Positive transient protection value also indicates the regulator's load dump capability.

Typical
Quiescent
Current
(mA)
10
10
3
3
2
2
2
14
0.400
0.400
0.075
0.075
0.075
0.075
0.075
0.009

Reverse
Polarity
Protection
(V)

-15
-15
-15
-15
-18
-18
-15
-15
-15
-15

-15

Transient
. Protection
(V)

Operating
Temperature
(Tj'C)

Page
No.

+60"/-50
+45/-45
+60"/-50
+60"/-50
+80"/-50
+80"/-50
+60"/-50
+60"/-35
+60"/-50
+60"/-50

-5510 +150
010+150
-4010 +150
-4010 +150
-4010 +125
-4010 + 125
-40 to +125
-40 to +150
-40 to +125
-40 to +125
-4010 +125·
-4010 +125
-55to +150
-4010 +125
-4010 +125
-4010 +125

2-55
2-55
2-9
2·37
2-15
2-15
2-50
2-72
2-29
2-29
2-116
2-116
2-116
2-116
2-116
2-45

+60/-50

~
~
~

...
.....

r

0

:e

c
"'"
0

"tJ

0

C

<:)

=

~

V)

C\)

....~
(")

::D
C'D
ca

0

D)

(")

-c

0
"",.

til

en
C'D

-n

C'D

O·

::s
Q

c

a:
C'D

~

~
~

......
0
""'t

I!J1National Semiconductor

LM330 3-Terminal Positive Regulator
General Description

Features

The LM330 5V 3-terminal positive voltage regulator features
an ability to source 150 mA of output current with an inputoutput differential of 0.6V or less. Familiar regulator features
such as current limit and thermal overload protection are
also provided.

•
•
•
•
•
•
•
•

The low dropout voltage makes the LM330 useful for certain
battery applications since this feature allows a longer battery discharge before the output falls out of regulation. For
example, a battery supplying the regulator input voltage may
discharge to 5.6V and still properly regulate the system and
load voltage. Supporting this feature, the LM330 protects
both itself and regulated systems from negative voltage inputs resulting from reverse installations of batteries.

Input-output differential less than 0.6V
Output current of 150 mA
Reverse battery protection
Line transient protection
Internal short circuit current limit
Internal thermal overload protection
Mirror-image insertion protection
P+ Product Enhancement tested

Other protection features include line transient protection
up to 26V, when the output actually shuts down to avoid
damaging internal and external circuits. Also, the LM330
regulator cannot be harmed by a temporary mirror-image
insertion.

Schematic and Connection Diagrams

GND
TUH/9306-1

(TO-220)
Plastic Package
OUTPUT

GND
INPUT
TL/H/9306-2

Front View

Order Number LM330T·5.0
See NS Package Number T03B

2-5

•

Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Input Voltage
Operating Range
Line Transient Protection (1000 ms)

Electrical
Symbol
Vo

OOCto +70'C

Maximum Junction Temperature

+ 125'C

Storage Temperature Range

26V
40V

-65'Cto + 1500C

Lead Temperature (Soldering, 10 sec.)

, Conditions

Parameter'
Output Voltage

Line Regulation
Load Regulation

1'j = 25'C

\

5 < 10 < 150mA
'6< VIN < 26V;O'C S:'Tj

Min

Typ

Max

,4.8

5

5.2

+3000C

Quiescent Current

Line Transient
Reverse Polarity
dlo

Quiescent Current
Change

VIN

Overvoltage Shutdown
Voltage

1000C

<

9 < VIN 16V, 10 7 5 mA
6 < VIN < 26V, 10 = 5 mA

4.75

14

25

= 10mA
= 50mA
= 150mA
VIN = 40V, RL = 1000,1s
VIN = -6V, RL = 1000

3.5
5
18

10
10
10

.,

60
50

20

.:

mV

..
mV/1000hrs

,

7
11 '
,40
,",

mA

14

-80

6 < VIN < 26V

%

10
26

-,
1s, Vo

Reverse Polarity
Input Voltage

5.25
7
30

"

5 < 10 < 150mA

Max Line Transient

Units

V

s:

Long Term Stability

10

Internally Limited

Chara~teristics (Note 1)

Output Voltage
Over Temp
!:,vo

Internal Power Dissipation
Operating Temperature Range

38
60

s: 5.5V

V

50
-30

DCVo >

...: 0.3V, RL =

Output Noise Voltage

10 Hz-100 kHz

Output Impedance

10

= 100 mADC +

1000

-12
50

/LV'

10 mArms

200

mO

Ripple Rejection

dB

58.

Current Limit

150

Dropout Voltage

10 = 150mA

Thermal Resistance

Junction to Case
Junction to Ambient

400

700

mA

0.32

0.6

V

4
50

'C/W

Note 1: Unless otherwise specified: VIN ~ 14V, 10 ~ 150 rnA, Tj ~ 25'C, Cl = 0.1 IIF, cl! = 10 liE All charac1eristics excep1 noise yoltall!' and ripple rejection
are measured using pulse techniques (tw s: 10. ms, duty cycle s: 5%). Output Yoltage changes due 10 changes In internal temperature must be taken into account
separately.

~

"

:

·2-6

Typical Performance Characteristics
Dropout Voltage

Dropout Voltage

0.6

8

I
is

:8

0.5
0'"

L...---' f..-

0.3

~

10=

If0 rnA

~
~

f!:
::> 0.2
0

~

~_

TJ=250 C

0.5

8

0.4

!--"

V

0.1

ii5

o

10-jOmA

,!.
~

o

ii5

10= OmA

~
25

50

75

100

125

o.IV k-'

o

o

150

::>

50

V

50

JUNCTION TEMPERATURE (CC)

IO=150mA

/

/

100

150

/
,/

3.0

2.5
2.0
1.5
1.0

I
1.5 2.0 2.5 3.0 3.5

200

Line Transient Response
T,=25CC
10= 150 rnA

LI!330T-5.0
RL = loon

4J)

Load Transient Response
V1N =14V
C2=10pF

C2= 10pF

,/1\

r
I

4.5 5.0 5.5 6.0 6.5

INPUT VOLTAGE (V)

OUTPUT CURRENT (rnA)

High Voltage Behavior
8

....

,/'
0.2

6.0
5.5
5.0
4.5

t:l 4J)
~ 3.5
~

0.3

5

5

,!.

Low Voltage Behavior

0.6

,....

II'

W

1\

I

I

I
o

w

o

~

~

~

25

~

~

~

15

INPUT VOLTAGE (V)

Peak Output Current
600

1

-

~ TJ=-40O C

~

V

!

~

DC

TJ=1250 C

,

15

0

~~

Quiescent Current
22

VIN = 14V
TJ=250 C

30

!....

25

i5
DC

20
15

~

.... '

10

5

DC

10

15

20

25

o
o

~

30

INPUT VOLTAGE (V)

Quiescent Current

is<.>
~

CI

z

0

~

§
;J

10

o
o

DC

10= 150mA

fL

~

10=OrnA 1o=50mA

~

INpUT VOLTAGE (V)

~

so

1~

160

"

<>

1~

10=0
3

Ripple Rejection

so

T,= 250 C

~

~r
10= 50 rnA

OUTPUT CURRENT (rnA)

70

!

90

16

!:l
::>

CI

60

10= 150 rnA
18

....0

i-""

o
o

VIN = 14V

~

i5
<>

","'"

CI

45

30

TIllE (PO)

Quiescent Current
~

~.. c

f ~~

45

TIllE (p.)

1

10

100

lk

10k lOOk

FREQUENCY (Hz)

2-7

111

o
o

50

100

OUTPUT CURRENT (rnA)

150

TUH/9306-3

Typical Performance Characteristics
Output Impedance
10

Overvoltage Supply Current
30

'o=50mA
T)=25CC

!

If"'-.

I

I

V

O. I

0.01
1

10

100

IK

10K lOOK

25 T)=25CC

~

10

25

30

/'

-ISO

V'

-200

D.2

J

5.D25

J

I\=CD
T)=25"C

VIN= 14V

.,..

"I

I

-D.2

-

~

-12 -10

-e

-e

-4

"

5

r-

o

i

r-

.30

-2

U25
~-~-200

35

\.

4.900

INPUT VOLTAGE (V)

INPUT VOLTAGE (V)

-2

-4

Output Voltage (Normalized
to 5V at TJ = 25'C) .

I

-D.3

-6

INpUT VOLTAGE (Y)

5.000

-0.1

-e

-12 -10

35

10"

",/

-100

Output at Overvoltage

I\=CD
T)=25CC

~

~

/'

-so

INPUT VOLTAGE (y)

£
!i!
5

~

T)=25CC

-250

20

Output at Reverse Supply

!:l

I

",

lli

o

1M

!

20
15

Reverse Supply Current

so

RL = 10011

mEQUENCY (Hz)

0.1

(Continued)

20

~ 5O.501001201~

JUNCTION TEMPERATURE (CC)

TLlH/9306-4

Typical Applications
The LM330 is designed specifically to operate at lower input
to output voltages. The device is deSigned utilizing a power
lateral PNP transistor which reduces dropout voltage from
2.0V to O.3V when compared to Ie regulators using NPN
pass transistors. Since the LM330 can operate at a much
lower input voltage, the device power dissipation is reduced,
heat sinking can be simpler and device reliability im·

proved through lower chip operating temperature. Also, a
cost savings can be utilized through use of lower powerl
voltage components. In applications utilizing battery power,
the LM330 allows the battery voltage to drop to within O.3V
of output voltage prior to the voltage regulator dropping out
of regulation.

50
VIN

UNREGULATED
INPUT

CI"

o.I)'FI

+

VOUT
REGULATED

J

OUTPUT

/" i"'-

.I

C2""

I'0)'F

'"

TL/H/9306-5

• Required if regulator is located far from power supply filter.
•• C2 may be either an Aluminum or Tantalum type capaCitor but
musl be rated to operate at - 40"C to guarantee regulator stability
to that temperature extreme. 10 p.F Is the minimum valus required
for stability and may be increased without bound. Locate as close
as possible to the regulation.

o
o

25

50

75

"

100

\

125

150

. loUT (mA)
TL/H/9306-6

Note: Compared to IC regulator with 2.0Y dropout voltage and
la"""". = 6.0 mAo

2-8

,-------------------------------------------------------------------------, r
i:
I\)

:sen

t;(INational Semiconductor

LM2925 Low Dropout Regulator with Delayed Reset
General Description

Features

The LM2925 features a low dropout, high current regulator.
Also included on-chip is a reset function with an externally
set delay time. Upon power up, or after the detection of any
error in the regulated output, the reset pin remains in the
active low state for the duration of the delay. Types of errors
detected include any that cause the output to become
unregulated: low input voltage, thermal shutdown, short circuit, input transients, etc. No external pull-up resistor is necessary. The current charging the delay capacitor is very low,
allowing long delay times.
Designed primarily for automotive applications, the LM2925
and all regulated circuitry are protected from reverse battery
installations or twO-battery jumps. During line transients,
such as a load dump (SOV) when the Input voltage to the
regulator can momentarily exceed the specified maximum
operating voltage, the 0.75A regulator will automatically
shut down to protect both internal circuits and the load. The
LM2925 cannot be harmed by temporary mirror-image insertion. Familiar regulator features such as short circuit and
thermal overload protection are also provided.

•
•
•
•
•
•
•
•
•
•
•

5V, 750 mA output
Externally set delay for reset
Input-output differential less than O.SV at 0.5A
Reverse battery protection
SOV load dump protection
- 50V reverse transient protection
Short circuit protection
Internal thermal overload protection
Available in plastic TO-220
Long delay times available
P+ Product Enhancement tested

Typical Application Circuit

-:r

1

+Cl*
1 ,.F

RES~2 RESET
FLAG

11
INPUT
VOLTAGE VOLTAGE

VDUT 5V
750mA

OUTPUT~·
+

-:r

C2**
1O ,.F

'Required if regulator Is located far from
power supply filter.

LM2925

~ELAY

GNO

1
3

"COUT must be at least 10 "F to maintain
stability. May be increased without bound
to maintain regulation during transients.
Locate as close as possible to the regulator. This capaCitor must be rated over the

'1'~3
0.1 pF

same operating temperature range as the

regulator. The equivalent series resistance (ESR) of this capac~or is critical;
sse curve.

~

TL/H/5268-1

FIGURE 1_ Test and Application Circuit

Connection Diagram
TO-220 5-Lead

!

1~.1 I

5 RESET OUTPUT
4 DELAY
3 GROUNO
2 OUTPUT VOLTAGE (VDUT)
1 INPUT VOLTAGE (V,N)

FRONT VIEW

TL/H/5268-2

Order Number LM2925T
See NS Package Number T05A
2-9

Absolute Maximum Ratings
If Military/Aerospace specified devices are required,

Input Voltage
Operating Range
Overvoltage Protection
Internal Power Dissipation (Note 1)

-40·Cto + 125·C

' Operating Temperature Range

please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.

Maximum Junction Temperature
Storage Temperature Range
Lead Temperature
' (Soldering, 10 seconds) , ,

26V
60V
Internally I,.imited

1500C
-65·Cto + 150·C
"

" 2600C

ESD rating is to be determined

Electrical Characteristics for VOUT
VIN = 14V, C2 = 10 /Lf, 10 = 500 mA;TJ ,.; '25·C (Note 3) (unless otherwise specified)
Parameter

'Min

Conditions

Typ

Max

Units

Note 2
Output Voltage
6V!:. VIN'!:. 26V, 10 !:. 500 mA,
-40·C!:. TJ!:' +125·C
Line Regulation

9V !:. VIN !:. 16V, 10 = 5 mA
6V !:. VIN !:. 26V, 10 = 5 mA

,V
4.75
,

,

5.00

5.25

4
10

25
50

10

' ,50

mV
mV

Load Regulation

5mA !:.Io!:. 500mA

Output Impedance

500 mAcc and 10 mArms,
100 Hz·10 kHz

200

Quiescent Current

10 !:.10mA
10 = 500mA
10 = 750mA

,3
'40
90

10 Hz-100 kHz

100

/LVrms

20

mV/1000 hr

Output Noise Voltage
Long Term Stability

fo = 120Hz

66

Dropout Voltage

10= 500mA
10 = 750mA

0.45
0.82

Maximum Operational
Input Voltage

mA
mA
mA

10b

Ripple Rejection

Current Limit

mV
mO

dB
0.6

V
V

0.75

1.2

A

26

31

V

Maximum Line Transient

Vo!:. 5.5V

60

70

V

Reverse Polarity Input
Voltage,DC

Vo ~ - 0.6V, 100 Load

-15

-30

V

Reverse Polarity Input
Voltage, Transient

1% Duty Cycle,
100 Load,

~50

-80

V

T

!:. 100 ms,

Electrical :Characteristics for Reset Output
VIN = 14V, C3 = 0.1 /LF, TA = 25·C (Note 3) (unless otherwise specified)
Min

Conditions

Parameter

Typ

Max

Units

Note 2
Reset Voltage
Output Low
Output High

ISINK = 1.6 mA, VIN = 35V
ISOURCE = 0

4.5

Reset Internal Pull-up Resistor
Reset Output Current Limit

VRESET = 1.2 V

Delay Current

Cs = .005/LF
Cs = 0.1 /LF
Cs = 4.7 /LF tantalum
Pin4,

0.6
5.5

V
V

30

kO

5

mA

4.5

V

150

12
250
12

300

ms
.rns
s

1.2

1.95

2.5

/LA

VOUT Threshold
Delay Time

0.3
5.0

Note 1: Thermal resistance without a heat sink for junction to case temperature Is 3"C/W (TO·220). Thermal resistance for TO-220 case to ambient temperature Is
5rrC/W.
Note 2: These parameters are guaranteed and 100% production tested,

Note 3: To ensure constant ,unction temperature, low duty cycle

pul~

testing is used.,

2-10

,---------------------------------------------------------------------------------,
Typical Circuit Waveforms

~

s::
N
CQ

N
UI
60V
INPUT

26V

VOL~~G~ 14V
(VI

14V

3V

OV
5V

OUTPUT
VOLTAGE
PIN 2
(VI

OV

RESET
VOLTAGE
PIN 5
(VI

OV

SYSTEM
CONDITION

I

TURN
ON

LOWVIH

I

LINE NOISE. ETC.

I

Your

I

THERMAL
SHUTDOWN

SHORT
CIRCUIT

TURN
OFF
TL/H/S268-3

FIGURE 2

Typical Performance Characteristics
Reset Voltage

Reset Voltage

6
HIGH
IR=O

:e:

:ll

~>

l - I--

LOW
IR=l.& rnA

-- r--

!ll

-

o
-40

Ii;

10'

2.0

10'

1.&

0.8

TL/H/S268-6

Reset pun-up
ResistorR10

....

2
4
INPUT VOLTAGE (VI

C3=0.1

~

~ 40
~

200

100

50

~

~co

-

0.1
10-' 10- 3 10- 2 10- 1 1
10
DELAY CAPACITOR (~FI

_ 210

~

/

.... V'

;r

o

220

II

;r
;r

10

Delay Time

cJ=O I
I-ID=500 rnA

V

TUH/S268-S

Reset Voltage
on Power-up

o

S

RESET CURRENT (mAl

6

V

103
100

:l:

TUH/S268-4

o

w

v

10'

::s

;:

~V

0.4
0.0

!

J

-

1.2

40
80
120 160
JUNCTION TEMPERATURE ('CI

V

Delay Time

2.4

........

,/

190
180
-40

40

00

"

120

160

JUNCTION TEMPERATURE ('CI

TUH/S268-7

TUH/S268-8

2·11

.

/'
./

z
;!

~

3D

/ ' .........

V

20
-40

40
80
120 160
JUNCTION TEMPERATURE ('CI
TL/H/S268-9

EI

Typical Performance Characteristics
Dropout Voltage

(Continued)
Ripple Rejection

Line Transient Response

1.0

80

20

10=120 Hz

11\

8

I
$

50

"--

D.8

'"

lOUT = 500 rnA

D.4

Z

Q

~

50

~

,

I

60

tl
~.
iC

40

Q.2

...

$

-

-

:!!.

II

-

0.6

70

'OUT=100 rnA

l5

40

80

120

o

160

10

20

30

40

50

3D '-----'---'---'--'----'
o 150 300 450 600 750
OUTPUT CURRENT (rnA)

60

TIME (~.)

JUNCTION TEIotPERAlURE ("C)

TL/H/5268-12

TLlH/526B-ll

'TLlH/5268-10

Ripple Rejection

Quiescent Current

80 r-1rTTTIII1r-1"TT

Output Voltage

100
RL=1011

iii 70

!

:!!.

i§
~ 60
iil
a::

50

iC

40

~

YoUT
lOUT =500 rnA

I

60

ISu

40

a

20

~

::>

C2=10~F

u

~

100

so

lk

V
~

o
o

10k

FREQUENCY (Hz)

150

V

1/
~

-1

-2
300

450

-40 -20
0
20
40
INPUT VOLTAGE (VI

750

600

OUTPUT CURRENT (mA)

TL/H/526B-13

60

TL/H/526B-15

TLlH/5268-14

-

Quiescent Current
50

, I.!

lOUT = 500 rnA

!

40

~

I

30

'"
0

~

20

a

10

!:!
::>

-

'-

lOUT = 250 rnA

I
lOUT = 50 rnA

Quiescent Current
150

~> 100

!....

-40

40

0

80

120

~~

::d;:

75

....

tl~

50

5

O.S
~!z 0.6

a

25

9i 0.4

'"::>
u

o

u

....
~
::>
Q

o

3D

I

50

60

Output CapaCitor ESR

('

....

S
tl
~

100

1O"C W HEAT SINK

r-..

....

~

o

10

~
~

CaUT =

~

~

I- NO HEAT J'NK
3D

40

TLlH/5268-1B

INfINITE HEAT 51NK

I

10 15 20
25
INPUT VOIJAGE (V)

20

TLlH/526B-17

20
18
'16
14
12
10
8

~

o

10

TIMEt".,

Maximum Power
DIssipation (TO-220)

1.0

o

~

INPUT VOLTAGE (V)

"."

0.5

0.2

160

22

til

"

-150

3:

Peak Output Current

a::

I

~ ~-~OO

TlIH/526B-19

::>

.I

0
50

Iil

JUNCTION TEMPERAlURE ("C)

1.5

~

~g 50

100

I

o

....3:

Load Transient Response

125

10pf

V~ ~

ST~~LE - ~--:

V
V

REGION

~

/.

0.1

::>

o 10 20 30 40 50 60 70 80 9D 100

AMBIENT TEMPERATURE ("C)

TL/H/5268-20

TLlH/52BB-21

Ii!

0.01

o

100

200

300

4DO

500

OUTPUT CURRENT (mA)
TLlH/5268-22

2·12

~-----------------------------------------------------------------------------'r

Definition of Terms

Application Hints

Dropout Voltage: The input-output voltage differential at
which the circuit ceases to regulate against further reduction in input voltage. Measured when the output voltage has
dropped 100 mV from the nominal value obtained at 14V
input, dropout voltage is dependent upon load current and
junction temperature.

EXTERNAL CAPACITORS

:s:
N

CD
N
U'I

The LM2925 output capacitor is required for stability. Without it, the regulator output will oscillate, sometimes by many
volts. Though the 10 ,.,.F shown is the minimum recommended value, actual size and type may vary depending upon the
application load and temperature range. Capacitor effective
series resistance (ESR) also effects the IC stability. Since
ESR varies from one brand to the next, some bench work
may be required to determine the minimum capacitor value
to use in production. Worst-case is usually determined at
the minimum junction and ambient temperature and maximum load expected.

Input Voltage: The DC voltage applied to the input terminals with respect to ground.
Input-Output Differential: The voltage difference between
the unregulated input voltage and the regulated output voltage for which the regulator will operate.
Line Regulation: The change in output voltage for a
change in the input voltage. The measurement is made under conditions of low dissipation or by using pulse techniques such that the average chip temperature is not significantly affected.
Load Regulation: The change in output voltage for a
change in load current at constant chip temperature.

Output capacitors can be increased in size to any desired
value above the minimum. One possible purpose of this
would be to maintain the output voltages during brief conditions of negative input transients that might be characteristic of a particular system.
Capacitors must also be rated at all ambient temperatures
expected in the system. Many aluminum type electrolytics
will freeze at temperatures less than - 30'C, reducing their
effective capacitance to zero. To maintain regulator stability
down to -40'C, capacitors rated at that temperature (such
as tantalums) must be used.

Long Term Stability: Output voltage stability under accelerated life-test conditions after 1000 hours with maximum
rated voltage and junction temperature.
Output Noise Voltage: The rms AC voltage at the output,
with constant load and no input ripple, measured over a
specified frequency range.

RESET OUTPUT

Quiescent Current: The part of the positive input current
that does not contribute to the positive load current. The
regulator ground lead current.
.

The range of values for the delay capacitor is limited only by
stray capacitances on the lower extreme and capacitance
leakage on the other. Thus, delay times from microseconds
to seconds are possible. The low charging current, typically
2.0 microamps, allows the use of small, inexpensive disc
capacitors for the nominal range of 100 to 500 milliseconds.
This is the time required in many microprocessor systems
for the clock oscillator to stabilize when initially powered up.
The RESET output of the regulator will thus prevent erroneous data and/or timing functions to occur during this part of
operation. The same delay is incorporated after any other
fault condition in the regulator output is corrected.

Ripple Rejection: The ratio of the peak-to-peak input ripple
voltage to the peak-to-peak output ripple voltage.
Temperature Stability of Vo: The percentage change in
ouput voltage for a thermal variation from room temperature
to either temperature extreme.

fI

2-13

~

C'II

~

,--------------------------------------------------------------------------,
Circuit Schematic

::&i

.....

~

-

>

~r_------~------~~----~------_+~

i!1

D

,-

'-I---------------+-------+-.......-'IN~_ill

2-14

r-------------------------------------------------------------------------,
t!lNational Semiconductor

~

~
N
CD

....~

~

~

r&
NI

LM2926/LM2927
Low Dropout Regulator with Delayed Reset

.......

General Description
The LM2926 is a 5V, 500 mA, low dropout regulator with
delayed reset. The microprocessor reset flag is set low by
thermal shutdown, short circuits, overvoltage conditions,
dropout, and power-up. After the fault condition is corrected,
the reset flag remains low for a delay time determined by
the delay capacitor. Hysteresis is included in the reset circuit to prevent oscillations, and a reset output is guaranteed
down to 3.2V supply input. A latching comparator is used to
discharge the delay capacitor, which guarantees a full reset
pulse even when triggered by a relatively short fault condition. A patented quiescent current reduction circuit drops
the ground pin current to 8 mA at full load when the inputoutput differential is 3V or more.
Familiar PNP regulator features such as reverse battery protection, transient protection, and overvoltage shutdown are
included In the LM2926 making it suitable for use in automotive and battery operated equipment.
The LM2927 is electrically identical to the LM2926 but has a
different pin-out. The LM2927 is pin-for-pin compatible with

the L4947 and TLE4260 alternatives. The LM2926 is pinfor-pin compatible with the LM2925.

Features
•
•
•
•
•
•
•
•

5% output accuracy over entire operating range
Dropout voltage typically 350 mV at 500 mA output
Externally programmed reset delay
Short circuit proof
Reverse battery proof
Thermally protected
LM2926 is pin-for-pin compatible with the LM2925
P+ Product Enhancement tested

Applications
• Battery operated equipment
• Microprocessor-based systems
• Portable instruments

Typical Application

Unregulated
Input

'Required if regulator is located far (> 2') from power supply filter.

"Co must be at least 10 ,.F to maintain stability. May be increesed without
bound to maintain regulation during transients. Locate as close as possible
to the regulator. This capacitor msut be rated over the same operating temperature range as the regulator. The equivalent series resistance (ESR) of
this capacitor is critical; see curve under Typical Performance CharacterIstleL

Delayed
Reset
Output

LII2926

t-=-~,....-Vo =5V; 500 rnA

+ Co"
I,o~r
TL/H/l0759-1

Connection Diagrams and Ordering Information
S·Lead TO·220
FronlVlew
Order Number LM2926T
See NS Package Number TOSA

5 DELAYED RESET OUTPUT
4 DELAY CAPACITOR
3 GROUND
2 OUTPUT VOLTAGE (VO)
I INPUT VOLTAGE (VIN)
TL/H/l0759-2

S·Lead TO·220
FronlVlew
Order Number LM2927T
See NS Package Number TOSA

5 OUTPUT VOLTAGE (VO)
4 DELAY CAPACITOR
3 GROUND
2 DELAYED RESET OUTPUT
I INPUT VOLTAGE (VIN)
TLlH/l0759-14

2·15

•

Absolute Maximum Ratings

(Note 1)

If Military/Aerospace specified devices are required,

ESD Susceptibility (Note 2)

2kV

please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.

Power Dissipation (Note 3)

Internally Limited

Input Voltage
Survival
t = 100ms
t = 1 ms
Continuous

Junction Temperature {TJMAxl
Storage Temperature Range
Lead Temperature (Soldering, 10 sec.)

80V
-50V
-18Vto +26V

Reset Output Sink Current

Operating Ratings (Note 1)
Junction Temperature Range (TJ)
Maximum Input Voltage

10mA

Electrical Characteristics VIN =

150"C
-40"Cto +.150·C
260·C

-40"Cto + 125·C
26V

14.4V, Co = 10 p.F, -40·C ~ TJ ~ 125·C, unless otherwise specified.

Parameter,

Conditions

Typ
(Note 4)

Limit
(NoteS)

Units
(Limit)

4.85

V (min)
V
V (max)

REGULATOR OUTPUT
Output Voltage

5 mA ~ 10 s; 500 mA,
TJ = 25·C

5
5.15

S.2S

V (min)
V
V (max)

2S

mV
mV(max)

50

mV
mV(max)

60

mV
mV(max)

3

mA
mA(max)

30

mA
mA(max)

,10

mA
mA(max)

60

mA
mA(max)

200

mV
mV(max)

300

mV(max)

600

mV
mV(max)

10 = SOOmA

700

mV(max)

VIN'= 8V, RL = 10

800
3

mA(min)
A
A (max)

60

dB (min)

5 mA s; 10 s; 500 mA

4.7S
S

Line Regulation

' 10 = 5 mA, 9V s; VIN ~ 16V
10 = SmA, 7V s; VIN ~ 26V

Load Regulation
Quiescent Current

S mA ~ 10 ~ SOO mA
10= SmA

2
8
3

10 = SmA, VIN = SV
10 = 500 mA, VIN = 6V

Dropout Voltage (Note 6)

3
S

16 = 500mA
Quiescent Current at Low VIN

1

10 = SmA, TJ = 2S·C

25
60

10=5mA
10 = SOO mA, TJ = 2S·C

Short Circuit Current

350

2
Ripple Rejection

fRIPPLE = 120 Hz, VRIPPLE = 1 Vrms,lo = SO mA

Output Impedance

10 = SO mAdc and 10 mArms @ 1 kHz

Output Noise

10 Hz to 100 kHz, 10 = SO mA

Long Term Stability
Maximum Operational Input Voltage

Continuous

mO

100
1

mVrms

20

mVl1000Hr
26

2-16

V (min)

Electrical Characteristics
VIN

=

14.4V, Co

=

10 ,...F, -40'C ,;;: TJ ,;;: 125'C, unless otherwise specified (Continued)

Parameter

Typ
(Note 4)

Conditions

Limit
(Note 5)

Units
(Umlt)

REGULATOR OUTPUT (Continued)

=

Peak Transient Input Voltage

Vo';;: 7V, RL

Reverse DC Input Voltage

VO;;' -0.6V, RL

Reverse Transient Input Voltage

tr

=

1 ms, RL

=

100n, tf

=

=

100 ms

100n

100n

SO

V (min)

-1S

V (min)

-50

V (min)

-SO
-400

mV(min)
mV
mV(max)

0.4

V (max)

RESET OUTPUT
Threshold

aVo Required for Reset Condition (Note 7)
-250

Output Low Voltage

ISINK

=

1.6 rnA, VIN

=

0.15

3.2V

Internal Pull-Up Resistance

=

Delay Time

COELAY

Minimum Operational VIN
on Power Up

Delayed Reset Output,;;: O.SV,
ISINK = 1.6 rnA, RL = 100n

Minimum Operational Vo
on Power Down

Delay Reset Output,;;: O.SV,
ISINK = 10,...A, VIN = OV

10 nF (See Timing Curve)

30

kn

19

ms

2.2
3.2
0.7

V
V (min)
V

DELAY CAPACITOR PIN
Threshold Difference (aVOELAY)

Change in Delay Capacitor Voltage Required for
Reset Output to Return High

3.5
3.75
4.1

Charging Current (IOELAY)

V (min)
V
V (max)

1.0

,...A (min)
,...A
3.0
,...A(max)
Note 1: Absolute Maximum RaUngs indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional. but do not guarantee specific performance limits. For guaranteed specifications and test conditions. see the Electrical CharacterlaUce.
Note 2: Human body model; 100 pF discharged through a 1.5 kG resistor.
Note 3: The maximum power dissipation is a fUnction of TJMAX. and 6JA. and TA. and is limited by thermal shutdown. The maximum allowable power dissipation at
any ambient temperature is Po = (TJMAX-TAl/6JA. "this dissipation is exceeded. the die temperature will rise above 150'C and the device will go Into thermal
shutdown. For the LM2926 and LM2927, the junction-to-ambient thermal resistance is 53"C/W, and the junction-to-case thermal resistance is 3'C/W.
Note 4: Typlcals are at TJ = 25'C and represent the most likely parametric norm.
Note 5: Umits are 100% guaranteed by production testing.
Note 6: Dropout voltege is the input-output differential at which the circutt ceases to regulate against any further reduction in input voltage. Dropout voltage is
2.0

measured when the output voltage (Vo) has dropped 100 mV from the nominal vruue measured at VIN

=

14.4V.

Note 7: The reset flag is set LOW when the output voltage has dropped an amount, I!..Vo, from the nominal value measured at VIN = 14.4V.

•
2-17

Typical Performance Characteristics
Output Voltage

Low Voltage Behavior

5.0SO

Output at Voltage Extremes
7

6

RL = 10011

5.040
5.030

.!i

lL=S~.l

5.020

!:i 5.010

". = 500 mA

'"

/

~ 5.000

5

~

4.970

I
(

4.960

I

5 4.990
/
4.980
0

o

4.950
-so -25

0

25

50

75

1
-40

o

100 125

JUNCTION TEMPERATURE, TJ (\'C)

Supply Current

Quiescent Current

;
!:i

~

/

40
30

/
y

10

!i!

20

~

/

A

20

25

B
a

o

o

-40 -20

20

40

60

o

80

~

':i

.--

~

O.A

~

Te=12~

....-

--

./

D.2

o

o

100

200

i""'"

;;;;;;-

J..--

Te=-fO"C

J

I
i

400

o I~
o

500

80

70

!

50
40

iii

20

0

~

0

N-.

10

15

I

o
5

30

200

300

400

500

'--_1-_1--''---'_-'

o

I~O

200

300

400

500

OUTPUT CURRENT (mA)

Ripple Rejection
80

ESR = 0.311
1.= 250mA

!
~

"

30

100

O.IM_
0.01

25

20

T=12f"C

Output Impedance

90

VIN=14.4~~
C.= IO I'F

"

60

"

~V

1.0

Ti J25 J

INPUT VOLTAGE (V)

Ripple Rejection

!z

~

10 _ _ _

TJ =250 J

u_

I

300

~

~

a

Output Capacitor ESR

TJ 1=-40 J

OUTPUT CURRENT (mA)

~

;

~

~V

OUTPUT CURRENT (mA)

J

RL=IR

,Te=2S;s....

90

T=-~

2 3 4 -5 6 7 8 9 10

-s

~

T= 250 C,

il
~

Output Current LImit

D.8
D.6

:'

10

INPUT VOLTAGE (V)

Dropout Voltage

E

~

//1/ ~i~i .ii;;
lJ

INPUT VOLTAGE (V)

1.0

<"
.5

~

"

If

Te ),25!c

N::

10

80

Quiescent Current

-,')

Te = 125'1:

15

60

40

I'

IL = 50rm~

<"
.5

20

INPUT VOLTAGE (V)

30
RL =50011

SO

-20

INPUT VOLTAGE (V)

60

!

1

10

C.= IO I'F
1.=2S0mA
I rlpple =120Hz ' ESR=0.3R

-

60

g

50

~

30

~

I

70

40

20
10

o

o
100

10k

lOOk

FREQUENCY (Hz)

1M

o

8101214161820
INPUT VOLTAGE (V)

FREQUENCY (Hz)

TLlH/l0759-3

2-18

r-

Typical Performance Characteristics
Line Transient Response

3:

N
CD
N

(Continued)

Co= lapF
1o=5aamA

22
20

Co=lapF

x

0

!:l

"

20

40

60

Ba

40

.......

16
14
12
10

1\

laoc/W HEAT SINK \

ffi

-

~

60

CD

N

o
-so

BO

TIME (ps)

""t-..

\

-,....

""r--

I-- NO HEAT SINK

2

20

TIME (ps)

m
I'-'

3:

N

INFINITE HEAT SINK

IB

E

If
III

c:n
.....
r-

Maximum Power
Dissipation (TO-220)

Load Transient Response

-25

a

25

50

75

f-.;:

100 125

AMBIENT TEMPERATURE, TA (OC)

Reset Delay

Reset Delay

30

3
~.

20

Cd.~Y = lanF

.... .......

I:i

!ll

10

-so
DELAY CAPACITOR (nF)

-25

a

25

50

75

100 125

JUNCTION TEMPERATURE, TJ (OC)
TL/H/l0759-4

Typical Circuit Waveforms
BOV Load-dump Transient

Input Voltage

Thermal
Shutdown

Delay caPacitor
Voltage

OV

Delayed Reset
Output I-~OV:......._ _-!
TL/H/l0759-5

2-19

~

C'I

G)

C'I

:;

~
C'I

::E
-I

r-----------------------------------------------------------------------Applications Information
As shown in Figure 1, the delayed reset output is pulled low
by an NPN transistor (Q2), and pulled high to Vo by an
internal 30 kn resistor (R3) and PNP transistor (Q3). The
reset output will operate when Vo is sufficient to bias Q2
(0.7V or more). At lower voltages the reset output will be in a
high impedance condition. Because of differences in the
VeE of Q2 and Q3 and the values of R1 and R2, Q2 is
guaranteed by design to bias before Q3, providing a smooth
transition from the high impedance state when Vo < 0.7V,
to the active low state when Vo > 0.7V.

EXTERNAL CAPACITORS
The LM2926/7 output capacitor is required for stability.
Without it, the regulator output will oscillate at amplitudes as
high as several. volts peak-to-peak at frequencies up to
500 kHz. Although 10 IJ-F is the minimum recommended
value, the actual size and type may vary depending upon
the application load and temperature range. Capacitor
equivalent series resistance (ESR) also affects stability. The
region of stable operation is shown in the Typical Performance Characteristics (Output Capacitor ESR curve).
Output capaCitors can be increased in size to any desired
value above 10 IJ-F. One possible purpose of this would be
to maintain the output voltage during brief conditions of input transients that might be characteristic of a particular
system.

External Pull-up
Resistor

Capacitors must also be rated at all ambient temperatures
expected in the system. Many aluminum electrolytics freeze
at temperatures below -30'C, reducing their effective capaCitance to zero. To maintain regulator stability down to
-40"C, capaCitors rated at that temperature (such as tantalums) must be used.

...-1-....... Delayed Reset Output

DELAYED RESET
The delayed reset output is designed to hold a microprocessor in a reset state on system power-up for a programmable
time interval to allow the system clock and other powered
circuitry to stabilize. A full reset interval is also generated
whenever the output voltage falls out of regulation. The circuit is tripped whenever the output voltage of the regulator
is out of regulation by the Reset Threshold value. This can
be caused by low input voltages, over current conditions,
over-voltage shutdown, thermal shutdown, and by both
power-up and power-down sequences. When the reset circuit detects one of these conditions, the delay capacitor is
discharged by an SCR and held in a discharged state by a
saturated NPN switch. As long as the delay capaCitor is held
low, the reset output is also held low. Because of the action
of the SCR, the reset output cannot glitch on noise or transient fault conditions. A full reset pulse is obtained for any
fault condition that trips the reset circuit.

TUH110759-6

FIGURE 1. Delay Reset Output
The static reset characteristics are shown in Figure 2. This
shows the relationship between the input voltage, the regultor output and reset output. Plots are shown for various ex·
ternal pull-up resistors ranging in value from 3 kn to an
open circuit. Any external pull-up resistance causes the reo
set output to follow the regulator output until Q2 is biased
ON. CDELAY has no effect on this characteristic.

,8

When the output regains regulation, the SCR is switched off
and a small current (IDELAY = 2 IJ-A) begins charging the
delay capaCitor. When the capaCitor voltage increases
3.75V (~VDELAY) from its discharged value, the reset output
is again set HIGH. The delay time is calculated by:
delay time =
.

CDELAy~VDELAY

IY

RL =1004
Co= IOI'F
Cdelay =0

'/

1/

o
o

1I

1./ Your
/ II R=~k

VRESET

1k{~=5110k

200 400 600 800 1000 1200 1400

TIME (ps)

(1)

IDELAY

TUH/l0759-7

FIGURE 2. Reset Output Behavior during Power-Up
Figure 2 is useful for determing reset performance at any
particular input voltage. Dynamic performance at power-up
will closely follow the characteristics illustrated in Figure 2,
except for the delay added by CDELAY when Vo reaches 5V.
The dynamic reset characteristics at power-down are illustrated by the curve shown in Figure 3. At time t = 0 the input
voltage is instantaneously brought to OV, leaving the output
powered by Co. As the voltage on Co decays (discharged
by a 1000. load resistor), the reset output is held low. As Vo
drops. below 0.7V, the reset rises up slightly should there be
any external pull-up resistance. With no external resistance,
the reset line stays low throughout the entire power down
cycle. If the input voltage does not fall instantaneously, the
reset signal will tend to follow the performance characteristics shown in Figure 2.

or
delay time z 1.9 x 106 CDELAY
(2)
The constant, 1.9 x 106 , has a ±20% tolerance from device to device. The total delay time error budget is the sum
of the 20% device tolerance and the tolerance of the external capaCitor. For a 20% timing capaCitor tolerance, the
worst case total timing variation would amount to ± 40%, or
a ratio of 2.33:1. In most applications the minimum expected
reset pulse is of interest. This occurs with minimum CDELAy,
minimum ~VDELAY' and maximum IDELAY. ~VDELAY and
IDELAY are fully specified in the Electrical Characteristics.
Graphs showing the relationship between delay time and
both temperature and CDELAY are shown in the Typical
Performance Characteristics.

2·20

Applications Information

(Continued)

SYSTEM DESIGN CONSIDERATIONS
Many microprocessors are specified for operation at 5V
± 10%, although they often continue operating well outside
this range. Others, such as certain members of the COPS
family of microcontrollers, are specified for operation as low
as 2.4V.

-

...
...'"aj:!:
....::>>

....
::>
0-

4

\

3

9V Battery

Delayed
Reset
Output

RL =100n.

VIN

CO=10Jl'
Cdolay =0

5

£

Battery Powered Regulator with Flashing
LED for Low Battery Indication

Lt.i2926/27

5V/500 rnA

Vour

+

I

\

10JlF

"O~T

2

a

VRESET

~

R=510k

•

Rr ~ """"'=
k

0
o

Lhl3909

500 1000 1500 2000 2500 3000

TIME (Jls)
TL/H/10759-8

FIGURE 3. Reset Output Behavior during Power-Down
Of particular concern is low voltage operation, which occurs
in battery operated systems when the battery reaches the
end of its discharge cycle. Under this condition, when the
supply voltage is outside the guaranteed operating range,
the clock may continue to run and the microprocessor will
attempt to execute instructions. If the supply voltage is outside the guaranteed operating range, the instructions may
not execute properly and a hardware reset such as is supplied by the LM 292617 may fail to bring the processor under control. The LM292617 reset output may be more effiCiently employed in certain applications as a means of defeating memory WRITE lines, clocks, or external loads, rather than depending on unspecified microprocessor operating
conditions.
In critical applications the microprocessor reset input should
be fully characterized and guaranteed to operate until the
clock ceases, oscillating.

TLlH/10759-9

General Microprocessor Configuration
VINo--......-""""'-i

Delayed
Reset
Output

INPUT TRANSIENTS
The LM292617 are guaranteed to withstand positive input
transients to BOV followed by an exponential decay of
T = 20 ms (tf = 100 ms, or 5 time constants) while maintaining an output of less than 7V. The regulator remains
operational to 26 Voc, and shuts down if this value is exceeded.

VOUT

Lt.i2926/27

5V/500 rnA

ADDRESS
BUS

TLlH/1 0759-1 0

fII

2-21

~

N

Q)

N

,---------------------------------------------------------------------------------,
Applications Information

(Continued)

:E

-I
.....
CD
N

Using the Reset to De-Activate Power Loads. The LM1921Is a Fully Protected 1 Amp High-Side Driver.

Q)

N

VIN

:E

o-....- - - - - - - - -...........;+~I____,

.--_.....a.___
'I;F-,
-b

-I

Delayed
Resel
Oulpul

L~2926/27

Your

5V/500 mil

TUH/l0759-11

Using the Reset to Ensure an Accurate Display
on Power-Up or Power-Down .

Generating an Active High Reset Signal

V~o-.....--I

Lt.l2926/27

V~o-t--------~-~+ ~

1--...........-oVOUT

I~F

Delayed
Reset
Output

Reset

-b
VOUT

LM2926/27

5V!500rnA

r
+

1O

lk

l'F

TL/H/l0759-12

Ill'F

Rosel
I'P

..IWlll..

TUH110759-13

2-22

t!lNational Semiconductor

LM2930 3-Terminal Positive Regulator
General Description

Features

The LM2930 3-terminal positive regulator features an ability
to source 150 mA of output current with an input-output
differential of 0.6V or less. Efficient use of low input voltages
obtained, for example, from an automotive battery during
cold crank conditions, allows 5V Circuitry to be properly
powered with supply voltages as low as 5.6V. Familiar regulator features such as current limit and thermal overload
protection are also provided.

II Input-output differential less than 0.6V

Designed originally for automotive applications, the LM2930
and all regulated circuitry are protected from reverse battery
installations or 2 battery jumps. During line transients, such
as a load dump (40V) when the input voltage to the regulator can momentarily exceed the specified maximum operating voltage, the regulator will automatically shut down to
protect both internal circuits and the load. The LM2930 cannot be harmed by temporary mirror-image insertion.
Fixed outputs of 5V and BV are available in the plastic TO220 and TO-263 power packages.

II Output current in excess of 150 mA
II Reverse battery protection

13 40V load dump protection
CI

Internal short circuit current limit

III Inte'rnal thermal overload protection
CI

Mirror-image insertion protection

II P + Product Enhancement tested

Voltage Range
LM2930T-5.0
LM2930T-B.0

5V
BV

LM2930S-5.0

5V
BV

LM2930S-B.0

Connection Diagrams
(TO-220)

(TD-263)
Plastic Surface-Mount Package

Plastic Package

TAB IS [ ] ; OUTPUT
GND
GND

TLlH/5539-1

L

INPUT

Front View

TLlH/5539-7

Top View

Order Number LM2930T-5.0 or LM2930T-S.O
See NS Package Number T03B

TL/H/5539-8

Side View

Order Number LM29305-5.0 or LM2930S-S_0
See NS Package Number TS3B

fI

2-23

Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Input Voltage
Operating Range
Overvoltage Protection
Reverse Voltage (100 ms)
Reverse Voltage (DC)

Internal Power Dissipation (Note 1)

Internally Umited

Operating Temperature Range

- 40'C to

Maximum Junction Temperature

125'C

Storage Temperature Range

26V
40V
-12V
-6V

+ 85'C

- 65'C to

Lead Temp. (Soldering, 10 seconds)

+ 150'C
230'C

Electrical Characteristics (Note 2)
LM2930·5.0 VIN= 14V, 10= 150 mA,Tj=25'C (Note 5), C2= 10 ",F, unless otherwise specified
Parameter

Typ

Conditions

Output Voltage

5

Tested
Limit
(Note 3)
5.3
4.7

9V:S:VIN:S:16V, 10=5 mA
6V:S:VIN:S:26V, 10=5 mA

·Load Regulation

5 mA:S: 10:S: 150 mA .

.Output Impedance

100 mADe & 10 mArms, 100 Hz-10 kHz

Unit
VMAX
VMIN

5.5
4.5

6V:S:VIN:S:26V,5 mA:S:lo:S:150 mA
-40'C:S:TJ:S:125'C
Une Regulation

Design
Umlt
(Note 4)

VMAX
VMIN

7
30

25
·80

mVMAX
mVMAX

14

50

mVMAX

7
40

mAMAX
mAMAX

200

mO

Quiescent Current

10=10mA
10=150mA

4
18

Output Noise Voltage

10Hz-100kHz

140

",Vrms

20

mV/1000 hr

Long Term Stability
Ripple Rejection

fO=120Hz

56

Current Limit
Dropout Voltage

10=150mA

Output Voltage Under
Transient Conditions

-12V:S:VIN:S:40V, RL = 1000

dB

400

700
150

mAMAX
mAMIN

0.32

0.6

VMAX

5.5
-0.3

VMAX
VMIN

Electrical Characteristics (Note 2)
LM2930-8.0 (YIN = 14V, 10 = 150 mA, Tj = 25'C (Note 5), C2 = 10 ",F, unless otherwise specified)
Parameter

Typ

Conditions

Output Voltage

8

Tested
Umlt
(Note 3)
8.5
7.5

9.4V:S:VIN:S:26V, 5 mA:S: 10:S: 150 mA,
. -40'C:S:TJ:S:125'C
Line Regulation

9.4V:S:VIN:S:16V, 10=5 mA
9.4V:S:VIN:S:26V, 10= 5 mA

Design
Limit
(Note 4)

Unit
VMAX
VMIN

8.8
7.2

VMAX
VMIN

12
50

50
100

mVMAX
mVMAx

50

mVMAX

7
40

mAMAX
mAMAX

Load Regulation

5 mA:S: 10:S: 150 mA

25

Output Impedance

100 mADe & 10 mArms , 100 Hz-10 kHz

300

Quiescent Current

10=10mA
10=150mA

4
18

Output Noise Voltage

10 Hz-100 kHz

170

",Vrms

30

mVl1000 hr

Long Term Stability
Ripple Rejection

fo= 120 Hz

52

Current Umit
Dropout Voltage

10=150mA

Output Voltage Under
Transient Conditions

-12V:S:VIN:S:40V, RL =1000

mO

2-24

dB

400

700
150

mAMAX
mAMIN

0.32

0.6

VMAX

8.8
-0.3

VMAX
VMIN

Note 1: Thermal resistance without a heat sink for junction to case temperature is 3°C/W and for case to ambient temperature is 50a C/W for the TO-220, 73°C/W

for the TO·263. If the TO·263 package is used, the thermal resistance can be reduced by increasing the P.C. board copper area thermally connected to the
package. Using 0.5 square inches of copper area, 6JA is 50'C/W; with 1 square inch of copper area, 6JA is 37'C/W; and with 1.6 or more square inches of copper
area, 6JA is 32'C/W.
Note 2: All characteristics are measured with a capaCitor across the input of 0.1 p.F and a capacitor across the output of 10 p.F. All characteristics except noise
voltage and ripple rejection ratio are measured using pulse techniques (tw'; 10 ms, duty cycle,;5%). Output voltage changes due to changes in internal tempera·
ture must be taken into account separately.

Note 3: Guaranteed and 100% production tested.
Note 4: Guaranteed (but not 100% produclion tested) over the operaling temperature and input current ranges. These limits are not used to calculate outgoing
quality levels.
Note 5: To ensure constant junction temperature, low duty cycle pulse testing is used.
·Aequired if regulator is located far

Typical Application

from power supply filter.

LM293D
VIN

UNREGULATED
INPUT

VIN

VOUT
GNO

+

'I

• ·COUT must be at least 10 ,.,.F to
maintain stability. May be increased without
bound to maintain regulation during
transients. Locate as close as possible
to the regulator. This capaCitor must be
rated over the same operating temperature
range as the regulator. The equivalent

VDUT
REGULATED
OUTPUT
C2**

10 l'F

series resistance (ESR) of this capaCitor
should be less than 1n over the
expected operating temperature range.

TUH/5539-5

Typical Performance Characteristics
Output Impedance
10

Overvoltage Supply Current

§

.«

It'-..

...z
w

cco

~

..
'"
;:

50

oS

20

~
a:
a:

15

~

10

It

'"co

c

.

oS
~
a:

i;'" i--""

10

100

lk

10k

lOOk

20

1M

Output at Reverse
Supply

.
.

2:
w

f

~

0.2

2:

.

35
30
INPUT VOLTAGE (V)

-11.2

0.15

0.1

'"

co 0.05

-

-11.3 ..........-I.......................................L-J......................
-12 -10
-8
-G -4
-z
INPUT VOLTAGE (V)

-I-

-11

-2

1.005

r-r-,--r--r-.-,-.-,-,
~~+-+~-+~~~r-+-1

~ 0.995

1--+-+-+--1-1--+-*,-+--1

i.--'

.....

;:
6 0.990 l-+--+-+-+-+-+-!-+-l
co
~

~ 0.985 l-+--+-+-+-+-+-!-+-l
!-VIN '14V

z 0.9ao

INPUT VOLTAGE IV)

-4

2:
~ 1.000
o

::Ii

35

-6

Output Voltage (Normalized
to 1V at TJ = 25"C)

a:
co

30

-10

INPUT VOLTAGE (V)

.--;--,---r-,-.--;--,--,

~

'"
;:

-250
-12

40

w

~
co
>

co -11.1
>

25

Output at Overvoltage

"'-T-T,..,,r-r-r"T"';-"

V

V

-200

FREQUENCY (Hz)

0.1

V'

... V

...>-g; -100

0
1

/"

-50

== -150
ill

./

ill

0.01

6

Tj = 25'C

RL -IDOl!
Tj = 25'C

25

8

/'

0.1

Reverse Supply Current

30

10' SOmA
Tj' 25'C

40

f-+-+-+-+-t-l

L-.1-...1.......L..-1..--L--I_.l-...1.....J

-40 ~20

0 20 40 60 80 100 120 140

JUNCTION TEMPERATURE (" C)
TL/H/5539-4

2-25

Typical Performance Characteristics
Dropout Voltage
~

~

~is

0.5

DA
1.3

0-

"
~

D.2

iZ

0.1

:!

~
I--"

!!!

o

Dropout Voltage
0.1

0.6

I

~
~

---

10'5~mA

50

100

o

'o"llomA

r-

I

~

I

0.5

..

I

i

'O'lDmA

5.0

... V

0.2

o

lID

..,.

/

~

0.3

0.1

LM293D·5
'0"10mA

...
.. 4:0

OA

0-

"~
""-

Low Voltage Behavior
6.0

TI'25'C

0-

3.0

CI

2.0

~

, / i-""

/

V
1.0

o

·50

ISO'

100

2,0

200

3.0

High Voltage Behavior

4.0

&.D

1.0

INPUT VOLTAGE IV)

OUTPUT CURRENT (mA)

JUNCTION TEMPERATURE rCI

8

(Continued)

Line Transient Response

-~I'!.,:or·IV

TI'2S'C

LMZ830·5
RL • lOon

10 -1&amA

I

I
II
1
o

o

10

20

3D

40

II

INPUTVOLTAOE (V)

Peak Output Current
100

C
.!!
0-

l5

~

5
~

..

SOD
400
300

I

,

200

""

i

50C

C

,,!

.. Ii

.....
S
.
~

10
II
20
25
INPUT VOLTAGE (VI

C

60

....
I..

10

,!
0-

l5

C
.!!

25

l5

....."'"
.....

II
10

3D

~

.....

o

3D

10

90

I I
1-1- -

4D
80
120
160
JUNCTION TEMPERATURE rc)

Ripple Rejection
80

10 'SOmA
V'N-VOUT'IV
iii
3

·z

§.
...
i

/

'O',IOmA
10'1OOIA

20
10
INPUT VOLTAGE (V)

3D

o

SO

co

'",

0

4D

20

o
I

I

101.JJ

III
II

ISO

120

~

0

0-

Ripple ReJection'
60

40

[;I,., OmA

"

16

'0'0

3D

10

'o·IIOmA

I-""

.......

20

III

20

OUTPUT CURRENT (mAl

u.1z1 0·5

f;;

.."...
i~
0-

20

Quiescent Current
70

TI~2&'C

3D

o

o

Quiescent Current
22

VIN"4V

100

o

TIMEr..)

Quiescent Current

Tj"25'C

~

41

31

~ -:g0C

,.

3D

TIME ",.1

10

100

Ik

10k

FREQUENCY 'Hz!

lOOk

1M

V,N-VOUT'IV
fO ' 120Hz

o

50

100

ISO

OUTPUT CURRENT (mA)
TLlH/5539-2

2-26

.-----------------------------------------------------------------ir
5i:

Definition of Terms

~

Long Term Stability: Output voltage stability under accelerated life-test conditions after 1000 hours with maximum
rated voltage and junction temperature.

Dropout Voltage: The input-output voltage differential at
which the circuit ceases to regulate against further reduction in input voltage. Measured when the output voltage has
dropped 100 mV from the nominal value obtained at 14V
input, dropout voltage is dependent upon load current and
junction temperature.
Input Voltage: The DC voltage applied to the input terminals with respect to ground.

Output Noise Voltage: The rms AC voltage at the output,
with constant load and no input ripple, measured over a
specified frequency range.
Quiescent Current: That part of the positive input current
that does not contribute to the positive load current. The
regulator ground lead current.
Ripple Rejection: The ratio of the peak-to-peak input ripple
voltage to the peak-to-peak output ripple voltage.
Temperature Stability of Vo: The percentage change in
output voltage for a thermal variation from room temperature to either temperature extreme.

Input-Output Differential: The voltage difference between
the unregulated input voltage and the regulated output voltage for which the regulator will operate.
Line Regulation: The change in output voltage for a
change in the input voltage. The measurement is made un- .
der conditions of low dissipation or by using pulse techniques such that the average chip temperature is not significantly affected.
Load Regulation: The change in output voltage for a
change in load current at constant chip temperature.

Maximum Power
Dissipation (TO-220)
22

,

INFINITE HEAT SINK

20

g
z

0

!;;:
!!:

~

ffi
~

a..

18
16
14
12
10
8
6
4
2

~

-

°o

~

I\.
I""--.....!ooc

NO HEAT

~INK

W HEAT SINK

t-

1'000.
1'000.

I
10 20 30 40 50 60 70 80 90 100
AMBIENT TEMPERATURE (OC)

TUH/5539-6

Maximum Power Dissipation
(TO-263) (Note 1)

~
z0

...;::

e JA - 32°C/Y

4

N
3 I'L1'-..

eJA=37"C~"'"

Q.

iii
en
2i

,......
2

r-.

f5

;0

0

Q.

a
o

'"
~

i"- t--

~=500e/W' r.....
.....

~-~.:L""'" ~
~JA ~73~ ~ ~

i

",

r

10 20 30 40 50 60 70 80 90 100

AMBIENT TEMPERATURE (Oe)

2-27

TL/H/5539-9

CD
Co)

o

!!
C"I

::::E

Schematic Diagram

...I

GNO

TUH/5539-10

2-28

r-------------------------------------------------------------------------,~

i:
N
CD

(fINational Semiconductor

.....

Co)

LM2931 Series Low Dropout Regulators
General Description

Features

The LM2931 positive voltage regulator features a very low
quiescent current of 1 mA or less when supplying 10 mA
loads. This unique characteristic and the extremely low input-output differential required for proper regulation (0.2V
for output currents of 10 mAl make the LM2931 the ideal
regulator for standby power systems. Applications include
memory"standby circuits, CMOS and other low power processor power supplies as well as systems demanding as
much as 100 mA of output current.
Designed originally for automotive applications, the LM2931
and all regulated circuitry are protected from reverse battery
installations or 2 battery jumps. During line transients, such
as a load dump (60V) when the input voltage to the regulator can momentarily exceed'the specified maximum operating voltage, the regulator will automatically shut down to
protect both internal circuits and the load. The LM2931 cannot be harmed by temporary mirror-image insertion. Familiar
regulator features such as short circuit and thermal overload
protection are also provided.

•
•
•
•
•
•
•
•
•
•
•

Very low quiescent current
Output current in excess of 100 mA
Input-output differential less than 0.6V
Reverse battery protection
60V load dump protection
- 50V reverse transient protection
Short circuit protection
Internal thermal overload protection
Mirror-image insertion protection
Available in TO-220, TO-92, TO-263 or SO-8 packages
Available as adjustable with TTL compatible switch

Output Voltage Options
Output
Number

Part Number

Package
Type

LM2931T-5.0, LM2931AT-5.0 3-Lead TO-220

The LM2931 family includes a fixed 5Voutput (±3.8% tolerance for A grade) or an adjustable output with ON/OFF pin.
Both versions are available in a TO-220 power package,
TO-263 surface mount package, and an 8-lead surface
mount package. The fixed output version is also available in
the TO-92 plastic package.

5V

LM2931S-5.0, LM2931AS-5.0 3-Lead TO-263
LM2931Z-5.0, LM2931AZ-5.0 TO-92
LM2931 M-5.0, LM2931AM-5.0 8-Lead SO

Adjustable, LM2931CT

5-Lead TO-220

3Vt024V

LM2931CS

5-Lead TO-263

LM2931CM

8-LeadSO

Typical Applications
LM2931 Fixed Output
V,N
UNREGULATED •
INPUT

CO'.~

J

LM2931

GN~'Q

LM2931 Adjustable Output
Vee

VOUT
REGULATED
OUTPUT
+ C2**

JIOOI'F

R3
51k

IN

r--~~~O~U~Tt-~~~ YOUT

TUH/5254-4
LMZ931
ADJUSTABLE

'Required if regulator is located lar Irom power supply filter.

"·C2 must be at least 100 p.F to maintain stability. May be increased without
bound to maintain regulation during transients. Locate as close as possible
to the regulator. This capacitor must be rated over the same operating temperature range as the regulator. The equivalent series resistance (ESR) of

ON

this capacitor is critical; see curve.

TL/H/5254-5

RI + R2

VOUT ~ Reference Voltage x - R - l Note: USing 27k lor Rl will automatically compensate lor errors in VOUT due
to the input bias current 01 the ADJ pin (approximately I ",A).

2-29

,.. r-------------------------------------------------------------------------------------,
C")

re

:i

Connection Diagrams and Ordering Information
FIXED 5V OUTPUT
TO-220 3-Lead Power Package

To-263 Surface-Mount Package
T A B U S OUTPUT
GND.

GND

INPUT
TL/H/5254-11

TL/H/5254-6

Front View

Top View

Order Number LM2931T-5.0 or LM2931AT-5.0
See NS Package Number T03B

TUH/5254-12

Side View
Order Number LM2931S-5.0 or LM2931AS-5.0
See NS Package Number TS3B
S-Pin Surface Mount

To-92 Plastic Package

OUT-I.8-IN
GND- 2

7 -GND

GND -

6 .,...GND

3

OUTBIN

GND

NC· - ..4;...__5..- NC·

'Ne

TLlH/5254-8

BoHomVlew

TL/H/5254-7

= Not Internally connected

Order Number LM2931Z-5.0 or LM2931AZ-5.0
NS Package Number Z03A

See

Top View
Order Number LM2931M-5.0 or LM2931AM-5,O
See NS Package Number MOBA
ADJUSTABLE OUTPUT VOLTAGE
TO-220 5-Lead Power Package

To-263
5-Lead Surface-Mount Package·
TAB O S OUT
GND
b~D

2~?&H

TL/H/5254-9

TL/H/5254-13

Front View

Top View

Order Number LM2931CT
See NS Package Number. T05A

TLlH/5254-14

Side View
Order Number LM2931CS
See NS Package Number TS5B
B-Pln Surface Mount
OUT- I .

8 -IN

GND- 2

7 -GND

GND -

6

3

r- GND

ADJ - ..4;......;.;5;.ri- ON/OFF
TLlH/5254-10

Top View
Order Number LM2931CM
See NS Package Number MOBA

2-30

r-

s:::

Absolute Maximum Ratings

N

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
.Input Voltage
Operating Range
26V
Overvoltage Protection
LM2931A, LM2931CT, LM2931CS Adjustable
60V
LM2931
50V

co
Co)

Internal Power Dissipation
(Notes l' and 3)

Internally Limited

Operating Ambient Temper~ture Range
Maximum Junction Temper/dure
Storage Temperature Range
Lead Temp. (Soldering, 10 seconds)

-40'Cto +85'C
125'C
-65'Cto +150'C
230'C

ESD Tolerance (Note 4)

2000V

Electrical Characteristics for Fixed 5V Version
Y,N = 14V, 10 = 10 mA, TJ = 25'C, C2 = 100 p.F (unless otherwise specified) (Note 1)
LM2931A-5.0
Parameter

Conditions
Typ

Output Voltage

Limit
(Note 2)

9V ~ Y,N
6V:S: Y,N

Line Regulation

~

~
~

10

16V
26V

~

100mA

Typ

VMAX
VMIN

S.2S
4.7S

S.S
4.5

VMAX
VMIN

2
4

10
30

mVMAX
mVMAX

14

50

2
4

10
30

14

50

Load Regulation

SmA

100 mAoe and 10 mAnns,
100 Hz-l0 kHz

200

Quiescent Current

10 ~ 10 mA; 6V ~ Y,N ~ 26V
-40'C ~ Ti ~ 125'C
10 = 100 mA, Y,N = 14V, Ti = 25'C'

0.4

1.0

0.4

15

30
5

15

10 Hz-l00 kHz, COUT = 100 p.F

500

500

20

20

200

..

Long Term Stability
Ripple Rejection

fo = 120Hz

80

Dropout Voltage

10 = 10mA
10 = 100mA

0.05
0.3

Maximum Operational
Input Voltage

..

SS

80

0.2
0.6

0.05
0.3

33
RL = 5000, Vo ~ 5.5V,
T = 1 mS,T ~ lOOms

Reverse Polarity Input
Voltage, DC

Vo

Reverse Polarity Input
Voltage, Transient

T = 1 mS,T

~

mVMAX
mOMAX

1.0

mAMAX
mAMAX
mAMIN
p.Vrms

!All

mV/l000 hr
dBMIN
0.2
0.6

VMAX
VMAX

26

VMAX
VMIN

33
26

Maximum Line Transient

Units
Limit

5.25
4.75

Output Impedance

Output Noise Voltage

Limit
(Note 2)

5.19
4.81

5
6.0V ~ Y,N ~ 26V,Io = 100 mA
-40'C ~ Ti ~ 125'C

LM2931-5.0

70

60

70

50

VMIN

-30

-15

-30

-15

VMIN

-80

-50

-80

-50

VMIN

-0.3V, RL = 5000
~

100ms,RL = 5000

Note I: See circuit in Typical Applications. To ensure constant junction temperature, low duty cycte putse testing is used.
Note 2: AlllimHs are guaranteed for TJ = 2S"C (standard type face) or over the full operating junction temperature range of -40"C to + 12S'C (bold type face).
Note 3: The maximum power dissipation is a function of maximum iunction temperature TJmax, total thermal resistance 8JA, and ambient temperature TA. The
maximum allowable power dissipation at any ambient temparature is Po = (TJmax - TAJI8JA. If this dissipation Is exceeded, the die lemperature will rise above
150"C and the LM2931 will go into thermal shutdown. For the LM2931 in the T0-92 package, 8JA is 19S'C/W; in the so-a package, 8JA is 18O"C/W, and in Ihe TO·
220 package, 8JA is SO"C/W; and in Ihe TO·263 package, 8JA is 73'C/W. If the TO-220 package is used with a heal sink, 8JA Is Ihe sum of the package thermal
resistance junction·lo·case of 3'C/W and the thermal resistance added by the heat sink and thermal interface.
,,\he T0-263 package Is used,lhe thermal resistance can be reduced by Increasing the P.C. board copper area Ihermally connected to the package: Using O.S
square inches of copper area. 8JA is SO"C/W; with I square inch of copper area. 8JA is 37"C/W; and with 1.6 or more square inches of copper area, 8JA is 3Z'C/W.
Note 4: Human body model, 100 pF discharged through I.S kn.

2·31

.....

Electrical Characteristics for Adjustable Version
VIN = 14V, VOUT = 3V, 10 = 10 mA, .TJ = 25"C, Rl = 27k, C2 = 100 "F (unless 'otherwise specified) (Note 1)
Parameter

Conditions

Reference Voltage

Typ

Limit

Units
Umlt

1.20

1.26
1.14

VMAX
VMIN

1.32
1.0B

VMAX
VMIN

24
3

VMAX
VMIN

0.2

1.5

mVNMAX

0.3

1

'0 s; 100 mA, -40"C

S; Tj S; 125"C, Rl = 27k
Measured from VOUT to Adjust Pin

Output Voltage Range
Line Regulation

VOUT

,j-

0.6V

Load Regulation

5mA

S;

10

Output Impedance

100 mAce and 10 mAnns, 100 Hz-10kHz

40

Quiescent Current

10 =,10mA
10 = 100mA
During Shutdown RL =,5000

0.4
15
0.8

10Hz-100kHz

100

"VnnslV

0.4

%/1000 hr

Output Noise Voltage

S;

VIN

S;

26V

100mA

S;

Long Term Stability

%MAX
mON

1
1

mAMAX
mA
mAMAX

Ripple Rejection

'0 = 120Hz

0.02

Dropout Voltage

10 S; 10mA
10 = 100mA

0.05
0.3

0.2
0.6

VMAX
VMAX

33

26

VMIN

70

60

VMIN

-30

-15

VMIN

-80

-50

VMIN

2.0
2.2

1.2
3.25

VMAX
VMIN

20

50

p.AMAX'

Maximum Operational Input
Voltage
Maximum Line Transient

10 = 1P mA, Reference Voltage
T = 1 ms,

'T S;

1.5V

100 ms

Reverse Polarity Input
Voltage, DC

Vo ~ -0.3V, RL =5000

Reverse Polarity Input
Voltage, Transient

T = 1 ms,'T

On/Off Threshold Voltage
On
Off

Vo=3V

S;

S;

%IV

100 ms, RL = 5000

On/Off Threshold Current

2-32

.-----------------------------------------------------------------------------~ ~

s::

Typical Performance Characteristics

N
CD

....

Co)

Dropout Voltage

Dropout Voltage

0.8

E:o.s

i

I I

---.

I

!

U
0.3

I

ioo"""

0.2

i

~

0.1

o

i"""""

o

I

10 = lOOmA_

I

I

I I
80

aE: 0.5

5.0

Ii
IQ

.r'5

10=10mA

40

6.0

I

10 = 50mA

_........

0.2

1.0

3.0
4.0
5.0
Input YGItagI (V)

2.0

6.0

Load Transient Response
C2 = lOOpF

VIN'VOUT = IV
C2.1ooF~

500Q

-

J:

1o

;

I

2

I
IL

i".

-...

-2
-20 -10 0 10 20 30 40 50 80
Input Voltage (V)

I:

1j

J

2S'C

I

1

~

Tj = ....ooc

200
100

o

o

10

20

f

i

VIN = 14V

1

25

15

,

10
5

~ i""""

o
. 0

30

Quiescent Current

- - ~oo:mA ~=~~t

o

!
r-

-

10 = 10 mAl
-5
-20 -10 0 10 20 30 40 50 80
Input YGIIIgI (V)

15
10
~I-

I

,

,

C2

....0

75

j:

10 = 50mA I-f10'=

o

40

!m~- r-80

120

Junction rimpelllure (OCI

•

Ripple Rejection
85

100 ~F TANT

z

-

-r-.. -

o

30
60
90
Output Current (mA)

80

I I 11
>-- -

J

20

Ripple Rejection
85

45

Quiescent Current

j20

G

30

25

Input van.ge (V)

I I I
I I I

15

Time (PI)

Qule~nt Current

Tj = 8,!l...- " ,

i~

o

45

Tlme(~I)

30

-

30

15

Peak Output Current
800

f

,

2.0

Une Transient Response

E: •

500

"

~

100

50

L1I2I31-5.0

AL •

i
0

".

,J

3.0

Output CUrrent (mA)

Output at Voltage Extremes
10

~
~

V
o

120

,

& 4.0

D.3

0.1

LM2931·5.0
I = loomA

E:

D.4

Junction Timpelllure (C)

12

Low Voltage Behavior

0.6

;;; 80

.L

C2 = 100 pF AWM

tJ , J

I

I:

I

50 I- LM2931·5.Q
10 = 10mA
45
1 10 100 lk

l
10k lOOk 1M

Frequency (Hz)

:e.

75

"

10

-l

65
80

I
.l!-

II:

ss
50
45

,,,

10 = 120 Hz

o

25

50

75

100

Output Current (mAl
TLlH/5254-2

2-33

....

fJ

:5

Typical Performance Characteristics
Operation During Load
Dump
.

Output Impedance
10

Reference Voltage
1.30

LN2931-5.

10= lOrnA

:stl

:€

I I .......

I

~

~

~
~
~

~

~

V

0.1

~

0.01

1.28
1.26
1.2.
1.22

,10

100

Ik

10k 100k

1M

100

Maximum Power Dissipation
1.0

......

~

"

0.5

z

!2

......

0.•

.......

~
~

22
20
18
18
1.
12
10 ~i"'"

S

0.3
0.2
O. I

o

'0

-

o
o

10 20 30 .0 50 60 70 80 90
AMBIENT TEMPERATURE (OC)

:€

'I. I I
'l...N

~

,.~
~

w

r--.~

alA = 50 0c/w ~~
r l ' ! - [ , ...... '.-:::

-~al!=~30~/W~ ;;::r=t

o

DC W HEAT SIN ~ r-r'-

......

i<

12

1.0

,

~OH" T $[

9

15

18

21

I

0.9
~

....

6

2.

Maximum Power DlsslpaUon
, (To-92)

~

0,8
,0.7

~

,0.6

~
-

'0.5

fS

0.3

~

.'

I

.......

......

,0.2
0, 1

o

10 20 30 .0 50 60 70 80 90100

I
O.125':cLEAD LENGTH
...... ;:!.RO"
BOARO
,...:.
.......
0.... LEAD

L-

I
J
I

I J L

0.• '"7" LENGTH FRO

r" ~

,e JAR

N~

"-=

I
I

0102030.05060708090

AM~IENT ~EMPERA~URE (Oc)

On/off Threshold

alA = 32°C/W

eJA=37°C/W

o

3

OUTPUT VOLTAGE (V)

INrIIUTE HEAT SINK

....!.;

......

Output Capacitor ESR

..0

I I

:::::,

o

AMBIENT, TEMPERATURE (OC)

Maximum Power Dissipation
(To-263) (See Note 3)

"-J. I

300 .00 500

......
"

Maximum Power Dissipation
(TD-220)

(SO-8)

0.7
0.6

....... 1'0.

1.16
1.1.
1,12

, TIME(m.)

fREQUENCY (Hz)

0.9
0.8

200

......

1.20
1.18

1.10
I

LN2U1CT ADJUSTA LE

10 20 30 .0 50 60 70

~O

90100

~
!:;

lM2931CT ADJUSTA LE

3.8
'3.6

3··
3.2

orr

3.0

~

2.2
2.0

1

/'

2.8
!i! 2.6
1::, '2,.
0

.....

CoUT= 100 ",F
Vo=5V

,

.......

o

'~

STABLE
REGION

1

,~

1
3

6

AMBIENT TEMPERATU~E (OC)

9

12

15

18

OUTPUT ,VOLTAGE (V)

21

2.

20

.0

60

80

100

,OUTPUT, CIIRREHT (mA)
TL/H/5254-3

,

"

2-34

Schematic Diagram
V,No-t------------------------------1~--------------.

VOUT

01
5V:Z ••
ADJ:IIO

ADJUST

012

".
R2
5V: lOOk
ADJ:oo

016

14.1k
GNO

TLIH15254-1

,.
2-35

9- , - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ,

~
C\I
:::E

...I

Application Hints

At this point, the procedure for bench testing the mi~ir~um
value of an output capaCitor in a special application circuit
should be clear. Since worst-case occurs at minimum operating temperatures and maximum operating currents, the
entire circuit, including the electrolytic, should be cooled to
the minimum temperature. The input voltage to the regulator
should be maintained at 0.6V above the output to keep internal power dissipation and die heating to a minimum.
Worst-case occurs just after input power is applied and before the die has had a chance to heat up. Once the minimum value of capaCitance has been found for the brand
and type of electrolytic in question, the value should be doubled for actual use to account for production variations both
in the capacitor and the regulator. (All the values in this
section and the remainder of the data sheet were determined in this fashion.)

One of the distinguishing factors of the LM2931 series regulators is the requirement of an output capacitor for device
stability. The value required varies greatly depending upon'
the application circuit and other factors. Thus some comments on the characteristics of both capacitors and the regulator are in order.
High frequency characteristics of electrolytic capacitors depend greatly on the type and even the manufacturer. As a
result, a value of capacitance that wor~s well with the
LM2931 for one brand or type may not necessary be sufficient with an electrolytic of different origin. Sometimes actual bench testing, as described later, will be the only means
to determine the proper capacitor type and value. Experience has shown that, as a rule of thumb, the more expensive and higher quality electrolytics generally allow a smaller
value for regulator stability. As an example, while a highquality 100 p.F aluminum electrolytic covers all, general application circuits, similar stability can be obtained with a tantalum electrolytic of only 47 p.F. This factor of two can generally be applied to any special application circuit also.
Another critical characteristic of electrolytics is' their performance over temperature. While the LM2931 is designed
to operate to -40"C, the same is not always true with all
electrolytics (hot is generally not a problem). The electrolyte
in many aluminum types will freeze around -30·C, reducing
their effective value to zero. Since the capacitance is needed for regulator stability, the natural result is oscillation (and'
lots of it) at the regulator output. For all application circuits
where cold operation is necessary, the output capacitor
must be rated to operate at the minimum temperature. By
coincidence, worst-case stability for the LM2931 also occurs at minimum temperatures. As a result, in applications
where the regulator junction temperature will never be less
than 25·C, the output capacitor can be reduced approximately by a factor of two over the value needed for the
entire temperature range. To continue our example with the
tantalum electrolytic, a value of only 22 p.F would probably
thus suffice. For high-quality aluminum, 47 p.F would be adequate in such an application.

Definition of Terms
Dropout Voltage: The Input-output voltage differential at
which the circuit ceases to regulate against further reduction in input voltage. Measured when the output voltage has
dropped 100' mV from ihe nominal value obtained at 14V
input, dropout voltage is dependent upon load current and
junction temperature.
Input Voltage: The DC voltage applied to the input terminals'with respect·to ground..
Input-Output Differential: The voltage difference between
the unregulated input voltage and the regulated output volt'age for .."hich the regulator will operate.
Line, ,Regulation: The change in output voltage for a
: change in the input voltage. The measurement is made under conditions of low dissipation or by using pulse techniques such that the average chip temperature is not significantly affected.
Load Regulation: The change in output voltage for a
change in load current at constant chip temperature.
Long Term Stability: Output voltage stability under accelerated life-test conditions after 1000 hours with maximum
rated voltage and junction temperature.

Another regulator characteristic that is noteworthy is that
stability decreases with higher output currents. This sensible
fact has important connotations. In many applications, the
LM2931 is operated at only a few milliamps of output current or less. In such a circuit, the output capaCitor can be
further reduced in value. As a rough estimation, a circuit that
is required to deliver a maximum of 10 mA of output current
from the regulator would need an output capacitor of only
half the value compared to the same regulator required to
deliver the full output current of 100 mAo If the example of
the tantalum capacitor in the circuit rated at 25·C junction
temperature and above were continued to include a maximum of lOrnA of output current, then the 22 p.F output
capaCitor could be reduced to only 10 p.F.

Output Noise Voltage: The rms AC voltage at the output,
with constant load and no input ripple, measured over a
specified frequency range.
Quiescent Current: That part of the positive input current
that does not contribute to the positive load current. The
regulator ground lead current.
Ripple Rejection: The ratio of the peak-to-peak input ripple
voltage to the peak-to-peak output ripple voltage at a specified frequency.
Temperature Stability of Yo: The percentage change in
output voltage for a thermal variation from room temperature to either temperature extreme.

In the case of the LM2931 CT adjustable regulator, the minimum value of output capaCitance is a function of the output
voltage. As a general rule, the value decreases with higher
output voltages, since internal loop gain is reduced.

2-36

,-------------------------------------------------------------------------, r

3:

N

CD

t!lNational Semiconductor

Co)

CII

LM2935 Low Dropout Dual Regulator
General Description

Features

The LM2935 dual 5V regulator provides a 750 mA output as
well as a 10 mA standby output. It features a low quiescent
current of 3 mA or less when supplying 10 mA loads from
the 5V standby regulator output. This unique characteristic
and the extremely low input-output differential required for
proper regulation (0.55V for output currents of 10 mAl make
the' LM2935 the ideal regulator for power systems that include standby memory: Applications include microprocessor
power supplies demanding as much as 750 mA of output
current.
Designed for automotive applications, the LM2935 and all
regulated circuitry are protected from reverse battery installations or 2 battery jumps. During iine transients, such as a
load dump (60V) when the input voltage to the regulator can
momentarily exceed the" specified maximum operating voltage, the 0.75A regulator will automatically shut down to protect both internal circuits and the load while the standby
regulator will continue to power any standby load. The
LM2935 cannot be harmed by temporary mirror-image insertion. Familiar regulator features such as short circuit and
thermal overload protection are also provided.

• Two 5V regulated outputs
• Output current in excess of 750 mA
• Low quiescent current standby regulator
• Input-output differential less than 0.6V at 0.5A
• Reverse battery protection
• 60V load dump protection
• - 50V reverse transient protection
• Short circuit protection
., Internal t~ermal overload protection
• Available in 5-lead T0-220
• ON/OFF switch controls high current output
• Reset error flag
• P + Product Enhancement tested

Typical Application Circuit

6,

4-

'Required if regulator is located far from power
supply filter.

-J-C1*

" 11

S!
-:I:'O.l pi' r----:I::':NP:!::U:-T-O-U-TP-U"'T 2
ON/Off":"
VOLTAGE VOLTAGE
+T

~R1

~C2**

-+

",

20k

RESET
FLAG

Vour 5V
750 mA

4 SWITI:Hi

10~F

*

LM2935

o-~'----~RESET

IFOR Your ONLYI
5
GNO

13

...-_ _ _ _.....

"CoUT must be at least 10 "F to maintain stability.
May be increased without bound to maintain reg·
ulation during transients. Locate as close as possible to the regulator, This capaCitor must be rated over the same operating temperature range

as the regulator. The equivalent series resistance
(EBR) of this capaCitor is critical; see curve.

STANDBY 5V
OUTPUT 10 mA

,.

C3**
10~F

~
TL/H/5232-1

FIGURE 1_ Test and Application Circuit

Connection Diagram
TO-220 5-Lead

1~.1 I

~ 5 STANDBY OUTPUT
4 SWITCH/RESET
3 GROUND
2 OUTPUT VOLTAGE (Vour)
1 INPUT VOLTAGE (VIN)
TLiH/5232-B

Front View

Order Number LM2935T
See NS Package Number T05A
,2-37

Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Input Voltage
Operating Range
Overvoltage Protection

Internal Power Dissipation (Note 1)
Operating Temperature Range

Internally Limited
-40'Cto

+ 125'C

- 65'C to

+ 150'C

Maximum Junction Temperature

150'C

Storage Temperature Range
Lead Temp. (Soldering, 10 seconds)

26V
60V

230'C

Electrical Characteristics for VOUT
VIN = 14V, 10 = 500 mA, TJ = 25'C (Note 4), C2 = 10 ,...F (unless otherWise specified)

Parameter
Output Voltage

6V~VIN~26V,

Conditions

Typ

Tested
Limit
(Note 3)

Units
Limit

5 mA~lo~500 mA,
(Note 2)

5.00

5.25
4.75

VMAX
VMIN

4
10

25
50

mVMAX
mVMAX

50

" mVMAX

-40'C~TJ~125'C

Line Regulation

9V~VIN~16V,

6V~VIN~26V,

Load Regulation

10=5 mA
10=5 mA

" 5 mA~lo~500 mA

10

Output Impedance

500 mADe and 10 mArms, 100 Hz-10 kHz

200

Quiescent Current

10 ~ 10 mA, No Load on Standby
10 = 500 mA, No Load on Standby
10 = 750 mA, No Load on Standby

3
40
90

10 Hz-100 kHz

100

Output Noise Voltage
Long Term Stability

.

mO
mA"
100

mAMAX
mA
""Vrms
mV/1000 hr

20

Ripple Rejection

'0=120 Hz

66

Dropout Voltage

10=500mA
10=750mA

0.45
0.82

0.6

VMAX

1.2

0.75

AMIN

31

26

VMIN

70

60

V

-30

-15

V

Current Limit
Maximum Operational
Input Voltage
Maximum Line Transient

Vo~5.5V

Reverse Polarity" Input
Voltage, DC

dB

Reverse Polarity Input
Voltage, Transient

1% Duty Cycle, T ~ 100 ms,
100 Load

-80

-50

V

Reset Output Voltage
Low
High

R1 =20k, VIN=4.0V
R1 =20k. VIN= 14V

0.9
5.0

1.2
6.0
4.5

VMAX
VMAX
VMIN

Reset Output Current

Reset= 1.2V

ON/OFF Resistor

R1 (± 10% Tolerance)

20

kOMAX

5

mA

Note 1: Thermal resistance without a heat sink for junction to case temperature Is 3"C/W(TO-22O). Thermal resistance for TQ.220 cass to ambient temperature Is
50' C/W.
Note 2: The temperature extremes are guaranteed but not 100% production tested. This parameter is not used to calculate outgoing AQL
Note 3: Tested Limits are guaranteed and 100% teSted in production.
Note 4: To ensure constant junction temperature, low duty cycle pulse testing is used.

"

.

2·38

Electrical Characteristics for Standby Output
10= 10 mA, VIN= 14V, S1 open, Cour= 10 p.F, TJ=25·C (Note 4), (unless otherwise specified)
Standby Output
Conditions

Parameter

Typ

Tested
Limit

Units
Limit

5.00

5.25
4.75

VMAX
VMIN
mVMAX

Output Voltage

'0S:10 mA, 6VS:VINS:26V,
-40·CS:TJS: 125·C

Tracking

Your-Standby Output Voltage

50

200

Line Regulation

6V s: VIN s: 26V

4

50

mVMAX

Load Regulation

1 mAS:loS:10mA

10

50

mVMAX

Output Impedance

10 mADe and 1 mA rms, 100 Hz-10kHz

1

Quiescent Current

'0S:10 mA,
Your OFF (Note 2)

2

Output Noise Voltage

10 Hz-100 kHz

Long Term Stability

.0.
3

mAMAX

300

p.V

20

mVl1000 hr
dB

Ripple Rejection

fo=120 Hz

66

Dropout Voltage

'0S:10 mA

0.55

0.7

VMAX

70

25

mAMIN

70

60

VMIN

-30

-15

VMIN

-80

-50

VMIN

Current Limit
Maximum Operational
Input Voltage

VoS:6V

Reverse Polarity Input
Voltage, DC

Vo~

Reverse Polarity Input
Voltage, Transient

1% Duty Cycle T s: 100 ms
500.0. Load

-0.3V, 510.0. Load

Typical Circuit Waveforms
BOY

i\ ...31V·

INPUT
VOLTAGE 14V
PIN 1
(VI

......

3V

~n-n

S1~~~~ OPEN
OUTPUT
VOLTAGE
PIN2
(VI

LOSED
5V

OY-

STANDBY
VOLTAGE
PIN 5
(V)

5V

~V

/

OY-

J

~
OV

I

I

W
5V

5V

SYSTEM
CONDITION

OPEN

~

5V

RESET
VOLTAGE
PIN 4
(V)

14V

5V

ILl

I U

~
.-

5V

\..1:!!....1
TURN
ON

LOAD
DUMP

LOWVIN

UHE NOISE, E)'C •.

VOUY
SHORT
CIRCUIT

THERMAL
SHUTDOWN

TURN
OFF
TUH/5232-2

FIGURE 2

2-39

Ln

C")

~

Typical Performance Characteristics

:::iE

..J
Dropout Voltage (VOUT)

Dropout Voltage (VOUT)

Dropout Voltage (VSTBY)

E 1.0

l!I

....

~is

~!::_
'"o!.
~

is

lOUT ;'500 mA
0.4
0.2

~ o.B
!;
.... 0.7

-

0.6

~

-40

~

~

40
Bo
120 160
JUNCTION TEMPERATURE ("C)

0.1
0

~

/

~

'"

0.2
0.1

'"o!.

o 100 2DD 300 400 500 600 700 BOD

~ oo

Output Voltage (VOUT)

lOUT =500 mA
ISTYBv=IOmA

~

~ 0.3

§

10
15
OUTPUT CURRENT (mA)

OUTPUT CURRENT (mA)

Low Voltage Behavior

..,.,

1=_ :::
0.4 . /

10"'"

-0.3
~ 0.2

J

o

0.6

~

:!

0.9
0.8
0.7

i

~ 0.5
is 0.4

f-- I-louL,o)mA- f--

1

!

~ 0.9

~
~ 0.8

i

~

20

.

Output Voltage (VSTBY)
RL=500D

RL=1oD

II

VsT,~ "YoUT

~

rL
J

-I

o

2 3 4 5 B
INPUT VOLTAGE (V)

01

7

-2

B

20
lOUT =500 mA

IA

~
~

::0

i

40

-2

60

§

1

0

0
20
40
INPUT VOLTAG~ (V)

Load Transient Response
(VOUT)

iU.

6D

5i

0
-50

~=

""""" IV"

ill -5

60

-40 -20

150
!!I- 100

IA

10

!§i '" -10

IW

-20

20

Line Transient Response
(VSTBY)
"'z

'--- U

",'"

-40 -20

INPUT VOLTAGE (V)

Line Transient Response
(VOUT)

~ i' 10
~i 0
.... r:;
~ ~ -10

-I

"""

~

...I

ii!!-Ioo

I'

-ISO
g o.B
~!:: 0.6
0.4

!:!li!

a

o

10

20

30

40

50

60

TIME(,..)

20 30 40
TIME (pi)

Load Transient Response
(VSTBY)

Peak Output Current (VOUT)

150 r--'-"""-,..-,.--r--.--.
~
100 1-+-+-1-+-+-1--1
>- !:i 50 1--1--+-1-+-+-1--1
~~ 0
c~Ei
ti iii -50 1-+-+-1-+-+-1--1
6 ..- 100 1-+-+-1-+--+-1--1
-150 1:-+-+-1-++-4-1
liiI c 20

o

10

50

I-+-+-+-+-+-+--I

e:

f-t---t-+-+-++....:r

ge 15r-~-+~--i-~-+~

!5
~~

10

1-+--+-I-+-4-.J--I

t-+-t-t-+-+-+--I
0L-..1.--'--'--'-.......L.......J1......I
5

o

10

20 30 40
TlME(,..)

50

60

I-

o

10

20 30 40
TIME (,..)

50

60

Peak Output Current (VSTBY)
100

i'

ii

0.2

60

g

1.5

::0

1.0

Iii
...

~
'"
::0

BO

i

60

I

~

40

I

'"

20

B

0.5

o

!

i-'"
~

o

10 15 20
25
INPUT VOLTAGE (V)

3D

o

,-

./

II
o

10

20
3D 40 50
INPUT VOLTAGE (V)

60

TL/H/5232-3

2-40

r-----------------------------------------------------------------------------'r
Typical Performance Characteristics

==
CD

(Continued)

I\)

Co)

U1

Quiescent Current (VOUT)

Quiescent Current (VSTBY)

120

5

I

i~ :

I

30
20
10

I-'"

"

o

o

Quiescent Current (VSTBY)
4

81 OPEN
VoUTOFF

3

I..'"

I==- I-Isr!Y=101nA- f---

IITIY=O mA

i
o

-40

-

i

fa

II

Your

fauT~500

30

160
1"40

lOUT =750 mA',= ~

~120

.iii

lOUT =
500mA

'"

IOUTOmA

::1100
a:
'" BO
60
M 40
co 20
0

-40

...ili

!!.

.1
I

ill
B

'j'=t~ ~

i~

co
'"

~

~

~
ill

mA

C2=10jiF

I--

60

40
3D

-20 -10 0 10 20 3D 40 50 6D
INPUT VOLTAGE (V)

Ripple Rejection (VSTBY)
80

-

10k

Output Impedance

10=120 Hz

iii' 70

~

:z

~UI

50

'"

60
50

E 40

30
100
lk
FREOUENCY (Hz)

'fByr1- I--

1

o

10=120 Hz
z·

S10PEN
Vour OFF

:c-

Ripple Rejection (VOUT)

co

150 300 450 600
OUTPUT CURRENT (mA)

0

750

Reset on Startup

3D

0

1'0.,._

RL=100

I

0.01

9

10

100
1k
FREOUENCY (Hz)

10k

,/

1/

"

18
16
14
12
10
8

t--I- NO HEAT

o l/

25

INFINITE HEAT SINK

ZO

1-~=20k

IORlln

5
10
15
20
OUTPUT CURRENT (mA)

Maximum Power
-Dissipation (TO-220)
22

§:

r-

0
40
BO no 160
JUNcnON TEMP£RATURE ('C)

9

-20 -10 0 10 20 30 40 5060
INPUT VOIJAGE (V)

iii' 70

II!..

IDUT=250 RIA

20

10 H- t:Lo~r ='50 InA

Quiescent Current (VSTBY)

E 40
10

50

40

o

10
15
20
25
STANDBY OUTPUT CURRENT (mA)

80

VsT6y""'''
Imy=10mA
C3=10pF

70

60
50

a:

'"

IsTIY -10 mA

Ripple Rejection

i

..~Iii
.

Quiescent Current

0
40
80
120 160
JUNcnON TEMP£RATURE ('C)

80

!

/

101"

VDur-OUTPUT CURRENT (mA)

!!.

...V

-.l.

ISTIy-10mA

70

1 60 ,-+- r-I'O~=~RIA -~
S
co

o~
o 100 200 300 400 500 600 700 BOO

:c-

/

II

60

ill

SI0P£N
Your OFF

I

~ ~

'"B

80

ISTly=10 mA

110

1"00
_ 10

Quiescent Current (VOUT)

1O"C W HEAT SINK

r-..
~INK

~b.

o

012345678
INPUT VOIJAGE (V)

o 10 20 30 40 50 60 70 BD 90 100
AIIBIENT lEMPERATURE (OC)
TL/H/5232-4

2-41

Load Regulation: The change in output voltage for a
change in load current at constant chip temperature.

Typical Performance
Characteristics (Continued)

Long Term Stability: Output voltage stability under accelerated life-test conditions after 1000 hours with maximum
rated.voltage and junction temperature.

Output CapaCitor ESR
(Standby Output, Pin 5)

Output Noise Voltage: The rms AC voltage at the output,
with constant load and no input ripple, measured over a
specified frequency range.
Quiescent Current: The part of the positive input current
that does not contribute to the 'positive load current. The
regulator ground lead current.
Ripple ReJection: The ratio of the peak-to-peak input ripple
voltage to the peak-ta-peak output ripple voltage.
Temperature Stability of VO: The percentage change in
output voltage for a thermal variation from room temperature to either temperature extreme.

Application Hints
EXTERNAL CAPACITORS
The LM2935 output capacitors are required for stability.
Without them, the regulator outputs will oscillate, sometimes
by many volts. Though the 10p.F shown are the minimum
recommended values, actual size and type may vary depending upon the application load and temperature range.
Capacitor effective series resistance (ESR) also factors in
the IC stability. Since ESR varies from one brand to the
next, some bench work may be required to determine the
minimum capaCitor value to use in production. Worst-case is
usually determined at the minimum ambient temperature
and maximum load expected.
Output capaCitors can be increased in size to any desired
value above the minimum. One possible purpose of this
would be to maintain the output voltage during brief conditions of negative input transients that might be characteristic of a particular system.

OUTPUT CURRENT (rnA)
TLlH/5232-9

Output CapaCitor ESR
(Main Output, Pin 2)

§

0.11--1--11--1--1--1

~

:::>

f3 0.01 '--_'-----''-----'_.......1_.......1

o

100

200

300

400

500

Capacitors must also be rated at all ambient temperatures
expected in the system. Many aluminum type electrolytics
will freeze at temperatures less than -30'C, redUCing their
effective capaCitance to zero. To maintain regulator stability
down to -40'C, capacitors rated at that temperature (such
as tantalums) must be uSed.

OUTPUT CURRENT (rnA)
TLlH/5232-10

Definition of Terms
Dropout Voltage: The input-output voltage differential at
which the circuit ceases to regulate against further reduction in input voltage. Measured when the output voltage has
dropped 100 mV from the nominal value obtained at 14V
input, dropout voltage is dependent upon load current and
junction temperature.

No capaCitor must be attached to the ON/OFF and ERROR
FLAG pin. Due to the internal circuits of the IC, oscillation on
this pin could result.
STANDBY OUTPUT
The LM2935 differs from most fixed voltage regulators in
that it is equipped with two regulator outputs instead of one.
The additional output is intended for use in systems requiring standby memory circuits. While the high current reglilator output can be controlled with the ON/OFF pin described
below, the standby output remains on under all conditions
as long as sufficient input voltage is applied to the IC. Thus,
memory and other circuits powered by this output remain
unaffected by positive line transients, thermal shutdown,
etc.

Input Voltage: The DC voltage applied to the input terminals with respect to ground.
Input-output Differential: The voltage difference between
the unregulated input voltage and the regulated output voltage for which the regulator will operate.
Line Regulation: The 'change in output voltage for a
change in the input voltage. The measurement is made under conditions of low dissipation or by using pulse techniques such that the average chip temperature is not significantlyaffected.

The standby regulator circuit is designed so that the quiescent current to the IC is very low «3 mAl when the other
regulator output is off.

2-42

Application Hints (Continued)
In applications where the standby output is not needed, it
may be disabled by connecting a resistor from the standby
output to the supply voltage. This eliminates the need for a
more expensive capacitor on the output to prevent unwanted oscillations. The value of the resistor depends upon the
minimum input voltage expected for a given system. Since
the standby output is shunted with an internal 5.7V zener
(Figure 3), the current through the external resistor should
be sufficient to bias R2 and R3 up to this point. Approximately 60 /LA will suffice, resulting in a 10k external resistor
for most applications (Figure 4).
'

ON/OFF AND ERROR FLAG PIN
This pin has the ability to serve a dual purpose if
desired. When controlled in the manner shown in Figure 1
(common in automotive systems where S1 is the ignition
switch), the pin also serves as an output flag that is active
low whenever a fault condition is detected with the high
current regulated output. in other words, under normal
operating conditions, the output voltage of this pin is high
(5V). This is set by an internal clamp. If the high current
output becomes unregulated for any reason (line transients,
short circuit, thermal shutdown, low input voltage, etc.) the
pin switches to the active low state, and is capable of sinking several milliamps. This output signal can be used to initiate any reset or start-up procedure that may be required of
the system.

RD
10k

The ON/OFF pin can also be driven directly from open collector logic circuits. The only requirement is that the 20k
pull-up resistor remain in place (Figure 5). This will not affect
the logic gate since the voltage on this pin is limited by the
internal clamp in the LM2935 to 5V.

STANDBY

OUTPUT
LM2935

LM2935
CMOS MM74CD4
DR EQUIVALENT

TL/H/5232-6

DELAYED
RESET

FIGURE 4. Disabling Standby Output to Eliminate C3

OUT

HIGH CURRENT OUTPUT
Unlike the standby regulated output, which must remain on
whenever possible, the high current regulated output is fault
protected against overvoltage and also incorporates thermal shutdown. If the ir:Jput voltage rises above approximately 30V (e.g., load dump), this output will automatically shutdown. This protects t~e internal circuitry and enables the IC
to survive higher voltage transients than would otherwise be
expected. Thermal shutdown is effective against die overheating since the high current output is the dominant source
of power dissipation in the IC.

Rl

20k

SWITCH I
RESET

TL/H/5232-11

FIGURE 6. Reset Pulse on Power-Up
(with approximately 300 ,ms delay)

LM293S'

DM740S
TLlH/5232-7

FIGURE 5. Controlling ON/OFF Terminal with
a Typical Open Collector Logic Gate

fII

2-43

LM2935

o=i'

n

SWlTCHIRESET

•

c

;;
YIN

en

n

::T
CD

3&»

0'

•

k

[Pl.

YO\I'

R33

R30

82

R3

":"

R31

1M

N28

GND

TL/H/5232-5

FIGURE 3

t!lNational Semiconductor

LM2936 Ultra-Low Quiescent Current 5V Regulator
General Description

Features

The LM2936 ultra-low quiescent current regulator features
low dropout voltage and low current in the standby mode.
With less than 15 p.A quiescent current at a 100 p.A load,
the LM2936 is ideally suited for automotive and other battery operated systems. The LM2936 retains all of the features that are common to low dropout regulators including a
low dropout PNP pass device, short circuit protection, reverse battery protection, and thermal shutdown. The
LM2936 has a 40V operating voltage limit, -40'C to
+ 125'C operating temperature range, and ±3% output
voltage tolerance over the entire output current, input voltage, and temperature range. The LM2936 is available in
both a TO-92 package and an B-pin surface mount package
with a fixed 5V output.

• Ultra low quiescent current (IQ ,;; 15 p.A for
10 ,;; 100 p.A)
II Fixed 5V, 50 mA output
• Output tolerance ±3% over line, load, and temperature
• Dropout voltage typically 200 mV @ 10 = 50 mA
• Reverse battery protection
• - 50V reverse transient protection
• Internal short circuit current limit
• Internal thermal shutdown protection
• 40V operating voltage limit

Typical Application
• Required if regulator is located more than 2' from power supply filter

capacitor.
.. Required for stability. Must be reted for 10 p.F minimum over intended
operating temperature range. Effective series resistance (ESR) is critical,

see curve. Locate capacitor as close as possible to the regulator output and
ground pins. Capacitance may be increased without bound.

10
Input-I-- VIN

100 nF'

T

LM2936

VoH~~Output

Ground

I

=r}
+

tlo

0 pFo.

IC

out

L -_________~---------~

~

TL/H/9759-1

Connection Diagrams
TO-92 Plastic Package (Z)

8-PlnSO{M)

'.Q~
Ground

IN

GND

GND

a

TL/H/9759-2

BoUomVlew

OUT

Order Number LM2936Z-S.0
See NS Package Number Z03A

GND

GND

Ne

Ne

TL/H/9759-6

Top View
Order Number LM2936M-S.O
See NS Package Number M08A

2-45

Absolute Maximum Ratings (Note 1)
Storage Temperature Range
Lead Temperature (Soldering, 10 sec.)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
+60V, -50V
Input Voltage (Survival)
ESD Susceptabilit}i(Note 2)
1900V
Power Dissipation (Note 3)
Internally limited
150·C
Junction Temperature (TJmaxl

-65·C to + 150"C
260"C

Operating Ratings
Operating Temperature Range
Maximum Input Voltage (Operational)

-40·C to + 125·C
40V

Electrical Characteristics
VIN = 14V, 10 = 10 mA, TJ = 25"C, unless otherwise specified. Boldface limits apply over entire operating temperature range
Parameter
Output Voltage

Line Regulation
Load Regulation
Output Impedance

Typical
(Note 4)

Conditions
5.5V ~ VIN ~ 26V,
10 ~ 50 mA (Note 6)

..

,

Output Noise Voltage

Dropout Voltage
Reverse Polarity
DC Input Voltage

5.15

Vmax

~

VIN

~

16V

5

10

6V

~

VIN

~

40V, 10 = 1 mA

10

30

100 IJoA ~ 10 ~ 5 mA

10

30

5mA~loS:50mA

10

30

. 10 = 100 poA, BV
10 = 10 mA, BV
10 = 50 mA, BV
10 Hz-100 kHz

~

VIN

~

~

24V

~

VIN

~

VIN ~ 24V

24V

450

10 = 50mA
RL = 500n, Vo

~

mn

0.20

0.50

1.5

2.5

mAmax
poVrms
mVl1000Hr

RL = 500n, T = 1 ms

Output Leakage with
Reverse Polarity Input

VIN = -15V, RL = 500n

Maximum Line Transient

RL = 500n, Vo

Short Circuit
Current

Vo= OV

~

IJoAmax
mAmax

60

40

0.05

0.10

dBmln
Vmax

0.20

0.40

Vmax

-15

Vmln

-BO

-50

Vmin

-0.1

-600

poAmax

-0.3V

Reverse Polarity
Transient Input Voltage

mVmax

15

20
Vrloole = 1 Vrms, frioole = 120 Hz
10 = 100 poA

mVmax

9

500

Long Term Stability
Ripple Rejection

Vmin
V

9V

10 = 30 mAde and 10 mArms,

Units

4.85
5

f = 1000 Hz

Quiescent Current

Tested
Limit
(Note 5)

5.5V, T = 40 ms
120

60

Vmin

250
65

mAmax
mAmin

Note 1: Absolute Maximum Ratings Indicate limits beyond which damage to the device may occur. DC and AC electrical speCifications do not apply when operating
the device beyond its specHied operating ratings.
Note 2: Human body model, tOO pF discharge through a 1.S kG resistor.
Note 3: The maximum power dissipation Is a function of TJmax, @JA, and TA. The maximum allowable power dissipation at any ambient temperature is
Po = (TJmax - TNI@JA' If this dissipation Is exceeded, the die temperature will rise above 15O'C and the LM2936 will go into thenmal shutdown. For the
LM2936Z. the junctlon·to·amblent thermal resistance (@IN is 19S'C/W. For the LM2936M, Bia is 160'C/W.
No~e 4: Typlcals are at 25'C (unless otherwise specified) and represent the most likely parametric nonm.
Nole 5: Tested limits are guaranteed to National's AOQL (Average Outgoing Quality Level) and 100% tested.
Nole 6: To ensure constant junction tem~rature, pulse testing is used.

2·46

Typical Performance Characteristics
Maximum Power
Dissipation (TO-92)

Dropout Voltage

o.s

1.0
0.9
DB
0.7

8

I

D.6

o.s

D.2

D.3
D.2
0.I

I-

0.1

0.0

0.0

~

120

110

Quiescent Current

A'o=1 ~P
1'o=OpA

4

10 20 30 40 50 60

i0

-50

I
0

25

I

100

150

50

I
I

o
o

-

10

/
./
V

20

30

40

50

OUTPUT CURRENT(mA)

Quiescent Current

Output Capacitor ESR

I
10~501mA

IOO~~~~~-r~~~

U
1.2
1.0

10=50mA

D.8
D.8

1.0

o.s

'0 =110 mA

V'

0
-10

D.4

'o=IOmA

D.2

-0.5
-20

50

2.D
rt1N=14
IB
1.6

3D

1.5

40

Quiescent Current

JUNCTION TEYPERAlURE(OC)

TJ=25OC

2.D

30

'o=IOOpA

o

Quiescent Current
3.S

20

OUTPUT CURRENT (mA)

I

INPUT VOLTAGE (V)

!

10

VIN = 14V
_ TJ =25OC

12

-10

o4JI

~ I---'

14

8

-20 -10 0

o
o

20
VIN=14V
18
16

10
10

150

Quiescent Current
J=25"1

11'0=1 mA

20

100

0., / "

JUNCTION TEMPERAlURE(OC)

60

n

D.2

IoUT=IOmA

50

TJ=i5OC

5

'oUT:;!l? i""'"

-so

AMBIENT IDIPERAlURE(OC)

50

-

Dropout Voltage

i

0.4

5

D.4

o.s

10
INPUT VOLTAGE (V)

20

30

o
-so

50

100

JUNCTION TEMPERAlURE (OC)

150

10

20

30

40

50

OUTPUT CURRENT (mA)

TLlH/9759-3

fI

2-47

Typical Performance Characteristics (Continued)
Peak Output Current

Peak Output Current

250
TJ =25"C

.- ~ I--

I

0

-

I

!

~..!i

Io
~

I

~~t:~~~4:4:j

20

15

-50

Cour= IO I'F
lo=10mA
0.D2 VIN =14V

0

lD'
:!!.
z
0

1.2

1.4

-10 0

~~ IID4
5~

0

§<>-DJ12
-o.D4
-oJJ6

1

5i!~

91

~

40

1\
\

/

U

1

~

30

20

10

40

30

50

60

1

10

1/

/

2.0

TlME(P.)

3D

I
I

40

INPUT VOLTAGE (V)

lk

10k lOOk

1M

Output Impedance

g

1.0
1.0

100

, fREQUENCY(Hz)

10.0

1o=10mA
TJ =25"C

(

102030«15060

~

Ii!

I

«I
30
20
10
0

~

Low Voltage Behavior
50

g~ IID2

60
50

'INPUT VOLTAGE (V)

Load Transient Response
Cour= 10l'F

I

20

TlWE(m.)

D.06

250

VIN= 14V,
1o=10mA
70 CouT= 10l'F

!;!
ii1
II:

II
0.& DB 1.0

100, 150 .. 200

Ripple ReJection
60

-2
OA

50

OUTPUT CURRENT (mA)

I

lID D.2

,

o

~~~

~-0JJ6

14

o

150

,

0

~~

100

Output at
Voltage Extremes
10

-o.D4

i5

50

I
J

1

JUNGTION TEMPERATURE("C)

12

§-DJ12

!i!!l!

/

5O~+-+-t-+-+-+-~,

25

~~:

17

/

100 1-1=-+-+-+-+-+-+-1-1

Line Transient Response

!:i~

)

150 1-+-+-+--+--+--I-+---1

INPUT VOLTAGE (V)

5~

TJ=25'C
VIN =14V

200 HH-t-t-t-+-t--l

O~~L-L-L-~~~~

10

~S

Current Limit.

25O~V~=~14~V-'-'~~-'-'

50

50

VIN=14\1
10 =30 mA
CouT= 10l'F

['1'

1.0

lL J

0.5

1'--'

0.2
0.1
1

10

100"

lk,

10k lOOk

1M

fREQUENCY (Hz)
TL/H/9759-4

Applications Information
Under conditions of higher ambient temperatures, the voltage and current calculated in the previous examples will
drop. For instance, at the maximum ambient of 125°C the
lM2936 can only diSSipate 128 mW, limiting the input voltage to 7.34V for a 50 mA load, or 3.5 mA output current for
a 40V input.

Unlike other PNP low dropout regulators, the lM2936 remains fully operational to 40V. Owing to power dissipation
characteristics of the TO-92 package, full output current
cannot be guaranteed for all combinations of ambient temperature and input voltage. As an example, consider an
lM2936 operating at 25°C ambient. Using the formula for
maximum allowable power dissipation given in Note 3, we
find that POmax = 641 mW at 25°C. Including the small
contribution of the quiescent current to total power dissipation the maximum input voltage (while still delivering 50 mA
output current) is 17.3V. The device will go into thermal
shutdown if it attempts to deliver full output current with an
input voltage of more than 17.3V. Similarly, at 40V input and
25°C ambient the lM2936 can deliver 18 mA maximum.

While the lM2936 maintains regulation to 60V, it will not
withstand a short circuit above 40V because of safe operating area limitations in the internal PNP pass device. Above
60V the lM2936 will break down with catastrophiC effects
on the regulator and possibly the load as well. Do not use
this device in a design where the input operating voltage
may exceed 40V, or where transients are likely to exceed
60V.

2-48

rn
.a

I:SI

I I

T

c

;:Dl

~4S

CD

"~

i

I

0

I
I
10

20

YOUT

~

I

~

f

"

30

.0

.

Output Capacitor ESR

= 1SV

Cour =,101"
YOUT =,5V

It""'"

12

>
!;

Vour = SV.

J
-2
-30 -20 -10

loon

·16

Vou:;' 10V

~

1\ =

-.

-30' -20 -10

INPUT VOLTAGE (v)

1/1

Your = 12V

10

20 '30

.0

100

INPUT VOlTAGE (v)

200

300

.00

500

OUTPUT CURRENT (r';A)

Peak Output, Current
VIN

= 14V

o~~~~~~~~~~

-40

.0'

80

120

TEMPERATURE (oc)
TL/H/11280-4

Typical Application
~~~_ REGULATED

UNREGULATED _ ........;;.;...
INPUT

OUTPUT.

TLlH/I12BO-l

'Required ff the regulator is located more than 3 inches from the power supply fiUer capacitors,
"Required for stability. Cout must be at least 10 p.F (over the full expected operating temperatura range) and located as closa as possible to the regulator. The
equivalent series resistance, ESR, of this capacitor may be as high as 30.
.

2-54

,-------------------------------------------------------------------------,

~

s:

N
CD

l!fINational Semiconductor

8
.....
~
s:

N

:

LM2940/LM2940C 1A Low Dropout Regulator

8

General Description
The LM2940/LM2940C positive voltage regulator features
the ability to source 1A of output current with a dropout
voltage of typically 0.5V and a maximum of 1V over the
entire temperature range. Furthermore, a quiescent current
reduction circuit has been included which reduces the
ground current when the differential between the input voltage and the output voltage exceeds approximately 3V. The
quiescent current with 1A of output current and an input-output differential of 5V is therefore only 30 mAo Higher quiescent currents only exist when the regulator is in the dropout
mode (VIN - VOUT :S: 3V).
Designed also for vehicular applications, the LM29401
LM2940C and all regulated circuitry are protected from reverse battery installations or 2-battery jumps. During line
transients, such as load dump when the input voltage can
momentarily exceed the specified maximum operating volt-

age, the regulator will automatically shut down to protect
both the internal circuits and the load. The LM29401
LM2940C cannot be harmed by temporary mirror-image insertion. Familiar regulator features such as short circuit and
thermal overload protection are also provided.

Features
•
•
•
•
•
•
•

Dropout voltage typically 0.5V @Io = 1A
Output current in excess of 1A
Output voltage trimmed before assembly
Reverse battery protection
Internal short circuit current limit
Mirror image insertion protection
P + Product Enhancement tested

Typical Application
YIH
UNREGULATED
INPUT
Cl*

YoU!

LM2940

.41 1 FJ

!Ig

REGULATED
OUTPUT

+

Cagy"

J2Z~

~

TLIH/BB22-3

'Required il regulator is located lar Irom power supply Iliter.
"CoUT must be at least 22 p.F to maintain stability. May be increased without bound to maintain regulation during transients. Locate as close as possible to
the regulator. This capaCitor must be rated over the same operating temperature range as the regulator and the ESR is critical; see curve.

Ordering Information
Output Voltage

Temperature
Range
O'C:S;; TA:S;; 12S'C

Package
5_0

8_0

9_0

10

12

15

LM2940CT-S.0

LM2940CT-9.0

LM2940CT-12

LM2940CT-15

T0-220

LM2940CS-S.0

LM2940CS-9.0

LM2940CS-12

LM2940CS-15

T0-263

-40'C :s;; TA :s;; 125"C LM2940T-S.O

LM2940T-8.0

LM2940T-9.0

LM2940T-l0 LM2940T-12

TO-220

LM2940S-S.0

LM2940S-8.0

LM2940S-9.0

LM2940S-10 LM2940S-12

TO-263

-55"C:S;; TA :s;; 125'C LM2940K-5.0/883 LM2940K-8.0/883

LM2940K-12/883 LM2940K-15/883

2-55

T0-3

•

Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and speciflcatlons_
(Note 2)
LM2940S, T ,;: 100 ms
SOV
LM2940T, T ,;: 100 ms
SOV
LM2940K/883, T ,;: 20 ms
40V
LM2940CT, T ,;: 1 ms
45V
LM2940CS, T ';:,1 ms
45V
Internal Power Dissipation (Note 3)
Internally Limited
Maximum Junction Tempe~ature ,
150'C
Storage Temperature Range
-65'C';: TJ';: +150'C

Lead Temperature (Soldering, 10 seconds)
TO-3 (K) Package
TO-220 In Package
TO-2S3 (S) Package
ESD SusceptibilitY (Note 4)

300'C
2SO'C
2SO'C
2kV

Operating Conditions (Note 1)
2SV

Input Voltage,
Temperature Range
LM2940K/883
LM2940T, LM2940S
LM2940CT, LM2940CS

-55'C ,;; T A.';: 125'C
-40'C';: TA.';: 125'C
O'C ,;: TA';: 125'C

Electrical Characteristics

VIN = Vo + 5V, 10 = 1A, Co = 22 ",F, unless otherwise specified. Boldface
limits applv over the entire operating temperature range of the indl.cated device. All other specifications apply
for TA = TJ = 25'C
Output Voltage (Vo)
Parameter

Conditions

Typ

6.2SV ,;:
Output Voltage

5mA,;: 10';: 1A

Line Regulation

Vo + 2V ,;: VIN ,;: 26V,
10 = 5mA

Load Regulation

50mA,;: 10';: 1A
LM2940, LM2940/883
LM2940C

Output
Impedance

100mADCand
20mArms,
fo = 120 Hz

Quiescent
Current

V6+2V %- VIN ,;: 2SV,
10=5mA
LM2940, LM2940/883
LM2940C

8V

5V
LM2940
Limit
(Note 5)
~IN

LM2940/883
Limit
(Note 6)

Typ

,;: 26V

LM2940
Limit
(Note 5)

. LM2940/883
Limit
(Note 6)

Units

9.4V ,;: ,VIN ,;: 26V

5.00

4.85/4.75
5.15/5.25

4.85/4.75
5.15/5.25

8.00

7.76/7.60
8.24/8.40

7.76/7.60
8.24/8.40

VMIN
VMAX

20

50

40/50

20

80

50/80

mVMAX

35
35

50/80
50

501100

55
55

80/130

80/130

35

10
10

15/20

VIN = Vo + 5V,
10= 1A

30

45/60

Output Noise
Voltage

10 Hz - 100 kHz,
10 = 5mA

150

Ripple Rejection

fO = 120 Hz, 1 Vrms ,

80

mYMAX

ma

1000/1000

55

15/20

10

15/20

15/20

50/60

30

45/60

50/60

mAMAX

700/700

240

1000/1000

",Vrms

1000/1000

15

mAMAX

10=100m~

LM2940
. LM2940C

72
72

60/54

66
66

SO

fo = 1 kHz, 1 Vrms,
10 = 5mA
Long Term
Stability
Dropout Voltage

54/48

60/50
20

dBMIN

54

54/48

dBMIN
r'{1V/

32

1000 Hr

10 = 1A

0.5

0.8/1.0

0.7/1.0

0.5

0.8/1.0

0.7/1.0

VMAX

10 = 100mA

110

150/200

150/200

110

150/200

150/200

mVMAX

2-5S

Electrical Characteristics VIN = Vo + 5V, 10 = 1A, Co = 22 ~F, unless otherwise specified. Boldface
limits apply over the entire operating temperature range of the Indicated device. All other specifications apply
for TA = TJ = 25°C (Continued)
Output Voltage (Vo)
Parameter

Conditions

Short Circuit
Current

(Note 7)

Maximum Line
Transient

Ro = 1000
LM2940, T s: 100 ms
LM2940/883, T s: 20 ms
LM2940C, T s: 1 ms

Reverse Polarity
DC Input Voltage

Ro = 1000
LM2940, LM2940/883
LM2940C

Reverse Polarity
Transient Input
Voltage

Ro = 1000
LM2940, T s: 100 ms
LM2940/883, T s: 20 ms
LM2940C, T s: 1 ms

5V

8V

Typ

LM2940
Limit
(Note 5)

LM2940/883
Limit
(Note 6)

1.9

1.6

1.5/1.3

75

60/60

LM2940/883
Limit
(Note 6)

Units

Typ

LM2940
Limit
(Note 5)

1.9

1.6

1.6/1.3

AMIN

75

60/60
40/40

VMIN

55

45

-30
-30

-15/-15
-15

-75

-50/-50

40/40
55

45

-30
-30

-15/-15
-15

-75

-50/-50

-15/-15

-45/-45
-55

-15/-15

-45/-45

VMIN

VMIN

-45/-45

PI

'\.

"

2·57

Electrical Characteristics. VIN = Vo +. 5V, 10 = 1A, Co = 22 /LF, unless otherwise specified. Boldface
limits apply over the entire operating temperature range of the Indicated device. All other specifications apply
for TA

= TJ = 25°C (Continued)
Output Voltage (Vo)

Parameter

9V
Typ

Conditions

10V
LM2940
Limit
(Note 5)

10.5V ,;; VIN ,;; 26V
Output Voltage

5mA,;; 10 ,;;1A

Line Regulation

Vo + 2V ,;; VIN ,;; 26V,
10 = 5mA

Load Regulation

50 mA,;; 10';; 1A
LM2940
LM2940C

Output Impedance

Quiescent
Current

100mADCand
20mArms,
fo = 120Hz
Vo +2V,;; VIN
10 = 5mA
LM2940
LM2940C
VIN

= Vo +

5V, 10

Ripple Rejection

fo

Long Term
Stability

10.00

20

90

20

100

mVMAX

60
60

90/150

9.70/9.50
. 10.30/10.50

65

100/165

mVMAX

VMIN
VMAX·

90
65

= 1A

10
10

15/20

mO

30

45/60

10

15/20

mAMAX

30

45/60

mAMAX

15

270

300

52/46

64
64

/LVrms

34

= 1A
10 = 100mA

10

63

51/45

dBMIN

52
mVl
1000 Hr

36

0.5

0.8/1.0

0.5

0.8/1.0

VMAX

110

150/200

110

150/200

mVMAX

1.9

1.6

1.9

1.6

AMIN

75

60/60

VMIN

-30

-15/-15

VMIN

-75

-50/-50

VMIN

Short Circuit
Current

(Note 7)

Maximum Line
Transient

Ro = 1000
T,;; 100ms
LM2940
LM2940C

75
55

60/60

Ro = 1000
LM2940
LM2940C

-30
-30

-15/-15

Ro = 1000
T,;; 100ms
LM2940
LM2940C

-75
-55

-50/-50
-45/-45

Reverse Polarity
Transient Input
Voltage

11.5V,;; VIN ,;; 26V

8.73/8.55
9.27/9.45

= 120 HZ,1 Vrms,
= 100mA

LM2940
LM2940C

Reverse Polarity
DC Input Voltage

Units

< 26V,

10 Hz - 100 kHz,
10 = 5mA

Dropout Voltage

LM2940
Limit
(Note 5)

9.00

60

Output Noise
Voltage

10

Typ

45

2-58

-15

Electrical Characteristics VIN = Vo + 5V,Io = 1A, Co = 22 p.F, unless otherwise specified. Boldface
Ilmlta applv over the entire operating temperature range of the Indicated device. All other specifications apply
for TA = TJ = 25°C (~ontinued)

Parameter

Conditions

Typ

LM2940
LImit
(Note 5)
13.6V

~

~1A

Output Voltage

5mA

Line Regulation

Vo + 2V ~ VIN ~ 26V,
10 = 5mA

Load Regulation

50mA ~ 10 ~ 1A
LM2940, LM2940/883
LM2940C

10

~

VIN

75/120

55
55

120/200
120

120/190

1000/1000

80

15/20

VIN = Vo + 5V,Io = 1A

30

45/80

Output Noise
Voltage

10 Hz - 100 kHz,
10 = 5mA

360

Ripple Rejection

fo = 120 Hz, 1 Vrms,
10 = 100mA
LM2940
LM2940C

16.75V

~

66
66

20

150

70

150

VIN

LM2940/833
Limit
(Note 6)
~

100

95/150

1000/1000

15/20
15

50/60

30

45/80

1000/1000

450

64

mVMAX

mVMAX

mO

mAMAX
mAMAX

1000/1000

p.Vrms

dBMIN

52

52/48

VMIN
VMAX

50/60

54/48
54

Units

26V

150/240

10

48

48/42

dBMIN

mVI
1000 Hr

60

10 = 1A

0.5

0.8/1.0

0.7/1.0

0.5

0.8/1.0

0.7/1.0

VMAX

10 = 100mA

110

150/200

150/200

110

150/200

150/200

mVMAX

1.9

1.6

1.6/1.3

1.9

1.6

1.6/1.3

AMIN

75

60/60
40/40

VMIN

55

45

55

45

-30
-30

-15/-15

-30

-15

-75

-50/-50

-55

-45/-45

-55

-45/-45

Short Circuit
Current

(Note 7)

Maximum Line
Transient

Ao = 1000
LM2940, T ~ 100ms
LM2940/883, T ~ 20 ms
LM2940C, T ~ 1 ms

Reverse Polarity
Transient Input
Voltage

LM2940
Limit
(Note 5)

15/20

15

fO = 1 kHz, 1 Vrms,
10 = 5mA

Reverse Polarity
DC Input Voltage

Typ

26V

120

10
10

Dropout Voltage

~

20

Vo +2V ~ VIN ~ 26V,
10 = 5mA
LM2940, LM2940/883
LM2940C

Long Term
Stability

LM2940/833
LImit
(Note 6)

. 12.00 11.64/11.40 11.64/11.40 15.00 14.55/14.25 14.55/14.25
15.45/15.75 15.45/15.75
12.36/12.80 12.36/12.80

Output Impedance 10QmADCand
20mArms,
fo=120Hz
Quiescent
Current

15V'

12V

Output Voltage (Vo)

Ao = 1000
LM2940, LM2940/883
LM2940C
Ao = 1000
LM2940, T ~ 100 ms
LM2940/883, T ~ 20 ms
LM2940C, T ~ 1 ms

40/40

-15/-15

-15

-15/-15

-45/-45

2·59

-45/-45

VMIN

VMIN

Note 1: Absolute Maximum Ratings are limits beyond which damage to the devi'?9 may occur. Operating qon,ditions are conditions under which the device

functions but the specifications might not be guaranteed. For guaranteed specifications and test conditions see the Eleclrlcal Characteristics.
Note 2: Milijary specifications complied with RETS/SMD at the time of ·printing. For current specifications refer to RETS LM2940K-5.0, LM2940K-~.O, LM2940K-12,
and LM2940K-15. SMD numbers are 5962-8958701YA(5V), 5962-9083301YA(8V), 5962-9088401YA(12V), and 5962-9088501YA(15V):
Note 3: The maximum power dissipation is a function of the maximum junction temperature, TJ = 150'C, the junction-ta-ambient thermal resistance, 9JA, and the
ambient temperature, TA. The maximum alloweble power dissipation at any ambient temperature is POMAX = (150 - TJJI9JA. If this dissipation Is exceeded, the
die temperature will rise above 150'C and the LM2940 will go into thermal shutdown. For the LM2940T and LM294OCT, the junction-to-ambient thermal resistance
(9JJJ is 5:rC/W. When using a heatsink, 9JA is the sum of the 3'C/W junction-to-case thermal resistance (9Jcl of the LM2940T or LM2940CT and the case-to-ambientthermal resistance of the heatsink. If the TO-263 package is used, the thermal resistance can be used by increasing the P.C. board copper area thermally
connected to the package. Using 0.5 square Inches of copper area, 9JA is 50'C/W; with 1 square inch of copper area, 9JA is 37"C/W; and with 1.6 or more square
Inches of copper area , 8JA is 3'Z'C/W. For the LM2940K, 9JA is 39'C/W and 9JC is 4·C/W,.
Note 4: ESD rating' is based on the human body model, 100 pF discharged through 1.5 kO.
Note 5: All limits are guaranteed at TA = TJ = 25'C only (standard typeface) or over the entire operating temperature range of the indicated device (bolc!faca
type). All limits at TA = TJ = 25'C are 100% production tested. All limits at temperature extremes are guaranteed via correlation using standard statistical Quality
Control methods.
Note 6: All limits are guaranteed at TA = TJ = 25'C only (standard typeface) or over the entire operating temperature range of the indicated device (boldface
t,pe). All limits are 100% production tested and are used to calculate OutgOing Quality Levels.
Note 7: Output current will decrease with increasing temperature but will not drop below lA at the maximum specified temperature.

Typical Performance Characteristics
Dropout Voltage
vs Temperature

Dropout Voltage
0.9

E

o.a

;;!.

0.7

~

::c
5

E

0.2

~

V

0.4
0.3

~

o/
o

~

~
~

I--"

:.,...1-""

0.1

5.10

0.9

0.5

.!.

~

1.0

TJ = 25°C

0.6

§

5.0a

0.8
0.7
0.6
0.5

....

I'"""

0.4
0.3

600

800

40

i,..-

B

~

;;

'"

160

-40

......

......

......

"<

160

~

140

is

120

B

100

:l§
~

~

SOOmA

10mA

10

;;

a

L
I I
40

40

80

TEMPERATURE (OC)

120

40
20

160

"<

o
o

£
is

~

30

tl

20

;;

10

~

r'OOmA

::l

r500 mA

y

lA

10

15

'"
20

25

INPUT VOLTAGE (V)

160

I
I
I

40

~

t\

60

120

Quiescent Current
50

80

80

TEMPERATURE (oC)

Quiescent Current

£

~

20

120

lao

40

1A

4.96
4.94
4.90

80

200

- I - .!IN = ro+SV

30

... f--I'"""

TEMPERATURE (oC)

50

~

5.00

4.92

I

-40

1000

·4.9a

100mA

0.1
400

5.02

g
5

~

... -1'"""

0.2

5.04

~
~

SOOm ! - -

Quiescent Current
vs Temperature

£

-

5.06

~

1A

OUTPUT CURRENT (mA)

"<

:;

o
200

Output Voltage
vs Temperature

30

35

VIN = uv
VO= SV
TJ = 2SoC

1--7'
t;;;~-

i,..--

-f-

o
o

0.2

0.4

0.6

0.8

1.0

LOAD CURRENT (A)

TlIH/8822-9

2-60

Typical Performance Characteristics
Line Transient Response
~>

~.5
0",
>0

~~

~i5

0°

30
20
10

Load Transient Response

~~

f--f- YIN = OV
0.3 1--1- CaUl = 22 "r ~~ 0.2 f--f- TJ = 25°C

1/

..gl'"

ov

10.00

10

20

30

40

50

60

-10

75h1~~~~~~~tffiM

10

~o

30

10

~

I

g

0.50

_

0.20

Ei
is

~

0.10

=>
o

0.05

~

~

22
20
18
16
14
12
10
8

~
0

14

z

1OOcl W HEAT SINK

~
Ei

"

12
10

~

-r-..L

~

lk

10k lOOk

1M

Maximum Power
Dissipation (TO-3)
22
20
18
I.

INrlNITE HEAT SINK

......

100

FREQUENCY (Hz)

Maximum Power
Dissipation (TO-220)

Output Impedance
V,N = 10~ 111,.

5.00 CaUT=22~r
101:: SOmA
2.00
Vo = Sv
1.00

"\.

......

10 o C/W HEAT SINK

~

'"~

l'!-..

INFINITE HEAT SINK

I

1"'-......

NO HEAT SINK

0.02
0.0 1

20

TIME (".)

~_:
~

-ttlltl-ttttlliHrtttIIl+HtffiI

0.5

TI~E (,,,)

"'"

10~ 1111.

CaUl =22 "r

85 '0 = 10 mA.
Vo = 5V

o
-10 0

~

95 V,N =

O.~

0.1 1--1- Vo = SV
0
~~
gO -0.1
-0.2
-0.3
-0.4
~ -0.5
1.0
O~
~:;

3V

S

Ripple Rejection

0.5

~

<>.. >
~~

-10
-20
-30

(Continued)

to

100

lk

10k tOOk

1M

r-

o
o

10 20 30

rREQUENCY (Hz)

~o

50 60 70 80 90 100

o
o

NO HEAT SINK

10 20 30 40 50 60 70 80 90 100
AMBIENT TEMPERATURE (OC/W)

AMBIENT TEMPERATURE (OC)

TLlH/8822-4

Maximum Power Dissipation
(TO-263) (See Note 3)

I

I

a'A =32°C/W

N.
I
N..N

a'A = 37°C/W

......

~
o

o

I"-~

... r-~~ ~:::::f-

aIA' =~'c/~';;::~
i I' 'j

10 20 30 40 50 60 70 80 90100
AMBIENT TEMPERATURE (Oc)

TLlH/8822-10

fII

2·61

Typical Performance Characteristics
Low Voltage Behavior
5.0
'o01A
'TJ
25°C

=

.~

~
~. 3.0

~

~~

//

S

2.0

.~

2.0

3.0

4.0

5.0

6.0

14

10' IA -'
15 TJ = 25°C
Vo • 10V
12

~
0

o
o

10

~

E
~

4

6,

8

10

Output at
Voltage Extremes

Output at
Voltage Extremes

12

16

Vo • 5V

E

I
0

10

20

30

lJOII

16

Vo • 8V

E

~~

E
~

15

~

10

~

0

10

20

Output at
Voltage Extremes

Output at
Voltage Extremes

3D

16

Vo' 10V

~

E

I

0

-5
-30 -20 -10

0

~~

/
20

30

40

"

0

10

20

30

40

30

40

INPUT VOLTAGE (v)

Output at
Voltage Extremes

lJOII

20

Vo • 12V

E

12

~

i

I
II

~

10

- -

I

25

ttl.

S

INPUT VOLTAGE (v)

9V

12

-4
-30 -20 -10

40

20

lJOII

18

lJolI

6

INPUT VOLTAGE (v)

1\ I.

ttl.
vo'

~

I

INPUT VOLTAGE (v)

25
20

J

.

-4
-30 -20 -10

40

15

20

1\ I.

6

-2

12

Output at
Voltage Extremes

~

~
'~

I
I~PUT VOLTAGE (v)

12

III

/

/

o

14

20

1~01l

18

/

,3

o

o

15

/

~

0

/

18

10 ' IA -'
15 TJ = 25°C
Vo' 15V
12

~

/
o

15

12

Low Voltage Behavior

/

~

9

!:i

INpUT VOLTAGE (v)

-30 -20 -10

6

INPUT VOLTAGE (v)

/

~'

12

r

o

14

1/

INPUT VOLTAGE (v)

ttl •

12

18

10 ' lA
TJ = 25°C
Vo' 12V

12

E

1/
1/
I

12
10

10

Low Voltage Behavior

Low Voltage Behavior

~.

o
8

L

j

6

6

9V

12

~

II

IA

= 25°C

vo'

INPUT VOLTAGE (v)

18

~

~~

/
o
o

INPUT VOLTAGE (v)

E

E

/

I
1.0

10'
15 TJ

L

0

1.0

Low Voltage Behavior
18

10 ' IA

12 'TJ = 2.5 OC·
Yo = BV
10

E

/

/

~

Low Voltage Behavior
14

V

/

Vo • 5V

4.0

(Continued)

-4
-3D -20 -10

0

ttl.

lJOII

Vo' 15V

15

II

10

/

S

~

10

20

INPUT VOLTAGE (v)

30

40

V
-5
-30 -20 -10

0

10

20

INPUT VOLTAGE (v)
TLlH/8822-5

2·62

r-----------------------------------------------------------------------------~

r

3:

Typical Performance Characteristics (Continued)

N
CD
0l:Io

....
r
Q

Output Capacitor ESR

S

100

Peak Output Current

3:

3.0

=
=

N
CD

COUT
22}JF
Vo
5V-

I

.s
.) ~""
~"".

0.0 1

o

"
200

15

STABLE _
REGION

-"

~

600

800

Q

o

i'"

"

1.0

:::>

o

o
400

0l:Io

I

= 14V

....'-'

~

.,~

.,'

2.0

"":::>""

'\

1~'

~,"

....

,"" ,"""""'\

.......

Y,N

-40

1000

OUTPUT CURRENT (mA)

o

40

80

120

160

TEMPERATURE (OC)
TLlH/8822-R

TLlH/8822-6

Equivalent Schematic Diagram
r-----~------------------------------------------------------_.--_1~~~N

r---_1~+-...::;:.--+_--_+----_1~--1I_+H:::1VDUT

2.7k

TLlH/8822-1

2·63

•

Connection Diagrams
TO-3 Metal Can Package (K)

(TO-220) PlastlC1 Package

TL/H/8822-2

'Front View
Order Number LM2940CT-S.0, LM2940CT-9.0,
LM2940CT-12, LM2940CT-1S, LM2940T-S.0,
LM2940T-8.0, LM2940T-9.0,
LM2940T-10 or LM2940T-12
See NS Package Number T03B

TLlH/8822-7

a

Bottom View
Order Number LM2940K-S.0/883,
LM2940K-8.0/883, LM2940K-12/883, LM2940K-1S/883
See NS Package Number K02A

(TO-263) Surface-Mount Package

TAB IS

GND

OUTPUT

GND
INPUT
TL/H/8822-11

Top View

TL/H/8822-12

Side View
Order Number,LM2940C5-S.0, LM2940CS-9.0, LM2940CS-12,
LM2940CS-1S, LM2940S-S.0, LM29405-8.0,
LM29405-9.0, LM2940S-10 or LM2940S-12
See NS Package Number TS3B

2-64

I!J1National Semiconductor
LM2941/LM2941 C 1A Low Dropout Adjustable Regulator
General Description
The LM2941 positive voltage regulator features the ability to
source 1A of output current with a typical dropout voltage of
O.SV and a maximum of 1V over the entire temperature
range. Furthermore, a quiescent current reduction circuit
has been included which reduces the ground pin current
when the differential between the input voltage and the output voltage exceeds approximately 3V. The quiescent current with 1A of output current and an input-output differential of SV is therefore only 30 mAo Higher quiescent currents
only exist when the regulator is in the dropout mode (VIN VOUT ~ 3V).
Designed also for vehicular applications, the LM2941 and
all regulated circuitry are protected from reverse battery installations or two-battery jumps. During line transients, such
as load dump when the input voltage can momentarily exceed the specified maximum operating voltage, the regu-

lator will automatically shut down to protect both the internal
circuits and the load. Familiar regulator features such as
short circuit and thermal overload protection are also provided.

Features
•
•
•
•
•
•
•
•
•

Output voltage adjustable from SV to 20V
Dropout voltage typically O.SV @
= 1A
Output current in excess of 1A
Trimmed reference voltage
Reverse battery protection
Internal short circuit current limit
Mirror image insertion protection
P+ Product Enhancement tested
TTL, CMOS compatible .ON/OFF switch

'0

Connection Diagram and Ordering Information
4·Lead TO·3 (K)

(To-220)
Plastic Package

GroB"
0
-

Ca.. ADJUST
I.

OUT

ON/orr

0

IN

1

TUH/8823-7

0

I

1

:~
ADJUST

TUH/8823-2

Bottom VIew
Front View

Order Number LM2941K/883
See NS Package Number K04A

Order Number LM2941Tor LM2941CT
See NS Package Number TOSA

(TO·263)
5·Lead Surface-Mount Package
TABIS
GND [ l O U T
IN

L.

GND
ON/Off
ADJUST

TOP VIEW

SIDE VIEW

TUH/8823-8

TUH/8823-9

Order Number LM2941S or LM2941CS
See NS Package Number TS5B

2-6S

•

Lead Temperature (Soldering, 10 seconds)
TO-3 (K) Package
TO-220 (T) Package
TO-263 (S) Package
ESD susceptibility to be determined.

Absolute Maximum Ratings

(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Input Voltage (Survival Voltage, ,,; 100 ms)
LM2941 K, LM2941T, LM2941S
60V
LM2941CT,LM2941CS
45V
Internally Limited
Internal Power Dissipation (Note 3)
Maximum Junction Temperature
150'C
-65'C,,; TJ"; + 150'C
Storage Temperature Range

300'C
260'C
260'C

Operating Ratings
Maximum Input Voltage
Temperature Range
LM2941K
LM2941T
LM2941CT
LM2941S
LM2941CS

26V
-55'C,,;
-40'C";
-O'C ,,;
-40'C";
-O'C ,,;

TJ
TJ
TJ
TJ
TJ

,,;
,,;
,,;
,,;
,,;

150'C
125'C
125'C
125'C
125'C

Electrical Characteristics-LM2941K, LM2941T, LM2941S

5V ,,; VA ,,; 20V, VIN = VA + 5V, Co = 22 f-LF, unless otherwise specified. Specifications in standard typeface apply for TJ =
25'C, while those in boldface type apply over the full Operating Temperature Range.

Parameter

Conditions

Typ

LM2941K
Limit
(Notes 2, 4)

LM2941T
LM2941S
Limit
(NoteS)

Units
(Limits)

1.275

1.237/1.211
1.313/1.339

1.237/1.211
1.313/1.339

V(min)
V(max)

Reference Voltage

5 rnA,,; 10"; 1A (Note 6)

Line Regulation

Va

4

10/10

10/10

mVIV(max)

Load Regulation

50 rnA,,; 10"; 1A

7

10/10

10/10

mVIV(max)

Output Impedance

100 mADC and 20 mArms
fa = 120Hz

7

Quiescent Current

Va

+ 2V,,; VIN

,,; 26V, 10 = 5 mA

+ 2V ,,; VIN < 26V, 10 =
+ 5V,I0 = 1A

5 rnA

VIN = Va

10

15/20

15/20

mA(max)

30

45/60

45/60

mA(max)

RMS Output Noise,
% ofVOUT

10 Hz-100 kHz
10 = 5mA

0.003

Ripple Rejection

fa = 120 Hz, 1 Vrms,lL = 100 mA

0.005

%
0.02/0.04

0.02/0.04

10 = 1A

0.5

%1V(max)
%/1000 Hr

0.4

Long Term Stability
Dropout Voltage

mnlV

0.8/1.0

0.8/1.0

V(max)
mV(max)

10 = 100mA

110

200/200

200/200

Short Circuit Current

VIN max = 26V (Note 7)

1.9

1.6/1.3

1.6

A(min)

Maximum Line
Transient

Va max 1V above nominal Va
Ro = 100n, T,,; 100 ms

75

60/60

60/60

V(min)

31

26/26

26/26

VOC

-30

-15/-15

-15/-15

V(min)

-75

-50/-50

-50/-50

V(min)

1.30

0.80/0.80

0.80/0.80

V(max)

1.30

2.00/2.00

2.00/2.00

V(min)

50

100/300

100/300

f-LA(max)

Maximum Operational
Input Voltage
Reverse Polarity
DC Input Voltage

Ro = 100n, Va

Reverse Polarity
Transient Input Voltage

T,,; 100 ms, Ro = 100n

ON/OFF
Threshold Voltage
ON

10"; 1A

ON/OFF
Threshold Voltage
OFF

10"; 1A

ON/OFF
Threshold Current

VON/OFF = 2.0V.
10"; 1A

~

-0.6V

2-66

Electrical Characteristics-LM2941 CT,LM2941CS
+

5V s: Vo s: 20V, VIN = Vo
5V, Co = 22 p.F, unless otherwise specified. Specifications in standard typeface apply for TJ =
25'C, while those in boldface type apply over the full Operating Temperature Range.
Parameter
Reference Voltage

Typ

Conditions
5 mA

s:

10

s:

1A (Note 6)

Load Regulation
Output Impedance

100 mADC and 20 mArms

Vo

5 mA

+ 2V s: VIN < 26V, 10 =
+ 5V,lo = 1A

Vo

1.237/1.211

V(min)
V(max)

4

10

mVIV(max)

7

10

mVIV(max)
mo.lV

7

fo=120Hz
Quiescent Current

Units
(Limits)

1.313/1.339

1.275

+ 2V s: VIN s: 26V, 10 =
50mA s: 10 s: 1A

Line Regulation

Limit
(Note 5)

5 mA

VIN = Vo
RMS Output Noise,

10 Hz-100 kHz

% ofVOUT

10 = 5mA

Ripple Rejection

fo = 120 HZ,1 Vrms, IL = 100 mA

10

15

mA(max)

30

45/60

mA(max)

0.003

Long Term Stability

0.005

%
0.02

%IV(max)
%/1000 Hr

0.4

10 = 1A

0.5

0.8/1.0

V(max)

10 = 100mA

110

200/200

mV(max)

Short Circuit Current

VIN max = 26V (Note 7)

1.9

1.6

A(min)

Maximum Line

Vo max 1 V above nominal Vo

Transient

Ro = 1000., T

55

45

V(min)

31

26

Voc

-30

-15

V(min)

-55

-45

V(min)

1.30

O.BO

V(max)

1.30

2.00

V(min)

50

100

p.A(max)

Dropout Voltage

s:

100 ms

Maximum Operational
Input Voltage
Reverse Polarity

Ro = 1000., Vo:;' -0.6V

DC Input Voltage
Reverse Polarity

T

s:

100 ms, Ro = 1000.

Transient Input Voltage
ON/OFF

10

s:

1A

Threshold Voltage
ON
ON/OFF

10

s:

1A

Threshold Voltage
OFF
ON/OFF

VON/OFF = 2.0V,

Threshold Current

10

s:

1A

Note I: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating ratings Indicate conditions for which the device is
intended to be functional, but device parameter specifications may not be guaranteed under these conditions. For guaranteed specifications and test conditions,
see the Electrical Characteristics.
Note 2: A military RETS specification available upon request. At the time of printing, the LM2941/883 RETS specification complied with the boldface limits in this
column. The LM2941 K/883 may also be procured to a Standard Military Drawing.
Note 3: The maximum power dissipation is a function of TJ(max), '9JAo and TA. The maximum allowable power dissipation at any ambient temperature is Po =
(TJ(max) - TpJl9JA.lfthis dissipation is exceeded, the die temperature will rise above 150'C and the LM2941 will go into thermal shutdown. For the LM2941T and
LM2941CT, the junction·to·ambient thermal resistance (9JpJ is 53'C/W. and tha junction.to-case thermal resistance (9Jcl is 3'C/W. For the LM2941K, 9JA is
35'C/W and 9JC is 4'C/W. The junction-Io-ambient thermal resistance of the TO-263 is 73'C/W, and junction-to-case thermal resistance, 9JC is 3'C.1f the T0-263
package Is used, the thermal resislaJ]ce can be reduced by increasing the P.C. board copper area thermally connected to the package: Using 0.5 square inches of
copper area, IJJA is 50'C/W; with 1 square inch of copper area, IJJA is 37"C/W; and with 1.6 or more square inches of copper area, 9JA is 3Z'C/W.
Note 4: All limits guaranteed at room temperature (standard typeface) and at temperature extremes (boldface type). All IimHs are used to calculate Outgoing
Quality Level, and are 100% production tested.
Note 5: All limits guaranteed at room temperature (standard typeface) and at temperature extremes (boldface type). All room temperature IImHs are 100%
production tested. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods.
Note 6: The output voltage range is 5V to 20V and is determined by the two external resistors, R1 and R2. See Typical Application Circuit
Note 7: Output current capability will decrease with increasing temperature, but will not go below 1A at the maximum specified temperatures.

2-67

Typical Performance Characteristics
Dropout Voltage vs
Temperature

Dropout Voltage
0.9

~
~

<

~

is
~
~
~

?

~

0.8

0.9

0.7

0.8

5.08
5.06

0.7

0.6

0.6

0.5

V"

0.4

0.2

0.4
0.3

...... f"'"

0.1

ISOOm

o
200

400

600

800

40

Quiescent Current vs
Temperature

-

~

~

~

g

30
20
10

1

-I-

lA

~

500 mA

-

-1-10mA

-40

40

80

~~
Oz

>0

100

~g

80

160

=

VIN 14V
Vo =5V
TJ = 25°C

40

-1--f--

~

~

~

40

z

30

g

,,;

20

!:i

r500 mA

lA

o
o

160

10

15

20

25

30

35

INPUT VOLTAGE (v)

10

~

1-"'""

Vo=~

r--

-10
-20
-30

g~
~~

S~

0

3:
3V

o
o

0.2

0.4

0.6

0.8

1.0

LOAD CURRENT (A)

Load Transient Response
~~

<>
~~

~;::

~~
0 0

"<
oS

rl00mA

60

120

Quiescent Current

1

i"\

120

80

20
120

1\

40

TEMPERATURE (OC)

,

140

Line Transient Response
30
20
10

-40

160

Vo=5V

TEMPERATURE (OC)

~s:-

4.90
120

50

160

il

1

o

4.96

4.92

80

1

180

Vo =5V

40

_r-

I4.98

4.94

200
..L-_ Vn~=14V

Vo=5V

5.00

Quiescent Current

50

~

~

I-t-

1-+- _

TEMPERATURE (OC)

OUTPUT CURRENT (mA)

oS

5.02

1

-40

1000

~

100 mA

O. 1

oV

5.04

g
!5

1-1- - I

0.2

~

~

1 A ......

-

0.5

i-'"

...

0.3

o

<

Output Voltage
5.10

1.0

TJ = 25°

D~



is
i!i

~

40

./

./

12

.",

,..... / '

500

400

500

600

~

B
:;

1.0

~

20

30
20

\J1=J50~A-'

II'..

J
0

I I I
•I I I
5

60

40

80

100

~

120

Quiescent Current (Vstby)

~

I

10

"

B
~

laUF

) wr =
-5
-10 5

10 15 20 25 30

0

5

= 100 mA

,2

I

~

B

50 mA

~

10 15 20 25 30

7

RsTBY = 1 kn

fo"'"

-1
-40

40

-20

INPUT VOLTAGE (vl

~
,- V

\JUT = 250 mA

\JUT =500 mA

20

40

-1
-40

-20

INPUT VOLTAGE (vl

Low Voltage Behavior (VOUT)

6'

Low Voltage Behavior (Vbud

:€
-\Jure

5

SOmA

S

20

I

40

INPUT VOLTAGE (vl

6

Low Voltage Behavior (Vstby)

/

~~

30

Output Voltage (Vstby)

Ilsur = loon

20

20

10

INPUT VOLTAGE (vl

Output Voltage (Vbud

loon

1sr~=rAI

-1
-10

INPUT VOLTAGE (vl

fo"'"

.. ,'j

Ismy = 10 mA-

<.>

7

-20

10

2'

~

15

Output Voltage (VOUT)

-1
-40

o

OUTPUT CURRENT (mAl

~

ii:l

-I-

4

INPUT VOLTAGE (vl

RoUT"

1-- f-ol-

0.5

Quiescent Current (Vbuf)
~

'~

40

-10
-10 -5

1.5

20

LI I

'"

<.>

is
i!i

OUTPUT CURRENT (mAl

I I I

60
50

10

I

o

o

Quiescent Current (VOUT)
70

i:l

2.5
2.0

o
200

OUTPUT CURRENT (mAl

~

~

~

~~

~

20

16

i:l

/'

o 1,.....-0-"""
o 100

~

Quiescent Current (Vstby)
3.0

20

/

/
ISlBY

lour = 100 mA

=

1mA

2

I

I

IsyBy =7,5 mA

0

o

o

o
3

4

INPUT VOLTAGE (vl

'0,

,I

6,
INpUT VOLTAGE (Vl

o
o

2

3

4

5

INPUT VOLTAGE (vl

TL/H/11252-6

2-80

Typical Performance Characteristics
Line Transient
Response (Your)

Line Transient
5
0
5

5

0

5

5

1\

0

3
1

3
2
1

0

0

10

20

30

40

50

3
2
1
0

1
-10

60

10

TIUE (1'.)

30 0
20 0

g:~

100

!;~

0

20

30

40

50

1
-fO

60

Load Transient
Response (Vbu,) -

I

750
~_ 50 0

0
5

\

I
V

5
0

....

40

50

60

Load Transient
Response (Vstby)

n

5
0

lJ

0 ° -20 0

30

0

0

1\
1\

20

TIME (1'.)

5

~~-10

fO

TIME (1'.)

Load Transient
Response (Your)
~'>

0
5
0

V

5
0

2

1
-10

/,

0

"

5
0

0
-250
-100

15 0
~
100
l:l~
~! 5 0
0
-5 0
-100 0

In

\

0
5
0

"

....

B~ 250

~-

Line Transient
Response (Vstby)

Response (Ybu,)

5
0

~..5.

(Continued)

5
0

9
0

100 200 300 400 500 600
TIUE (1'.)

100 200 300 400 500 600

-fOO 0

TIUE (1'.)

Output Impedance (Your)

fOO 200 300 400 500 600
TIME (1'8)

Output Impedance (Vbu,)

Output Impedance (Vstby)

10

fOO

s
~

~
O!

....

"5

0.1

0

O.Of L-L.LUllIlL.L.J.J.IlJllL.-LJ.LIlIJJJ
10
100
fOK
fK
FREQUENCY (Hz)

FREQUENCY (Hz)

Ripple Rejection (Your)
90 r0;-

80

r-

70

rr-

60

~

3

l!J

g
:il
~

..

0;-

III

l!J

70

~

60

~

..~

50
40

90

II
"~F~I'0.mA
I;;;;;

80

3

r-

FREQUENCY (Hz)

Ripple Rejection (Vbu,)
90

111111111
111111111
io!T~5~IJ'~A

r-

0;-

l!J-

~

-

:il
~

..

-

50

100

lK

FREQUENCY (Hz)

fOK

Ripple Rejection (Vstby)
111111111
111111111

80

1~~lm~-

3
70
60
50
40

40
10

0.10 '-'-'-.l.LI.W!..-L.I-1'LWl'--'-'-.l.LI.WI
fO
fOO
fK
fOK

fO

100

fK

FREQUENCY (Hz)

fOK

fO

100

fK

10K

FREQUENCY (Hz)

TL/H/ff252-7

2-81

Typical Performance Characteristics

(Continued)

Device Dissipation vs
Ambient Temperature

Output Voltage
5.30 r-;-.-"'T"-;--;-'-'-'
5.201-+-+-+-+--+--1-1--1

s..

g
z
S

5.101-+-++-+-t-i-H

~

i

Of

~~+-~~-+~~--~

I

~

6

4.901-+-++-+-t-i-H

22
20
18
16
14
U
10

INFINITE HEAT SINK

...

r-.

~

I'

I
I

:--. 50 C/W HEAT SINK

..... .....

...

i"-o

10°C
H!TJINK

f5

. 4.801-+-+-+-+--+--1-1--1

I
I

.....
i"'"

NO HEAT SINK

o
o

4.70 '---'-...l.-....1..-L---'--'_~
-so -25 0 25 50 75 100 125 ISO

10 20 30 40 50 60 70 80 90100
AMBIENT TEMPERATURE (OC)

JUNCTION TEMPERATURE (OC)
TL/H/11252-8

S
~
~

fi

§

Output Capacitor ESR
(Buffer Output, Pin 10)

Output Capacitor ESR
(Standby Output, Pin 9)
~

100

10

~

Cour=IOI'F

5
~

"

~

:~~~~;-

I

~

~

O.

1.5

3.0

~

Cour = 101'

4.5

7.5

10 ~0
STABLE
REGION -

I

OUTPUT CURRENT (mA)

o

100

5

i

CoUT= 10l'F

tl

---;

tl

...~

-

t?'-'l: ~
"""

10

I~

"
STABLE
REGION _

~,

''''',
~ o. I~

§ o.1 ° '
~
S 0.0 I

~

Output Capacitor ESR
(Main Output, Pin 11)

100

~

o. I

S 0.0 I

TUH/11252-9

~

S 0.0 I

20

40

60

80

100

OUTPUT CURRENT (mA)

TUH/11252-10

TL/H/11252-11

o

100

200

300

400

500

OUTPUT CURRENT (mA)
TL/H/11252-12

Application Hints
outputs are controlled with the ON/OFF pin described later,
the standby output remains on under all conditions as long
as sufficient input voltage is supplied to the IC. Thus, memory and other circuits powered by this output remain unaffected by positive line transients, thermal shutdown, etc.

OUTPUT CAPACITORS
The LM2984 output capacitors are required for stability.
Without them, the regulator outputs will oscillate, sometimes
by many volts. Though the 10 p.F shown are the minimum
recommended values, actual size and type may vary depending upon the application load and temperature range.
Capacitor effective series resistance (ESR) also affects the
IC stability. Since ESR varies from one brand to the next,
some bench work may be required to determine the minimum capacitor value to use in production. Worst case is
usually determined at the minimum ambient temperature
and the maximum load expected.
Output capacitors can be increased in size to any desired
value above the minimum. One possible purpose of this
would be to maintain the output voltages during brief conditions of negative input transients that might be characteristic of a particular system.
Capacitors must also be rated at all ambient temperatures
expected in the system. Many aluminum type electrolytics
will freeze at temperatures less than - 30"C, reducing their
effective capacitance to zero. To maintain regulator stability
down to -40"C, capacitors rated at that temperature (such
as tantalums) must be used.
Each output must be terminated by a capacitor, even if it is
not used.

The standby regulator circuit is designed so that the quiescent current to the IC is very low ( < 1.5 mAl when the other
regulator outputs are off.
The capacitor on the output of this regulator can be Increased without bound. This will help maintain the output
voltage during negative input transients and will also help to
reduce the noise on all three outputs. Because the other
two track the standby output: therefore any noise reduction
here will also reduce the other two noise voltages.

BUFFER OUTPUT
The buffer output is designed to drive peripheral sensor circuitry in a p.P system. It will track the standby and main
regulator within a few millivolts in normal operation. Therefore, a peripheral sensor can be powered off this supply and
have the same operating voltage as the p.P system. This Is
important if a ratiometric sensor system is being used.
The buffer output can be short circuited while the other two
outputs are in normal operation. This protects the p.P system from disruption of power when a sensor wire, etc. is
temporarily shorted to ground, i.e. only the sensor signal
would be interrupted, while the p.P and memory circuits
would remain operational.

STANDBY OUTPUT
The standby output is intended for use in systems requiring
standby memory circuits. While the high current regulator

The buffer output is similar to the main output in that it is
controlled by the ON/OFF switch in order to save power In
2-82

~-------------------------------------------------------r~

i:

Application Hints (Continued)
the standby mode. It is also fault protected against overvoltage and thermal overload. If the input voltage rises above
approximately 30V (e.g. load dump), this output will automatically shut down. This protects the internal circuitry and
enables the IC to survive higher voltage transients than
would otherwise be expected. Thermal shutdown is necessary since this output is one of the dominant sources of
power dissipation in the IC.

DELAYED RESET
Resistor Rt and capacitor Ct set the period of time that the
RESET output is held low after a main output error condition
has been sensed. The delay is given by the formula:
Tdly = 1.2 RtCt (seconds)
The delayed RESET will be initiated any time the main output is out of regulation, i.e. during power-up, short circuit,
overvoltage, low line, thermal shutdown or power-down.
The p.P is therefore RESET whenever the output voltage is
out of regulation. (It is important to note that a RESET is
only initiated when the main output is in error. The buffer
and standby outputs are not directly monitored for error
conditions.)

MAIN OUTPUT
The main output is designed to power relatively large loads,
i.e. approximately 500 rnA. It is therefore also protected
against overvoltage and thermal overload.
This output will track the other two within a few millivolts in
normal operation. It can therefore be used as a reference
voltage for any signal derived from circuitry powered off the
standby or buffer outputs. This is important in a ratiometric
sensor system or any system requiring accurate matching of
power supply voltages.

p.P MONITOR RESET
There are two distinct and independent error monitoring
systems in the LM2984. The one described above monitors
the main regulator output and initiates a delayed RESET
whenever this output is in error. The other error monitoring
system is the p.P watchdog. These two systems are OR'd
together internally and both force the RESET output low
when either type of error occurs.
This watchdog Circuitry continuously monitors a pin on the
p.P that generates a positive going pulse during normal operation. The period of this pulse is typically on the order of
milliseconds and the pulse width is typically on the order of
10's of microseconds. If this pulse ever disappears, the
watchdog circuitry will time out and a RESET low will be
sent to the p.P. The time out period is determined by two
external components, Rt and Crnon , according to the formula:
Twindow = 0.82 RtCrnon (seconds)
The width of the RESET pulse is set by Crnon and an internal resistor according to the following:
RESETpw = 2000 Crnon (seconds)
A square wave signal can also be monitored for errors by
filtering the Crnon input such that only the positive edges of
the signal are detected. Figure 2 is a schematic diagram of a
typical circuit used to differentiate the input signal. Resistor
Rtc and capaCitor Ctc pass only the rising edge of the
square wave and create a short positive pulse suitable for
the p.P monitor input. If the incoming signal continues in a
high state or in a low state for too long a period of time, a
RESET low will be generated.

ON/OFF SWITCH
The ON/OFF switch controls the main output and the buffer
output. The threshold voltage is compatible with most logic
families and has about 20 mV of hysteresis to insure 'clean'
switching from the standby mode to the active mode and
vice versa. This pin can be tied to the input voltage through
a 10 kn resistor if the regulator is to be powered continuously.
POWER DOWN OVERRIDE
Another possible approach is to use a diode in series with
the ON/OFF signal and another in series with the main output in order to maintain power for some period of time after
the ON/OFF signal has been removed (see Figure 1). When
the ON/OFF switch is initially pulled high through diode 01,
the main output will turn on and supply power through diode
02 to the ON/OFF switch effectively latching the main output. An open collector transistor Q1 is connected to the
ON/OFF pin along with the two diodes and forces the regulators off after a period of time determined by the p.P. In this
way, the p.P can override a power down command and store
data, do housekeeping, etc. before reverting back to the
standby mode.
MAINb I
ON/orr
OUTPUT I
O-N/-o-rr--=R1:-O-"'1.:!D~1~8:rl;'~;:;2""";~R::-2;.;..1
CONTROL

10kn~.4."

s~~~~::

'i

.....

10kn

I TI

MAIN OUTPUT
10 pr

rf7

..L.L

~L-J~L."lJt-".....
! ..,•

..J

~ Rio

TL/H/11252-13

FIGURE 1_ Power Down Override

n7

RESET OUTPUT
This output is an open collector NPN transistor which is
forced low whenever an error condition is present at the
main output or when a p.P error is sensed (see p.P Monitor
section). If the main output voltage drops by 350 mV or rises
out of regulation by 600 mV typically, the RESET output is
forced low and held low for a period of time set by two
external components, Rt and Ct. There is a slight amount of
hysteresis in these two threshold voltages so that the RESET output has a fast rise and fall time compatible with the
requirements of most p.P RESET inputs.

pP MONITOR INPUT

jcmo.
TL/H/11252-14

FIGURE 2. Monitoring Square Wave p.P Signals
The threshold voltage and input characteristics of this pin
are compatible with nearly all logic families.
There is a limit on the width of a pulse that can be reliably
detected by the watchdog circuit. This is due to the output
resistance of the transistor which discharges Crnon when a
high state is detected at the input. The minimum detectable
pulse width can be determined by the following formula:
PWrnin = 20 Crnon (seconds)

2-83

i!
0l:Io

LM2984

rn

.a

c

~"

CD

:::J

e()n

:T
CD

3
c:;"

II)

C
~"

DJ

3

~

Ii:

~National

N

co
co

Semiconductor

o

LM2990
Negative Low Dropout Regulator
General Description
The LM2990 is a three-terminal, low dropout, 1 ampere negative voltage regulator available with fixed output voltages
of -5, -5.2, -12, and -15V.
'
The LM2990 uses new circuit design techniques to provide
low dropout and low quiescent current. The dropout voltage
at 1A load current is typically O.6V and a guaranteed worstcase maximum of 1V over the entire operating temperature
range. The quiescent current is typically 1 mA with 1A load
current and an input-output voltage differential greater than
3V. A unique circuit design of the internal bias supply limits
the quiescent current to only 9 mA (typical) when the regulator is in the dropout mode (VOUT - Y,N ,;; 3V). Output voltage accuracy is guaranteed to ± 5% over load, and temperature extremes.
The LM2990 is short-circuit proof, and thermal shutdown
includes hysteresis to enhance the reliability of the device
when overloaded for an extended period of time. The

LM2990 is available in a 3-lead TO-220 package and is rated for operation over the automotive temperature range of
-40·C to +125·C.

Features
•
•
•
•
•
•
•

5% output accuracy over entire operating range
Output current in excess of 1A
Dropout voltage typically O.6V at 1A load
Low quiescent current
Internal short circuit current limit
Internal thermal shutdown with hysteresis
Functional complement to the LM2940 series

Applications
• Post switcher regulator
• Local, on-card, regulation
• Battery operated equipment

Typical Application
~
-

Unregulated
Input

+T

c.n'

IGND

~'0~Fr-__~~~

T

V,N

lM2990

'Required if the regulator Is located further than
6 Inches from the power supply filter capacitors.

;be:-

A 1 "",F solid tantalum or a 10 p.F aluminum

T '0~F

1--4~- Regulated
Vo
Output
TUH/10B01-1

electrolytic capaCitor is recommended.
"Required for stability. Must be at least a 10 ",F
aluminum electrolytiC or a 1 ",F solid tantalum
to maintain stability. May be increased without
bound to maintain regulation during transients.
Locate the capaCitor as close os possible to the
regulator. The equivalent series resistance
(ESR) is critical, and should be less than 10n
over the same operating temperature range as
the regulator.

Connection Diagram and Ordering Information
3-Lead TQ-220

TO-263 Surface-Mount Package
TAB IS [ g o U T P U T
INPUT
INPUT
TL/H/10BOl-2

L

GND

Front View

TL/H/10B01-11

Top View

Order Number LM2990T-S.0, LM2990T-S.2, LM2990T-12 or LM2990T-1S
See NS Package Number T03B

fII
TL/H/10BOl-12

Side View
Order Number LM2990S-S.0,
LM29908-12 or LM2990S-1S
See NS Package Number TS3B
Temperature
Range
-40·C to + 125·C

Output Voltage

Package

-S.O

-S.2

-12

-1S

LM2990T-5.0

LM2990T-5.2

LM2990T-12

LM2990T-15

TO-220

LM2990S-12

LM2990S-15

TO-263

LM2990S-5.0
2-85

Absolute Maximum Ratings (Note 1)

Input Voltage
ESD Susceptibility (Note 2)
Power Dissipation (Note 3)

- 26V to

+ 0.3V

Internally Limited
125·C

+ 150·C
260"C

Operating Ratings (Note 1)
-40·Cto
Junction Temperature Range (TJ)
Maximum Input Voltage (Operational)

2kV,

Junction Temperature (TJmaxl

-65·Cto

Storage Temperature
Lead Temperature (Soldering, 10 sec.)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.

+ 125·C
-26V

Electrical Characteristics VIN = -5V + VO(NOM) (Note 6), 10 = 1A, Co "" 47 ,...F, unless otherwise specified.
Boldface limits apply over the entire operating temperature range, -40·C ,,; TJ ,,; 125·C, all other limits apply for TJ = 25·C.
LM2990-5.2

LM2990-5.0
Parameter
Output Voltage (Vo)

Typ
(Note 4)

Conditions
5mA,,; 10"; 1A

-5

Load Regulation
Dropout Voltage

Quiescent Current (Iq)

10 = 5mA,
VO(NOM) -tv >VIN

Maximum 'Output Curr!lnt
Ripple Rejection

> ''':'26V

50mA,,; 10"; ,1A

-4.94
-5.46

V (max)
V (min)
V
V (max)
V (minI
'niV(max) .

-5.10
-5.30

-5.2

4

40

4

40

1

40

1

40

=: 0.1A,aVo"; 100mV

0.1

0.3

0.1

0.3

10

= 1A, aVo"; 100 mV

0.6

1

0.6

1

1

5

1

5

10"; 1A

Rt:

= 1A, VIN = VO(NOM)
= 10 (Note 7)

,(Note 7)
Vripple = 1 Vrms•
fripple = 1 kHz, 10

Units
(Limit)

Limit
(Note 5)

10

10

Short Circuit Current

-4.90 '
-5.10 '

Typ
(Note 4),

,-4.75
-5.25

5mA,,; 10"; 1A
Une Regulation

Limit
(Note 5) ,

mV(max)
' V (max)
V (max)
",

"

mA(max)

9

50

9

50

rnA (max)

1.8

1.5

1.8

1.5

A (min)

1.8

1.5

1.8

1.5

A (min)

58

50

dB (min)

250

750

,...V(max)

58

50

Output Noise Voltage

= 5 rnA
10 Hz-100 kHz, 10 = 5 rnA

250

750

Long Term Stability

1000 ,Hours

2000

,

'

2000

ppm

',.,

,

.

;

, ,

2-86

,

Electrical Characteristics Y,N = -SV + VO(NOM) (Note 6),10 = 1A, Co = 47 ,...F, unless otherwise specified.
Boldfae.limits apply over the entire operating temperature range, -40"C ,;; TJ ,;; 12SoC, all other limits apply for TJ = 2SoC.
(Continued)
LM2990·12
Parameter
Output Voltage (VO)

Conditions

Typ
(Note 4)

SmA,;; 10';; 1A
-12

LM2990·15

Limit
(Note 5)
-11.76
-12.24

Typ
(Note 4)

-1S

-11.40
-12.80

SmA,;; 10';; 1A

Limit
(Note 5)

Units
(Umlt)

-14.25
-15.75

V (max)
V (min)
V
V (max)
V (min)

-14.70
-1S.30

Line Regulation

10 = SmA,
VO(NOM) -1V > Y,N > -26V

6

60

6

60

mV(max)

Load Regulation

SO mA,;; 10';; 1A

3

SO

3

SO

mV(max)

Dropout Voltage

10

0.1

0.3

0.1

0.3

V (max)

0.6

1

0.6

1

V (max)

10';; 1A

1

S

1

5

mA(max)

= 1A, Y,N = VO(NOM)
RL = 10 (Note 7)

9

SO

9

50

mA(max)

1.2

0.9

1.0

0.7S

A (min)

Maximum Output Current

(Note 7)

1.8

1.4

1.8

1.4

A (min)

Ripple Rejection

Vripple = 1 Vrms,
fripple = 1 kHz, 10

S2

42

dB (min)

600

1800

,...V(max)

10
Quiescent Current (Iq)

= 0.1A, aVo';; 100 mV
= 1A, avo';; 100 mV

10
Short Circuit Current

S2

42

Output Noise Voltage

= S mA
10 Hz-100 kHz, 10 = SmA

500

1S00

Long Term Stability

1000 Hours

2000

2000

ppm

Note 1: Absolute Maximum Ratings Indicate limits beyond which damage to the device may occur. Operating Ratings Indicate conditions lor which the device Is
intended to be lunctional, but do not guarantee spacific performance IimHs. For guaranteed spacifications and test conditions, see the Electrical Characteristics.
Nole 2: Human body model, 100 pF discharged through a 1.5 kfl resistor.
Nole 3: The maximum power dissipation is a lunction 01 TJmax. 8JA. and TA. The maximum allowable power dissipation at any ambient temperature Is Po = (TJmax
- TpJI8JA. II this dissipation is exceeded. the die temperature will rise above 125'C. and the LM2990 will eventually go into thermal shutdown at a TJ 01
approximately 160'C. For the LM2990. the junction-Io·ambient thenmal reSistance. is 53'C/W, 73'C/W lor the T()'263, and the junction-to-case thenmal resistance
is 3'C. II the TO-263 package is used, the thenmal resistance can be reduced by increaSing the P.C. board copper area thermally connected 10 the package. Using
0.5 square Inches 01 coppar area. 8JA Is 50'C/W; wHh 1 square Inch 01 copper area. 8JA Is 37"C/W; and with 1.6 or more square Inches 01 copper area. 8JA Is
32'C/W.

Nole 4: Typicals are at TJ = 25'C and represent the most likely parametriC nonm.
Nole 5: Limits are guaranteed and 100% production tested.
Nole 6: VO(NOM) is the nominal (typical) regulator output voltage. -5V. -5.2V. -12V or -15V.
Note 7: The short circuit current Is less than the maximum output current with the -12V and -15V versions due to Internal'oldback current limiting. The - 5V and
- 5.2V versions, tested with a lower Input voltage, does not reach the loldback current limit and therelore conducts a higher short circuit current level. lithe
LM2990 output Is pulled above ground. the maximum allowed current sunk back into the LM2990 Is 1.5A.

Definition of Terms
Dropout Voltage: The input-output voltage differential at
which the circuit ceases to regulate against further reduction in input voltage. Measured when the output voltage has
dropped 100 mV from the nominal value obtained at (Vo +
5V) input, dropout voltage is dependent upon load current
and junction temperature.
Input Voltage: The DC voltage applied to the input terminals with respect to ground.
Input·Output Differential: The voltage difference between
the unregulated input voltage and the regulated output volt·
age for which the regulator will operate.
Line Regulation: The change in output voltage for a
change jn the Input voltage. The measurement is made under conditions of low dissipation or by using pulse techniques such that the average chip temperature is not significantly affected.

Load Regulation: The change in output voltage for a
change in load current at constant chip temperature.
Long Term Stability: Output voltage stability under accel·
lerated life-test conditions after 1000 hours with maximum
rated voltage and junction temperature.
Output Noise Voltage: The rms AC voltage at the output,
with constant load and no input ripple, measured over a
specified frequency range.
Quiescent Current: That part of the positive input current
that does not contribute to the positive load current. The
regulator ground lead current.
Ripple ReJection: The ratio of the peak-to-peak input ripple
voltage to the peak-to-peak output ripple voltage.
Temperature Stability of Vo: The percentage change in
output voltage for a thermal variation from room temperature to either temperature extreme.
2-87

•

C)

g

('I

...

Typical Performance Characteristics

:::::iii

. 1.010

1.0

:e:

I I
I I

O. 8

~

~

TJ = 125°C ' "
TJ = 25 0 C-J.,;f

~ o.6
g
.~

LM2990-5.0 and LM2990-5.2 '
Quiescent Current

Normalized Output Voltage

Dropout Voltage

..-:

0.4

....-: k:: ~J

~ o.2

=

~:::>'

~

o~
o

-~OoC .

0.6

0.8

5

1.00 2

Q

1.000
0.gge ~

~

i

I I I
I I
O.~

0.2

I.OO~

N

I I

II
11'0 = 1A
1\

"i
~

I'~

10

1.008
1.006

10.,0

0.99 6

~mA

0.99~

M

0,99 2

0.990
-40

1.0

OUTPUT CURRENT (A)

-10

20

50

80

o

110125

LM2990-12
Quiescent Current
~

-6
-IO~

,

I
I

o

o

-5

-10

'0

o
-IS

-20

-25

o

-30

-5

INPUT VOLTAGE (V)

I
I
I

I

-10

-IS

/11'

IV

II

r

I

I

~

o
-20

-25

o

-30

-I

TJ = 25°C

-IS

~

I'

r\

I\.
20

40

60

~

-12

,§

-6

I(
80

100

~O

20

TI~E (".)

-3

60

80

'0

./

o
o

100

-3

r-

">
..s
z

50

60

80

100

-9

-12

-IS

-18

;;;
~

-50

~

I\.

0

40

-6

Ca = 47 "F
10 = 100mAIt

I\.

20

A

LN2990T-l

LM2990-12 and LM2990-15
Load Transient Response

Co .. ,,47 I'f
TJ := 25°C

J

-7

INPUT VOLTAGE (V)

,LM2990-12 and LM2990-15
Line Transient Response

r1

-6

/

1/
J

TIME (".)

If

-5

i~299~T-15

= 1A

-9

5

I/'

-4

I.,

Ca = ~7 "F

'If

-3

LM299D-12 and LM2990-15
Low Voltage Behavior
-18

Ca=47"F

-2

INPUT VOLTAGE (V)

LM2990-5 and LM2990-5.2
Load Transient Response

r- 'o=IOOmAr

-30

,IV

INPUT VOLTAGE (V).

LM2990-5 and LM2990-5.2
Line Transient Response

-25

= lA

10= I~A

II
I
I

-20

I

-5

I
\

'o=I~A

l

-IS

LM2990-5 and LM2990-5.2
Low Voltage Behavior

LM2990-15
Quiescent Current

-I
I

,

-10

INPUT VOLTAGE (V)

10

10 = IA

-5

JUNCTION TEMPERATURE, TJ (OC)

10

I--

o

I(
20

~O·

60

80

100

TIUE (".) •

TIME (".)

.'"

2-88

TL/H/I0801-3

r-----------------------------------------------------------------------------~

Typical Performance Characteristics
LM2990-5 and LM2990-S.2
Ripple Rejection
90

a;
~

10

60

i

50

..s

ll:

'"

~

"

0

~

o
Maximum Output Current

co

70

z

N

Ik

= 5mA

40

--

~

~O!!

~

20
10
0

0
100

Ik

10k

lOOk

1M

Ik

FREQUENCY (Hz)

90

z

'0 = 5mA

iil

40

it

30

'"

co

I.S

3

~

~

~

O!!

5

r-

IO
100

Ik

10k

lOOk

I

1.6

~

1.2

=>

=>
~

20

100

Ik

FREQUENCY (Hz)

10k

lOOk

1.4

VIN - YOUT = -IOV
VIN - Your = -15V

VIN - VOUT = -21V

110 125

''IN

~

~I
i=.NO'HEAT ~
50

SO

"l I I

I ,

r

50

I I

e JA =37"C/'I!.......

.....

............' ooc/w HEAT SINK\.

20

20

e J• = 32oC/~

J J

-10

-10

Maximum Power Dissipation
(TO-263) (See Note 3)

II-'NFIN'TE HEAT SINK

-

I

O.S
-40

1M

24

-40

-30

JUNCTION TEMPERATURE. TJ (oc)

Maximum Power
Dissipation (TO-220)

o

-25

I

FREQUENCY (Hz)

I

-20

......... ~UI=-SV

1.0

1M

-15

Maximum Output Current

..s

60

-10

INPUT-OUTPUT DifFERENTIAL (v)

2.0

0

50

-5

0

1M

LM2990-12 and LM2990-1S
Output Impedance

70

g

lOOk

Co = 47 ~F

SO

'"

10k

fREQUENCY (Hz)

LM2990-12 and LM2990-1S
Ripple Rejection

~

..........

~

30

t:s~

SO

~

::::::"",

\
o

110 125

I

i'o~

~~

.;::::

I.~ ~7~".:: ;;::~
I ),J. -, r

o 10 20 30 40 50 60 70 SO 90100

JUNCTION TEMPERATURE, TJ (Oc)

ANSIENT TEMPERATURE (OC)
TL/H/l0801-4

2-89

r
i:
CD
CD

LM299D-S and LM2990-S.2
Output Impedance

Co = 47 ~f

so

(Continued)

I
N

Typical Applications

:E

Post Regulator for an Isolated Switching Power Supply

...I

+12V INPUT

+5V
@400mA

+

.I 10 pF

+
+VIN

22pF

r-..........;;~sw
1-----e....J
COMP
150

LIoI2577ADJ

FB

COIoiIoi.

Uk

+ 4.7

.I pF

-5V
@400mA
TLlHI10BOI-5

The LM2490 is a positive 1A low dropout regulator; refer to its datasheet for further information.
Fixed Current Sink

VIN

-24V

LM2990-S.0

VOUT
CO

GN
10pF *

10pF *
TL/H/I0801-7

Adjustable Current Sink
COMMON

VIN

-24V

LM2990-S.0

VOUT

5.0

Co

GN
10pF *

10 P F *
TLIH/IOBOI-IO

Application Hints
EXTERNAL CAPACITORS

Output CapaCitor ESR
20r---r---r---r---r-~

The LM2990 regulator requires an output capacitor to maintain stability. The capacitor must be at least 10 ,..,F aluminum
electrolytic or 1 ,..,F solid tantalum. The output capacitor's
ESR must be less than 100, or the zero added to the regulator frequency response by the ESR could reduce the
phase margin, creating oscillations (refer to the graph on
the right). An input capacitor, of at least 1 ,..,F solid tantalum
or 10 ,..,F aluminum electrolytic, is also needed if the regulator is situated more than 6" from the input power supply
filter.

10

1.0

I:l

~

I-

is
....

0.1

~

~

FORCING THE OUTPUT POSITIVE
Due to an internal clamp circuit, the LM2990 can withstand
positive voltages on its output. If the voltage source pulling
the output positive is DC, the current must be limited to
1.5A. A current over 1.5A fed back into the LM2990 could
damage the device. The LM2990 output can also withstand
fast positive voltage transients up to 26V, without any current limiting of the source. However, if the transients have a
duration of over 1 ms, the output should be clamped with a
Schottky diode to ground.

0.02

========::::1.._--'

0.0

0.25

0.5

0.75

1.0

1.25

OUTPUT CURRENT (A)
TLIH/IOBOI-9

2-90

m

.a

c

<'
I»

ii'
::J

GIlD

en
n
J
CD

3

I»

(;'

Ulc

~

lOp

300

j

1 1680 ,

T t ~u
~k'

•

W;
50

0.035 VII

TlIH/l0801-B

066~W'

II

.r--------------------------------------------------------------------------------,
g

~

t!lNational Semiconductor

LM2991 Negative Low Dropout Adjustable Regulator
General Description

Features

The LM2991 is a low dropout adjustable negative regulator
with a output voltage range between -2V to .-25V. The
LM2991 provides up to 1A of load current and features a
On/Off pin for remote shutdown capability.
The LM2991 uses new circuit design techniques to provide
a low dropout voltage, low quiescent current and low tem'perature coefficient precision reference. The dropout voltage at 1A load current is typically 0.6V and a guaranteed
worst-case maximum of 1V over the entire operating temperature range. The quiescent current is typically 1 mA with
a 1A load current and an input-output voltage differential
greater than 3V. A unique circuit design of the internal bias
supply limits the quiescent current to only 9 mA (typical)
when the regulator is in the dropout mode (VOUT - VIN
,,:; 3V).

• Output voltage adjustable from - 2V to - 25V
• Output current in excess of 1A
• Dropout voltage typically 0.6V at 1A load
• Low quiescent current
.. Internal short circuit current limit
• ·Internal thermal shutdown with hysteresis
• TIL, CMOS compatible ON/OFF switch
• Functional complement'to the LM2941 series

Applications
• Post switcher regulator
.• local, on-card, regulation
• Battery operated eqUipment

The LM2991 is short-circuit proof, and thermal shutdown
includes hysteresis to enhance the reliability of the device
when inadvertently overloaded for extended periods. The
LM2991 is available in a 5-lead TO-220, TO-263, and is rated for operation over the automotive temperature range of
-40·C to +125·C.

Connection Diagrams and Ordering Information
5-Lead TO·220
Straight Leads

~

5-Lead TO·220
Bent, Staggered Leads

i

s-outPut

~i

4- Ground
3- Input
2- On/Off
1- Adjust

s4321-

Output
Ground
Input
On/Off
Adjust

TLlH/11260-9

Front View
Order Number LM2991T
See NS Package Number T05A

TL/H/1126D-2

Front View
Order Number LM2991T Flow LB03
See NS Package Number T05D

T0263
5·Lead Surface-Mount Package
TAB IS [ [ ] 5- OUTPUT
INPUT
4- GROUND

L

3- INPUT

, .

2- ON/OFF
,- ADJUST
TLlH/1126D-11

Top View

TLlH/1126D~12

Side View
Order Number LM2991S
See NS Package Number TS5B
2-92 :

Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Input Voltage

- 26V to

2kV

Power Dissipation (Note 3)

Internally limited

230'C

-40'C to

125'C

Parameter

Conditions
5mA:S: 10:S: 1A

Min

Max

Units

-1.210

-1.234

-1.186

V

-1.27

-1.15

V

-3

V

0.04

%/V

0.04

0.4

%

0.1

0.2

-2
VIN

= -26V

-25

= 5 mA, Vo - 1V;;, VIN;;' -26V

Line Regulation

10

Load Regulation

50mA:S: 10:S: 1A

Dropout Voltage

10

= 0.1A, b.Vo :s: 100 mV

= 2.7k, TJ = 25'C, unless

Typical
(Note 4)

5mA:S: 10:S: 1A,
Vo - 1V ;;, VIN ;;, -26V

-24

0.004

V

0.3
10

+ 125'C
-26V

Maximum Input Voltage (Operational)

Electrical Characteristics

Output Voltage
Range

+ 150'C

Operating Ratings (Note 1)
Junction Temperature Range (TJ)

VIN = -10V, Vo = -3V, 10 = 1A, Co = 47"F, R1
otherwise specified. Boldface limits apply over the entire operating junction temperature range.

Reference Voltage

- 65'C to

Lead Temperature (Soldering, 10 sec.)

+ 0.3V

ESD Susceptibility (Note 2)
Junction Temperature (TJmax)

Storage Temperature Range

= 1A, b.VO :s: 100 mV

0.6

0.8

1
Quiescent Current

10:S: 1A

Dropout Quiescent
Current

VIN

Ripple Rejection

Vripple = 1 Vrms, fripple
10 = 5mA

= VO, 10 :s: 1A
= 1 kHz,

10 Hz - 100 kHz, 10
(VOUT:ON)
(VOUT:OFF)

ON/OFF Input
Current

VON/OFF
VON/OFF

Output Leakage
Current

VIN = -26V, VON/OFF
VOUT = OV

Current Limit

VOUT

= 0.8V (VOUT: ON)
= 2.4V (VOUT: OFF)
= 2.4V

= OV

V

0.7

5

mA

16

50

mA

60

= 5 mA

Output Noise
ON/OFF Input
Voltage

V

50

dB

200

450

1.2
1.3

0.8
2.4

"V
V

0.1
40

10
100

"A

60

250

"A

2

1.5

A

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the deivce is
intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: Human body model, 100 pF discharged through a 1.5 kn reSistor.
Note 3: The maximum power dissipation is a function of TJmax. OJA and TA. The maximum allowable power dissipation at any ambient temperature is Po = (TJmax
- TA)/8JA. If this dissipation is exceeded, the die temperature will rise above 12SoC and the LM2991 will go into thermal shutdown. For the LM2991, the junctionto·ambient thermal resistance is 53°C/W for the TO·220, 73°C/W for the TO·263, and junction·to·case thermal resistance is 3°C. If the TO·263 package is used,
the thermal resistance can be reduced by increasing the PC board copper area thermally connected to the package. Using O.S square inches of copper area, 8JA is
SO°C/W; with 1 square inch of copper area, 8JA is arc/w; and with 1.6 or more square inches of copper area, (JJA is 32:'C/W.
Note 4: Typicals are at T J

=

2SoC and represent the most likely parametric norm.

2-93

....
en

re

::i!

Typical Performance Characteristics

....I

Dropout Voltage

Normalized Output Voltage

1.0

:E

~
g
~
ill

1 I' ·1
1 TJ = 150·C

0.8

1/ AlP'
.-"'l i::=='
:?r

0.4
0.2

0.2

0.4

1

1

0.6

0.8

.~

1.002

5.

1.000

~

"~.

:E

V
0.998

~

I.o!lI

o/

~

1.006
1.004

i!:

TJ = -55 c C

...-!dI=

"25

~
~

~

20

SO

80

110

1/

o

-5

-10

-15

-20

o

-S

OUTPUT VOLTAGE (V)

-10 -IS -20

o

If

Vo=SV

1.8

3,

i\.

1.6

~

i

1.4

u,

~~
~~

I-++-+-+-I--I---+--+-IH

'50

!::;~

~

~ ~ ':'50 1--1--+-+-+-+-+-+-+-+-1

60

80

100

0'

20

TINE (1'.)

40

60

80

V,N -Vour =-10V

V,N-VOur=-15V

i--

-

-10-

0.8
-40 -10

100

I
20

SO

80

110 12S

JUNCTION TEMPERATURE, TJ (·C)

Ripple Rejection

Output Impedance
Ik

...

1:0= 471'F
80
SmA
70 VO=SV

d

z

60

w

~

I
~"i VOUTI= -SVI

V,N -Vour =-21V

\.0

TINE (1'.)

90

3

'-

1.2

0 0

40

-10 -IS -20 -2S -30

Maximum Output Current
2.0

1:o=471'F
1 1-71-1-+-+-+-+"TJ = 2S·C
Vo=SV

'o=10DmA

'-S

INPUT-OUTPUT DIFFERENTIAL (V)

Load Transient Response

1:0= 47 I'F

20

I'-.

o

-2S, -30

INPUT VOLTAGE (V)

Line Transient Response

-2S

i--

o

-25

-20

= 25°C

--

1"\

5

o

-IS

pllo= I?OmA f-;-- f--;---

i!:

0

TJ

1\

/.

!5

-10

Maximum Output Current

V'

~

-S

3

'0 = lA

"

j"

soo

Vo = -3V

INPUT VOLTAGE (V)

Vo ='-SV
TJ = 25°C

lo=5mA

10NI00kHz

V

(

o
o

140

V

/

-5

Quiescent Current
10

TJ 7 25°C

~

-10

JUNCTION TEMPERATURE, TJ (·c)

Output Noise Voltage

-3

-15

5

-40 -10

1000

~

-

0.992
0.990

1.0

Vo = - 2 / '

-20

~

0.996
0.994

OUTPUT CURRENT (A)

S'

10 = ~.IA

1.008

~

~

TJ = 25°C

0.6

, 0

li
!::;
g

Output Voltage

1.010

'0=

~

~

SO

iil

40

.~

30

1-.

20

~

100

l!
~

to

10
0
100

lk

10k

lOOk

IN

Ik

FREQUENCY (Hz)

10k

lOOk

1M

FREQUENCY (Hz)
TLlH/11260-3

2-94

r-----------------------------------------------------------------------------,
Typical Performance Characteristics
ON/OFF Control Voltage

Adjust Pin Current
-18

10= IA

~

~
g
1i!

2.~

2

I1
0.8

o
-50

i3

--10

30

z

50

ii:

~

!ii

E

~g

.......

=>

§

~o

110

150

20

50

80

110

1
-10

..........

50

-18

80

JUNCTION TEMPERATURE. TJ

9JA=3

OC/'ll

~~

~~

..... ~ 1 "";l"

\
~

20

-15

.""l 1
'4.. 1'-J

\

NO HEAl SINK

-12

1

10 o C/W HEAT SINK \

1"--..

-9

9JA = 32°C/~

15

......

I
-6

Maximum Power Dissipation
(TO-263) (See Note 3)

\

-~O

-3

INPUT VOLTAGE (V)

INFINITE HEAT SINK

18

1

J

o

1~0

12V

vJ= SV

/

JUNCTION TEMPERATURE. TJ (OC)

1

o

/

-6

o
-10

-~o

Maximum Power
Dissipation (TO-220)

12

Vo

-9

-3

JUNCTION TEMPERATURE. TJ (OC)

24

.Lli
/

-12

30
70

Vo = 15V

-15

--

60

~
~

!<

8

70

z

~

CD
....

Low Voltage Behavior

80

E

~

iii:
N
CD

(Continued)

110

o

o

140

t....

~

11 I
:"'1 rJA=73~/r..: F"=::::t

10 20 30 40 50 60 70 80 90100
AMBIENT TEMPERATURE (Oc)

(Oc)

TlIH/i 1260-4

•
2-95

~

0)
0)

C'I

r-----------------------------------------------------------------------------------------------,
Typical Applications

:iE
....I

"Required if the regulator is located further than 6 inches from the power
supply filter capacitors. A 1 p.F solid tantalum or a 10 J-tF aluminum electrolytic capacitor is recommended.
-"Required for stability. Must be at least a 10 /-I-F aluminum electrolytic or a
1 J-tF solid tantalum to maintain stability. May be increased without bound to
maintain regulation during transients. Locate the capacitor as close as possible to the regulator. The equivalent series resistance (ESR) is critical, and
should be less than 10n over the same operating temperature range as the
regulator.
TLlH/11260-1

VOUT ~'VREF (1

+ R2/Rl)

Application Hints
EXTERNAL CAPACITORS

The LM2991 regulator requires an output capacitor to maintain stability. The capacitor must be at least ,10 )LF aluminum
electrolytic or 1 )LF solid tantalum. The output capacitor's
ESR must be less than 100, or the zero added to the regulator frequency response by the ESR could reduce the
phase margin, creating oscillations. The shaded area in the
Output Capacitor ESR graph indicates the, recommended
ESR range. An input capacitor, of at least 1 I1F solid tantalum or 10 )LF aluminum electrolytic, is also needed if the
regulator is situated more than 6 inches from the input power supply filter.
MINIMUM LOAD

A minimum load current of SOO )LA is required for proper
operation. The external resistor divider can provide the minimum load, with the resistor from the adjust pin to ground set
to 2.4 kO.
SETTING THE OUTPUT VOLTAGE

The output voltage of the LM2991 is set externally by a
resistor divider and the adjust pin current using the following
equation:
VOUT = VREF· (1 + R2/ R1) - IADJ • R2
where VREF = - 1.21V. The output voltage can be programmed within the range of -2V to -2SV. The adjust pin
current is about 60 nA, causing a slight error in the output
voltage. However, using resistors lower than 100 kO makes
the adjust pin current negligible. For example, neglecting
the adjust pin current, and setting R2 to 100 kO and VOUT
to -SV, results in an output voltage error of only 0.16%.
ON/OFFPIN

The LM2991 regulator can be turned off by applying a TTL
or CMOS level high signal to the ON/OFF pin (see Current
Sink Application).

'10_
1.0

Output Capacitor ESR

20.---,---,---,----,--,

...
(.)

:z

~
i:i
'"

;0.1111&
!3

"'

;:!'

::;

S

0.02

0.0

0.25

0.5

0.75

1.0

1.25

OUTPUT CURRENT (Al
TL/H/11260-5

FORCING THE OUTPUT POSITIVE

Due to an internal clamp circuit, the LM2991 can withstand
positive voltages on its output. If the voltage source pulling
the output positive is DC, the current must be limited to
1.SA. A current over 1.SA fed back into the LM2991 could
damage the device. The LM2991 output can also withstand
fast positive voltage transients up to 26V, without any current limiting of the source. However, if the transients have a
duration of over 1 ms, the output should be clamped with a
Schottky diode to ground.

,---------------------------------------------------------------------------------, r-

:s:::

Typical Applications (Continued)

N
CD
CD

....

Fully Isolated Post·Swltcher Regulater
+12Y INPUT
+10Y
@ 250mA

IN5818

+

I

10JlF

sw
COMP

LM2577-

ADJ

I

+

INS818
1.6k

FB

100

4 •7J1F

LM2991
INS818

OUT

-10V
@ 250mA

TL/H/112S0-S

Adjustable Current Sink

COMM

GND

LM2991

TL/H/112S0-10

2-97

LM2991
I'll

.a

c

.;;
~

Oii/OFF

GND

tn

r-i'--~tr-------~,----t~,r---~----'~4'~'-'~~T--~T---------Og
CD
3

a(;'
ADJ

;

300

TUH/ll260-B

t!lNational Semiconductor
LM3420-4.2, -8.4, -12.6
Lithium-Ion Battery Charge Controller
General Description
The LM3420 series of controllers are monolithic integrated
circuits designed for charging and end-of-charge control for
Lithium-Ion rechargeable batteries. The LM3420 is available
in three fixed voltage versions for one, two, or three cell
charger applications (4.2V, 8.4V, and 12.6V respectively).

The LM3420 is available in a sub-miniature 5-lead SOT23-5
surface mount package thus allowing very compact designs.

Included in a very small package is an (internally compensated) op amp, a bandgap reference, an NPN output transistor, and voltage setting resistors. The amplifier's inverting
input is externally accessible for loop frequency compensation. The output is an open-emitter NPN transistor capable
of driving up to 15 mA of output current into external .
circuitry.

•
•
•
•
•

A trimmed preciSion bandgap reference utilizes temperature
drift curvature correction for excellent voltage stability over
the operating temperature range. Available with an initial tolerance of 0.5% for the A grade version, and 1% for the
standard version, the LM3420 allows for precision end-ofcharge control for Lithium-Ion rechargeable batteries.

Features
Voltage options for charging 1, 2, or 3 cells
Tiny SOT23-5 package
Precision (0.5%) end-of-charge control
Drive capability for externai power stage
Low quiescent current, 85 ".A (typ.)

Applications
• Lithium-Ion battery charging
• Suitable for linear and switching regulator charger designs

Typical Application and Functional Diagram
Rl 10k
Inpul
Vollage

+VIN

...+_-..;;;;;;;;...--o lA Charge

~~-_-

+13V -:-10-+--"-'"1

Currenl

+20V

31k

COMP

OUT

Cl

(-)

GND

Rf • 75k for 4.2V
181k for 8.4V
287k for 12.6V

TL/H/12359-2

TLlH/12359-1

LM3420 Functional Diagram

Typical Constant Current/Constant Voltage
LI-Ion BaHery Charger

Connection Diagrams and Order Information
5·Lead Small Outline Package (M5)
Actual Size
'No internal connection. but should be soldered
+ I N O S OUT

GND

2

•

3

10 PC board for besl heat transfer.
TLlH112359-4

4

CaMP
TLlH112359-3

Top View
For Ordering Information
See Figure 1 In this Data Sheet
See NS Package Number MA05A

2-99

•

Absolute Maximum Ratings

(Note 1)
ESD SusCeptibility (Note 3)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Input Voltage V(lN)
20V
Output Current
Junction Temperature

1500V
Human Body Model
See AN·450 "Surface Mounting Methods and Their Effect
6n Product Reliability", for methods on soldering surfacemount devices.

20mA
150"C
-65·Cto + 150"C

Storage Temperature
Lead Temperature

Operating Ratings (Notes 1 and 2)
Ambient Temperature Range
Junction Temperature Range

+215·C
+ 220·C

Vapor Phase (60 seconds)
Infrared (15 seconds)
Power Dissipation (TA = 25·C) (Note 2)

-40·C:S: TA:S: +85·C
-40·C:s: TJ:S: +125·C

Output Current

1SmA

300mW

LM3420-4.2
Electrical Characteristics
Specifications with standard type face are for TJ = 2S·C, and those with boldface type apply over full Operating Tem·
perature Range. Unless otherwise specified, V(IN) = VREG, VOUT = 1.SV.
Symbol

VREG

Iq
Gm

Av

VSAT
IL
RI

En

Parameter
Regulation Voltage

Typical
(Note 4)

Conditions

lOUT = 1 mA

Quiescent Current

lOUT = 1 mA

3.3

1 mA:S: IOUT:S: 15mA
VOUT = 2V

6.0

1V:s: VOUT:S: VREG -1.2V(-1.3)
RL = 2000 (Note 6)

1000

1V:S: VOUT:S: VREG - 1.2V(-1.3)
RL = 2kO

3500

Output Saturation
(Note 7)

V(IN) = VREG + 100 mV
lOUT = 15mA

1.0

Output Leakage
Current

V(IN) = VREG -100 mV
VOUT = OV

0.1

Internal Feedback
Resistor (Note 8)
Output Noise
Voltage'

4.221/4.242
4.179/4.158

4.242/4.284
4.158/4.116

V
V(max)
V(min)

±0.5/± 1

±1/±2

% (max)

110/115

125/150

/LA
/LA(max)

1.3/0.75

1.0/0.50

mAlmV
mAlmV(min)

3.0/1.5

2.5/1.4

mAlmV
mAlmV(min)

550/250

450/200

VIV
VIV(min)

1500/900

1000/700

VIV
VIV(min)

1.2/1.3

1.2/1.3

V
V(max)

0.5/1.0

0.5/1.0

/LA
/LA(max)

94
56

94
56

kO
kO(max)
kO(min)

85

Transconductance 20 /LA :s: lOUT :s: 1 mA
'VOUT = 2V
alOUTI a VREG

Voltage Gain
aVouT/aVREG

LM3420-4.2
Limit
(Note 5)

4.2

lOUT = 1 mA

Regulation Voltage
Tolerance

LM3420A-4.2
Limit
(Note 5)

75

lOUT = 1 mA,10Hz:s: f:s: 10kHz

2-100

70

Units
(Limits)

/LVF\MS

LM3420-8.4
Electrical Characteristics
Specifications with standard type face are for TJ = 25°C, and those with boldface type apply over full Operating Tem.
perature Range. Unless otherwise specified, V(IN) = VREG, VOUT = 1.5V.
Symbol

VREG

Iq
Gm

Av

VSAT
IL
Rt

En

Parameter
Regulation Voltage

lOUT = 1 mA

Quiescent Current

lOUT = 1 mA

Voltage Gain
AVOUT/AVREG

LM3420-a.4
Limit
(NoteS)

8.442/8.484
8.358/8.316

8.484/8.568
8.316/8.232

V
V(max)
V(min)

±0.5/± 1

±1/±2

% (max)

110/115

125/150

/LA
/LA(max)

1.3/0.75

1.0/0.50

mAlmV
mAlmV(min)

3.0/1.5

2.5/1.4

mAlmV
mAlmV(min)

550/250

450/200

VIV
VIV(min)

85

20 /LA ,;;: lOUT';;: 1 mA
VOUT =6V

3.3

1 mA ,;;: lOUT';;: 15 mA
VOUT = 6V

6.0

1V,;;: VOUT';;: VREG - 1.2V(-1.3)
RL = 4700 (Note 6)

1000

1V,;;: VOUT';;: VREG - 1.2V(-1.3)
RL = 5kO

3500
1500/900

Output Saturation
(Note 7)

V(lN) = VREG + 100 mV
lOUT = 15mA

1.0

Output Leakage
Current

V(IN) = VREG -100 mV
·VOUT = OV

0.1

Internal Feedback
RE1sistor (Note 8)
Output Noise
Voltage

LM3420A-a.4
Limit
(NoteS)

8.4

lOUT = 1 mA

Regulation Voltage
Tolerance

Transconductance
AIOUT/ AVREG

Typ!cal
(Note 4)

Conditions

. 1000/700

140

VIV
VIV(min)

1.2/1.3

1.2/1.3

V
V(max)

0.5/1.0

0.5/1.0

/LA
/LA(max)

227
135

227
135

kO
kO(max)
kO(min)

181

lOUT = 1 mA, 10 Hz,;;: f,;;: 10 kHz

Units
(Limits)

/LVRMS

•
2-101

LM3420-12.6
Electrical Characteristics
Specifications with standard type face are for TJ = 25'C, and 1hose with boldface tnte apply over full Operatlnll Temperature Ranlle. Unless otherwise specified, V(IN) = VREG,VOUT = 1.5V.

Symbol

VREG

Parameter

Regulation Voltage

Typical
(Note 4)

Conditions'

LM342D-12.6
Limit
(NoteS)

LM3420A·12.6
Limit
(NoteS)

12.6

lOUT = 1 mA

V

12.663/12.72. 12.7261 12.8S2
12.537/12.474 12.474/12.348

Iq
Gm

Regulation Voltage
Tolerance

lOUT = 1 mA

Quiescent Current

lOUT = 1 mA

Transconductance
aIOUT' a VREG

Av

Voltage Gain
aVOUT/aVREG

VSAT
IL
R,

En

3.3

1 mA ~ lOUT ~ 15 mA
VOUT = 10V

6.0

1V ~ VOUT ~ VREG- 1.2V(-1,3)
RL = 7500 (Note 6)

1000

1V S; VOUT S; VREG- 1.2V(-1.3)
RL =,10kO

,3500

Output Saturation
(Note 7)

V(IN) = VREG +100mV
lOUT = 15mA

Output Leakage
Current

V(lN) = VREG -100mV
VOUT = OV

Internal Feedback
,Resistor (Note 8)

Output Noise
Voltage

±1/±2

%(max)

110/118

125/1S0

p.A
p.A(max)

1.3/0.7S

1.0/0.S

mAlmV
mAlmV(mln)

3.0/1.S

2.5/1.4

mAlmV
mAlmV(min)

550/2S0

450/200

V/V
V/V(min)

1500/900

1000/700

V/V
V/V(min)

, 1.2/1.3

1.2/1.3

V
V(max)

0.5/1.0

p.A
p.A(max)

359
215

kO
kO(max)
kO(min)

1.0

;

0.1

0.5/1.0

,

287
359
215
lOUT = 1 mA, 10Hz ~f ~ 10kHz

210

"(max)
V(min)

±0.5/±1
85

20 p.A ~ lOUT ~ 1 mA
VOUT = 10V

Units
(Llnilts)

P.VRMS

Note 1: Absolute Maximum Ratings indicate limits beyond which damsge to the device may occur. Operating Ratings indicate conditions tor which the device Is
Intended to be functional. but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
The guaranteed spacifications apply only for the test conditions listed. Some performance characteristics may degrade when the device Is not operated under the
listed test conditions.
Note 2: The maximum power dissipation must be derated at elevated temperatures and Is dictated by TJmax (maximum function temperature), 9JA gunction to
ambient thermal resistance), and TA (ambient temperature). The maximum allowable power dissipation at any temperature Is POrn.. = ITJrnax - TAJ/9JA or the
number given In the Absolute Maximum Ratings, whichever Is lower. The typical thermal resistance (9J11l when soldered to a printed circuit board Is approximately
306"C/W for the MS peckage.
Note 3: The human body model Is a 100 pF capacitor discharged through a 1.S kO resistor into each pin.
Note 4: Typical numbers are at 2S'C and represent the most likely parametric norm.
Note 5: LimHs are 100% production tested at 2S'C. Umlls over the operating temperature range are guaranteed through correlation using Statistical QualHy Control
(sac) methods. The IimHs are used to calculate National's Averaging Outgoing Quality Level (AOOL).
Note 6: Actual test Is done using equivalent current sink instead of a resistor load.
Note 7: VSAl = V(IN) - VOllT, when the voltage at the IN pin Is forced 100 mV above the nominal regulating voltage (VREGl.
Note 8: See Applications and CUrves sections for information on this resistor.

Typical Performance Characteristics
Output Saturation
Voltage (VSAT)

Circuit Used for Response Time

Circuit Used for Bode Plots

1.2

V(IN) = VREG + , 00 mY

:E

~

5!
z
0

~
~

1.1

r--- --. I !
~=lt
r---

1.0
0.9
0.8

I-r-,

---I'---

0.7
0.6
0.5
-50

....... 5mA

I

~A

I
-25

0

25

50

75

100

125

JUNCTION TEMPERATURE (OC)

---

60
50
40

-;

~

20
10
~

1

".
", ~.s~GAI~..
I

'"

30

-m

10V

,

"

.,.

~

.

"4.
_'I..

./
","

~c,=

~

...,,'
~~

0

"

:E
~

I
~

ov

-45

IV

-90

0.5V

I-

100

Ik

10k

lOOk

I
I
I

~

-'.'"

40

""'

30

'ai'

20

;-

10

~

~

- • .1
~

"
10

cc =; 100pt

OV

"Y.'c, = I n f c - -

..

0
~

.'- '.
. / ..-",
,

i

.......: "

~

~

lOOk

".

3V

"

IV

40
30

!z

,

10

g,

C'=IOOpf_

"

"

20

V iCc=..l...nL-1<. )<

"-

PHASE

"·.1

""""

V

'" .J><:: ",

1

10

100

~ 10
~

"
~

~

8V
4V

=

10nf

Vs

~

c- L v~'G

ov

~

3V
2V

I'

IV

Your

Your

OV

TINE (5 "./DIV)

TINE (5 m./DIV)

Response Time
for 12.6V Version

Response Time
for 12.6V Version
20V

Cc = 0 pF'

Cc

10V

il!

0v
3v

v

Lrt--

,....,:::::.

VREG

r\
'\

I"

Your

= 10 nf

Vs
OV

v~

VI-

V

"

fREQUENCY (Hz)

""

V

~

.......
lOOk

Cc

10V

Vs

~

'"

10k

20V

~

VREG

10 V

V
Ik

I

ov

20 V

OIGAI~:t--

Cc =

Your

IN

1

..

'"

~

I

TIME (2 m./DIV)

:E

~

2V

-45
-90

10k

\.

'Response Time
for 8.4V Version

~

~

OV
Ik

I
I

~

0.5V

Vs

:E 8V
r.-::::::
4V
"e ov I -

12.6V
Bode Plot
60

OV
1.5Y
IV

Cc = 0 pF

fREQUENCY (Hz)

50

~

VREG

OV

10V

1
100

~

I

20V
GAIN

'"
~ ~.
'<;

2V

Response Time
for 8.4V Version

'~

PHASE

4V

i

TIME (5 "./DIV)

Cc = 0

, .

~

IN

8.4V
Bode Plot
50

~

OV

Your

fREQUENCY (Hz)

60

?>

VREG

OV
10

Cc = 10 nF

5V
Vs

1

4V
2V

I.SV

10V

= opr

Vs

ov

I nf_

... "

Cc

5V

Cc =II OOpF'

....... "'.If

PHASE

Response Time
for 4.2V Version

Response Time
for 4.2V Version

4.2V
Bode Plot

~

IOV

~

~

5Y 1-,-

~

OV

~

3V
2V
IV
OV

V~'G

\
Your

IN
TINE (10 "./DIV)

TINE (IOm./DIV)
TL/H/12359-5

2-103

II

Typical Performance Characteristics
Normalized
Temperature Drift
0.5

E
~

~

i5

0.2
0.1

,

-0.3

-

-

+'

g

:;

'"

-40 ppm/oC

~ '-D."
-0.5
-50 -25

0

25

I

I

50

75

90
80,/
70

50
-50 -25

100 125

~

I

il
j

~ ".200

.?

4.199
0

~

0

~I~=2kll

> 8.402

i!i

~~ 8.400

"-

I
I

1

2

25

50

3

4

75

5

-

8.398
0

~

12.612 LM3420-12.6
~

OUTPUT VOLTAGE (V)

~

-:-,2.608

f---40°C

I
I

4

25

6

50

75

100 125

Regulation Voltage vs
Output Voltage and
Load Resistance

...-1

I\. = 5.1 kll

2

0

JUNCTION TEWPERATURE (·c)

I\. = 470/l,& ~
/.

V

,..- V

0.9
-50 -25

100 125

-40·C ......

~ 8.40.4

~

0

0

8.406 LW3420-8.4

<.....

1\.=200n#

> .4,201

1.0

Regulation Voltage vs
Output Voltage and
Load Resistance

4.202

~

/

JUNCTION TEMPERATURE (·C)

Regulation Voltage vs
Output Voltage and
Load Resistance
-40jC

/

1.1

60

JUNCTION TEMPERATURE (·C)

4.203 LW3420-4.2

--

-3

,

I

1/

Normalized at 25°C

100

~

"

1.2
Your = 1.5V

-;c

ia

,- "

... , , ,

~ -0.2

Quiescent Current

,-

\

Internal Feedback
Resistor (Rf)
Tempco' ,

110

I

+.40 ppm/OC

~~,

~> -0.10
~

I

Your = 1.SV
0.4
I\. = 2kn
0.3

(Continued)

8

10

I I
I I

!:! '

k±-L.\

~ 12.604

I- 12C.~

5'

~:::;;.r-1\.=10kn

~

~ 12.600

~50A

=
-40°C and 1250Ci>1""

12.596
0

-40°C

I I
I I

2

4

6

8

10

12' 14

16

OUTPUT VOLT AGE (V)

OUTPUT YOLTAGE (V)

TL/H/12359-6

Five Lead Surface Mount Package Information
The small SOT23-5 package allows only 4 alphanumeric characters to identify the product. The table below contains the field
information marked on the package.
Grade

Order
Informatl,!n

4.2V

A (Prime)

Voltage

Package
Marking

,Supplied as

LM3420AM5·4.2

D02A

250 unit increments on tape and reel
3k unit increments on tape and reel

4.2V

A (Prime)

LM3420AM5X·4.2

D02A

4.2V

8 (Standard)

LM3420M5·4.2

D028

250 unit increments on tape and reel '

4.2V·

8 (Standard)

LM3420M5X·4.2

D028

3k unit increments on tape and reel

S.4V

A (Prime)

LM3420AM5·S.4

D03A

250 unit increments on tape and reel

LM3420AM5X·S.4

D03A

3k unit increments on tape and reel

S.4V

A (Prime)

S.4V

8 (Standard)

LM3420M5-8.4

D038

250 unit increments on tape and reel

S.4V

8 (Standard)

LM3420M5X·S.4

D038

3k unit increments on tape and reel .

12.6V

A (Prime)

LM3420AM5·12.6

D04A

250 unit increments on tape and reel

12.6V

A (Prime)

LM3420AM5X·12.6

D04A

3k unit increments on tape and reel

12.6V

8 (Standard)

LM3420M5·12.6

D048

250 unit increments on tape and reel

12.6V

8 (Standard)

LM3420M5X·12.6

D048

3k unit increments on tape and reel

FIGURE 1. S0T2~5 Marking
'The first letter "D" identifies the part as a Driver, the next two numbers indicate the voltage, "02" for a 4.2V part; "03" for a S.4V
part and "04" for a 12.6Vpart. The fourth letter indicates the grade, "8" for standard grade, "A" for the prime grade.
The SOT23·5 surface mount package is only available on tape in quantity increments of 250 on tape and reel (indicated by the
letters "M5" in the part number), or in quantity increments of 3000 on tape and reel (indicated by the letters "M5X" in the part
number).

Product Description
The LM3420 is a shunt regulator specifically designed to be
the reference and control section in an overall feedback
loop of a Lithium-Ion battery charger. The regulated output
voltage is sensed between the IN pin and GROUND pin of
the LM3420. If the voltage at the IN pin is less than the
LM3420 regulating voltage (VREG), the OUT pin sources no
current. As the voltage at the IN pin approaches the VREG
voltage, the OUT pin begins sourcing current. This current is
then used to drive a feedback device, (opto-coupler) or a
power device, (linear regulator, switching regulator, etc.)
which servos the output voltage to be the same value as
VREG·
In some applications, (even under normal operating conditions) the voltage on the IN pin can be forced above the
VREG voltage. In these instances, the maximum voltage applied to the IN pin should not exceed 20V. In addition, an
external resistor may be required on the OUT pin to limit the
maximum current to 20 mAo

Analyzing more complex feedback loops requires additional
information.
The formula for AC gain at a frequency (f) is as follows;
. Z(f)

Gain (f) = 1
where Z, (f)

+ -'R,

1

= ..,-_"':""'_-

j-21T-f- Cc

where R, :::: 75 kfl for the 4.2V part, Rf :::: 181 kfl for the
8.4V part and R, :::: 287'kfl for the 12.6V part.
The resistor (R,) in the formula is an internal resistor located
on the die. Since this resistor value will affect the phase
margin, the worst case maximum and minimum values are
important when analyzing closed loop stability. The minimum and maximum room temperature values of this resistor
are specified in the Electrical Characteristics section of this
data sheet, and a curve showing the temperature coefficient
is shown in the curves section. Minimum values of R, result
in lower phase margins.

Compensation
The inverting input of the error amplifier is brought out to
allow overall closed-loop compensation. In many of the applications circuits shown here, compensation is provided by
a sil'19le capacitor (Cel connected from the compensation
pin to the out pin of the LM3420. The capacitor values
shown in the schematics are adequate under most conditions, but they can be increased or decreased depending on
the desired loop response. Applying a load pulse to the output of a regulator circuit and observing the resultant output
voltage response is an easy method of determining the stability of the control loop.

Test Circuit
The test circuit shown in Figure 2 can be used to measure
and verify various LM3420 parameters. Test conditions are
set by forcing the appropriate voltage at the VOUT Set test
point and selecting the appropriate RL or lOUT as specified
in the Electrical Characteristics section. Use a DVM at the
"measure" test points to read the data.

100

r:-:-:-:-:-:-:-----llJ"h--------1I-------.
(+)

Rl

Cl

IN

+V
R2

Measure
VREG

COMP

OUT

LM3420

lOOk

'-...... Device
::::::::~J
Under
(-) GND
10k
Test

L.______

-v
VOUT Set
(Voltage Range 'rom
OV to VREG - 1.2V)
lOUT
D2
lNS817

R4

!

100

Measuro

IQ
100 pA/V

-v

-v

FIGURE 2_ LM3420 Test Circuit

2-105

TL/H/12359-7

•

VREG External Voltage Trim
The regulation voltage (VREG) of the LM3420 can be externally trimmed by adding a single resistor from theCOMP.
pin to the + IN pin or from the COMPo pin to the GND pin,
depending on the desired trim direction. Trim adjustments
up to ± 10% of VREG can be realized, with only a small
increase in the temperature coefficient. (See temperature
coefficient curve shown below)

For LM3420-8.4

12

....

+101"'-

8

::I:

+5fo-

...'"z
c.>

4

...'"
:;

0

>
z
0

-4

:5
::>

-8

....

154 ~ 105
181
decrease = % decrease -

R

decrease

.1

-5~_

-lok_
0

25

50

75

=

259 X 105 _ 287 X 103
% decrease

The LM3420 regulator/driver provides the reference and
feedback drive functions for a Lithium-Ion battery charger. It
can be used in many different charger configurations using
both linear and switching topologies to provide the precision
needed for charging Lithium-Ion batteries safely and efficiently. Output voltage tolerances better than 0.5%' are possible without using trim pots or preciSion resistors. The circuits shown are designed for 2 cell operation, but they can
readily be changed for either 1 or 3 cell charging applications.
'

-2~_

-12
-50 -25

3

Application Information

I

~

'"

R

+2%-

;::

.

x 10

For LM3420-12.6
28 x 105
Rincrease = % increase'

No Trim-

0

% increase'

Increase,

Normalized Temperature Drift with
Output Externally Trimmed

g

=26 x 105

R

100 125

JUNCTION TEMPERATURE (DC)
TL.lH/12359-8

FIGURE 3

Application Circuits
The circuit shown in Rgure 5 performs constant-current,
constant-voltage charging of two Li-Ion cells. At the beginning of the charge cycle, when the battery voltage is less
than 8.4V, the LM3420 sources no current from the OUT
pin, keeping Q2 off, thus allowing the LM317 Adjustable
voltage regulator to operate as a constant-current source.
(The LM317 is rated for currents up to 1.5A, and the LM350
and LM338 can be used for higher currents.) The LM317
forces a constant 1.25V across RUM, thus generating a constant current of

Rineresse
Rdecrease

TL.lH/12359-9

TL/H/12359-10

Increasing VREG

Decreasing VREG
FIGURE 4

IUM =1.25V
--

Formulas for selecting trim resistor values are shown below.

RUM

For LM3420-4.2

R

=

Increase

R
decrease

=

22 X 105
% increase'
53 X 105 _ 75 X 103
% decrease
Rl 10k

Input
VOlt.g;:,._+-......::"'I

lA Charge
Current

+13V to
+20V

Cl

TL.IH/12359-1

FIGURE 5. Constant Current/Constant Voltage LI-Ion Battery Charger

2-106

Application Circuits (Continued)
He.t Sink
V+-----1----~------------~~~~~------,
9.4V to 20V

TL/H/12359-11

FIGURE 6. Low Drop-Out Constant Current/Constant Voltage 2-Cell Charger
Transistor 01 provides a disconnect between the battery
and the LM3420 when the input voltage is removed. This
prevents the S5 p.A quiescent current of the LM3420 from
eventually discharging the battery. In this ap'plication 01 is
used as a low offset saturated switch, with the majority of
thEi base drive current flowing through the collector and
crossing over to the emitter as the battery becomes fully
charged. It provides a verY low collector to emitter saturation voltage (approximately 5 mY). Oiode 01 is also used to
prevent the battery current from flowing through the'LM317
regulator from the output to the input when the OC input
voltage is removed.
,
As the battery charges, its voltage begins to rise, and is
sensed at the IN pin of the LM3420. Once the battery volt·
age reaches S.4V, the LM3420 begins to regulate and starts
sourcing current to the base of 02. Transistor 02 begins
controlling the ADJ. pin of the LM317 which begins to regulate the voltage across the battery and the constant voltage
portion of the charging cycle starts. Once the charger is in
the constant voltage mode, the charger maintains a regulated S.4V'across the battery and the charging current is de;
pendent on the state of charge of the battery. As the cells
approach a fully charged condition, the' charge currerit falls
to'a very low value.
'

flows through R2 developing 50 mV across it. This 50 mV is
used as a reference to develop the constant charge current
through the current sense resistor R1.
ThEi constant current feedback loop operates as follows.
Initially, the emitter and collector current of 02 are both
approximately 1 rnA, thus providing gate drive to the MOSFET 03, turning it on. The output of the lM301A op-amp is
low. As 03's current reaches lA, the voltage across Rl
approaches 50 'mY, thus canceling the 50 mV drop across
R2; and causing the op-amp's output to start going positive,
and begin sourcing current into' RS. As more current is
forced into RS from the op-amp, the collector current of 02
is reduced by the same amount; which decreases the gate
drive to 03, to maintain a constant 50 mV across the 0.050
current sensing resistor, thus maintaining a constant 1A of
charge current.
The current limit loop is stabilized by compensating the
LM301A with Cl '(the standard ,frequ~ncy compensation
used with this op-amp) and C2, which i,s additional compensationneeded when 03 is forward biased. This helps speed
up the response time during the reverse bias of 03. When
the LM301 A output is low, diode 03 reverse biases and
prevents the op-ampfrom' pulling more current through the
emitter of 02. This is important when the battery voltage
reaches S.4V, and the 1A charge current is no longer needed. Resistor R5 isolates the LM301A feedback node at the
emitter of 02.

Figure 6 shows a Li-Ion battery charger that features a dropout voltage of less than one volt. This charger is a constantcurrent, constant-voltage charger (it operates in ,constant~
current mode at the beginning of the charge cycle and
switches over to a constant-voltage mode near the end of
the charging cycle). The circuit consists of two basic feedback loops. The first loop controls the constant charge current delivered to the battery, and the second determines the
final voltage across the battery.

The battery voltage is sensed and buffered by the op-amp
section of the LM10C, connected as a voltage follower driving the LM3420. When the battery voltage reaches SAV, the
LM3420 will begin regulating by sourcing current into RS,
which controls the collector current of 02, which in turn reduces the gate voltage of Q3 and becomes a constant voltage regulator for charging the battery. Resistor R6 isolates
the LM3420 from the co'mmon feedback node at the emitter
of 02. If R5 and R6 are omitted, oscillations could occur
during the transition from the constant-current to the constant-voltage mode. 02 and the PNP transistor input stage
of the LM10C will disconnect the battery from the charger
circuit when the input supply voltage is removed to prevent
the battery from discharging.

With a discharged battery connected to the charger, (battery voltage is less than S.4V) the circuit begins the charge
cycle with a constant charge current. 'The value of this current is set by using the reference section of the LM 1OC to
force 200 mV across R7 thus causing approximately 100 p.A
of emitter current to flow through 01, and approximately
1 rnA of emitter current to flow through 02. The collector
current of 01 is also approximately 100 p.A, and this current

2-107

•

C

~
C')

::i
....I

r-----------------------------------------------------------------------------~

Application Circuits (Continued)
V+
llV to 30V

V+
10V to 15V

+ C4

,

1 J.!F

R7

4.7k
C3
0.02
J.!F

R6

R6

10k

10k

R7

•. 7k
C3
0.02
J.!F

Dual Op Amp

TLlH/12359-12

,

FIGURE 7. High Efficiency Switching Regulator
Constant Current/Constant Voltage 2-Cell Charger
A switching regulator, constant-current, constant-voltage
two·cell Li-Ion battery charging circuit" is shown in Figure 1.
This circuit provides much better efficieney, especially Over
a wide input voltage range than the linear topologies., For a
1A charger an LM2575-ADJ. switching regulator IC is used
in a,standard buck topology. For other currents, or other
packages, other members of the SIMPLE SWITCHERII!>
buck reglilator family may be used.

,

TLlH/12359-13

FIGURE 8. Low Dropout Constant Current/Constant
Voltage LI-Ion Battery Charger
The circuit in Figure 8 is very similar to Figure 7, except the
sV1(itching regulator has been replaced with a low dropout
IineaJ: regulator, allowing the input voltage to be as low as
10V. The qonstant current and constant voltage control
loops are the same as the previous circuit. Diode D2 has
been changed to a Schottky diode to provide a reduction in
the overall dropout voltage of this circuit, but Schottky di~
odes typically have higher leakage currents than a standard
silicon diode. This leakage current could diScharge the bat·
tery if the input voltage is removed for an extended period of
time.'
,

Circuit operation is as follows. With a discharged battery
connected to the charger, the circuit o'perates as ,a constant
current source. The constant-current portion of the charger
is formed by the loop consisting of one half of the LM358 op
amp along with gain setting resistors R3 and R4, current
sensing resistor R5, and the feedback reference voltage of
1.23V. Initially the LM358's output is !qw causing the output
of the LM2575-ADJ. to rise thus causing some charging current to flow into the battery. When the current reaches 1A, it
is sensed by resistor R5 (50 mO), and produces 50 mV. This
50 mV is amplified by the op.amps gain of 25 to produce
1.23V, 'which is applied to the feedback pin of the LM2575ADJ. to,satisfy the feedback loop.

Another variation of a constant current/constant voltage
switch mode charger is shown in Rgure 9. The basic feed·
back loops for current and voltage are similar to the previous circuits. This circuit has the current sensing resistor, for
the constant current part of the feedback loop, on the positive side of the battery, thus allowing ,a common ground
be~een the input supply and the battery. Also, the
LMC7101 op-amp is available in a very small SOT23-5
package thus allowing a very compact pc board deSign. Diode D4 prevents the battery from discharging through the
charger circuitry if the inpui voltage is removed, although
the quiescent current of the LM3420 will still be present
(approximately 85 p.A).

Once the battery voltage reaches 8.4V, the LM3420 takes
over and begins to control the feedback pin of the LM2575ADJ. The LM3420 now regulates the voltage across the bat·
tery, and the charger becomes a constant-voltage charger.
Loop compensation network R6, R7, and C3 ensure stable
operation of the charger circuit under b'oth constant·current
and constant~voltage conditions . .If the input supply voltage
is removed, diode D2 and the PNP input stage ot'the LM358
become'reve.rsed biased and disconnects the battery to ensure that the battery is not discharged. ,Diode D3 reverse
biases to prevent the op-amp from sinking current when the
charger changes to constant voltage mode.

-=
Rl

1.2k

R4
lk
lk
R5

The minimum supply voltage for this charger is approximately 1W, and the ,maximum is around 30V (limitEid by the
32V maximum operating voltage of the LM358). If another
op-amp is substituted for the LM358, make sure that the
input common-mode range of the op·amp extends down to
ground so that it can accurately sense 50 mV. R1 is included to provide a minimum load for the switching regulator to
assure that switch leakage current will not cause the output
to rise when the battery is removed.

03
lN4148

R6
0.111
04
lN4001
2-coll

TLlH/12359-14

FIGURE 9. High Efficiency Switching Charger
with High Side Current Sensing
2-108

.---------------------------------------------------------~.~

Application Circuits (Continued)

Co)

0I:loo

~

TUH/12359-15

FIGURE 10. (Fast) Pulsed Constant Current 2-Cell Charger
A rapid charge Lithium·lon battery charging circuit is shown
in Figure 10. This configuration uses a switching regulator to
deliver the charging current in a series of constant current
pulses. Althe beginning of the charge cycle (constant-current mode), this circuit performs identically to the previous
LM2575 charger by charging the battery at a constant current of 1A. As the battery voltage reaches B.4V, this charger
changes from a constant continuous current of 1A to a 5
second pulsed 1A. This allows the total battery charge lime
to be reduced considerably. This is different from the other
charging circuits that switch from a constant current charge
to a constant voltage charge once the battery voltage
reaches B.4V. After charging the battery with 1A for 5 seconds, the charge stops, and the battery voltage begins to
drop. When it drops below B.4V, the LM555 timer again
starts the timing cycle and charges the battery with 1A for
another 5 seconds. This cycling continues with a constant 5
second charge time, and a variable ofltime. In this manner,
the battery will be charged with 1A for 5 seconds, fOllowed
by an off period (determined by the battery's state of
charge), setting up a periodic 1A charge current. The off
time is determined by how long it takes the battery voltage
to decrease back down to B.4V. When the battery first
reaches B.4V, the off time will be very short (1 ms or less),

but when the battery approaches full charge, the off lime will
begin increasing to tens of seconds, then minutes, and
eventually hours.
The constant-current loop for this charger and the method
used for programming the 1A of constant current is identical
to the previous LM2575-ADJ. charger. In this circuit, a second LM3420-B.4 has its VREG increased by approximately
400 mV (via R2), and is used to limilthe output voltage of
the charger to B.BV in the event of a bad battery connection,
or the battery is removed or possibly damaged.
The LM555 timer is connected as a one-shot, and is used to
provide the 5 second charging pulses. As long as the battery voltage is less than the B.4V, the output of IC3 will be
held low, and the LM555 one-shot will never fire (the output
of the LM555 will be held high) and the one-shot will have
no effect on the charger. Once the battery voltage exceeds
the B.4V regulation voltage of IC3, the trigger pin of the
LM555 is pulled high, enabling the one shot to begin timing.
The charge current will now be pulsed into the battery at a 5
second rate, with the off time determined by the battery'S
state of charge. The LM555 output will go high for 5 seconds (pulling down the collector of 01) which allows the IA
constant-current loop to control the circuit.

fII

2-109

Application Circuits (Continued)
9V-12V

OC Source

, with +....-

....~~-a. 1"!~:::-I'*".....---1~--""I

Current
Limit
8.4V
+
2 Li-ion-=Cells

+

R5

C2

22 pf

05

lQV ....._ . . . - - - - - - - - - - -....- -....
TLlH/l 2359-16

FIGURE 11. MOSFET Low Dropout Charger
Note: Although the application circuits shown here
have been built and tested, they should be thoroughly
evaluated with the same type of baHery the charger will
eventually be used with.
Different baHery manufacturers may use a slightly different baHery chemistry which may require different
charging characteristics. Always consult the baHery
manufacturer for Information on chl!rglng specifications and baHery detlills, and always observe the manufacturersprticautlons when using thel,r baHerles. Avoid
overcharging or shorting Lithium-Ion baHerles.

Figure 11 shows a low dropout constant voltage charger
using a MOSFET as the, pass element, but this circuit does
not include current limiting. This circuit uses 03 and a
Schottky diode to isolate the battery from the charging circuitry when the input'voltage is removed, to prevent the
battery from discharging. 02 should be a high current (0.20)
FET, while 03 can be a low current (20) device.

'.1

'.

2-110

r-------------------------------------------------------------------------.~

==
~

f}1National Semiconductor

~

LM3940
1A Low Dropout Regulator for 5V to 3.3V Conversion
General Description

Features

The LM3940 is a 1A low dropout regulator designed to provide 3.3V from a SV supply.

•
•
•
•
•
•

The LM3940 is ideally suited for systems which contain both
SV and 3.3V logic, with prime power provided from a SV bus.
Because the LM3940 is a true low dropout regulator, it can
hold its 3.3V output in regulation with input voltages as low
as4.SV.
The TO-220 package of the LM3940 means that in most
applications the full 1A of load current can be delivered
without using an additional heatsink.

Output voltage specified over temperature
Excellent load regulation
Guaranteed 1A output current
Requires only one external component
Built-in protection against excess temperature
Short circuit protected

Applications
• Laptop/Desktop Computers
• Logic Systems

The surface mount TO-263 package uses minimum board
space, and gives excellent power dissipation capability
when soldered to a copper plane on the PC board.

Connection Diagram/Ordering Information
INPUT~

INPUT
GNO

GNO

"""'

m-

OUTPUT

~

TL/H/120BO-2

3-Lead TO-220 Package (Front View)
Order Part Number LM3940IT-3.3
NSC Drawing Number T03B

GNO

o.

TL/H/I2080-3

3-Lead TO-263 Package (Front View)
Order Part Number LM394018-3.3
NSC Drawing Number TS3B

Typical Application

',.""t

Lt.t3940

5V IN+----4,....:'_N_----tGNI""D_ _
OU_T~-.....
T+-+3.3V@IA

f "".,

'-----.----'

TLlH/I2DBO-l
'Required if regulator is located more that I' from the power supply filter capacitor or if batiery power is used.
"See Application Hints.

2-111

fII

Absolute Maximum Ratings (Note 1)
260·C
Lead Temperature (Soldering, 5 seconds)
Power Dissipation (Note 2)
Internally Limited

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
- 65·C to + 150·C
Storage Temperature Range
Operating Junction Temperature Range -40·C to + 125·C

Input Supply Voltage
ESD Rating (Note 3)

7.5V
2kV

Electrical Characteristics

Limits in standard typeface are for TJ = 25·C, arid limits in boldface tvpe apply
over the full operating temperature range. Unless otherwise specified: VIN = 5V, IL = lA, COUT = 33/LF.
Symbol

"

Conditions

Parameter

Typical

LM3940 (Note 4j
min

Vo
AVo

Line Regulation

flVI
AVo

5 mA:s; IL:S; lA

Output Voltage

Load Regulation

"

IL= 5mA
4.5V:s; Vo:S; 5.5V
50mA:S; IL:S; lA

IL

Zo

en
Vo - VIN
'

10

VIN = 5V
IL = lA

110

Output Noise Voltage

BW = 10 Hz-l00 kHz
IL = 5mA

150

Dropout Voltage
(Note 5)

IL = lA

40
,50

80
mn
15

20
250

/LV (rms)

O.S
1.0
150

110
1.7

mA

200

0.5

RL = 0

V

mV

4.5V :s; VIN :s; 5.5V
IL = 5mA

Short Circuit Current

3.40

3.47

35

35

,IL = 100mA
ILCSc)

3.20,

3.13

20

!dOC) = 100 mA
IL (AC) = 20 mA (rms)
f = 120Hz

Quiescent Current

IQ

,

Output Impedance

3.3

Units

max

200
1.2

V
mV
A,

Note 1: Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specHications do not apply when operating the
device outside of its rated operaling condilions.
Note 2: The maximum allowable power dissipation is a funclion of the 'maXimum junction temperatura, TJ, the junclion-Io-ambient thennal raslstanca, OJ-A, and
the ambient temperature, TA. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thennal
shutdown. The value of OJ -A (lor devices In still air with no heatslnk) is 6rt'C/W for the "T" package, and 8rt'C/W for the "S" package. The effeclive value of 0J-A
can be reduced by using a heatsink (see Application Hints for specific infonnation on heatsin~lng).
Note 3: ESD rating Is based on the human body model: tOO pF discharged through 1.5 kit
Note 4: All limits guaranteed for TJ = 25'C are '100% tested and are used to calculate OutgOing Quality Levels. All limits at temperature extremes are guaranteed
via correlation using standard Statistical Qualily Control (SOC) methods.
Note 5: Dropout voRage is defined as the input-<>utput differential voltage where the regulator output drops to a value that is 100 mV below the value that is
measured at VIN = 5V.

2-112

Typical Performance Characteristics

0.9

E

0.8

""

0.7

I

= 25°C

TJ

0.5

V

0.4

~
~

~

~

0.3
0.2

~

0.1

o

V

""' .......

o

3.4
3.38

~
g

0.5

5

0.4

1A

0.6

f500~

0.3

~

400

600

800

-

~

f-

~

a

120

r-!lb

80

~

z

IL~

20

ILl

-40 -20 0

20 40 60

=1~O mlA-

~O

l-

I--

~
~

40

r- f.."\

20

100 120 140,

ffi
tl

o. 1
DeY(~;lon

20mV

I
_

o

".

o

0.5

I
I

LOAD CURRENT (A)

Ripple Rejection

In

V--

-0. I

V

(v) 4.5V

=100mA

7
TJ - 25°C

TI =25 0 C

0

10mV

5.5V

g

70
60
50
40
30
20
10

Load Transient Response

Output Voltage

Input Voltag'

IL

= SOOmA

90
80

INPUT VOLTAGE (v)

I

-10mV

IL

J

o
o

'L = lA
G. =331'F f0-

OmV

~

B

Line Transient Response
Dev!e.tion

'<

..5
z

JUNCTION TEMPERATURE (oC)

Output Voltege

Quiescent Current vs Load
110
100

60

tl
g

20 40 60 80 100 120 140

JUNCTION TEMPERATURE (Oc)

z

40

o

3.2
-40 -20 0

160

~
~

B

60

~

(v

100

<.s

-~

80

;;

80

Quiescent Current vs VIN
120

I-"

3.26
3.24
3.22

I

Quiescent Current
vs Temperature

100

;;;;;

3.3

TEMPERATURE (OC)

140
120

!5
o

40

1000

3.34

~ 3.28

ICOmA

OUTPUT CURRENT (mA)

<.s

~

.-

I

1--

0.2

3.36

~ 3.32

~

0.1

200

z:

0.7

~

~

1.0
0.9
0.8

E

0.6

i5

Output Voltage
vs Temperature

Dropout Voltage
vs Temperature

Dropout Voltage

J
.;:;:

Load

lA

I

Current

o LlJlllIII-Llllllll-LllJllll-LlillJlll...lllllilll

(A) OA

10

10p.s/djy~

50p.s/div-

100

Ik

10k

lOOk

1M

FREQUENCY (Hz)

Low Voltage Behavior
4

Tj

=25°C

:s

/"

~

u

z

I

Peak Output Current

Output Impedance
I

~ = lAI

2r-,,-.~-.-.-.-r~

IL'~lg~~A

O. I

~

~

~

2!
~
~

!;

1

~
~

0.0 I

§

0

o
o

0.5

i-'--I-+-I--.J.-I-l--I--l--...j

0L-L-~~-L-L-L~~~

2

3

4

5

6

INPUT VOLTAGE (v)

10

100

lk

10k

FREQUENCY (Hz)

lOOk

10M

-40

40

80

120

JUNCTION TEMPERATURE (OC)

TL/H/12080-4

2-113

fI

Application Hints
The figure below shows the voltages and currents which are
present in the circuit, as well as the formula for calculating
the power dissipated in the regulator:

EXTERNAL CAPACITORS
The output capacitor is critical to maintaining regulator stability, and must meet the required conditions for both ESR
(Equivalent Series Resistance) and minimum amount of capacitance.

V,N

I ' N - ,..---....,
Your
I N ' OUTI--""---....,

MINIMUM CAPACITANCE:
The minimum output capacitance required to maintain stability is 33 p.F (this value may be increased without limit).
Larger values of output capacitance will give improved transient response.
ESR LIMITS:
The ESR of the output capacitor will cause loop instability if
it is too high or too low. The acceptable range of ESR plotted versus load current is shown in the graph below. It Is

GND

TLlH/l2OBO-B

liN = IL + IG
Po = (V,N - VOUT) IL

essential that the output capacitor meet these requirements, or oscillations can result

+

(V,N) IG

FIGURE 2. Power Dissipation Diagram

S...

100

33 pF

The next parameter which must be calculated is the maximum allowable temperature rise, T R (max). This is calculated by using the formula:

,,:,"" ," , 0..'-" ,,"
~
,~

where: TJ (max) is the maximum allowable junction temperature, which is 125·C for commercial
grade parts.

Cour =

<.>

~

10

TR (max) = TJ (max) - TA (max)

III

i:i

'"~

...ii!
...

~

III
Z

~

O.

~ ~"

~
:;

8'

STABLE _
REGION

,'" ,'"

,,""

TA (max) is the maximum ambient temperature
which will be encountered in the application.
USing the calculated values for T R(max) and Po, the maximum allowable value for the junction-to-ambient thermal resistance, 8(J-A), can now be found:

0.0 1

a

200

400

600

BOO

1000

OUTPUT CURRENT {mAl

8(J-A) = TR (max)/Po
IMPORTANT: If the maximum allowable value for 8(J-A) is
found to be ;;;: 60·C/W for the "T" package, or ;;;: 80" /W for
the "S" package, no heatsink is needed since the package
alone will dissipate enough heat to satisfy these requirements.

Tl/H/I20BO-5

FIGURE 1. ESR Limits

It is important to note that for most capacitors, ESR is specified only at room temperature. However, the designer must
ensure that the ESR will stay inside the limits shown over
the entire operating temperature range for the design.

I! the calculated value for 8(J-A) falls below these limits, a
heatsink is required. Methods for heatsinking the TO-220
and TO-263 packages will be addressed separately:

For aluminum electrolytic capacitors, ESR will increase by
about 30X as the temperature is reduced from 25·C to
-40·C. This type of capacitor is not well-suited for low temperature operation.
Solid tantalum capacitors have a more stable ESR over
temperature, but are more expensive than aluminum electrolytics. A cost-effective approach sometimes used is to
parallel an aluminum electrolytic with a solid Tantalum, with
the total capacitance split about 75/25% with the Aluminum
being the larger value.
If two capacitors are paralleled, the effective ESR is the
parallel of the two individual values. The "flatter" ESR of the
Tantalum will keep the effective ESR from rising as quickly
at low temperatures.

HEATSINKING TO·220 PACKAGE PARTS
The TO-220 can be attached to a typical heatsink, or secured to a copper plane on a PC board. If a copper plane is
to be used, the values of O(J-A) will be the same as shown
in the next section for the TO-263.
If a manufactured heatsink is to be selected, the value of
heatsink-to-ambient thermal resistance, O(H - A), must first
be calculated:
O(H-A) = O(J-A) - O(C-H) - O(J-C)
Where: O(J-C) is defined as, the thermal resistance from
the junction to the surface of the case. A
value of 4·C/W can be assumed for O(J-C)
for this calculation.

HEATSINKING
A heatsink may be required depending on the maximum
power dissipation and maximum ambient temperature of the
application. Under all possible operating conditions, the
junction temperature must be within the range specified under Absolute Maximum Ratings.

O(C-H) is defined as the thermal resistance between the case and the surface of the heat·
sink. The value of O(C-H) will vary from
about 1.5·C/W to about 2.5·C/W (depending on method of attachment, insulator,
etc.). If the exact value is unknown, 2"C/W
should be assumed for O(C-H).

To determine if a heatsink is required, the power dissipated
by the regulator, Po, must be calculated.

2·114

Application Hints (Continued)
When a value for 8(H-A) is found using the equation shown,
a heatsink must be selected that has a value that is less
than or equal to this number.

As shown in the figure, increasing the copper area beyond 1
square inch produces very little improvement. It should also'
be observed that the minimum value of 8(J-A) for the
TO-263 package mounted to a P.C. board is 32°C/W.

8(H-A) is specified numerically by the heatsink manufactur-

er in the catalog, or shown in a curve that plots temperature
rise vs power dissipation for the heatsink.

As a design aid, a plot is shown below which iIIustrates'the
maximum allowable power dissipation compared to ambient
temperature for the TO-263 device (assuming 8(J-A) is
35°C/Wand the maximum junction temperature is 125°C):

HEATSINKING TO-263 PACKAGE PARTS
Heat is conducted away from the TO-263 by soldering the
tab of the device to a copper plane on the PC board.
The graph below shows the measured values of 8(J-A) for
different copper area sizes using a typical P.C. board with 1
ounce copper and no solder mask over the copper area
used for heatsinking:
~
......

80

~

70

~ 4

'z

3

'"

2

~

. 1

illis

.~

~

'<

i

o
;::
~

''''

60

~

"z

~

50

......

40

i:

30

AMBIENT TEMPERATURE (oC)

~

TL/H/120BO-8

FIGURE 4. Maximum Power Dissipation vs T~MB

~

COPPER rOil AREA (SQ. IN.)

TUHI12080-7

FIGURE 3. 8(J-A) va Copper Area

'

PI

2-115

t;tINational Semiconductor

LP2950/A-XX and LP2951 lA-XX Series
of A~justable Micropower Voltage Regulators
General Description
The LP2950 and LP2951 are micropower voltage regulators
with very low quiescent current (75 p.A typ.) and very low
dropout voltage (typ. 40 mV at light loads and 380 mV at
100 mAl. They are ideally suited for' use in battery-powered
systems. Furthermore, the quiescent current of the
LP2950/LP2951 increases only slightly in dropout, prolonging battery life.
The LP2950-5.0 in the popular 3-pin TO-92 package is pincompatible with older 5V regulators. The 8-lead LP2951 is
available in plastic, ceramic dual-in-line, or metal can packages and offers additional system functions.
One such feature is an error flag output which warns of a
low output voltage, often due to fallh'lg batteries on the input. It may be used for a power-on reset. A second feature
is the logic-compatible shutdown input which enables the
regulator to be switched on and off. Also, the part may be
pin-strapped for a 5V, 3V, or 3.3V output (depending on the
version), or programmed from 1.24V to 29V with an external
pair of resistors.
Careful design of the LP2950/LP2951 has minimized all
contributions to the error budget. This includes a tight initial

tolerance (.5% typ.), extremely good load and line regulation (.05% typ.) and a very low output voltage temperature
coefficient, making the part useful as a low-power vqltage
reference.
.

Features
•
•
•
•
•
•
•
•
•
•

5V, 3V, and 3.3V versions available
High accuracy output voltage
Guaranteed 100 mA output current
Extremely low quiescent current
Low dropout voltage
Extremely tight load and line regulation'
Very low temperature coefficient
Use as Regulator or Reference
Needs minimum capaCitance for stability
Current and Thermal Limiting

LP2951 versions only
• Error flag warns of output dropout
• Logic-controlled electronic shutdown
• Output programmable from 1.24 to 29V

Block Diagram and Typical Applications
LP29511A-XX

LP2950/A·XX

Your

tL ::$ 100 rnA

SEE APPLICATION
HINTS
SEE APPLICATION
HINTS

1.23V
REFERENCE

---------------------------!

TLlH/8546-25

TL/H/8548-1

2-116

r------------------------------------------------------------------------------,r"U
Connection Diagrams

I\)

CD

UI

o

TO-92 Plastic Package (Z) .

t

Dual-In-Llne Packages (N, J)
Surface-Mount Package (M)

.?<
r

OUTPUTBINPUT
OUTPUT
SENSE

GND

TL/H/8546-2

2

8

•

7

SHUTDOWN

BoHomVlew

GROUND

Order Number LP2950ACZ-3.0, LP2950CZ-3.0,
LP2950ACZ-3.3, LP2950CZ-3.3 LP2950ACZ-5.0
or LP2950CZ-5.0
See NS Package Number Z03A

"U
I\)
CD

INPUT

....
UI

FEEDBACK
VTAP

4

ERROR
TL/H/8546-26

t><

Top View

Order Number LP2951CJ, LP2951ACJ, LP2951J,
LP2951J/883 or 5962-3870501MPA
See NS Package Number J08A
Order Number LP2951ACN, LP2951CN, LP2951ACN-3.0,
LP2951CN-3.0, LP2951ACN-3.3 or LP2951CN-3.3
See NS Package Number N08E
Order Number LP2951ACM, LP2951CM,
LP2951ACM-3.0, LP2951CM-3.0,
LP2951ACM-3.3 or LP2951CM-3.3
See NS Package Number M08A

,

Metal Can Package (H)

Leadless Chip Carrier (E)

INPUT

OUTPUT

3

2

INPUT

/

1

4

B
9

GND

ERROR

GROUND

TL/H/8546-24
TLlH/8546-19

TOp View

Top View

Order Number LP2951E/883 or 5962-3870501M2A
See NS Package Number E20A

'or

Order Number LP2951H/883
5962-3870501MGA
See NS Package Number H08C

FJI

2·117

><
~
.....
.,...
II)
Q)

Ordering Information
Output Voltage

Package

N

a.

3.0V

3.3V

Temperature
5.0V

('C)

..J

.TO-92(Z)

LP2950ACZ-3.0
LP2950CA-3.0

LP2950ACZ-3.3
LP2950CZ-3.3

LP2950ACZ-5.0
LP2950CZ-5.0

-40 < TJ < 125

-i:
.....

N (N-OSE)

LP2951ACN-3.0
LP2951CN-3.0

LP2951 ACN-3.3
LP2951 CN-3.3

LP2951ACN
LP2950CN

-40 < TJ < 125

Q)

M(MOSA)

LP2951 ACM-3.0
LP2951CM,3.0

LP2951 ACM-3.3
LP2951CM-3.3

LP2951ACM
LP2951CM

-40 < TJ < 125

LP2951ACJ
LP2951CJ

-40 < TJ < 125

LP2951J
LP2951J/883
5926-3870501 MPA

-55<
><
~

N

a.

..J

J (J08A)

r

."

Absolute Maximum Ratings

I\)

CD

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.

Input Supply Voltage

-0.3 to +30V

Feedback Input Voltage
(Notes 9 and 10)

-1.5to +30V

Power Dissipation·
Lead Temp. (Soldering, 5 seconds)

Internally Limited

Shutdown Input Voltage
(Note 9)

-0.3 to +30V

Storage Temperature Range

-65'to +150'C

260'C

Electrical Characteristics

Typ

TJ

=

25'C

-25'C ,;; TJ ,;; 85'C

Output Voltage

,

)

3.0

LP2950AC·XX
LP2951AC·XX

LP2950C·XX
LP2951C·XX

Tested
Tested Design
Tested Design
Limit
Typ Limit
Limit Typ limit
Limit
(Notes 3, 16)
(Note 3) (Note 4)
(Note 3) (Note 4)

Units

3.015
2.985

3.0

3.0

3.015
2.985

3.0
3.030
2.970

3.0

3.030
2.970

3.0

V max
Vmin
3.045
2.955

V max
Vmin

Full Operating
Temperature Range

3.0

3.036
2.964

3.0

3.036
3.0
2.964

3.060
2.940

V max
Vmin

100/LA,;; IL';; 100 mA
TJ ,;; TJMAX

3.0

3.045
2_955

3.0

3.042
3.0
2.958

3.072
2_928

V max
Vmin

3.3

3.317
3.284

3.3

TJ

=

25'C

-25'C ,;; TJ ,;; 85'C
Full Operating
Temperature Range
Output Voltage

100 /LA,;; IL ,;; 100 mA
TJ';; TJMAX

3.3

3.317
3.284

3.3
3.333
3.267

3.3

3.333
3.267

3.3

V max
Vmin
3.350
3.251

V max
Vmin

3.3

3.340
3.260

3.3

3.340
3.3
3.260

3.366
3.234

V max
Vmin

3.3

3.350
3.251

3.3

3.346
3.254

3.379
3.221

V max
Vmin

5.0

5.025
4.975

5.0

3.3

SV VERSIONS (Note 17)
Output Voltage

TJ

=

25'C

-25'C ,;; TJ ,;; 85'C
Full Operating
Temperature Range
Output Voltage

100 /LA,;; IL ,;; 100 mA
TJ';; TJMAX

5.0

5.025
4.975

5.0

5.05
4.95

V max
Vmin

5.0

5.05
4.95

5.0

5.075
4.925

V max
Vmin

5.0

5.06
4.94

5.0

5.06
4.94

5.0

5.1
4.9

V max
Vmin

5.0

5.075
4.925

5.0

5.075
4.925

5.0

5.12
4.88

V max
Vmin

20

120

20

100

50

150

ppml'C

0.1

0.03

0.4

% max
% max

0.3

% max
% max

ALL VOLTAGE OPTIONS
(Note 12)
Output Voltage
Temperature Coefficient
Line Regulation
(Note 14)

(VoNOM + 1)V';; Vin';; 30V 0.03
(Note 15)

Load Regulation
(Note 14)

100/LA,;; IL ,;; 100 mA

0.04

.....

><
><

3.3V VERSIONS (Note 17)
Output Voltage

CD

U1

.......
~

3V VERSIONS (Note 17)
Output Voltage

t

~><
I\)

-0.3 to +30V

(Note 1)

Conditions
(Note 2)

.......

r-

ESD Rating is to be determined.

LP2951
Parameter

C)

."

Error Comparator Output
Voltage (Note 9)

Operating Junction Temperature Range (Note 8)
LP2951
-55' to + 150'C
LP2950AC-XX, LP2950C-XX,
LP2951 AC-XX, LP2951C-XX
-40' to + 125'C

U1

0.1

0.5
0.1

0.3
2-119

0.04

0.2

0.2
0.04

0.1

0.1

0.2

0.2

Electrical Characteristics (Note 1) (Continued)
Parameter

Typ

LP295iic~xx

LP2950AC-XX
Lp2951AC-XX

LP~951

Conditions
(Note 2)

..

"

LP2951C-XX ,

Tested Design
.Tested Design
Tested
Limit
Typ
Limit
Limit Typ
Limit
Limit
(Notes 3, 16)
(Note 3) (Note 4)
, (Note 3) (Note 4)

,Units

ALL VOLTAGE OPTIONS (Continued)
Dropout Voltage
(Note 5)

Il = 100 ",A

50

80

50

80

150
Il = 100mA

380

450

380

450

600
Ground
Current

Il = 100 ",A

75

120

8

12

75

Yin = (VONOM - 0.5)V 110
Il = 100 ",A

Current Limit

You! = 0

160

170

8

75

12

8

170

160

110

200

600

mVmax
mVmax

140

",A max
",A max

14

mAmax
mAmax

200

",A max
",A max

220

mA.max
mAmax

12
170

200

220

mVmax
mVmax

120

14
110

150
450

140

200
200

380

120

14
Dropout
Ground Current

,80

600

140
Il=100mA

50

150

160

200

220

Thermal Regulation

(Note 13)

0.05

Output Noise,
10 Hz to 100 KHz

Cl = 1 ",F (5V Only)

430

430

430

",Vrms

Cl = 200",F

160

160

160

",Vrms

Cl = 3.3 ",F
(Bypass = 0.Q1 ",F
Pins 7 to 1 (LP2951»

100

100

100

. ",V'rms

8-PIN VERSIONS ONLY

0.2

0.05

LP2951

Reference
Voltage

1.235

LP2951AC-XX

0.2

%/Wmax

LP2951C-XX·

1.2

1.2

1.2

1.27
1.19

1.27
1.19

1.285
1.185

V max
Vmin

60

nAmax
nAmax

1.235

1.25

1.26

(Note 7)

0.05

V max
V max
Vmin
Vmin

1.25

1.235

1.26

1.26

1.22
Reference
Voltage

0.2

1.27
1.21

1.22

Feedback Pin
Bias Current

20

(Note 12)
Reference Voltage
Temperature Coefficient

20

20

50

, ppm/'C,

Feedback Pin Bias
Current Temperature
Coefficient

0.1

0.1

0.1

nAI'C

40

20

20,

40

60

40

60

Error Comparator
Output Leakage
Current

VOH =30V

0.Q1

Output Low' ,
Voltage

Yin = (VONOM - 0.5)V 150
IOl = 400 ",A

Upper Threshold
Voltage

(Note 6)

Lower Threshold
Voltage

(Note 6)

Hysteresis

(Note 6)

1

0.01

1

2

,60

250

150

250

400
40
95

60
75

60

40
95 -

75

140
15

2-120

150

15

",A max

2

",A~~

400

mVmax
,mY max

25

mVmin
mVmin

140

mvrriiix

250
40

25

140
15

1

400

25
75

0.01

2

mV"1~

95

mV

r-

"'Q
N

Electrical Characteristics (Note 1) (Continued)

CD

U1

LP2951
Parameter

Conditions
(Note 2)

LP2951AC-XX

Tested
Typ

Limit

Typ

(Notes 3, 16)

Tested

Design

Limit

Limit

(Note 3)

(Note 4)

Q

LP2951C-XX

Typ

Tested

Design

Limit

Limit

(Note 3)

(Note 4)

Units

><
.?<
r-

"'Q
N

a-PIN VERSIONS ONLY (Continued)

CD

U1
.....

Shutdown Input
1.3

Input
Logic

Low (Regulator ON)

Voltage

High (Regulator OFF)

Shutdown Pin

Vshutdown

= 2.4V

1.3

1.3

0,6
2.0
30

V shutdown

= 30V

450

50

30

50

3

Current in Shutdown

0.7
2.0
30

50

100

600

450

600

750
(Note 11)'

V

0.7
2.0

100

Input Current

Regulator Output

.......
~

600

750

10

3

20

10

20

~

><
><

/LA max
/LA max

750
3

Vmin
/LA max

100
450

V max

10

/LA max
/LA max

20

/LA max

Note 1: Boldface limits apply at temperature extremes.
Note 2: Unless otherwise specified all limits guaranteed forTJ = 2S·C, Vln = (VONOM .j. I)V,IL = 100 "A and CL = I "F for 5V versions, and 2.2 "F for 3V and
3.3V versions. Additional conditions for the B-pin versions are Feedback tied to VTAP, Output tied to Output Sense and Vshutdown ,;; 0.8V.
Note 3: Guaranteed and 100% production tested.
Note 4: Guaranteed but not 100% production tested. These limits are not used to calculate outgoing AQL levels.

Note 5: Dropout Voltage is defined as the input to output differential at which the output voltage drops 100 mV below its nominal value measured at I V differential.
At very low values of programmed output voltage, the minimum input supply voltege of 2V (2.3V over temperature) must be !eken into account.
Note 6: Comparator thresholds are expressed in terms of a .voltage differential at the Feedback terminal below the noininal reference voltege measured at
Yin = (VONOM + I)V. To express these thresholds in terms of output voltage change, multiply by the error amplifier gain = VoutlVr.f = (RI + R2)/R2.
For example, at a programmed output voltage Of SV, the Error output is guaranteed to go low when the output drops by 95 mV x 5VI1.23SV = 384 mY.
Thresholds remain constant as a percent of Vout as Vout is varied, with the dropout waming occurring at typically 5% below nominal, 7.5% guaranteed.
Note 7: Vref ,;; You, ,;; (Vln - 1V),2.3V ,;; Vln ,;; 30V, 100 ,.A ,;; IL ,;; 100 mA, TJ ,;; TJMAX.
Note 8: The junction·to·ambient thermal resistence of the TO-92 package is 180"C/W with 0.4" leads and 16O"C/W with 0.25· leads to a PC board. The thermal
resistence of the 8-pin DIP packages is 10S·C/W for the molded plastiC (N) and 130"C/W for the cerdlp (J) junction to ambient when soldered directly to a PC
board. Thermal reslstence for the metel can (H) is 160"C/W junction to ambient and 2O"C/W junction to case. Junction to ambient thermal resistance for the S.O.
(M) package is 160·C/W. Thermal resistance for the leadless chip carrier (El package is 95"C/W junction to ambient and 24·C/W junction to case.
Note 9: May exceed input supply voltege.
Note 10: When used in dual-supply sy~tems where the output terminal sees loads returned to a negative supply; the output voltege should be diode-clamped to
ground.
Note 11: VShutdown ;;, 2V, Vln ,;; 30V, Vout = 0, Feedback pin tied to VTAP.
Note 12: Output or reference voltage temperature coefficient Is defined as the worst case voltage change divided by the totel temperature ra~ge.
Note 13: Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding load or line regulation
effects. SpeCifications are for a 50 rnA load pulse at VIN = 30V (1.25W pulse) for T = 10 ms.
Note 14: Regulation Is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes In output voltage due to heating effects are
covered under the specification for thermal regulation.
Note 15: line regulation for the LP2951 is tested at 150"C for IL = 1 mA. For IL = 100,.A and TJ = 125"C, line regulation is guaranteed by design to 0.2%. See
Typical Performance Characteristics for line regulation versus temperature and load currenl
Note 16: A Military RETS spec is available on requesl At time of printing, the LP2951 RETS spec complied with the boldface limits in this column. The LP2951 H, E,
or J may also be procured as Standard Military Drawing Spec # 5962-3870501 MGA, M2A, or MPA.
Note 17: All LP29S0 devices have the nominal output voltage coded as the last two digits of the part number. In the LP29S1 products, the 3.0V and 3.3V versions
are deSignated by the last tWo digits, but the SV version is denoted with no cOde at this location of the part number (refer to ordering IntOrmation teble).

fI

2-121

ci:
....
=
...

Typical Performance Characteristics

in
G)

....

><

~o

in
G)

N

a.

....

Dropout Characteristics

Quiescent Current

10

N

a.

"<

::;
£

.5-

~B
0

z

i

0.1

,~

'"
10

~

o
o

-

i

I'

4 5

6 7

8

4.98

~

Quiescent Current ..

~

i:i

&

6

7 8

120

~I=JA

~

100
80

I

60

~=O

I

40

I

20

o

o

25 50 75 100125 ISO

INPUT VOLTAGE (VOLTS)

Quiescent Current

Quiescent Current
5V OUTPUT

5V OUTPUT

r---.

100
VIN =6C

...... r-.

80

I'-

- f-

-

lL = 100 JjA

r- I-

70
60

VIN = 6V-

r...

50
-75-50-25 0 25 50 75 100125150

-

IL=100m~

1/

f--:

~

TEMPERATURE (Oc)

Short Circuit Current

INPUT VOLTAGE (V)

Dropout Voltage

170

Dropout Voltage

600

160

/'

150

,

/'

r-

V

130

".5-

i
I

110
100
-75 -50-25 0 25 50 75 100125150
TEMPERATURE (OC)

50°r-rrrrnmr"nmmT-rTrmm

500
400
300

~

120

I L =1aOmA

7
-75 -50-25 0 25 50 75 100125150

TEMPERATURE (oc)

140

9 10

10
5V OUTPUT

90

5

5V OUTPUT

140

TEMPERATURE (Oc)

120

~

&

_I

INPUT VOLTAGE (VOLTS)

B

i:i

t
0.2"

4.94
-75-SO -25 0

9 10

.3

iB

4.96

o

"<

5.0

,.

~

,~<>

4

Quiescent Current

......

5,02

3

160

5V OUTPUT

5,04
~

3

2

I
I
I

INPUT VOLTAGE (VOLTS)

Output Voltage vs.
Temperature of 3
Representative Units

:E

1 2

,•

75

"INPU,T VOLTAGE (VOLTS)

1\ = 50n-

o

100
50

5,06

I
I
~=.;,- -~

125

25

o
o

100

5V OUTPUT

100
90
80
70
60
50
40
30
20
10

110

~

=>

z

Input Current
120

150

B

1\ = 50n-

lOAD CURRENT (mA)

110

175

~

I

~=~okh--

200

.3

~

!

=>
<>

.
.3

1\=50 kn

I

5V OUTPUT

225

"<

f-

~

z

ii:

Input Current
250

V OUTPUT

.'"

~

'"

K,;;oolmA
L

c-r-

o

..00
300r-t+tHmr-+++Hffi~t+~

200 r-t+tHmr-+++

100
50

~

I-_f-f-

--

(1

-75 -50-25 0

1OO
(

25 50 75 100125150

TEMPERATURE (OC)

'10mA

100mA

OUTPUT CURRENT

TUH/8546-3

2-122

r-

Typical Performance Characteristics
2.2

~

2.1

~

§!

2.0

'"
~

1.9

~

1.8

z

LP2951

LP2951

Feedback Bias Current

Feedback Pin Current

,

~

r-

10

!

,~

~

..... r--.

.....

i3

1/

-10

~
-20

o~

1--+-+-h4F---+--j

-50

-100

1--+....4-,....,,f-f-f--+--j

"~

-150

F--l",c."","""",+-='-::--l--!

~

-200

F-"7If'-+--I-f-I--+--j

;;
1.6
-75 -50 -25 0

TEMPERATURE (Oc)

LP2951

LP2951
Comparator Sink Current
2.5

IVOUT = SV

T.!

I

E~R~AL ,5V SUP~LY

2.0

f-

"C

11+

5Dk RESISTOR

-

Y

.§.

'II I HY~rERESls

~

-

i3

1.5

1//
J

1.0

~

~rT 1

Vi
0.5

il I I

0.0

12345678

-1.0 -0.5

0.5

1.0

Line Transient Response

12~OC

1.1\

I I

r

V
8V

fA = -55°C

G.

= I"F_

IL = 1 mA

-

ViUT j5V -

1

II

.ll

4V

l

0.00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

INPUT VOLTAGE (V)

~

><
><

v

JL

V

.....
.....

FEEDBACK VOLTAGE (V)

Error Comparator Output

SDk RESISTOR TO

-2.0 -1.5

25 50 75 100125150

"til
N

CO
UI

<-_ _-'-_.!-'-'-.....L_-'

-250

-30
-75 -50-25 0

25 50 75 100 125 ISO

TEMPERATURE (oc)

-

~

20

1.7

Z

o
.....

LP2951
Minimum Operating Voltage

e;

,.~

"til

N
CO
UI

(Continued)

200

400

600

800

TINE (1'.)

OUTPUT LOW VOLTAGE (V)

LP2951
Load Transient Response

Load Transient Response

250

Enable Transient

80

200

~'> 150

~

60
40

6.5

20

~>'

~..s 100
: ~ 50
~:i 0
~:
-50

-

I

'\

-F.:(

I
I
I
IL =lOrnA

I pF

I

>~

~'"

aU

'I

~:Ii
-20
~:

-

5u
G.=I"F-

-100

G. = 10pF

-40

- pi

VOUT =5~_

-60

V,N =8V-

/
G.=IO"F

VOUT =5V -

VOUT=,SV;+

1~A '-,
100
I' A

A'I

r-2

'2
TIME

(m.)

16

-100 0

20

TIME (m.)

Output Impedance

TINE (".)

Ripple Rejection

Ripple Rejection

10

90

,.

"ii>
3
z

.e
~

~

0.5

~
;!

0.2

~

0.1

is

PI

80

"in"
l:j

100 200 300 400 500 600 700

iii

70
60

50

~.

.

!t

0.05
0.02
100

IK

10K

FREQUENCY

(Hz)

lOOK

1M

40
30

10'
FREQUENCY

(Hz)

FREQUENCY

Ill'

1If'

(Hz)
TL/H/8546-4

2-123

Typical Performance Characteristics

(Continued)

LP2951 Output Noise

Ripple Rejection
80
~=

50 mA

70
~

60 IL=

~

50

B
iii
~

..
It

100mA~

1111

~

~

:s

1\

~3
~~

<;'=1 "F \

"'z
~ ~

3.0 ~IIII
2.5
20

win

40

t--

30

t - - Y,N =6V
VOUT = 5\'

\

20
10

'0'

10'

10'

I

~~

"- .J
lif'

, 0.0

1.0

"

"- i'...REGULATOR OFF

12

l- f-'"

100

N

Z

r'"

PIN7 1

,0'

1(i'

-

'"

~

,...

~
5

REGULATOR ON

~

0.8
0••

-75 -50 -25 0

"..

200

~

z

0:

30
25
20
15
10 T '=' 15O
J

'>
..5

1.2

!il

".

0:

1(f

o

lif'

-75-50-25

10
5 TJ
0
-5
-10

25 50 7S 100 125 150

5

120
100

°c:....

~

..5

~=lmA

~

80

z

~
~

G

~

~ = 100 "A

6

60
40
20
0

10

15

20

25

30

0

10

INPUT VOLTAGE (V)

LP2950 Maximum
Rated Output Current

15

20

25

30

INPUT VOLTAGE (V)

Thermal Response

r---r-r---r-,-----,-----,

5

.... 1-1-

100
80

25 50 75100125150

LP2951 Maximum
Rated Output Current

'L = 1DO::?.

125°

TEMPERATURE (ec)

120

a

TEMPERATURE (ec)

Line Regulation

1.8

~

z

FREQUENCY (Hz)

Shutdown Threshold Voltage

1.4

1/

300

u

g

O.OllA r
BYPASS

FREQUENCY (Hz)

1.6

C-

0i]L

~~~~3"

0.5 PIN I TO

,,"

Ci'

c" ~,'!~

"

<;. =220" - '

1.0

~'"

J

1(f

1.5

LP2951 Divider Resistance
400

;~lkl00 ~M

f--I-+-Hc-l--

g

...... --:-

-2

+
1. 5W
1 f---r---

~g
20
OL--L_L--L_~-L~

o

10

15

20

25

30

INPUT VOLTAGE (v)

~~

0

a~

-1

o

10

20

30

40

50

TIME (",)

TUH/8546-5

Application Hints
EXTERNAL CAPACITORS
A 1.0 ",F (or greater) capacitor is required between the output and ground for stability at output voltages of 5V or more.
At lower output voltages, more capacitance is required
(2.2 ",F or,more is recommended for 3V and 3.3V versions).
Without this capacitor the part will oscillate. Most types of
tantalum or aluminum electrolytiCS work fine here; even film
types work but are not recommended for reasons of cost.
Many aluminum electrolytics have electrolytes that freeze at
about -30'C, so solid tantalums are recommended for operation below -25'C. The important parameters of the capacitor are an ESR of about 5 n or less and a resonant
frequency above 500 kHz. The value of this capacitor may
be increased without limit.

0.33 ",F for currents below 10 rnA or 0.1 ",F for currents
below 1 rnA. Using the adjustable versions at voltages below 5V runs the error amplifier at lower gains so that more
output capacitance is needed. For'the worst-case situation
of a 100 mA load at 1.23V output (Output shorted to Feedback) a 3.3 ",F (or greater) capacitor ,should be used.
Unlike ,many other regulators, the LP2950 will remain stable
and in regulation with no load in addition to the internal voltage divider. This is especially 'important in CMOS RAM
keep-alive applications. When setting the output voltage of
the LP2951 versions with ,external resistors, a minimum load
of 1 ",A is recommended.
A 1 ",F tantalum or aluminum electrolytic capacitor should
be placed from the LP2950/LP2951 input to ground if there
is more than 10 inches of wire between the input and the AC
filter capacitor or if a battery is used as the input.

At lower values of output current, less output capacitance is
required for stability. The capacitor can be reduced to
2-124

r-

-a

Application Hints (Continued)

I\)

CD

VOUT = VREF· (1

C

t

:t<
r-

-a

I\)

CD

en
......

....

t><

=

1

BYPASS - 2'ITRI .200 Hz

or about 0.01 /LF. When doing this, the output capacitor
must be increased to 3.3 /LF to maintain stability. These
changes reduce the output noise from 430 /LV to 100 /LV
rms for a 100 kHz bandwidth at 5V output. With the bypass
capaCitor added, noise no longer scales with output voltage
so that improvements are more dramatic at higher output
voltages.

VOUT

+VIN

.:;E:;:,RR:::O::::R,..--"I ERROR
OUTPUT

Your

r--4....-~I...2_.........,30"'V_

LP2951

.. SHUTDOWN 3 SD

V~~~=~~~
:

+ :~) + IFBRI

REDUCING OUTPUT NOISE
In reference applications it may be advantageous to reduce
the AC noise present at the output. One method is to reduce
the regulator bandwidth by increasing the size of the output
capacitor. This is the only way noise can be reduced on the
3 lead LP2950 but is relatively inefficient, as increasing the
capacitor from 1 ,.F to 220 ,.F only decreases the noise
from 430,.V to 160 ,.V rms for a 100 kHz bandwidth at 5V
output.
Noise can be reduced fourfold by a bypass capaCitor accross Rl, since it reduces the high frequency gain from 4 to
unity. Pick

PROGRAMMING THE OUTPUT VOLTAGE (LP2951)
The LP2951 may be pin-strapped for the nominal fixed output voltage using its internal voltage divider by tying the
output and sense pins together, and also tying the feedback
and VTAP pins together. Alternatively, it may be programmed for any output voltage between its 1.235V reference and its 30V maximum rating. As seen in Figure 2, an
external pair of resistors is required.

----.

o
....

where VREF is the nominal 1.235 reference voltage and IFB
is the feedback pin bias current, nominally -20 nA. The
minimum recommended load current of 1 ,.A forces an upper limit of 1.2 MO on the value of R2, if the regulator must
work with no load (a condition often found in CMOS in
standby). IFB will produce a 2% typical error in VOUT which
may be eliminated at room temperature by trimming RI. For
better accuracy, choosing R2 = lOOk reduces this error to
0.17% while increasing the resistor program current to
12 ,.A. Since the LP2951 typically draws 60 ,.A at no load
with Pin 2 open-circuited, this is a small price to pay.

ERROR DETECTION COMPARATOR OUTPUT
The comparator produces a logic low output whenever the
LP2951 output falls out of regulation by more than approximately 5%. This figure is the comparator's built-in offset of
about 60 mV divided by the 1.235 reference voltage. (Refer
to the block diagram in the front of the datasheet.) This trip
level remains "5% below normal" regardless of the programmed output voltage of the 2951. For example, the error
flag trip level is typically 4.75V for a 5V output or 11.4V for a
12V output. The out of regulation condition may be due either to low input voltage, current limiting, or thermal limiting.
Figure 1 below gives a timing diagram depicting the ERROR
signal and the regulated output voltage as the LP2951 input
is ramped up and down. For 5V versions, the ERROR signal
becomes valid (low) at about 1.3V input. It goes high at
about 5V input (the input voltage at which VOUT = 4.75).
Since the LP2951's dropout voltage is load-dependent (see
curve in typical performance characteristics), the input voltage trip point (about 5V) will vary with the load current. The
output voltage trip point (approx. 4.75V) does not vary with
load.
The error comparator has an open-collector output which
requires an external pull up resistor. This resistor may be
returned to the output or some other supply voltage depending on system requirements. In determining a value for
this resistor, note that while the output is rated to sink
40P ,.A, this sink current adds to battery drain in a low battery condition. Suggested values range from lOOk to 1 MO.
The resistor is not required if this output is unused.

ERROR'

en

The complete equation for the output voltage is

Stray capacitance to the LP2951 Feedback terminal can
cause instability. This may especially be a problem when
using high value external resistors to set the output voltage.
Adding a 100 pF capacitor between Output and Feedback
and increasing the output capacitor to at least 3.3 ,.F will fix
this problem.

INPUT

.--.:
TL/H/6546-7

INPUT

FIGURE 2. Adjustable Regulator

VOLTAGE

·See Application Hints

Vout

TL/H/B546-20

'When Y,N ,;; 1.3V, the error flag pin becomes a high impedance, and the
error flag voltage rises to its pull-up voltage. Using VOUT as the pull-up
voltage (see Figure 2), rather than an external 5V source, will keep the error
flag voltage under 1.2V (typ.) in this condition. The user may wish to divide
down the error flag voltage using equal-value resistors (10 kll suggested), to
ensure a low-level logic signal during any fault condition, while still allowing a
valid high logic level during normal operation.

= VRat ( 1 +~)

"'Drive with TTL.high to shut down. Ground or leave open if shutdown feature is not to be used.

Nole: Pins 2 and 6 are left open.

FIGURE 1. ERROR Output Timing
2-125

•

Typical Applications
1A Regulator with 1.2V Dropout
UNREGULATED--....- - -....---~--.....,
INPUT

+-_.

IN

SENSE .,2;....._ _

+

.:c.

LP2951

220 P'

out

7 ,B

OUTPUT
5Vt I %@
OTOIA

I

-'

2kn

INn

TUH/B546-22

300 mA Regulator with 0.75V Dropout

Wide Input Voltage Range
, Current Limiter

UNREGULATED-....-------------~~-.,
, INPUT

+Y,N

2N5432

,(2)

..:;E:,:;RR::;O.::,R:-~
OUTPUT

t=:---....--..--+~~TPUT

+Y,N
ERROR

Your

LP2951
SHUTDOWN 3 SO
INPUT

TUH/8546-21
TUH/8548-9
'Minimum' Input·output voltage ranges from
40 mY to 400 mY. depending on load current.
Current limit is typically 160 mAo

Low Drift Current Source
+V = 2-+ 30V

.__ L.
I

I

'd:

5 Volt Current Limiter

LOAD : 't = 1.;3

._-[-I

I

5V BUS

fa
Y,N
VOUT

LP2950Z-5.0

I
r--

Your

LP2951
SHUTDOWN 3
SD
INPUT
GND

=~

riP'
+

0.1 P'

GND

,B

4

'VOUT R:5V

1--+--

7
TUH/8548-10

I~ •

'Minimum input-output voltage ranges from 40 mY to 400 mY. depending on
load current. CUrrent limit is typically 160 mAo

IP'T

..... ....
TUH/8548-8

2-126

r

Typical Applications

"'tI

(Continued)

N
CD
U1

2 Ampere Low Dropout Regulator
CURRENT
,
LIMIT SECTION'

Regulator with Early Warning
and Auxiliary Output

o
......
~

~

><

0.05

.?<
r

"'tI

470
MJE2955

7

F8

2N0906

VOUT

VTAP

LP2951
#1

I'"i

10 k!l

20

4.7

~!l

+

ERROR

ERROR
FLAG

=,.'"

GND

4

LP2951

NICAD

+---....-...::.! SO
220

27 kn
Do

+VOUT@2A

20 k!l

EARLY WARNING

GNO

,
.055',

...

......

t><

RI +
+
4.7
100
F8 1-----.1% ,J2ANT.I!'F

VOUT

R2

47

I'
Voul

N
CD
U1

~ 1.23V (1 +~)

TL/H/8546-13

For 5Vout, use internal resistors. Wire pin 6 to 7, & wire pin 2 to +Vout Buss.

+VIN

SV Regulator with 2.SV Sleep Function

VTAP

+VIN
F8

LP2951
#2
• SLEEP

SD

INPUT

GND

4

47 kn
+VIN

TL/H/8546-11

,:E,:,:RR=O,:,:R~~

• Early warning flag on low input voltage

ERROR

OUTPUT

• Main output latches off at lower input voltages

LP2951

• Battery backup on auxiliary output

SHUTDOWN 3 SD
INPUT

Operation: Reg. #1's Vout is programmed one diode drop above 5V. Its error
flag becomes aclive when Vin ,; 5.7V. When Vin drops below 5.3V, the error
flag of Reg. # 2 becomes aclive and via Ot latches Ihe main output off.
When Vin again exceeds 5.7V Reg. #1 is back in regulation and the early
warning signal rises, unlatching Reg. #2 via 03.

Latch Off When Error Flag Occurs
'High input lowers Vout to 2.SV

TLlH/8546-14

Open Circuit Detector for
4 ~ 20 mA Current Loop
+5V
4----20mA

fII

LP2951

+

--IoL..l...lor--,SD
RESET

I"

IN
4001

VOUT
LP2951

TLlH/8546-12

• HIGH FOR
IL < 3.. 5 mA

MIN. VOLTAGE'" 4V

2-127

TL/H/8546-15

~r-----------------------------------------------------------------------,

>:=
~

-

Typical Applications (Continued)

1 ft

Regulator with State-o'-Charge Indicator '

~

~

39 kll

I

RESET

t---....g.u:r-",;S"I

ERROR

+ VOUT = 5V
VOUT j..:-.....- -....-

LP29S1

~-,~~SD

+

-=..L

FB

6V
LEAD-ACID
BATTERY

7

100 kll

< S.8V··
1%

100 kll

< 6.0V··
C'I-C4
LP339

1%

100 kll

< 6.2V~"

Tl/H/8548-18

"Optional latch off when drop out occurs. Adjust R3 for C2 Switching when Vln is B.OV.
"Oulputs go low when Vln drops below designated thresholds.

Low Battery Disconnect
For values ,s,hown. Regulator shuts down when Vln < 5.5V and turns on again at B.OV. Current drain in disconnected mode Is :::: 150 pA.

+_

::=:::

..L
_

6V
SEALED
LEAD-ACID
BATTERY
SOURCE

120 kll

I.Skll"

8
+VIN
MAIN V+
VOUT
LP29S1

RI 400 kll"
FOR S.SV

SENSE
SO

2

MEMORY V+

7

lJ.lF

"Sets disconnect Voltage
..Sets disconnect HYste~

r
+

2011

+'

-=-T

..L

NI-CAD
BACKUP
BATTERY
TLlH/8546-17

2-128

Typical Applications (Continued)
System Overtemperature Protection Circuit
+VIN

10 IUl

5° PRE-SHUTDOWN FLAG

:;::AU::::X:.,;.S:::iH:.::.UTDOlf.'i::W::;Nr~3 SD
INPUT
LP2951

Vour

GND

TEMP.
SENSOR

~

____..... __________ _

FB

EXTERNAL CIRCUIT
PROTECTED FROM
OVER TEMPERATURE
(V+ GOES OFF WHEN
TEMP.> 1250)

TL/H/B546-1B
LM34 for 125'F Shutdown
LM35 for 125'C Shutdown

•
2-129

LP29501 A-XX, LP29511A-XX

en

IN

n

:r
CD

3

S»

n'
c

iii'
cc

Dl
3

R28

~

Co)

o

R30
30 kO

R22
150 kO

---- DENOTES CONNECTION ON
LP2950 ONLY

GND

TL/H/8546-23

r-

."
N

co

f}1National Semiconductor

CI1

N
.....
r-

."
N

LP2952/LP2952A/LP2953/LP2953A
Adjustable Micropower Low-Dropout Voltage Regulators

co
CI1

N

~
r-

."
N

General Description

Features

The LP2952 and LP2953 are micropower voltage regulators
with very low quiescent current (130 /LA typical at 1 rnA
load) and very low dropout voltage (typ. 60 mV at light load
and 470 mV at 250 rnA load current). They are ideally suited
for battery-powered systems. Furthermore, the quiescent
current increases only slightly at dropout, which prolongs
battery life.

•
•
•
•
•
•
•
•
•
•

The LP2952 and LP2953 retain all the desirable characteristics of the LP2951, but offer increased output current, additional features, and an improved shutdown function.
The internal crowbar pulls the output down quickly when the
shutdown is activated.
The error flag goes low if the output voltage drops out of
regulation.
Reverse battery protection is provided.
The internal voltage reference is made available for external
, use, providing a low-T.C. reference with very good line and
load regulation.
The parts are available in DIP and surface mount packages.

co
CI1
Co)

.....
r-

Output voltage adjusts from 1.23V to 29V
Guaranteed 250 rnA output current
Extremely low quiescent current
Low dropout voltage
Extremely tight line and load regulation
Very low temperature coefficient
Current and thermal limiting
Reverse battery protection
50 rnA (typical) output pulldown crowbar
5V and 3.3V versions available

."
N

co
CI1
Co)

l>

LP2953 Versions Only
• AuxiliarY comparator included with CMOS/TTL compatible output levels. Can be used for fault detection, low
input line detection, etc.

Applications
•
•
•
•

High-efficiency linear regulator
Regulator with under-voltage shutdown
Low dropout battery-powered regulator
Snap-ON/Snap-OFF regulator

Block Diagrams
LP2952

LP2953

._-------------------I

TL/H/11127-1

2-131

TL/H/l 1127-2

c:c

C')

r.n
en

Absolute Maximum Ratings (Note 1)

D.

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
-65·C s: TA s: +150·Q
Storage Temperature Range

C'I

....I

......
C')
r.n
en
C'I

D.

....I

......

~

r.n
en
C'I

D.

....I

......
~

en

C'I

D.

Operating Temperature Range
LP29521, LP29531, LP2952AI,
LP2953AI, LP29521-3.3, LP29531-3.3,
-40·C s: TJ
LP2952AI-3.3, LP2953AI-3.3
-55·C s: ,TA
LP2953AM

s:
s:

Maximum Junction Temperature
LP29521, LP29531, LP2952AI,
LP2953AI, LP29521-3.3, LP29531-3.3,
LP2952AI-3.3, LP2953AI-3.3
LP2953AM

260·C

Lead Temp. (Soldering, 5 seconds)
Power Dissipation (Note 2)
Input Supply Voltage

+ 125·C
+ 125·C

Internally Limited
-20Vto +30V

Feedback Input Voltage (Note 3)
Comparator Input Voltage (Note 4)
Shutdown Input Voltage (Note 4)

-0.3Vto +5V
-0.3Vto +30V
-0.3Vto +30V

Comparator Output Voltage (Note 4)
ESD Rating (Note 15)

-0.3Vto +30V
2kV

+ 125·C
+ 150·C

....I

Electrical Characteristics

Limits in standard typeface are for TJ = 25·C, bold typeface applies over the full
operating temperature range. Limits arEi guaranteed' by production testing or correlation techniques using standard Statistical
Quality Control (SQC) methods. Unless otherwise specified: VIN = Vo(NOM) + tV, IL = 1 mA, CL = 2.2 /LF for 5V parts and
4.7/LF for 3.3V parts. Feedback pin is tied to V Tap pin, Output pin is tied to Output Sense pin.

3.3V Versions
Symbol

Parameter

Conditions

LP2952AI-3.3, LP2953AI-3.3

Typical

Min
Output Voltage

Vo

3.3
1 mA

s:

IL

s: 250 mA

3.3,

Max

LP29521-3.3, LP29531-3.3
Min

'Units

Max

3.284

3.317

3.267

3.333

3.260

3.340

3.234

3.366

3.254

3.346

3.22t

3.379

V

5VVersions
Symbol

Parameter

Conditions

LP2952AI, LP2953AI,
LP2953AM (Note 17)

Typical

Min
Vo

Output Voltage

5.0
1 mA

All Voltage Options
Symbol

Parameter

s:

IL

s: 250 mA

5.0

.

Conditions

Typical

Output Voltage
(Note 5)
Temp. Coefficient

AVo

Output Voltage
Line Regulation

VIN

Output Voltage
Load Regulation
(Note 6)

IL
IL

=
=

1 mAt0250mA
0.1 mAtol mA

VIN-VO Dropout Voltage
(Note 7)

IL

=

1 mA

Vo
AVO
Vo

IL

=

=

Vo(N9M) + tV
t030V

50mA

IL

=

100mA

IL

=

250mA

20

5.025

4.950

5.050

5.060

4.900

5.100

4.930

5.070

4.880

5.120

Max

0.04

60
240
310
470
2-132

LP29521, LP29531,
LP29521-3.3, LP29531-3.3
Min

Units

Max

4.975

100

0.03

Min

4.940

LP2952AI, LP2953AI,
LP2952AI-3.3, LP2953AI-3.3,
LP2953AM (Note 17)
Min

t.vo
AT

Max

LP29521, LP29531

V

Units

Max

150

0.1

0.2

0.2

0.4

0.16

0.20

0.20

0.30

100

100

150

150

300

300

420

420

400

400

520

520

600

600

800

800

ppml"C
%
%

mV

r-

"V

Electrical Characteristics

Limits In standard typeface are for TJ = 25°C, bold typeface applies over the full
operating 'temperature range. Limits are ·guaranteed by production testing or correlation techniques using standard Statistical
Quality Control (SQC) methods. Unless otherwise specified: VIN = Vo(NOM) + 1V, IL = 1 mA, CL = 2.2 p.F for 5V parts and
4.7p.F for 3.3V parts. Feedback pin is tied to V Tap pin, Output pin is tied to Output Sense pin. (Continued)

N

CD

en
N

r-

"V

N

CD

All Voltage Options (Continued)
Symbol

Conditions

Parameter

en

N

LP2952AI, LP2953AI,
LP2952AI-3.3, LP2953AI-3.3,
Typical
LP2953AM (Note 17)
Min

IGND

Ground Pin Current
(Note 8)

IL= 1 rnA
IL = SOmA
IL = 100 rnA
IL = 250 rnA

IGND

Ground Pin Current
at Dropout (Note 8)

VIN = Vo(NOM) -0.5V
IL = 100,..A

IGND

Ground Pin Current (Note 9)
at Shutdown (Note 8)

ILiMIT

Current Limit

VOUT = 0

l;.Vo
l;.Pd

Thermal Regulation

en

Output Noise Voltage CL = 4.7 p.F
(10 Hzto 100 kHz)
CL=33,..F
IL = 100 rnA
CL = 33·,..F (Note 11)

VREF

Reference Voltage

(Note 10)

(Note 12)

l;.VREF Reference Voltage
VREF Line Regulation

VIN = 2.5V to VO(NOM) + 1V
VIN = VO(NOM) + 1Vto 30V
(Note 13)

l;.VREF Reference Voltage
VREF Load Regulation

IREF = 0 to 200 ,..A

l;.VREF Reference Voltage
Temp. Coefficient
l;.T

(NoteS)

le(FB)

Feedback Pin
Bias Current

Output "OFF"
10
(SINK) Pulldown Current

130
1.1
4.S
21
165
10S
380
0.05

J>
.....
rUnits

"V

N

CD

Min

en
Co)

Max

170

170

200

200

2

2

2_5

2.5

6

6

8

8

28

28

33

33

210

210

240

240

140

140

500

500

530

530

0.2

0.2

,..A

.....
r"V

N

CD

en

§::
rnA

,..A
,..A
rnA

%/W

400
,..VRMS

260
80
1.230

1.215

1.245

1.205

1.255

0.03

0.2S

1.205

1.190,

1.25S

1.270

0.1

0.2

0.2

0.4

0.4

0.8

0.6

1.0

20

V

%

%
ppml"C

20
(Note 9)

Max

LP29521, LP29531,
LP29521-3.3, LP29531-3.3

50

40

40

60

60

30

30

20

20

nA
rnA

•
2-133

~
an

G)

N

a.

...J
.....
(W)

Electrical Characteristics

Limits in standard typeface are for TJ = 2SoC, bold typeface applies over the fun
operating temperature range. Limits are guaranteed by production testing or correlation techniques using standard Statistical
Quality Control (SQC) methods. Unless otherwise specified: VIN = Vo(NOM) + W, IL = 1 mA, CL = 2.2 ,...F for 5V parts and
4.7,...F for 3.3V paris. Feedback pin is lied to V Tap pin, Output pin is tied to Output Sense pin. (Continued)

an

G)

N

a..

...J
.....

Symbol

Parameter

Condition.

Typical

:i
an

LP2952AI, LP2953AI,
LP2952A1-3.3, LP2953AI-3.3,
LP2953AM (Note 17)
Min

Max

LP29521, LP2953I,
LP29521-3.3, LP29531-3.3
Min

Units

Max

G)

N

a.

...J

DROPOUT DETECTION COMPARATOR

.....
N

IOH

N

VOL

an
G)

a.

...J

= 30V

OUlput "HIGH"
Leakage

VOH

O~lput "LOW"
Voltage

VIN = Vo(NOM) - 0.5V
lo(COMP) = 400,..A

Upper Threshold

(Note 14)

VTHR
(MAX)

Voltage

VTHR
(MIN)

Lower Threshold
Voltage

(Note 14)

HYST

Hysteresis

(Note 14)

0.01

150

-60

-85

1

1 :

2

2

250

250

400

400

-80

-35

-80

-35

-85

-25

-85

-25

-110

-55

-110

-55

-180

-40

-180

-40

15

,..A

mV

mV

mV
mV

SHUTDOWN INPUT (Note 16)
vas

HYST
Ie

Input Offset Voltage

(Referred to VREF)

Hysteresis
Input Bias Current

±3

-7.5

7.5

-7.5

7.5

-10

10

-10

10

' mV

6
VIN(SfD)

= OV to 5V

I

LP2953AM

mV

10

10

-30

30

-50

50

-30

30

-75

75

-7.5

7.5

-10

10

-30

-'30

-50

50

-7.5

7.5

-10

10

nA

AUXILIARY COMPARATOR (LP2953 Only),
Vas

Input Offset Voltage

(Referred to VREF)

I
HYST

Hysteresis

Ie

Input Bias Current

Output "HIGH"
Leakage

VIN(COMP)

= OV to 5V
LP2953AM

VOH = 30V
VIN(COMP) = 1.3V

I

LP2953AM

VOL

Output "LOW"
Voltage

±3

-7.5

7.5

-12 '

12

-30

30

-50

50

6

I
IOH

LP2953AM

±3

VIN(COMP) = 1.W
lo(COMP) = 400,..A

I

LP2953AM

'mY'

mV

10

10

-30

30

-75

78

-30

30

-50

50

nA

1

0.01

2
1

0.01

1

2

,...A

2.2
250

150

400
250

150

420

2-134

250

400

mV

NOle I: Absolute maximum ratings Indicate limits beyond which damage to the component may occur. Electrical specifications,do not apply when operating the
device outside 01 its rated operating condijions.
Nola 2: The maximum allowable power dissipation Is a lunction 01 the maximum junction temperature, TJ(MAX), the junction·to·ambient thermal resistance, 8 J-A,
and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using: P (MAX)
,

= TJ(MAX) 8J-A

TA .

Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go Into thermal shutdown. See APPLICATION
HINTS for additional Information on heatsinking and thermal resistance.
Note 3: When used in dual·supply systems where the regulator load is returned to a negative supply, the output voltage must be diode-clamped to ground.
Note 4: May exceed the input supply voltage.
Nota 5: Output or relerence voltage temperature coefficient is delined as the worst case voltage change divided by the total temperature range.
Nota 8: Load regulation Is measured at constant junction temperature using low duty cycle pulse testing. Two separate tests are performed, one lor the range 01
100 p.A to 1 mA and one lor the 1 rnA to 250 mA range. Changes In output voltage due to heating effects are covered by the thermal regulation specilication.
Nota 7: Dropout voltage is deli ned as the input to output differential at which the output voltage drops 100 mV below the value measured with a t V differential. At
very low values 01 programmed output voltage, the Input voltage minimum 01 2V (2.3V over temperature) must be observed.
Nota 8: Ground pin current Is the regulator quiescent current The total current drawn Irom the source is the sum 01 the ground pin current, output load current, and
current through the extarnal resistive divider (il used).
Note 9: VSHlITDOWN ,; 1.lV, VOUT

= Vo(NOM).

Note 10: Thermal regulation Is the change in output voltage at a time T alter a change In power dissipation, excluding load or line regulation effects. Specifications

are lor a 200 mA load pulse at VIN = VO(NOM)+ 15V (3W pulse) lor T = 10 ms.
Note 11: Connect a 0.1 p.F capaCitor lrom the output to the leedback pin.
Note 12: VREF ,. VOUT ,. (YIN - lV), 2.3V ,; VIN ,. 30V, 100 p.A ,. IL ,. 250 mAo
Note 13: Two separate tests are performed, one covering 2.5V ,. VIN ,. VO(NOM)+ lV and the other test lor Vo(NOM)+ lV ,. VIN ,. 30V.
Note 14: Comparator thresholds are expressed in terms 01 a voltage differential at the Feedback terminal below the nominal relerence voltage measured at
VIN = VO(NOM) + lV. To express these thresholds In terms 01 output voltage change, multiply by the Error amplifier gain, which is VOUTIVREF = (Rl + R2)/R2
(reler to Figure 4).
Note 15: Human body model, 200 pF discharged through 1.5 kO.
Note 18: Drive Shutdown pin with TIL or CMOS·low level to shut regulator OFF, high level to turn regulator ON.

Note 17: A military RETS specification is available upon request. At the time 01 printing, the LP2953AMJ/883C RETS specification complied with the boldface

limits in this column.

2-135,

Typical Performance Characteristics Unles~ otherwise sp~Cified: Y,N = 6V"Ii. = 1 niA"c~ = 2.2 poF,
=: 5V.

VSD = 3V, TA = 25°C, VOUT

Quiescent Current
"<
3

I
z

L "
I-"" ~ t ~ 10~}'A

180
160
140
120

"<
3

150 r t - + + - t - t f - I - t - + - i

lu

140

z

130

f-+-+,,-"t.,.-/-f-f-f-+-+~
I-+-+-+'-"Io~-t-t-+-+

"

'IL

II
II

40
20

!i!

120I-++-t-tf-I-P"'""d-l

~

1101-++-t-tf--I'L

2

6

INPUT VOLTAGE (V)

Ground Pin Current
"<

.§.
~

i
z

'I.

14

--

"<

.§.

= 250mA

~

12
10

5
~
z

Ii:

Ii:

"

.i-

15

2

3

4

5

~

'"~

Ripple Rejection

IL

100

= 100mA
0

25 50 75 100125150

0.1

90

Ripple Rejection
80

I

-:a

3
z

70

"g
iil
~
Ii

1\
f1
\ ~ ='mAII
\\ )(/
\, ,;-y

60
50
40
30
0,01

0,1

1

10

100

60

v

0

90

= 100mA

-:a

3
z

~

g"

= 250mA 1\\

iil

\\

~

\
0.01

0.1

'\.... /

10

100

J

~

'"

/\

80

A

70

~ = O//,

60

VY

50

!
\Y;, i-""'
'L == 100 JJA

40

"V

20
1000

Line Transient Response

0.01

0,1

~

~>
~.§ 40

10

100

1000

Output Impedance

>~

~~

"

-40
~

~'"
:><
~~

.L

1

FREQUENCY (KHz)

C1. = 33}'F
~ = 10mA

80

~"
:>u

8Y.~

I

30

FREQUENCY (KHz)

W

1000

Ripple Rejection

......... ./'\~

30

1000

L
'L = lOmA

0

~

10

J

1\

..........

40

Line Transient Response
0

t'-....

50

FREQUENCY (KHz)

100

100

20

\..-/"Ia. = 10mA

20

70

10

LOAD CURRENT (mA)

90

80

6V

200

JUNCTION TEMPERATURE (oC)

100

'"

>

~

INPUT VOLTAGE (V)

"~
iil
~

,~
!il
~
g

10

-75 -50-25 0

6

500

3

o

o

3
z

'~. 250mA

~

2

o

-:a

--

tv

i-'"

1000

Output Noise Voltage

"z

z

:>

~

20

100

OUTPUT CURRENT (mA)

Ground Pin Current
25

16

10

TEMPERATURE (OC)

20
18

= 1 rnA

100 '-"'--'--'-....1.--"-'-"'--'--'
-75-50-250 255075100125150

'0

o

Ground Pin Current vs Load

160 r-,-,-,-..,,,-r-r-,-,

100

Ii: 80
~. 60

~

Quiescent Current

-

200

"

8Y

!E~ 6Y

I

0.2

0,4

0.6

TIME (m.)

0,8

3
TIME (m.)

0.01

0,1

10

100

1000

FREQUENCY (KHz)
TL/H/11127-3

2-136

Typical Performance Characteristics Unless otherwise specified: VIN = 6V. IL = 1 rnA. CL = 2.2I-'F.
VSD

= 3V. TA = 25°C. VOUT = 5V. (Continued)
Load Transient Response

......

0100

~'>

2i..s

or- -r- c,.

>~

~~

"....

= 2.2

"r- I"'t--

-0100

~r

100

No.

..

0

c,.

>~

~~

-,....

5

~

= 33",

~
5

~~
~r

gU

-800
~

6

~>

~..s
~

gu

~~

Dropout Characteristics

Load Transient Response
200

800

-100
-200

250mA I

~~

~

250mA

01

It = IDOpA

3

~

= 250mA

2
1

~a 100"A

100"A

0
01

0

8

12

16

20

0

10

20

TI~E (m.)

30

010

50

60

0

Enable Transient

~~
6

0

>

~i

01

5

6

600
6

.
s~

~~

550

I
G.. -2.2J'F

~

G. =2.2"'

6

4

G. =33"' 1-1---

4
2
0
2

VIN = 14V

-

~~

~~

0

~g
0

1

3

2

01

2

I--

,,' = lOrnA

o ,

500

§

450

~

400

~

300

5

2'r-

f-

t"-

350

f- r-

250

0

5

~ ..... ~T = 5V -r-'N
WAX OUTPUT CURRENT

"<
~

G. =33"'

~

IL = IOmA

~i

3

Short-Circuit Output Current
and Maximum Output Current

Enable Transient

8
~

2

INPUT VOLTAGE (V)

10

S::;

1

TI~E (m.)

0

1

2

TI~E (ms)

3

4

5HORT~CIR~UIl' CURREN~
VouT=OI

200
-75-50-250

5

TIME (m.)

I

I

I

25 50 75 100125150

JUNCTION TEMPERATURE (oC)

"

Feedback Bias Current

Feedback Pin Current

20

"<

10

..3

"<
-5.

~

Error Output
8

50

~

0

I

-10

!:!

~
~

~

iD

-20

0
'-50

V~

~

~

~

g

lA=1,2~

V"

-100

-150/

A

i"

/V1"\...TA = 25iC

S

I

-200

6'

r-HYSTERESIS - -

2
0

T' ~~~~~=T~E;~S~~Rp~~y

/rA=-S5 0 C
-30
-75 -50-25 0

-250
25 50 75 100125150

TEMPERATURE (OC)

TJ
2.0

"<
~
z

/

1.5

~
~

"u
'"z

1/11

1.0

1

in

0.5

V

-2
0

FEEDBACK VOLTAGE

Comparator Sink Current
2.5

.
-2.0 -1.5 -1.0 -0.5

12~OC

JLc
TA = -55°C

(,

o.o.ill
0.00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
OUTPUT LOW VOLTAGE (V)

0.5

1.0

1

~

'~
>~

300

l~

"~
~

u

~

~

:".

200

1..-'1'

-

....

".

~~

-600

-r-r-

=::5
0"

-"00

6

~ ~ -200
!;i~

::~

"
S

~

......

rS

~:=

25 50 75 100125150

LOWER THRESHOLD

g's -500
~ a:: -300

TEMPERATURE (OC)

5

(V)

-700

a:: ~ -100

100
-75-50-25 0

4

Dropout Detection
Comparator Threshold
Voltages

5V VERSION
400

3

INPUT VOLTAGE

500

z

C>

2

(V)

Divider Resistance

~c

r--

4

,....

- -

UPPER THRESHOLD

-0.
-75 -50-25 0

25 50 75 100125150

TE~PERATURE (OC)

TUH/11127-4

2-137

•

Typical Performance Characteristics 'Unless otherwise specified: VIN =

6V,IL= 1 mA, CL

VSD = 3V, TA = 25°C, VOUT = 5V. (Continued)
Thermal Regulation

Dropout Voltage

Minimum Operating Voltage
1,0

2.3

~'>

it
~i

!5 5
o

15
10

5
:0
-5

;

~

""

-

r-...

:E
w

'2.2

g

2. 1 -

~'

--'

"3

2.0

~

1.9

a

~

REFERENCE AND REGULATOR

(REGULATOR OUTPUT" 1.23V)

r-.....

~,

:E
~
~

30

TINE (m.)

40

1,7
-75

1 1
1 'I
1 1

0,8
0,6

-

I"'"

IL = 250;!.

>
~!; 0,4 -: :---K~\~~"'~:::;;

.......

.......

i

...

\. so 50",1\

0,2

~

20

2.2 ",F,

'0

~, 1.8
10

7"

"

I""'"~'I

- c- H~

=lmA

0.0
~50

-25 0 25 50 75 100 125 150
,TEMPERATURE (Oc)

-80

,-10

40

90

1<10

TEMPERATURE (Oc)

TLlHfll127-5

Schematic Diagram

TLfHflll27-6

Application Hints
Figure 2 shows copper patterns which may be used to dissipate heat from the LP2952 and LP2953:

HEATSINK REQUIREMENTS (Industrial Temperature
Range Devices)
The maximum allowable power dissipation for the
LP2952/LP2953 is limited by the maximum junction temperature (+ 125·C) and the external factors that determine how
quickly heat flows away from the part: the ambient temperature and the junction-to-ambient thermal resistance for the
specific application.
The industrial temperature range (-40·C' ~ TJ ~ + 125·C)
parts are manufactured in plastic DIP and surface mount
packages which contain a copper lead frame that allows
heat to be effectively conducted away from the die, through
the ground pins of the IC, and into the copper of the PC
board. Details on heatsinking using PC board copper are
covered later.
To determine if a heatsink is required, the maximum power
dissipated by the regulator, P(max), must be calculated. It is
important to remember that if the regulator is powered from
a transformer connected to the AC line, the maximum
specified AC Input voltage must be used (since this produces the maximum DC input voltage to the regulator). Figure 1 shows the voltages and currents which are present in
the circuil. The formula for calculating the power dissipated
'
in the regulator is also shown in Figure 1:

~I---- LO ---~'I

I-

LO

----1.1

'111 - . - - - - . ,

VIN "";;';"---1IN

OUT 1--"";;';;';--.
LP2952/
LP2953
TLlH/11127-8
'For best results. use L

~

2H

"14·Pin DIP is similar, refer to Table I for pins designated for heatsinking.

FIGURE 2. Copper Heatslnk Patterns
TL/H/11127-7

P-rOTAL = (VIN - VOUT) IL

+ (V,N) IG

FIGURE 1. Current/Voltage Diagram

Table II shows some values of junction-Io-ambient thermal
resistance (6J-A) for values of Land W for 1 oz. copper:

The next parameter which must be calculated is the maximum allowable temperature rise, T R(max). This is calculated by using the formula:

TABLE II

TR(max) = TJ(max) - TA(max)
where: TJ(max) is the maximum allowable junction temperature

Package

L(ln.)

H (In.)

6J_A("C/W)

16-Pin DIP

1

0.5

70

2

1

60

3

1.5

58

4

0.19

66

6

0.19

66

1

0.5

65

2

1

51

3

1.5

49

1

0.5

83

2

1

70

3

1.5

67

6

0.19

69

4

0.19

71

2

0.19

73

T A(max) is the maximum ambient temperature
Using the calculated values for T R(max) and P(max), the
required value for junction-to-ambient thermal resistance,
6(J-A), can now be found:
6(J-A) = TR(max)/P(max)

14-Pin DIP

The heatsink is made using the PC board copper. The heat
is conducted from the die, through the lead frame (inside
the part), and out the pins which are soldered to the PC
board. The pins used for heat conduction are:

Surface Mount

TABLE I
Package

'Pins

LP29521N, LP2952AIN,
LP2952IN-3.3, LP2952AIN-3.3

Part

14-Pin DIP

3,4,5,
10,11,12

LP29531N, LP2953AIN,
LP2953IN-3.3, LP2953AIN-3.3

16-Pin DIP

4,5,12,13

LP29521M, LP2952AIM,
LP2952IM-3.3, LP2952AIM-3.3, 16-Pin Surface
1,8,9,16
Mount
LP29531M, LP2953AIM,
LP2953IM-3.3, LP2953AIM-3.3
2-139

Application Hints (Continued)
HEATSINK REQUIREMENTS (Military Temperature
Range Devices)
.

EXTERNAL CAPACITORS
A 2.2 p.F (or greater) capaCitor is required between the output pin and ground to assure stability when the output is set
to 5V. Without this capacitor, the part will oscillate. Most
type of tantalum or aluminum electrolyticswlll work here.
Film types will work, but are more expensive. Many aluminum electrolytics contain electrolYtes which freeze at
- 30·C, which requires the use of solid tantalums beloVi'
- 25·C. The important parameters of the capaCitor are an
ESR of about 50 or less and a resonant frequency above
500 kHz (the ESR may increase by a factor 0(20 or 30 as
the temperature is reduced from 25·C to -30"C). The value
of ·this capacitor may be increased without limit.

The maximum allowable power dissipation for the
LP2953AMJ is limited by the maximum junction temperature
(+ 150"C) and the two parameters that determine how
quickly heat flows away from the die: the ambient temperature and the junction-ta-ambient thermal resistance of the

part.
The military temperature range (- 55·C s: TJ s: + 150"C)
parts are manufactured in ceramic DIP packages which contain a KOVAR lead frame (unlike the industrial parts, which
have a copper lead frame). The KOVAR material is necessary to attain the hermetic seal required in military applications.

At lower values of output current, less output capacitance is
required for stability. The capacitor can be reduced to
0.6B p.F for currents below 10 mA or 0.22 p.F for currents
below 1 mAo
Programming ·.the output for voltages below 5V runs the error amplifier at lower gains requiring more output capacitance for siabiliiy. At 3.3V output, a minimum of 4.7 p.F is
required. For ttle worst-case COfldition of .1.23V output and
250 mA of load current, a 6.B p.F (or larger) capacitor stlould
be used.

The KOVAR lead frame does not conduct heat as well as
copper, which means that the PC board copper can not be
used to significantly reduce the overall junction-to-ambient
thermal resistance in applications using the LP2953AMJ
part.
The power dissipation calculations for military applications
are done exactly the same as was detailed in the previous
section, with one important exception: the value for 8(J-A),
the junction-ta-ambient thermal resistance, is fixed at
95·C/W and can not be changed by adding copper foil patterns to the PC board. This leads to an important fact: The
maximum allowable power dissipation in anyappUcation using the LP2953AMJ is dependent only on the ambient temperature:

A 1 p.F capacitor should be placed from the input pin to
ground if there is more than 10 inches of wire between the
input and the AC filter capaCitor or if a batterY input is used.
Stray capacitance to the Feedback terminal can cause instability. This problem is most likely to appear when using
high value extemal resistors to set the output voltage. Adding a 100 pF capacitor between the Output and Feedback
pins and increasing the output capacitance to 6.B p.F (or
greater) will cure the problem.

P(max) = TR(max) 18(J_A)
P(max) = TJ(max) - TA(max)
8(J-A)
P(

) = 150 - TA(max)
max
95 .

MINIMUM LOAD
When setting the output voltage using an external resistive
divider, a minimum current of 1 p.A is recommended through
the resistors to provide a minimum load.

Figure 3 shows a graph of maximum allowable power dissipation vs. ambient temperature for the LP2953AMJ, made
using the 95·Ciw value for 8(J-A) and assuming a maximum junction temperature of 1500C (caution: the maximum
ambient temperature which will be reached in a given application must always be used to calculate maximum allowable
power dissipation).

It should be noted that a minimum load current is specified
in several of the electrical characteristic test conditions, so
this value must be used to obtain correlation on these tested limits.

:g
:z:
0

2

~

Q.

iii
is

II)

...'"
~

.0
Q.

::r
:::0
::r

~

::r
0
-55

0

50

100

AMBIENT TEMPERATURE (Oe)

150
TUH/11127-26

FIGURE 3. Power Derating Curve for LP2953AMJ

2-140

~------------------------------------------------------------------------------------,

Figure 5 gives a timing diagram showing the relationship
between the output voltage, the ERROR output, and input
voltage as the input voltage is ramped up and down to a
regulator programmed for 5V output. The ERROR signal becomes low at about 1.SV input. It goes high at about 5V
input, where the output equals 4.75V. Since the dropout
voltage is load dependent, the Input voltage trip pOints will
vary with load current. The output voltage trip point does
not vary.

PROGRAMMING THE OUTPUT VOLTAGE
The regulator may be pin-strapped for 5V operation using its
internal resistive divider by tying the Output and Sense pins
together and also tying the Feedback and 5V Tap pins together_
Alternatively, it may be programmed for any voltage between the 1.2SV reference and the SOV maximum rating
using an external pair of resistors (see Figure 4). The complete equation for the output voltage is:
VOUT = VREF X (1

+ ~~) + (IFB x

The comparator has an open-collector output which requires an external pull-up resistor. This resistor may be connected to the regulator output or some other supply voltage.
Using the regulator output prevents an invalid "HIGH" on
the comparator output which occurs if it is pulled up to an
external voltage while the regulator input voltage is reduced
below 1.SV. In selecting a value for the pull-up resistor, note
that while the output can sink 400 /LA, this current adds to
battery drain. Suggested values range from 100 kG to
1 Mil. This resistor is not required if the output is unused.

R1)

where VREF is the 1.2SV reference and IFB is the Feedback
pin bias current (-20 nA typical). The minimum recommended load current of 1 /LA sets an upper limit of 1.2 Mil
on the value of R2 in cases where the regulator must work
with no load (see MINIMUM LOAD). IFB will produce a typical 2% error in VOUT which can be eliminated at room temperature by trimming R1. For better accuracy, choosing
R2 = 100 kll will reduce this error to 0.17% while increasing the resistor program current to 12 p.A. Since the typical
quiescent current is 120 /LA, this added current is negligible.

VOUT
t.2-30V

>V,N

OUTPUT

+---

LP2952/3

OUTPUT
VOLTAGE

+----1f-1 SO
SHUTDOWN

INPUT··

ERROR

OFF--r° N

OUTPUT

75V--

~

.

---.:

I
I
I
I
I

------

I
I .
I
I
I

.

:.----

TLlH/l1t27-9

FIGURE 4_ Adjustable Regulator
'See Application Hints
"Drive with TTL·low to shut down

TLlH/ttt27-tO

FIGURE 5. ERROR Output Timing

DROPOUT VOLTAGE
The dropout voltage of the regulator is defined as the minimum input-to-output voltage differential required for the output voltage to stay within 100 mV of the output voltage measured with a 1V differential. The dropout voltage is independent of. the programmed output Voltage.

"In shutdown mode, ~ will go high if it has been pulled up to an
external supply. To avoid this invalid response, pull up to reguialar output.
"Exact value depends on dropout voltage. (See Application Hints)

OUTPUT ISOLATION
The regulator output can be left connected to an active voltage source (such as a battery) with the regulator input power shut off, as long as the regulator ground pin Is connected to ground. If the ground pin is left floating, damage
to the regulator can occur if the output is pulled up by an
external voltage source.

DROPOUT DETECTION COMPARATOR
This comparator produces a logic "LOW" whenever the output falls out of regulation by more than about 5%. This figure results from the comparator's built-in offset of 60 mV
divided by the 1.2SV reference (refer to block diagrams on
page 1). The 5% low trip level remains constant regardless
of the programmed output voltage. An out-ot-regulation condition can result from low input voltage, current limiting, or
thermal limiting.

2-141

fI

Pinout Drawings

Application Hints (Continued)
REDUCING OUTPUT NOISE

LP2952
14-Pln DIP

In reference applications it may be advantageous to reduce
the AC noise present on the output. One method is to reduce re~ulator bandwidth by increasing output capacitance.
This is relatively inefficient, since large increases in capacitance are required to get significant improvement.

SiiD'iiiCiiN

I,

ERROR

,
•
•

GROUND
GROUND

Noise can be reduced more effectively by a bypass capacitor placed across R1 (refer to Figure 4). The formula for
selecting the capacitor to be used is:

'-'

2

"

GROUND

1

13

OUTPUT

NC

12

GROUND

OUTPUT

,

11

GROUND

SENSE

GROUND

SHUTDOWN

REFERENCE

v TAP

SENSE

,
•

5

GROUND

LP2952
16-PlnSO

10

7

C _
1
B - 211" R1 X 20 Hz

INPur

ERROR
NC

FEEDBACK

GROUND

TL/H/11127-11

'-'

"
15

2

GROUND

INPUT

'''~fEEDBACK

•

13

V TAP

5

12

REFERENCE

•
•

10

I'I-Ne

7

NC

'I-GROUND

TLlH/11127-12

This gives a value of about 0.1 ,.,.F. When this is used, the
output capacitor must be 6.B ,.,.F (or greater) to maintain
stability. The 0.1 ,.,.F capacitor reduces the high frequency
gain of the circuit to unity, lowering the output noise from
260,.,.V to BO,.,.V using a 10 Hz to 100 kHz bandwidth. Also,
noise is no longer proportional to the output voltage, so improvements are more pronounced at high output voltages.

LP2953
16-Pln DIP
v TAPFEEDBACK

INPUT

'-'

I

"

,

15

2

GROUND- 4

AUXILIARY COMPARATOR (LP2953 only)

GROUND
OUTPUT

5

•
•

LP2953
16-PlnSO
REFERENCE

GROUND

1

NC

,

CONP INPUT

14

COMP OUT

"

GROUND

SENSE

12

GROUND

11

NC

SiiliT60iN
EiiiiOR

OUTPUT

The LP2953 contains an auxiliary comparator whose inverting input is connected to the 1,.23V reference. The auxiliary
comparator has an open-collector output whose electrical
characteristics are similar to the dropout detection comparator. The non-inverting input and output are brought ouUor
external connections.

Ordering Information

SHUTDOWN INPUT

LP2952

,

10

NC- 7
SENSE

ERROR

NC

SHUTDOWN

GROUND

'-'

To prevent possible mis-operation, the Shutdown input must
be actively terminated. If the input is driven from open-collector logic, a pull-up resistor (20 kO to 100 kO recommended) should be connected from the Shutdown input to the
regulator input.
If the Shutdown input is driven from a source that actively
pulls high and low (like an op-amp), the pull-up resistor is
not required, but may be used.
If the shutdown function is not to be used, the cost of the
pull-up resistor can be saved by simply tying the Shutdown
input directly to the regulator input.

ISr-INPUT

I. rFEEOBACK

•
•

"

•

•

5

V TAP
REFEREMCE

12

11 r-CONP INPUT
CONP OUT

10

7

TLlH111127-13

A logic-level signal will shut off the regulator output when a
"LOW" « 1.2V) is applied to the Shutdown input.

GROUND

"

2

GROUND

TL/H/11127-14

Order
Number

Temp.
Range
(TJ)'C

Package

NSC
Drawing
Number

LP29521N, LP2952AIN,
LP2952IN-3.3,
LP2952AIN·3.3

-40 to
+125

14-Pin
Molded DIP

N14A

LP29521M, LP2952AIM,
LP2952IM-3.3,
LP2952AIM-3.3

-40 to
+125

16-Pin
Surface
Mount

M16A

LP2953

IMPORTANT: Since the Absolute Maximum Ratings state
that the Shutdown input can not go more than 0.3V below
ground, the reverse-battery protection feature which protects the regulator input is sacrificed if the Shutdown input is
tied directly to 'the regulator input.
If reverse-battery protection is required in an application, the
pull-up resistor between the Shutdown input and the regulator input must be used

2-142

Order
Number

Temp.
Range
(TJ)OC

Package

NSC
Drawing
Number

LP29531N, LP2953AIN,
LP2953IN·3.3,
LP2953AIN-3.3

-40to
+125

16-Pin
Molded DIP

N16A

LP29531M, LP2953AIM,
LP2953IM-3.3,
LP2953AIM-3.3

-40 to
+125

16-Pin
Surface Mount

M16A

LP2953AMJ/BB3

-55 to
+150

16-Pin
Ceramic DIP

J16A

Typical Applications

BasIc 5V Regulator

5V Current LImIter wIth Load Fault IndIcator
svaus

+VIN
V TAP
Fa

VOUT
+VIN
V TAP

SV OUT

SENSE

LP2952/
LP2953

I }IF

Fa

• ·Rl

OUTPUT
• 4.3-SV

VOUT

SENSE
10k

LP2953
CaMP
INPUT

GND

CaMP
OUT

FAULT

S.lk
TLlH111127-15

TLlH/III27-16
'Output voltage equals + VIN mlnum dropout voltage. which varies with out·
put current. CUrrent IimHs at a maximum of 380 mA (typical).

"Select Rl so that the comparator Input voltage Is 1.23V at the output
voltage which corresponds to the desired fault current value.

Low T.C. Current SInk
v+ = 2.3 to 30V

5V Regulator wIth Error Flags for
LOW BATTERY and OUT OF REGULATION

., __ Lt~,
,

LOAD

1
===

'I - 1.23
R

6V

:
.__..: L-

374k

I

[
=~II'F

+VIN
V TAP V
OUT
Fa
SENSE

CaMP
INPUT

CaMP
OUT

INPUT

r-- 0N

lOOk

LP29S2/
LP2953

1M

• LOW BATT

GND

1
..L

Sii
GND

SV OUT
1M

ERR

VOUT

SiiUTiiii'ViN

r---

LP2953

I~

• OUT OF
REGULATION

12.2

I'F

Fa

TLlH/11127-16

orr --J

R

+ 10

jI'

'Connect to logic or ,..p control Inputs.
LOW BATT flag warns the user that the battery has discharged down 10
about 5.8V, giving the user time to recharge the battery or power down some
hardware with high power requirements. The output Is still In regulation at
thistime.
OUT OF REGULATION flag Indicates when the battery Is almost complataly
discharged, and can be used to initiale a power-down sequence.

TLlH/11127-17

2·143

fI

Typical Applications

(Continued)

5V Battery Powered Supply with Backup and Low Battery Flag
5V OUT
(MA IN)

RECHARGE
CIRCUITRY

cp

The circuit switches to the
NI·CAD backup battery
when the main batte ry volt·
age drops below about
5.6V, and returns to the
main battery when its volt·
age is recharged to about
6V.

lA SCHOTTKY

l'~F

PWR
ON

!-

383k
1%

So
1 ~F

.....==' - -

===

SNS
V TAP

CaMP
INPUT

FB

The 5V MAIN output pow·
ers circuitry which rsquires
no backup. and t he 5V
MEMORY output powers
critical circuitry whi ch can
not be allowed to losspow·
er.

lOOk

lOOk
1%

;b

2.2
~F

VP12A
51 k

~

3.65
MEG
1%

I:

CaMP
OUT

GND

~

1

'The BATTERY LOW flag
goes low whenever the cir·
cuit switches to the NI·CAD
backup battery.

150k

.J:.
-

!"---

5V
NICAD
BACKUP

• BATT LOW
FLAG

+

--"""
===

t

TL/H/11127-19

5V Regulator with Timed Power-On Reset

Timing Diagram for. Timed Power-On Reset

vIN

1 MEG

J

LP2953
510k

5V OUT
(ME MaRY)

VOUT

+V'N

IN
914

+
6V -_LEAD
ACID
INMAIN
914 .....

I

,......-

.... ,
..... ,

....... ,

V'NO~
[

RT

=~

1 ~F

+V'N
V TAP

VOUT
SENSE

FB

LP2953
CaMP
INPUT

== ~F
T

0.1

ERR

CaMP
OUT

GND

5V OUT

V

OUT

f-+

2.2

=~

o

.8V.'.
5V
~
I

,

lOOk

~F

.-

.' !
.

RESET

--128m.' ~ TIME DELAY

RESET
TO ~P

TL/H/11127-21

'RT

1

-L
TL/H/11127-20

2-144

=

1 MEG, CT

= 0.1

I'F

r-

Typical Applications

"tJ

to.)

(Continued)

CQ

CI1

to.)
......

r-

"tJ
to.)

CQ

V,N +--11----.....- - - - - - - - - - - - .
+VIN

1 !,F

t--+--4>--.....- ..

-=

CQ

10
M
1B7k

,

5V OUT
220
pF

SHUT
DOWN

FS

2k 1 !,F ;::

6V

CaMP
INPUT

Turns OFF at V,N

=

.....

Co)
......

r-

"tJ

1M

.j- 1M

to.)

CQ

CI1
CaMP
OUT

S7ii

'LOW SATT

~

ERR
'OUT OF
REGULATION

GND

1 I~

...l..

TL/H/11127-22

= 5.87V

5V OUT

VOUT
SENSE

LP2953

49.9k

'Turns ON al V,N

CI1

+VIN

V TAP

[

lOOk
1%

GND

rto.)

2~~
pF

t--.....- t - -.....---ir--

LP2952

to.)

):00

.......
"tJ

374k
1%

V TAP
VOUT
FS
SENSE

CI1

5V Regulator with Error Flags for
LOW BATTERY and OUT OF REGULATION
with SNAP·ON/SNAP·OFF Output

5V Regulator with Snap·On/Snap·Off
Feature and Hysteresis

112.2
TL/H/11127-23

5.64V

·Connect to Logic or J.tP control inputs.

(for component values shown)

OUTPUT has SNAP·ON/SNAp·OFF feature.
LOW BATT flag warns the user that the battery has discharged down to

about 5.8V, giving the user time to recharge the battery or shut down hardware with high power requirements. The output is still in regulation at this
time.
OUT OF REGULATION flag goes low if the output goes below abou14.7V,
which CQuid occur from a load fault.
OUTPUT has SNAp·ON/SNAP·OFF feature. Regulator snaps ON at about
5.7V input, and OFF at about 5.6V.

5V Regulator with Timed Power·On Reset, Snap·On/Snap·Off Feature and Hysteresis
Y,N

Jl

Timing Diagram

l20
pF 7.5M

374k
1%

;;;'"

+V'N
V TAP

",,,,,[

I'"

R
1M

!,F

FS

I-<

...:..- r-- S75
__ .. c
TO.l!'F

ERR

I
I

'

I
I

VOUTO~

--

RESET
TO !,p

-

lOOk
1%

IN

1M

LP2953
CaMP
INPUT CaMP
OUT

. _. S.64V
~

V S.87V. _ .

5V OUT

VOUT
SENSE

GND

1

..L

117

TL/H/11127-25

I 2.2
!,F

Td

TL/H/11127-24

2-145

=

(0.28) RC

=

28 ms for components shown.

EI

tt/National Semiconductor

LP29541LP2954A .....
.
..
5V Micropower Low-Dropout Voltage Regulators
General Description

Features

The LP2954 is a ~hree-terminal, 5V micropower voltage regulator with very low quiescent current (90 p.A typical at 1 mA
load)· and very low dropout voltage (typically 60 mV at light
loads and 470 mVat 250 mA load cLirrent).

•
•
•
•
•
•
•
•
•

The quiescent current increases only slightly at dropout
(120 p.A tYpical), which prolongs battery life.
'
The LP2954 is available in the three-lead TO-220 and
TO-263 packages.
Reverse battery protection is provided.
The tight line and load regulation (0.04% typical), as well as
very low output temperature coefficient make the LP2954
well suited for use as a low-power voltage reference.
The accuracy of the 5V output is guaranteed al both room
temperature and over· the entire operating temperature

5V output within 1.2% overternperature (A grade)
Guaranteed 250 mA output current .
Extremely low quiescent current
Low dropout voltage
Reverse battery protection
Extremely tight line and load regulation
Very low temperature coefficient
Current and thermal limiting
Pin compatible with LM2940 and LM340

Applications
• High-efficiency linear regulator
• Low dropout battery-powered regulator

rang~.

Package Outline and Ordering Information

il

TO-263 3-Lead Plastic Surface-Mount Package

To-220 3-Lead Plastic Package

OUTPUT

TAB IS

GND

GND

.

TLlH/III28-2

.

Front View

INPUT
TL/H/11128-9

Top View

Order Number LP2954AIT or LP29541T
See NS Package T03B

. TLlH/III28-10

Side View
Order Number LP2954AIS or LP29541S
see NS Package TS3B

Ordering Information
Order Number
LP2954AIT

Temp. Range
(TJ)OC

Package
(JEDEC)

NSPackage
Number

-40 to +125

TO-220

T03B

-40 to +125

TO-263

TS3B

LP29541T
LP2954AIS
LP29541S

2·146

I"'"
."
N
CD

Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.

Power Dissipation (Note 2)

Operating Junction Temperature Range
LP2954AI/LP29541
-40·Cto + 125·C
- 65·C to + 150·C
Storage Temperature Range

Electrical Characteristics

en

Lead Temperature
(Soldering, 5 seconds)

260·C

.co.
......

Internally Limited

."

-20Vto +30V
2kV

en

Input Supply Voltage
ESDRating

Limits in standard typeface are for TJ

=

I"'"
N

CD

~

25·C, bold typeface applies over the

-40·C to + 125·C temperature range. Limits are guaranteed by production testing or correlation techniques using
standard Statistical Quality Control (SQC) methods. Unless otherwise noted: VIN = 6V, IL = 1 mA, CL
Symbol

Parameter

Conditions

2954AI

Typical
Min

Vo

Output Voltage

5.0
1 mA :S: IL :S: 250 mA

!lVo
!IT

Output Voltage
Temp. Coefficient

(Note 3)

!lVo

Line Regulation

VIN = 6V to 30V

5.0

20
0.03

Vo
!lVo
Vo

Load Regulation

VIN-VO

Dropout Voltage
(Note 5)

IL = 1 to 250 mA
IL = 0.1 to 1 mA
(Note 4)
IL= 1 mA
IL

=

50mA

IL=100mA
IL = 250mA
IGND

Ground Pin Current
(Note 6)

IL= 1 mA
IL

=

50mA

IL = 100mA
IL = 250mA
IGND

ILiMIT

=

Ground Pin
Current at Dropout
(Note 6)

VIN

Current Limit

VOUT

0.04

60
240
310
470
!;IO
1.1
4.5
21

4.5V
120

=

OV

!lVo
!lPd

Thermal Regulation

(Note 7)

en

Output Noise
Voltage
(10 Hz to 100 kHz)
IL = 100mA

CL = 2.2 poF
CL

=

380
0.05

=

2.2 poF.

29541
Max

Min

Units
Max

4.975

5.025

4.950

5.050

4.940

5.060

4.900

5.100

4.930

5.070

4.880

5.120

100

150

0.10

0.20

0.20

0.40

0.16

0.20

0.20

0.30

100

100

150

150

300

300

420

420

400

400

520

520

600

600

800

800

150

150

180

180

2

2

2.5

2.5

6

6

8

8

28

28

33

33

170

170

210

210

500

500

530

530

0.2

0.2

V

ppml"C

0/0

0/0

mV

poA

mA

poA

mA

O/O/W

400
poVRMS

33 poF

260

2-147

fI

Electrical Characteristics (Continued)
Nole I: Absolute maximum ratings Indicate'limHs beyond which damage to the component may occur. Electrical specifications do not appiy when operating the
devlca outside of its rated operating conditions.
Nole 2: The maximum allowable power dissipalicn Is a function of the maximum Junction temperature, TJ (MAX), Ihe Juncl'ori-to-ambient thermal resistance, 8J.A,
and the ambient tamperatura, TA. The maximum allowable power dissipation at any ambient temperature is calculaled using: P(MAX)

= TJ (M~ -

TA •

J·A

Exceeding the maximum allowable power disslpetion will resu" In excessive die lemperature, and Ihe regulator will go Into thermal shutdown. The Junctlon-to-ambient thermal raslstanca of the T0-220 (wHhout heatsink) is 6I1'CIW and 73'C/W for the TO-263. If the T0-263 package Is used, the thermal resistance can be
reduced by Incraasing the P.C. board copper area thermally connected to the package: USing 0.5 square inches of copper area, 8JA is 5I1'C/W; wilh 1 square inch
of copper area, 8JA is 37'C/W; and wHh 1.6 or more square Inches of copper area, 8JA Is 3Z'CIW. The Junction-to·case thermal resistance is :fOC/W. If an external
heatsink is used, the effective Junction-to-amblent thermal resistance Is the sum of the Junction-to-case resistance (:fOC/W), the specified thermal resistance of the
heatsink selected, and the thermal raslstance of the Interface between the heatsink and the LP2954. Some typical values are listed for Interface materials used
wlih TO-220:
Typical Values 01 Ceae-Io-Heatalnk Thennal Resistance rC/W)
TABLE 1_ (Data Irom AAVID Eng_)

TABLE 11_ (Data from Thermalloy)

Silicone grease

1.0

Thermasilill

Dry Interface

1.3

Thermasilll

1.3
1.5

Mica wHh grease

1.4

Thermalfilm (0.002) with grease

2.2

Note 3: Output voltage lemperature coefficient Is defined as Ihe worsl casa voltage change divided by the total temperature range:
Note 4: Regulation is measured at constant Junction temperature using low duty cycle pulse testing. Parts are tested, separately for load regulation in the load
ranges 0.1 mA-l mA and 1 mA-250 mAo Changes in oulput voHage due to heating affects are covered by the thermal regulation specification.
Note 5: Dropout voHage Is defined as the Input to output differential at which the output voltage drops 100 mV below the value measured with a 1V differential.,
Note 6: Ground pin currani Is the regulator quiescent currant The total current drawn from the source Is the sum of the load current plus the ground pin current,
Note 7: Thermal regulation is defined as the change In output voltage at a time T after a change in power dissipation is applied, excluding load or line regulation
effects. Specifications ara for 200 mA load pulse at Y,N = 20V (3W pulse) for T = 10 ms.
Note 8: When used In dual-supply systems where the regulator load Is returned to a negative supply, the output voltage must be diode-clamped to ground.

2-148

r-

"U

Typical Performance Characteristics

N

CD

U'I

.Quiescent Current

Quiescent Current

140

1: 120

i

m
~

.3

i

~ .IOOp"

u

60

~O

z
;;:

I

~

a

a

3

4

90

.....
~

80
70
-75 -50-25

5

.s

16
14

§

12

is
u

':(

.s

~.250mA

--

20

i

15

z
;;:
a
z

10

u

10

~

z

~

z

~;J
a:

~

"'

L

~

z

40

"'

/

"

~"'0mA

I\.=2.2pF

20
0.01

/I
I
V

30 r-VINa~V

'"~
ii!
~

~=Im'/\

0.1

1

10

100

a

0.1

10

100 Ripple
90

l'... ./"'\
......... ....-"'\
60

= 100mA

l- 250mA

,\

50

~

30

~

20 f-VIN·~V

'\.. V

I\. =2,~pF

0.1

1

.....:!!.

80

S
;:::

70

f::l

\\

40

10

100

J
1000

ii!
~

"'

!1. '3~!!~=/!!"~

l =10mA

, VV '"
~

60
50

\V.

40

-0

Id

~IOOP'

"OJ

30 I-VIN=~Y

I\.=2.~pF

20
0.01

0.1

1

10

100

1000

100

1000

FREQUENCY (kHz)

Line Transient Response

C1. =2.2.I'F

1000

Rejection

J\

FREQUENCY (kHz)

Une Transient Response

100

LOAD CURRENT (mA)

80

FREQUENCY (kHd

1\

~

o

25 50 75 100125150

70

10
0.01

1000

"'"

100

i IOOlmA

Ripple Rejection

\
\\

50

~:.

~

200

90

.:!!.

1\

60

300

~

JUNCTION TEMPERATURE (OC)

....

~

70

.3
'~

~

-75 -50 -25

Ripple Rejection

80

400

~

a

90

...
~

INPUT VOLTAGE (V)

100

1000

v

500

~

~

4

100

Output Noise Voltage

~

I- .....

10

OUTPUT CURRENT(mA)

§

"

3

0.01 L.l..Lll1WLLJ.
0.1

Ground Pin Current

'1.1
I -,-

a
a

0.1

25 50 75 100 125150

25

a

....
.:!!.

a

r- .....

ill"

TEMPERATURE (oC)

Ground Pin Current
20
18

~

........

INPUT VOLTAGE (V)

':(

"U

10

I'...

~

I

20

tOO

Output Impedance
100

10

IV

v

-40

.....

... ~

BY

~Ei
>

6Y

~

...

0.1

0.01
0.2

U

0.6

TIME (ml)

0.8

2

TIME(m.)

0.01

0.1

10
FREQUENCY (kHz)

TLfHI11128-3

2-149

.....
"'r-"
N
CD
U'I

':(

80

~

,,~

-:r

100

~

Ground Pin Current vs Load
100

110

Typical Performance Characteristics
Load Transient Response
Lo.I

=
~~
5=
si!l
S

o

400

Load Transient Response

VrN-ev

800

200

~s

i-1H-f-f""C,-l--+-++-i

o~

>w
......

k-3

~~

-400 hHH-+-+-++++-l

Dropout Characteristics

VINII&Y

100

!:iE

~

l =100pA
-100

0

l"

-200

-800I-HH-+-+-+-+++-l

~

(Continued)

OmA

250mA'F-i-+-I-HH-+-+-+-I

100,..

t:tjjl:tjj::tt:1j
10

20

30

o-

40

10

20

30

40

50

Thermal Response
550

o~

55
0

3

4

800

!;is: 15
!:i E 10

~!

2

INPUT VOLTAGE(V)

Short-CIrcuit Output
Current and Maximum
Output Current

w

>w

o
o

80

TIME (m.)

TIME (m.)

"-

-'5
-5

v

i'

]: 500

I'

./

!Z

.......

450

Jo~lcu.lr

,

Iia 400

~ 350

§

300

--

~.c RCU

cu;mn

~

250

10

20

30

""

200
-75-50-25 0 25 50 75 100125150

40

TIME (m.)

JUNCTION TEMPERATURE (Oe)
TUH/11128-4

Maximum Power Dissipation
(TO-263) (See Note 2)

:§
z:

0

...
'"2i
;:::

4

~

.... ......
.... b.

8,JA-37OC/t...... "

D.

iii

..,'"

a JA = 32°C/~

"l
3 "l.:1-......
2

0

D.

o
o

r--; ~

~~ ...... ~
~

~ ~73r;W~ ~ ~
'fJA '1 'I

10 20 30 40 50 60 70 80 90 100

AMBIENT TEMPERATURE (DC)

2-150

TL/H/11128-11

r------------------------------------------------------------------------------,~

i§
:e:

Application Hints

UI

EXTERNAL CAPACITORS
A 2.2 "F (or greater) capacitor is required between the
output pin and the ground to assure stability (refer to Figure
1). Without this capacitor, the part may oscillate. Most types
of tantalum or aluminum electrolytics will work here. Film
types will work, but are more expensive. Many aluminum
electrolytics contain electrolytes which freeze at -30'C,
which requires the use of solid tantalums below - 25'C. The
important parameters of the capaCitor are an ESR of about
50 or less and a resonant frequency above 500 kHz (the
ESR may increase by a factor of 20 or 30 as the temperature is reduced from 25'C to -30'C). The value of this capacitor may be increased without limit. At lower values of
output current, less output capaCitance is required for stability. The capacitor can be reduced to 0.68 "F for currents
below 10 mA or 0.22 "F for currents below 1 mAo

~

~

~

:=
TUH/11128-5
·See External Capacitors
!'rota! = (YIN -5) IL + (YIN) IG

FIGURE 1. Basic 5V Regulator Circuit
the circuit. The formula for calculating the power dissipated
in the regulator is also shown in Figure 1.

A 1 "F capaCitor should be placed from the input pin to
ground if there is more than 10 inches of wire between the
input and the AC filter capacitor or if a battery input is used.

The next parameter which must be calculated is the maximum allowable temperature rise, T R(max). This is calculated by using the formula:

MINIMUM LOAD

TR(max) = TJ(max) - TA(max)

It should be noted that a minimum load current is specified
in several of the electrical characteristic test conditions, so
this value must be used to obtain correlation on these tested limits. The part is parametrically tested down to 100 "A,
but is functional with no load.

where: TJ(max) is the maximum allowable junction
temperature
TA(max) is the maximum ambient temperature
Using the calculated values for T R(max) and P(max), the
required value for junction-to-ambient thermal resistance,
B(J.A), can now be found:

DROPOUT VOLTAGE
The dropout voltage of the regulator is defined as the minimum input-ta-output voltage differential required for the output voltage to stay within 100 mV of the output voltage measured with a 1V differential. The dropout voltages for various
values of load current are listed under Electrical Characteristics.
If the regulator is powered from a rectified AC source with a
capacitive filter, the minimum AC line voltage and maximum
load current must be used to calculate the minimum voltage
at the input of the regulator. The minimum input voltage,
Including AC ripple on the filter capacitor, must not drop
below the voltage required to keep the LP2954 in regulation.
It is also advisable to verify operating at minimum operating
ambient temperature, Since the increasing ESR of the filter
capacitor makes this a worst-case test for dropout voltage
due to increased ripple amplitude.

B(J-A) = T R(max)/P(ml!X)
If the calculated value is 60' C/W or higher, the regulator
may be operated without an extemal heatsink. If the calculated value is below 60' C/W, an external heatsink is,required. The required thermal resistance for this heatsink can
be calculated using the formula:
B(H.A) = B(J.A) - B(J.C) - B(G-H)
where:
B(J-C) is the junction-to-case thermal resistance, which is
specified as 3' C/W maximum for the LP2954.
B(G-H) is the case-to-heatsink thermal resistance, which is
dependent on the interfacing material (if used). For details
and typical values, refer to Note 2 listed at the end of the
ELECTRICAL CHARACTERISTICS section.
B(H.A) is the heatsink-to-ambient thermal resistance. It is
this specification (listed on the heatsink manufacturers data
sheet) which defines the effectiveness of the heatsink. The
heatsink selected must have a thermal resistance which is
equal to or lower than the value of B(H.A) calculated from
the above listed formula.

HEATSINK
REQUIREMENTS
','
A heatsink may be required with the LP2954 depending on
the maximum power diSSipation and maximum ambient temperature of the application. Under all possible operating
conditions, the junction temperature must be within the
range specified under Absolute Maximum Ratings.
To determine if a heatsink'is required, the m'aximum power
dissipated by the regulator, P(max), must be calculated. It is
important to remember that if the regulator is powered from
a transformer connected to the AC line, the maximum
apeclfled AC Input voltage must' be used (since this produces the maximum DC input voltage to the regulator). Figure 1 shows the voltages and currents which are present in

OUTPUT ISOLATION'
The regulator output can be left connected to an active voltage source (such as a battery) with the regulator input power turned off, aa long aa the regulator ground pin la connected to ground. If the ground pin is left floating, damage
to the regulator can occur if the output is pulled up by an
external voltage source. ,

2-161

fI

Typical Applications
Typical Application Circuit

TL/H/11128-1

5V Regulator
VIN

5V Current Limiter

+-....-fi;---;;;;'1~...-~+VOUT

5V BUS

'

, }IF

Your 1-"'---+-+

LP2954

OUTPUT
·4.3V - 5V

TL/H/1 1128-6

GND

, }IF

TLlH/11128-7

'Output voltage equals + VIN minus dropout voltage, which varies with out·
put current. Current limits at 380 mA (typical).
'

Schematic Diagram'
IN

TL/H/1 1128-8

2-152

r-------------------------------------------------------------------------, r"U
N

co

t;tINational Semiconductor

U1

en
......
r
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co

.LP2956/LP2956A

U1

~

Dual Micropower Low-Dropout Voltage Regulators
General Description

Features

The LP2956 is a micropower voltage regulator with very low
quiescent current (170 /LA typical at light loads) and verY
low dropout voltage (typically 60 mV at 1 rnA load current
and 470 mV at 250 rnA load current on the main output).
The LP2956 retains all the desirable characteristics of the
LP2951, but offers increased output current (main output),
an auxiliary LOa adjustable regulated output (75 rnA), and
additional features.
The auxiliary output is always on (regardless of main output
status), so it can be used to power memory circuits.
Quiescent current increases only slightly at dropout, which
prolongs battery life.
The error flag goes low if the main output voltage drops out
of regulation ..

•
•
•
•
•
•
•
•
•
•
•

An open-collector auxiliary comparator is included, whose
inverting inpllt is tied to the 1.23V reference.

Output voltage adjusts from 1.23V to 29V
Guaranteed 250 rnA current (main output)
Auxiliary LOa (75 mAl adjustable output
Auxiliary comparator with open-collector output
Shutdown pin for main output
Extremely low quiescent current
Low dropout voltage
Extremely tight line and load regulation
Very low temperature coefficient
Current and thermal limiting
Reverse battery protection

Applications
• High-efficiency linear regulator
• Low dropout battery-powered regulator
• /LP system regulator with switchable high-current Vee

Reverse battery protection is provided.
The parts are available in plastic DIP and surface mount
packages.

Block Diagram

Connection Diagrams
16-Pin DIP
LP2956

5V TAP

16

COMP IN

FEEDBACK

15

AUX FB

INPUT

3

1~

AUX OUT

GROUND

4

13

GROUND

GROUND

12

GROUND

OUTPUT

11

COMP OUT

NC

10

ERROR

SENSE

SHUTDOWN
TLlH/11339-2

Order Number LP29561N or LP2956AIN
See NS Package Number N16A
16-Pin Surface Mount

TL/H/11339-1

GROUND

16

GROUND

OUTPUT

15

INPUT

SENSE

1~

FEEDBACK

SHUTDOWN

13

SV TAP

ERROR

12

COMP IN

COMP OUT

11

AUX FB

NC

10

GROUND

AUX OUT
GROUND
TLlH/11339-3

Order NumlJer LP29561M or LP2956AIM
See NS Package Number M16A

2-153

Absolute Maximum Ratings (Note 1)
Input Supply Voltage

If Military/Aerospace specified devices are required;
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
- 6S·C to + 1S0·C
Storage Temperature Range
Operating Junction
Temperature Range
Lead Temperature
(Soldering,S seconds)
Power Dissipation (Note 2)

-20Vt9 +30V
-0.3Vto +SV

Feedback Input Voltage (Note 3)
Aux. Feedback Input Voltage (Note 3)
Shutdown Input Voltage (Note 3)
Comparator Input Voltage (Notes 3, 4)

- 40·C to +. 12S·C

'Comparator Output Voltage (Notes 3, 4)
ESD Rating (Note 16)

2600C

-0.3Vto +SV
-0.3Vto +30V
-0.3Vto +.30V
-0.3Vto +30V
2kV

Internally Limited

Electrical Characteristics
Limits in standard typeface are for Tj' = ,2S·C; and limits in boldface type apply over the full operating temperature range.
Limits are guaranteed by production testing or correlation techniques using standard Statistical Quality Control (SQC) methods.
Unless otherwise specified: VIN = 6V, CI.: = 2.2 p.F (Main Output) and 10 p.F (AuxiliarY'Output), Feedback pin is tied to SV, Tap
pin, CIN = 1 p.F, Vso = OV, Main Output pin is tied to Output Sense pin, Auxiliary Output is programmed for SV. The main
regulator output has a 1 mA load, the auxiliary regulator output has a 100 p.A load.
Symbol

Parameter

Typical

Conditions

LP2956AI
Min

LP29S61

Max

Min

Units

Max

MAIN OUTPUT
Vo

Output Voltage

,['

,1 mA

S;

II.:

S;

5.0

250 mA

aVo
aT

Temperature Coefficient

(NoteS)

avo

Line Regulation

VIN = 6V to 30V

5.0

20
0.03

Vo
avo

Load Regulation

Vo
VIN-VO

Dropout Voltage
(Note 7)

II.: = 1 mA'to 250 mA
II.: = 0.1 mA to 1 mA (Note 6)
II.: = 1 mA

60

II.: = SOmA

240

II.: = 100mA

310

II.: = 2S0mA
ILiMIT

Current Limit

0.04

470

RI.: = 10.

380

avo
aPo

The~mal ReglJlation

(Note 8)

en

Output Noise,Voltage
(10 Hz to 100 KHz)
11.:=100mA

CI.: = 2.2p.F

400

CI.: = 33 p.F

260

CI.: ,;, 33 p.F (Note 9)

80

0.05

4.975

5.025

4.950

5.050

4.940

5.080

4.900

5.100

4.930

5.070

4.880

5.120

.,

100

150

0.1

0.2

0.2

0.4

0.16

0.20

0.20

0.30

100

100

150

150

300

300

420

420

400

400

520

520

600

600

800

800

500

500

530

530

0.2

0.2

2·154

ppm/·C
%
%

mV

mA

%/W

p.VRMS

"

.'

V

r-

"til

Electrical Characteristics

p,)

Limits in standard typeface are for TJ = 25'C, and limits in boldface type apply over the full operating temperature range.
Limits are guaranteed by production testing or correlation techniques using standard Statistical Quality Control (SQC) methods.
Unless otherwise specified: VIN = 6V, CL = 2.2 ,.,.F (Main Output) and 10 ,.,.F (Auxiliary Output), Feedback pin is tied to 5V Tap
pin, CIN = 1 ,.,.F, Vso = OV, Main Output pin is tied to Output Sense pin, Auxiliary Output is programmed for 5V. The main
regulator output has a 1 mA load, the auxiliary regulator output has a 100 ,.,.A load. (Continued)
Symbol

Parameter

Typical

Conditions

LP2956AI

LP29561

Units

Min

Max

Min

Max

1.215

1.245

1.205

1.255

MAIN OUTPUT (Continued)
VFB

Feedback Pin Voltage

IFB

Feedback Pin Bias Current

10
(OFF)

Output Leakage
In Shutdown

1.23
20
I(SO IN) :;, 1 ,.,.A
VIN = 30V, VOUT

=

OV

3

40

40

60

60

10

10

20

20

V
nA
,.,.A

AUXILIARY OUTPUT
VFB

Feedback Pin Voltage

1.23

AVFB
AT

Feedback Voltage
Temperature Coefficient

20

IFB

Feedback Pin Bias Current

10

AVO

Line Regulation

6V

s: VIN s: 30V

Load Regulation

Va
VIN-VO

Dropout Voltage

IL
IL
IL
IL
IL

en

ILiM
AVO

=
=
=
=
=

0.1 mA to 1 mA
1 mA to 75 mA (Note 10)
1 mA

=
=

Current Limit

VOUT

Thermal Regulation

CL

500

10,.,.F

300
100

OV (Note 13)

(Note 8)

20

20

30

30

0.3

0.4

0.5

0.8

0.3

0.4

0.8

1.0

200

200

300

300

600

600

700

700

700

700

850

850

nA
%
%

mV
mV
mV

,.,.VRMS

80
0.2

APo

V
ppml'C

0.1

33 ,.,.F (Note 9)

=

1.26

1.27

400

75mA

CL

1.21

1.20

100

50mA

Output Noise
(10 HZ-1 00 KHz)
IL = 10mA

1.25
~.26

0.07

Va
AVo

1.22

1.21

200

200

250

250

0.5

0.5

mA

%/W

DROPOUT DETECTION COMPARATOR
10H
VOL
VTHR
(max)

Output "HIGH" Leakage
Output "LOW" Voltage
Upper Threshold Voltage

VOH

=

30V

VIN = 4V
10 (COMP)

=

0.01
150

400 ,.,.A

(Note 11)

-240

2-155

1

1

2

2

250

250

400

400

-320

-150

-320

-150

-380

-100

-380

-100

,.,.A
mV
mV

CD

en
en
.....

r-

"til
p,)

CD

;

Electrical Characteristics

'

":,

"~.

Limits in standard typeface are for TJ 7' 25°C, and limits in boldface type apply over the'full operating temperature range.
Limits are guaranteed by production testing or correlation techniques using ,standard Statistical Quality,Control(SQC) methods.
Unless otherwise specified: VIN =. 6V, GL =.2.2 ,...F (Main Output) and 10 ,...F (Auxiliary Output), Feedback pin is tied to 5V Tap
pin"CIN = ..1 ,...F, Vso = OV, Main Output pin is tied to Output Sense pin, Auxiliary, Output is programmed for 5V. The main
regulator output has a 1 mA load, the auxiliary regulator output has a 100 ,...A load. (Continued)
Symbol

Parameter

Conditions

Typical

LP29561

LP2956AI

Units

Min

Max

Min

Max

-450
-840

-230
-180

-450,
":'840

-230
-180

DROPOUT DETECTION COMPARATOR (Continued)
VTHR
(min)

Lower Threshold Voltage

(Note 11)

HYST

Hysteresis

(Note 11)

110

0.03

-350

mV
mV

SHUTDOWN INPUT
liN

Input Current to Disable Output

(Note 12)

VIH

Shutdown Input High Threshold

1(50 IN) ~ 1 ,...A

Shutdown Input Low Threshold,

VIL

Va

~

0.5
,900
1200 .

4.5V

900
1200
400
200,

AUXILIARY COMFtARATOR
Upper Trip Point

(Note 14)

VT(iow)

L?wer Trip Point

(Note 14)

HYST

Hysteresis

VOL

.

Output "LOW" V~ltage
','

, Input Bias Current

Ie

,.

mV

400
,200

mV

1.236

1.20
1.19

1.211'
1.29

1.20
1.19

1.28
1.29

V

1.230

1.19
1.18

1.27
1.28

1.19
1.18

1.27
1.28

V

6

'Output "HIGH" L~akllge
,

,...A

"

VT(high)

IOH'

0.5

VOH = 30V
VIN (COMP)

= 1.3V
VIN (COMP) = 1.1V
lo(COMP) = 400,...A
o ~ VIN (COMP) ~ 5V

mV

0.01

1
2

1
2

!LA

150

250
400

250
400

mV

30
50

nA

!LA

10

-30
-50

30
50

-30
-50

GROUND PIN CURRENT
IGNO

,,
,

Ground Pin Current
(Note 15)

IL (Main Out) = 1 mA
iL(Aux. Out) = 0.1 mA "
IL (Main Out) = 50 rnA
IL (Aux. Out) = 1 mA

170

250
280

250
280

, 1.1

2
2.5

2
2.5

6
8

6
8

28
33

28,
33

iL(Main Out) = 100 mA
IL (Aux. Out) = 1 mA

3

IL (Main Out) = 250 mA
IL (Aux. Out) = 1 mA

16

IL (Main Out) = 1 mA
IL (Aux. Out) = 50 mA

3

IL (Main Out) = 1 mA
iL(Aux: Out) = 75 mA

6

2-156

:

6

6

B

B'

8
10

8
10

mA

r-

"'D

Electrical Characteristics
Limits in standard typeface are for TJ = 25'C, and limits in boldface type apply over the full operating temperature range.
Limits are guaranteed by production testing or correlation techniques using standard Statistical Quality Control (SQC) methods.
Unless otherwise specified: VIN = 6V, CL = 2.2!LF (Main Output) and 10 !LF (Auxiliary Output), Feedback pin is tied to 5V Tap
pin, CIN = 1 !LF, VSD = OV, Main Output pin is tied to Output Sense pin, Auxiliary Output is programmed for 5V. The main
regulator output has a 1 mA load, the auxiliary regulator output has a 100 !LA load. (Continued)
Symbol

Parameter

Conditions

Typical

LP2956AI
Min

Max

Units

Max

GROUND PIN CURRENT (Continued)
IGND

IGND

Ground Pin Current
at Dropout (Note 15)

VIN = 4.5V
IL (Main Out) = 0.1 mA
IL (Aux. Out) = 0.1 mA

Ground Pin Current
at Shutdown (Note 15)

No Load on Either Output
I(SD IN) ~ 1 !LA

270

325

325

350

350

180

180

200

200

!LA
120

Note 1: Absolute maximum ratings indicale limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the
device outside of its rated operating conditions.
Note 2: The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(max),the junction-to·ambient thermal resistance, 0J.A,
and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using: P(max)

=

TJ(m;x) - TA.
J·A

Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. See Application Hints
for additional information on heat sinking and thermal resistance.
Note 3: When used in dual-supply systems where the regulator load is retumed to a negative supply, the output voltage must be diode-clamped to ground.
Note 4: May exceed the Input supply voltage.
Note 5: Output or referenca voltage temperature coefficient is defined as the worst case voltage change divided by the total

temperatur~

range.

Note 6: Load regulation is measured at constant junction temperature using low duty cycle pulse testing. Two separate tests are performed, one for the range of
100 p.A to 1 mA and one for the 1 rnA to 250 rnA range. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
Note 7: Dropout voltage is defined as the input to output differential at which the output voltage drops 100 mV balow the value measured with a 1V differential. At
very low values of programmed output voltage, the Input voltage minimum of 2V (2.3V over temperature) must be observed.
Note 8: Thermal regulation is the change in output voltage at a time T after a change in power dissipation, excluding load or line regulation effects. Specifications
are for a 200 mA load pulse at VIN = 20V (3W pulse) for T = 10 ms on the Main regulator output. For the Auxiliary regulator output, specifications are for a 66 mA
load pulse at VIN = 20V (IW pulse) for T = 10 ms.
Note 9: Connect a 0.1 p.F capaCitor from the output to the feedback pin.
Note 10: Load regulation is measured at constant junction temperature using low duty cycle pulse testing. Two seperate tests are performed, one for the range of
100 p.A to 1 mA and one for th~ 1 mA to 75 mA range. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
Note 11: Dropout dectection comparator thresholds are expressed as changes in a 5V output. To express the threshold voltages in terms of a differential at the
Feedback terminal, divide by the error amplifier gain = VourIVAEF.
Note 12: The shutdown input equivalent circuit is the base of a grounded-emitter NPN transistor in series with a current-limHing resistor. Pulling the shutdown input
high turns off the maln regulator. For more details, see Application Hints.
Note 13: The auxiliary regulator output has foldback limiting, which means the output current reduces with output voltage. The tested limit is for Vour
output current will be higher at higher output voltages.
'

= OV, so the

Note 14: This test is performed with the auxiliary comparator output sinking 400 p.A of current. At the upper trip pOint, the comparator output must be ;" 2.4V. At the
low trip pOint, the comparator output must be ,;: 0.4V.
Note 15: Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the ground pin current, output load current,
and current through the external resistive dividers (if used).

Note 16: All pins are rated for 2 kV, except for the auxiliary feedback pin which is rated for 1.2 kV (human body model, 100 pF discharged through 1.5 kO).

2-157

en
~

r-

"'D

N
CD

en

~

LP29561
Min

N
CD

Typical Performance Characteristics Unless otherwise specified: VIN = 6V, CL = 2.2 p.F (Main
Output) and 10 p.F (Auxiliary Output), Feedback is tied to 5V Tap pin, CIN = 1 p.F, VSD = OV, Main Output pin is tied to Output
Sense pin, Auxiliary Output'is programmed for 5V. The main regulator output has almA load, the auxiliary output has a 100 p.A
load.
Ground Pin Current
300

-:c

.3

200

i3

150

z

r-

250

§

\

iL
Q

!!i

~

Ground Pin Current
25

-:c

oS

"-

I

15

iL

10

z

..
!!i

Ii!

50

J
2

4

J

o
o

6

Ground Pin Current

::i
i3
z

iL

.~
~

170
165

-:c

,

oS

i
I'\.

160
155
150
-50 -25 0

o
o

i3
~

18
16
14
12
10

I I
La",

=',!
m

-

lmaln

Z

.

Ii

2345678

.....

,IT -I
\ 'Lao,

\laux = SOmA

I1 J

"-main = 100 rnA

\,,--~x

\.maln '= SO rnA

o

-50 -25 0

25 50 75 100 125 150

-50 -25 0

TEMPERATURE (OC)

TEMPERATURE (oc)

Ground Pin Current
vsMaln Load

= 75 mA

I1 J

I

o

25 50 75 100 125 150

I
~UX=
25mA

I I I
I I I

Q

""

I

~UX=
50mA

~

I I
= 250 mA

J

....

.....

_L.J....o1"J

~

~UX=

7T

Ground Pin Current

I I I.J

1.,..01'\ I

k"" -...L

INPUT VOLTAGE (V)

Ground Pin Current
20

r\

IJ

50 mA ~

'11:1

INPUT VOLTAGE (V)

180

"

la.mall'l

2345678

INPUT VOLTAGE (V)

175

I
If /

~mL J10~mA

Q

o

.3
~

II

/

I ~~:'n ,! 250'::;:

u

100

o

'-:c

I .I

,.

20

Ground Pin Current

= 25mA

25 50 75 100 125 150

TEMPERATURE (Oc)

Dropout Voltage vs
Temperature (Main Regulator)

Dropout Characteristics
(Main Regulator)
6r--r-'--~~--r-~

0.6
0.5
~

1--+-++-+-'c-l'7"F--l--:-!

0.41-++:"'+~

~ O~ 1-"'1--+.,.,."9

I
10

100

2

lk

Current Limit vs Regulator
(Main Regulator)

r-l-::;;j."""f::::"-I--+-+-+--l

0.1

1j:j::::I==It=n~1
o

4

INPUT VOLTAGE (V)

MAIN OUTPUT CURRENT (rnA)

0.2

25 50 75 100 125 150

TEMPERATURE (Oe)

Enable Transient
(Main Regulator)

Enable Transient
(Main Regulator)

Ca. r= 2.2 p.F

~
G. =2.2pF

600

-:c
oS
~
~

500

........

400

r--. <:

VOUT = 5V

~

300

>"
~~
~i

r-..

6

4

VOUT = OV

~ - lOrnA
V,N = 14V

~

~

!;
o

G. =33p.F

G,.=33pr-f--+-

200

tt-

~

= lOrnA

VUt = 6V

-

100

o
-50 -25 0

25 50 75 100 125 150

TEMPERATURE (oc)

TIME (m.)

TIME (ml)

TUH/11339-4

2-158

Typical Performance Characteristics

Unless otherwise specified: VIN = 6V, CL = 2.2 p.F (Main
Output) and 10 p.F (Auxiliary Output), Feedback is tied to 5V Tap pin, CIN = 1 p.F, VSD = OV, Main Output pin is tied to Output
Sense pin, Auxiliary Output is programmed for 5V. The main regulator output has a 1 rnA load, the auxiliary output has a 100 p.A
load. (Continued)
Load Transient Response
(Main Regulator)

Load Transient Response
(Main Regulator)
800

20 0

No...

0

~OO

~

- G.

G..maln = 33 pF'

"'
,-of-- ,.... G.

~

... co

20

30

50

~o

~~

60

S

TIME (m.)

TlWE (m.)

Ripple Rejection
(Main Regulator)
100

90

;

sO

3

70

~

0

ii!
it

.
~

~

60
50

ii!

40

.

.~

30
20

0.6

O.S

100

~

ii!
~

..

~'>

Ik

60

10

~~

5

...

~O

'"

""

-5

E

4

0

50

15

~..§.
>~

10k

lOOk

20

~

100

Ik

10k

lOOk

10

100

Ik

10k

lOOk

1M

fREQUENCY (Hz)

Output Impedance
(Main Regulator)

.....

:s

10

~

~

l!

:;

!;
0

10

IN

20

30

~O

100

Ik

Output Noise Voltage
(Main Regulator)

10k

lOOk

IN

fREQUENCY (Hz)

TIME (mo)

Feedback Bias Current

Divider Resistance
~OO

20

600
G..maln = 2.2 pF

....

500

>

~OO

~>'"

10

il:

~

-

"

fREQUENCY (Hz)

~

20

i:iis

10

~

lme.ln = 250 mA.

~O

30

1M

"'el~
...
~;;!;

30

0

!i!

50

100..,...._......,.,.,......,..
~

10

.3

60

Thermal Regulation
(Main Regulator)

90
sO

I

'-main = 100 mA

70

fREQUENCY (Hz)

100

70

1111111

o

O.~

Ripple Rejection
(Main Regulator)

3

1111111

sO

10

TIME (mo)

;

IIIIIIIIIIIIII~

90

;
3

10
0.2

6Y

20

100

= 10 mA

'Lmaln

\

>

16

Ripple Rejection
(Main Regulator)

11 11
1\

12

TIME (m.)

Line Transient Response
(Main Regulator)
0

sV

,~~

IDOl' A
10

6V

,

250mA

1001'A

sV

= 10 mA

-800

-20 0

~

.... 1-

-~OO

250mA

1!i~

'Lmaln

.,..."

= 2.21'f

= 33}'f

0

!;~

Line Transient Response
(Main Regulator)

300
.;'

"0
oz
"''''
E::a:

300

./

200

10

100

LOAD CURRENT (mA)

Ik

~o

ill'"

-20

100

~~
zz
i!~

-30
-50 -25 0

200

2-159

~

... f-

100

o
25 50 75 100 125 150

TEMPERATURE (OC)

;'

-50 -25 0

25 50 75 100 125 150

TEWPERATURE (OC)
TL/H/11339-5

r
-a

N
CD

en
Q)

......
r
-a
N
CD

en

;

Typical Performance Characteristics. Unless otherwise specified: VIN = 6V, CL = 2.2 ,..F (Main
Output) and 10 ,..F (Auxiliary Output), Feedback is tied to 5V Tap pin, CIN = 1 ,..F, VSD = OV, Main Output pin is tied to Output
Sense pin, Auxiliary Output is programmed for 5V. The main regulator output has a 1 rnA load, the auxiliary output has a 100 ,..A
load. (Continued)
Dropout Characteristics
(Auxiliary Regulator)

-

~.5

1....

= 100(A

~ 3.5

~

3

,I

!

~

75mA

I

0.5

~
!!!

0.3

!i!

/

0.5

'"~

I

O.~

':t'

l.--'

..s

100

is

80

::2

'Laux - 50 mA

It~'"' = 25mA

0.2

IL.UX~mA

o

o

120

r-:-r _ .

...... f-""

- ,-

I~O

= 75 mA

~~

...... f'

0.1

o

Current Limit vs Temperature
(Auxiliary Regulator)

V 10'

~ 0.6

/

1.5

'Laux

0.7

=

,ILaux

/

0.8

&/1

!:i 2.5
!i!

Dropout vs Temperature
(Auxiliary Regulator)

il

60

!

~O

r-

VOUT

25 50 75 100 125 150

-50 -25 0

Load Transient Response
(Auxiliary Regulator)

Load Transient Response
(Auxiliary Regulator)
C\.

r--.

1\

~

~~>

~

.... 75mA

8V

~~
.... 6

6V
0.2

OA

0.6

~

I-

0.8

10

20

z

~

iil

30

40

50

10

20

30

40

50

TIME (m.)

Output Impedance
(Auxiliary Regulator)

100
90
80
70
60
50

.....

:

TIMt (m.)

Ripple Rejection
(Auxiliary Regulator)

'ii1

'7SmA

= 331'F

.~~
. . BO.lmA

0.1 mA

TIME (m.)

3

25 50 75 100 125 150

TEMPERATURE (DC)

TEMPtRATURt (DC)

",

= OV

20

Lu~ =IIO~A

...

VO~I =15V

o

-50 -25 0

INPUT VOLTAOt (v)

Line Transient Response
(Auxiliary Regulator)

I- ....t.

Output Noise Voltage
(Auxiliary Regulator)

100

300
~

250 I-f-HHttbof';-I

3

200f-rrHtt~~~~~~~

~

~1-"t'i'"l'1oLI1il

150 FH-HttHl-+l-++I!HI-+++

~O

.~

100 I-H-HttHl-+l-++I!HI-+++

30
20
10
0

O~WU~L-~UW~~~

10

100

Ik

10k

lOOk

1M

100

FREQUtNCY (Hz)

2.5

7

':t'

.5

~

1.5

V'

JI

§
u

1i'"i

0.5

J,'I

~

~

-

~~O~C

o ~~

o 0.1 0.2 0.3 U

lOOk

0.1

1M

50k RESISTOR TO I
O(Z;R~AL 15V SUP~LY

~r'i I
J I I

0.5 0.6 0.7 0.8 0.9

OUTPUT LOW VOLTAGE (v)

Dropout Detection
Comparator Threshold
Voltages
-600

-

I I I HY~TERESIS
I 1+ I"5Dk RESISTOR
I--

0123~5678

INPUT VOLTAGE (v)

100

-700

I I I I
r-

10
LOAD CURRtNT (mA)

Error Output Voltage

\TA = 25°C

'\ =

10k

FRtQUtNCY (Hz)

Auxiliary Comparator
Sink Current
TA = 12~OC

Ik

-500

- -

-300

-100

-

V

-400

-200

LOWtR THRtsHOLD

~

-

.....
UPPtR THRtSHOLD

o
-50 -25 0

25 50 75 100 125 150

TEMPERATURE (DC)
TL/H/11339-6

2-160

Application Hints
HEATSINK REQUIREMENTS
A heatsink may be required with the LP2956 depending on
the maximum power dissipation and maximum ambient temperature of the application. Under all expected operating
conditions, the junction temperature must be within the
range specified under Absolute Maximum Ratings.
To determine if a heatsink is required, the maximum power
dissipated by the regulator, P(max) , must be calculated. It is
important to remember that if the regulator is powered from
a transformer connected to the AC line, the mallimum
specified AC input voltage must be used (since this produces the maximum DC input voltage to the regulator). Figure 1 shows the voltages and currents which are present in
the circuit. The formula for calculating the power dissipated
in the regulator is also shown in Figure 1 (the currents and
power due to external resistive dividers are not included,
and are typically negligible).

Figure 2 shows copper patterns which may be used to dissipate heat from the LP2956:

'""'1----

L'

I·

L' ---~.I

---~·I

LP2956

PTOTAL

= (v IN

- vM) ILM

+ (v IN - VA) ILA + (v IN) IG
TUH/11339-9
TLlH/11339-1O

FIGURE 1. Current/Voltage Diagram

= 2H
FIGURE 2. Copper Heatslnk Patterns

·For best results. use L

The next parameter which must be calculated is the maximum allowable temperature rise, TR(max). This is calculated by using the formula: '

Table II shows some typical values of junction-to-ambient
thermal resistance (6J-N for values of Land W (1 ·oz. copper).

TR(max) = TJ(max) - TA(max)
where: TJ(max) is the maximum allowable junction temperature '

TABLE II

TA(max) is the maximum ambient temperature

Package

Using the calculated values for TR(max) and P(max), the
required value for junction-to-ambient thermal resistance,
6(J-A), can now be found:

16-Pin
DIP

6(J-A) = TR(max)/P(max)
The heatsink for the LP2956 is made using the PC board
copper. The heat is conducted from the die, through the
lead frame (inside the part), and out the pins which are soldered to the PC board. The pins used for heat conduction
are shown in Table I.

16·Pin
Surface
Mount

TABLE I
Part
LP29561N
LP2956AIN

Package

Pins

16-Pin DIP

4,5,12,13

16-Pin DIP

4,5,12,13

LP29561M

16-Pin Surface Mt.

1,8,9,16

LP2956AIM

16-Pin Surface Mt.

1,8,9,16

2-161

L (In.) ,

H(ln.)

6J-A("C/W)

1

0.5

70

2

1

60

3

1.5

58

4

0.19

66

6

0.19

66

1

0.5

83

2

1

70

3

1.5

67

6

0.19

69

4

0.19

71

2

0.19

73

fII

Application Hints (Continued)
EXTERNAL CAPACITORS
Ai2.2 ",F (o(greater) capacitor is required between the main
output pin and ground to assure stability. The auxiliary output requires 10 ,...F to ground. Without these capacitors, the
part may oscillate. Most types of tantalum or aluminum electrolytics will work here. Film types will work, but are more
expensive. Many aluminum electrolytlcs contain electrolytes
which freeze at -30'C"which requires the use of solid tantalums below - 2S'O. The important characteristic of the
capacitors is an ESR of so (or less) on the main regulator
output and an ESR of 10 (or less) on the auxiliary regulator
output (the ESR may increase by a factor of 20 or 30 as the
temperature is reduced from +2S'C to ..,..30'C). The value
of these capacitors may be increased without limit.
The main output requires less capacitance at lighter load
currents. This capacitor can be reduced to 0.68 ,...F for currents below lOrnA or 0.22 ,...F for currents below 1 rnA.
Programming the main output for voltages below 5V requires more output capacitance for stability. For the worstcase condition of 1.23V output and 2S0 rnA of load current,
a 6.8 ,...F (or larger) capacitor should be used.
A 1 ,...F capacitor should be placed from the input pin to
ground if there Is more than 10 inches of wire between the
input and the AC filter capacitor or if a battery input is used.
Stray capacitance to the, Feedback terminal can cause instability. This problem is ,most likely to appear when using
high value external resistors to set the output voltage. Adding a 100 pF capacitor between ihe Output and Feedback
pins and increaSing the output capacitance to 6.8 ,...F (or
greater) will cure the problem.

If IFB is ignored in the calculation of the output voltage, it will
produce a small error in VMAIN OUT. Choosing R2 = 100 kO
will reduce,this error to 0.16% (typical) while increasing the
resistor program current to 12 ",A. Since the typical quiescent current is 130 ,...A, this added current is negligible.

VMA1N OUT

MAIN

·'I'F==
SHUTDOWN
INPUT·'

GNO

OUT

E+R'

FB

==
...,

r-1---4~1--'

'See Application Hints
"Drive with high to shut down

1

1-...._ _.'_.2_-_2-49,..V....

V!r

+'

0,o'T.8
I'F

•

I'F

•

R2

~~
,-

FIGURE 3. Adjustable Regulator

TL/HI11339-11

DROPOUT VOLTAGE
The dropout voltage of the regulator is defined as the minimum input-to-output voltage differential required for the output voltage to stay within 100 mV of the output voltage measured with a 1V differential. The dropout voltage is independent of the programmed output voltage.
DROPOUT DETECTION COMPARATOR
This comparator produces a logic "LOW" whenever the
main output falls out of regulation by more than about 5%.
This figure results from the comparator's built-in offset of
60 mV divided by the 1.23V reference (refer to block diagram). The S% low trip level remains constant regardless of
the programmed output voltage. An out-of-regulation condition can result from low input voltage, current limiting, or
thermal limiting.
Figure 4 gives a timing diagram showing the relationship
between the main output. voltage, the ERROR output, and
input voltage as the input voltage is ramped up and down to
a regulator whose main output is programmed for SV. The
'ERFiO'R signal becomes low at about 1.3V input. It goes
high at about SV input, where the main output equals 4.7SV.
Since the dropout voltage is load dependent, the Input voltage trip pOints will vary with load current. The main output
voltage trip point does not vary.
The comparator has an open-collector output which requires an external pull-up resistor. This resistor may be connected to the regulator main output or some other supply
voltage. Using the main output prevents an invalid "HIGH"
on the comparator output which occurs if it is pulled up to an
external voltage while the regulator input voltage is reduced
below 1.3V. In selecting a value for the pull-up resistor, note
that while the output can sink 400 ",A, this current adds to
battery drain. Suggested values range from 100 kO to
1 MO. The resistor is not required if the output is unused.

PROGRAMMING THE MAIN OUTPUT VOLTAGE
The main output may be pin-strapped for SV operation using
its internal resistive divider by tying the Output and Sense,
pins together and also tying the Feedback and SV Tap pins
together.
'
Alternatively, it may be programmed for any voltage between the 1.23V reference and the 29V maximum rating
using an external pair of resistors (see Figure 3). The complete equation for the output voltage is:

~~) +

LP2956

+---1-1 SO

MINIMUM LOAD ON MAIN OUTPUT
When setting the main output voltage using an external resistive divider, a minimum current of 10 ,...A is recommended
through the resistors to provide a minimum load.
It should be noted that a minimum load current is specified
in several of the electrical characteristic test conditions, so
the specified value must be used to o!>tain test limit correlation.

VMAINOUT = VREF X (1 +

1

lOOk

(IFB X Rl)

where VREF Is the 1.23V reference and IFB is the Feedback
pin bias current (-20 nA typical). The minimum recommended load current of 1 ",A sets an upper limit of 1.2 MO
on the value of R2 in cases where the regulator must work
with no load (see MINIMUM LOAD).

2-162

r-

."

Application Hints (Continued)

N

CD

,

OUTPUT
VOLTAGE

This gives a value of about 0.1,...F. When this is used, the
output capacitor must be 6.8 ,...F (or greater) to maintain
stability. The 0.1 ,...F capacitor reduces the high frequency
noise gain of the circuit to unity, lowering the output noise
from 260,...V to 80,...V using a 10 Hz to 100 kHz bandwidth.
Also, noise is no longer proportional to the output voltage,
so improvements are more pronounced at higher output
voltages.

~
--.
I

ERROR
OUTPUT

•

•

I
I

RI

LP2956 AUXILIARY REGULATOR

~----------------,
TL/H/11339-12

VAUX OUT

'In shutdown mode, ERROR will go high if it has been pulled up to an
external supply. To avoid this invalid response, pull up to regulator output.

(75mA)

"Exact value depends on dropout vollage. (See ApplicaUon Hints)
+

FIGURE 4. ERROR Output Timing

R2

.. ________________

10/Lf

01

If a single pull-up resistor is used to the regulator output, the
error flag may briefly rise up to about 1.3V as the input voltage ramps up or down through the OV to 1.3V region.

~EQUIRED
XOR STABILITY

TL/H/11339-13

In some cases, this 1.3V signal may be mis-interpreted as a
false high by a ,...p which is still "alive" with 1.3V applied to
it.

where: VREF

To prevent this, the user may elect to use two resistors
which are equal in value on the error output (one connected
to ground and the other connected to the regulator output).

AUXILIARY LDO OUTPUT

VAUXOUT
~

~ VREF (

1.23Vand IFB

~

1

+ ~ ) + (IFB X Rl)

-10 nA (lypical)

FIGURE 5. Auxiliary Adjustable Regulator
The LP2956 has an auxiliary LDO regulator output (which
can .source up to 75 rnA) that is adjustable for voltages from
1.23V to 29V.

If this two-resistor divider is used, the error output will only
be pulled up to about 0.6V (not 1.3V) during power-up or
power-down, so it can not be interpreted as a high signal.
When the regulator output is at 5V, the error output will be
2.5V, which is still clearly a high signal.

The output voltage is set by an external resistive divider, as
shown in Figure 5. The maximum output current is 75 rnA,
and the output requires 10 ,...F from the output to ground for
stability, regardless of load current.

OUTPUT ISOLATION
The regulator outputs can be left connected to an active
voltage source (such as a battery) with the regulator input
power shut off, as long as the regulator ground pin is connected to ground. If the ground pin is left floating, damage
to the regulator can occur if the output is pulled up by an
external voltage source.

SHUTDOWN INPUT
The shutdown input equivalent circuit is shown in Figure 6.
The main regulator output is shut down when the NPN transitor is turned ON.

REDUCING MAIN OUTPUT NOISE
In reference applications it may be advantageous to reduce
the AC noise present on the main output. One method is to
reduce regulator bandwidth by increasing output capacitance. This is relatively inefficient, since large increases in
capacitance are required to get significant improvement.

TL/H/11339-14

Noise can be reduced more effectively by a bypass capacitor placed across R1 (refer to Figure 3). The formula for
selecting the capacitor to be used is:
CB =

FIGURE 6. Shutdown Circuitry
The current into the input should be at least 0.5 ,...A to assure the output shutdown function. A resistor may be placed
in series with the input to minimize current draw in shutdown
mode, provided this minimum input current requirement is
met.

1
21T R1 X 20 Hz

IMPORTANT:
The shutdown input must not be left floating: a pull-down
resistor (10 kO to 50 kO recommended) must be connected
between the shutdown input and ground in cases where the
input is not actively pulled low.

2-163

U1

en
.......
r-

."

N
CD

U1

en

:J>

Schematic Diagram

IR

2-164

Typical Applications

I
VIN
MAI~

348k •

OUT

SENSE

6V
LEAD
ACID

~

SiD

SiD

+
+

.........-

=:=1 p.F
lOOk

5V TAP

INPUT

FEEDBACK

LJ

b

~ 1M •
~ 1M

l~

5V MAIN OUT

(Il '::; 250 mAl

2:2 p.

ERR
OUTPUT

AUX CaMP
INPUT

AUX CaMP
OUTPUT
,AUX OUT

LP2956

5V MEMORY OUT

....

(t ::; 75 mAl

309k

GNIi

AUX FB
lOOk

-,-

+
.. L..

1

0 P.F "

LTl/H/11339-16

•
2-165

iflNational

Sem~conductor

LP2957/LP2957A
5V Low-Dropout Regulator for p,P Applications
General Description

Features

The LP2957 is a 5V micropower voltage regulator with electronic shutdown, error flag, very low quiescent current
(150 p.A typical at 1 mA load), and very low dropout voltage
(470 mV typical at 250 mA load current):
Output can be wired for snap-on/snap-off operation to eliminate transition voltage states where p.P operation may be
unpredictable.
Output crowbar (50 mA typical pull-down current) will bring
down the output quickly when the regulator snaps off or
when the shutdown function is activated.
The part has tight line and load regulation (0.04% typical)
and low output temperature coefficient (20 ppm'oC typieal).
The accuracy of the 5V output is guaranteed at room temperature and over the full operating temperature range.
The LP2957 is available in the fIVe-lead TO-220 and TO-263
packages.

•
•
•
,.
•
•
•
•
•
•

5V output within 1.4% over temperature (A grade)
Easily programmed for snap-onlsnap-off output
Guaranteed 250 mA output current
Extremely low quiescent current
Low Input-Output voltage required for regulation
Reverse battery protection
Extremely tight line and load regulation
Very low temperature coefficient
Current and thermal limiting
Error flag Signals when output is out of regulation

Applications
• High-efficiency linear regulator
• Battery-powered regulator

Package Outline
Bent, Staggered Leads
5-Laad TO-220 (T)

::::='
151 .:: i i....

Plastic Surface Mount Package
5-Lead To-283 (S)

TAB IS [ ] ERROR
GND
SHUTDOWN

OUTPUT
INPUT

TlIH/11340-16

L '

GROUND
OUTPUT

Top View

INPUT

Order Number LP2957AIT or LP29571T
Sea NS Package Number T05D

TlIH/1134D-17

TopYlew

.J_~
..

TlIH/1134D-18

Side View
Order Number LP2957AIS or LP29571S
See NS Package Number TS5B

2-166

r-

'1lI
N

Absolute Maximum Ratings (Note 1)

co

Lead Temperature
(Soldering, 5 Seconds)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Operating Junction Temperature Range - 40·C to + 125·C
. -65·Cto + 150·C
Storage Temperature Range

260·C

Power Dissipation (Note 2)

Internally Limited

Input Supply Voltage
Shutdown Input

-20Vto +30V
- 0.3V to + 30V

ESDRating

2kV

Electrical Characteristics
Limits in standard typeface are for TJ = 25·C, and limits in boldface type apply over the full operating temperature range.
Unless otherwise specified: VIN = 6V, IL = 1 mA, CL = 2.2 J.l.F, VSO = 3V.
Symbol

Parameter

Conditions

Typical

Vo

Output Voltage (Note 9)

5.0
1 mA ,,;; IL ,,;; 250 mA

t..vo
4T

Output Voltage
Temperature
Coefficient

(Note 3)

Il.Vo

Line Regulation

VIN = 6V to 30V

5.0

4VO

Load Regulation

Vo
VIN-VO

Dropout Voltage
(Note 5)

5.050

5.100

4.930

5.070

4;880

5.120

.470

IL = 1 mA

150

IL = 50mA

1.1
.'

IL = 100mA

3

IL = 250mA
IGNO
IGNO

10
(Sink)

10
(Off)

. 16

Ground Pin Current
in Shutdown (Note 6)

IL = 0
VSO = 0.4V

13.0

Ground Pin Current
at Dropout (Note 6)

VIN = 4.5V
IL = 0.1 mA

180

Off-State Output
Pulldown Current

VIN = 5.3V
Vo = 5V, VSO = 0.4V

50

Output Leakage
in Shutdown

I(SO IN) ~ 1 J.l.A
VIN = 30V, VOUT = OV

3

2-167

. 150

100

310

IL = 250mA
Ground Pin Current
(Note 6)

4.950

4.900

240

IL=100mA

IGNO

5.025

60

IL = 50mA

Units

Max

5.060

0.04

IL = 1 mA

Min

4.975

0.03

IL = 1 mA to 250 mA
IL = 0.1 mA to 1 mA
(Note 4)

Max

4.940

20

Vo

LP29571

LP2957AI
Min

0.10

0.20

0.20

0.40

0.16

0.20

0.20

0.30

100

100

150

150

300

300

420

420

400

400

520

520

600

600

800'

800

200

200

230

230

2

2

2.5

2.5

6

6

8

8

28

28

33

33

180

180

200

200

230

230

250

250

30

30

20

20

V

ppml"C

%

%

mV

J.l.A

mA

J.l.A
J.l.A
mA

10

10

20

20

J.l.A

U1
.....
.....
r-

'1lI
N

co

U1

~

Electrical Characteristics
Limits in standard typeface are for T J
Unless otherwise specified: VIN

Symbol

= 25°C, and limits in boldface type apply over the, full operating temperature, range.

= 6V, IL = 1 mA, CL = 2.2 ,...F, Vso = 3V. (Continued)
Conditions

Parameter

Typical

Min
ILiMIT

Current Limit

INo

Thermal

aPd

Regulation

en

Output Noise

RL

= 10

400

(Note 7)

0.05

CL

= 2.2,...F

CL

= 33,...F

IL

= 100rilA

LP29571

Max

Min

Units

Max

500

500

530

530

0.2

0.2

mA

%/W

500

Voltage
(10 Hz to 100 kHz)

:

LP2957AI

,...VRMS
320

SHUTDOWN INPUT
Vso(ON)

Output Turn-On
Threshold Voltage

HYST

Hysteresis

18

Input Bias

1.155

1.305

1.155

1.305

1.140

1.320

1.140

1.320

-30

30

-30

30

-50

50

-50

SO

6
VIN(SO)

= OV to 5V

Current

V
mV

10

nA

DROPOUT DETECTION COMPARATOR
IOH

Output "HIGH"

VOH

= 30V

0.01

Leakage
VOL

= 4V

Output "LOW"

VIN

Voltage

lo(COMP)

Upper Threshold

(NoteS)

VTHR
(Max)

Voltage

VTHR
(Min)

Voltage

HYST

Hysteresis

Lower Threshold

= 400 /LA

150

-'240

(NoteS)

-350

(NoteS)

1

1

2

2

250

250

400

400

-320

-150

-320

-150

-3BO

-100

-3BO

-100

-450

-230

-450

-230

-640

-160

-640

-160

60

p.A
mV

mV

mV
mV

Note 1: Absolute maximum ratings indicate IimHs beyond which damage to the component may occur. Electrical specifications do not apply when operating the
device outside of its rated operating condHions.
Note 2: The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(MAX), the junction-to-amblent thermal resi~nce, 9JA,
and the ambient temperature, TA. The maximum allowabfe power dissipation at any ambient temperatura is calculated using:
P(MAX) ~ TJ(MAX) - TA
9JA
Exceeding the maximum allowable power dissipation will result in excessive die temperature. and the regulator will go into thermal shutdown. The junction-ta-ambi-

ent thermal resistsnce of the T()'220 (without heatsink) Is 6IY'C/W and 7:r'C/W for the TO·263. J.f the T()'263 package is used, the thermal resistance can be
reduced by increasing the P.C. board copper area thermally connectad to the package: Using 0.5 Square Inches of copper area, 9JA is 50"C/W, wHh 1 square inch
of copper area, 9JA Is 3rC/W; and with 1.6 or more square Inches of copper area, 9JA Is 3'Z'C/W. The junction·to·case thermal resistance is :r'C/W.lf an external
heatsink Is used, the effective junction-to-ambient thermal resistance is the sum of the junction-to-case resistance (:r'C/W), the specifiad thermal resistance of the
heatsink selected, and the tharmal resistance of the interface between the heatsink and the LP2957 (see Application Hints).
Note 3: Output voltage temperature coefficient is definad as the worst case voltage change divided by the total temperatura range.
Note 4: Regulation Is measurad at constsnt junction temperature using low duty cycle pulse testing. Parts are testad separately for load regulation in the load
ranges 0.1 mA-l mA and 1 mA-250 mAo Changes in output voltage due to heating effects are covered by the thermal regulation specilication.
Note 5: Dropout voltage Is definad as the Input to output voltage differential at which the output voltage drops 100 mV below the value measured with a 1V input to
output differential.
Note 6: Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the load

curr~nt

plus the ground pin current.

Note 7: Tharmal regulation I. defined as the change in output voltage at a time T after a change In power dlsslpaUon Is appliad, excluding load or line regulation
effects. Specifications are for a 200 mA load pulse at VIN ~ 20V (3W pulse) for T ~ 10 ms.
Note 8: Voltages are referenced'to the nominal regulated output voltage.
Note 9: When usad In dual·supply systems where the regulator load Is retumed to a negative supply, the output voltage must be diode-clamped to ground.

2-168

Typical Performance Characteristics
Unless otherwise specified: VIN

=

6V, IL

=

1 rnA, CL

Ground Pin Current
250

!

200

..3

..3

IL = tOO pA

t50

o
o

~

IJ
2

,

6

""

=250mA

2

0:
c

t5

,

"III"

~ I.!OO~A

L ="lmA

~
~
w

~

Ripple Rejection
ltIII-+!ftttllhft
ItIII--f+HfHII--I+

70~~~-H~r+Hffi~~

90

GOItlll-ft~~~~~~~HfHII

~.tl

50
40

~~tH~~~~oorHffi~
40 1IIIII--H-Hl!IH~1I- ~ = tOO mA

30

30

20

~

to

'"m

"'"

tOO

tk

tOk

tOOk

tOO

tW

tOk

tk

Line Transient Response
~S

).

!:is

o~

>w

~ ·to mA

.

40
30
20
to
0

tM

tOO

r'-

0.8

tOk

tOOk

tM

•

Output Impedance

~. O.t mA

,,--'OmA

'1. -33pF

~~

8V

>

6V

!5o

tk

FREQUENCY (Hz)

to

-so

TIME (m.)

iiiw
it

GO
50

tOO

~

SD
0
w

O.G

~

tOO

~~

IV

~

0.4

i'l

80
70

Line Transient Response
w

0.2

tOOk

7i1
.3

FREQUENCY (Hz)

FREQUENCY (Hz)

1\11

+~A

to

111111111111111

0

1tIII-++HIIIIIH+IIIII1Poc
IlIlIr...!"tJ..LII-ItiIlIH
1'l""'Uftfllllf

201lllll-~mI-H~~~~~

= tOmA

tOOO

tOO

70
60

tOO

Ripple Rejection

tOO mnr-rrrmm"'TT
80

6V

w

to

90

!5o
, >

>

LOAD CURRENT (mA)

90

8V

~

JUNCTION TEMPERATURE (DC)

80

w

.

.5

-75 -50-25 0 25 50 75 100125150175

Ripple Rejection

tOOO

..3

to

INPUT VOLTAGE (v)

tOO

tOO

~

fo-'

~

5

to

Output Noise Voltage

1--' .... ~50~A

z

• SOmA

3

O.t

OUTPUT CURRENT (mA)

II I

':<' 20

§

-V

:i!

O.t

..s

r- - ~ = tOOmA r- -

o

I

.

......

Ground Pin Current

z

o

z

0:

TEMPERATURE (DC)

tl

~

I

§

-75 -50 -25 0 25 50 75 100125 150 175

r--.
-

I

to

tl

25
~

~~

~

~

r\

1-40

Ground Pin Current

.

..s

\

130

20

iii
~

Ground Pin Current
vs Load

1\

INPUT VOLTAGE (V)

§.

25'C

':<'

0:
c

6
50

160

_ t50
z

I

z

z

=

tOO

I

,..-

r

z

7i1
.3

3V, T A

t70

':<'

0:
c tOO

~

=

2.2 IlF, VSD

Ground Pin Current

300

'<

=

2"
TIME (m.)

0.0 t L..LWllJL..L.LLWUII....I..LWUL..L
10
tOO
lk
10k tOOk

tM

FREQUENCY (HI)

TL/H/11340-5

2·169

Typical Performance Characteristics Unless otherwise specified:
VIN = 6V, Il = 1 rnA, Cl = 2.2 p.F, VSD = av, TA = 2SoC (Continued)
Load Transient'
Response

Load Transient
Response

,.,-,-,-.-.--r......,-,-.,

1.0

Dropout
Characteristics

100

w

~s

as
>w

~

~~
SO

11. =331'F

0

I--HI--HHHHr-lr-lr-l

-1.0

-200

....

~ ~ 250mAltt:t::t:t:j::::j::::j::::j::::j:::j

~

~"

~"

0",

"

f-HI-lHHHH-I-I-I

O.lmA

10

20

30

40

i

~

-300
250mA

(,)

A

~

= 250mA

/
10

50

20

30

40

50

1

TIWE (m.)

Enable Transient

INPUT VOLTAGE (V)

Short-Circuit Output
Current and Maximum
Output Current

Enable Transient

10

't;;.G. =2.2I'F

:A V

O.1mA

TIME (m.)

I-

= 1 rnA

-100

=11. =2.2I'F

-f-

1-1--

H+
~=

11. =331'F 1-1--

lOrnA

11. =331'F ~~r-

-f-

600

-:c

"-

450

~

i!i

400

300

.....

II

350

I

:;;

MAX OUTPUT CURRENT
I'Vour; 5V -r--

500

..s
~

V1N =14V
~ =IOmA

r-

550

SHORT CIRCUIT CURRENT
VOUT = OV

-f-

250
200
-75 -50 -25 0 25 50 75 100 125150 175

TIME (m.)

TIME (m.)

. JUNCTION TEMPERATURE (OC)

Error Output
Sink Current

Thermal Regulation
10

Dropout Detection
Threshold Voltages

2.5

-:c

..s

1\

T) I2~OC

2.0

§

1.5

B

1.0

V-

10'

1//
J

><
z
in

Jt
1 1

TA = -55°C

0.5

~r;
0.0
10

20

30

40

~

..'"

2

r-.;~

~~~

"
J ~ !73OC/W~

o

o

1

~e

-200

~~
"''''
~~

-100

Error Output Voltage

T'"

'1

i'

50k RESISTOR TO I
E~RNAL 5V SUPPLY I-

I I I ~Y~rER'SiS
I 1+
SDk RESISTOR

9... =3 OC

~

;::r=a;

10 20 30 40 50 60 70 80 90100
AMBIENT TEMPERATURE (OC)

~

-300

....,. """

-~ _

-

UPPER THRESHOLD

TEMPERATURE (oC)

-

"'I..b.

li!

LOWER THRESHOLD
-400

Dropout Voltage
1.0

I I I I

'I.

....

~3
g~
.,'"

-75 -50 -25 0 25 50 75 100125150175

I

~

-500

w'"

OUTPUT LOW VOLTAGE (V)

1
9JA = 32oc/~

~

-600

~S
_0

0.00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

TIME (m.)

Maximum Power Dissipation
(To-263) (See Note 2)

II

-700

!;

- ~ V'I' I
J

1 1

012345678
INPUT VOLTAGE (V)

~

~

I I 1
1 I 1
1 1 1

0.8

!:;

0.6 l -

I

0.2

.,>

.... '

I: = 1250'mA

."

;;0- I~
0.4 I-: .,.
\. = \~."'~I;:
~ =somA

...

~I

I- 0.0
-60

-41. = lmA
-10

40

90

140

TEMPERATURE (OC)
TUHI11340-6

2-170

r-----------------------------------------------------------------------------,~

"'a

Block Diagram

N

~

::::!
EO

N
CD
CI'I

):

~-------------------

TLlH/11340-1

Typical Application Circuits
LP2957 Basic Application
VIN + - -....-1 IN

+

(6V-30V)
1 J'F

OUT

1-....---1-+

SV OUT

LP2957

•

~T+""';--I--I S7D GNO ERR I - + - - -....-.O~~~UT

TLlH/11340-2

LP2957 Application with Snap·On/Snap·Off Output
VIN +-+-1-~P--1IN
(6V-30V) •

OUT

1-....- -......- .

SV OUT

LP2957

.........-"'-i--I S7D GNO ERR I-+---....-.O~~~UT

'See Application Hints

TL/HI11340-4

2-171

Application Hints
age at the input of the regulator. The minimum input voltage
is the lowest voltage level Including ripple on the filter
capaCitor. It is also advisable to verify operation at minimum operating ambient temperature, since the increasing ESR of the filter capacitor makes this a worst-case test
due to increased ripple amplitude.

EXTERNAL CAPACITORS
A 2.2 ,...F (or greater) capacitor is required between the output pin and ground to assure stability (refer to Figure 1).
Without this capacitor, the part may oscillate. Most type of
tantalum or aluminum electrolytics will work, here. Film types
will work, but are more expensive. Many aluminum electroIytics contain electrolytes which freeze at -30"C, which requires the use of solid tantalums below -25'C. Th,e important parameters of the capacitor are an ESR of about 50. or
less and a resonant frequency above 500 kHz (the ESR
may increase by a factor of 20 or 30 as the temperature is
reduced from 25'C to -30'C). The value of this capacitor
may be increased without limit. At lower values of output
current, less output capacitance is required for stability. The
capacitor can be reduced to 0.68 ,...F for currents below
10 mA or 0.22 ,...F for currents below 1 mA.
A 1 ,...F capacitor should be placed from the input pin to
ground if there is more than 10 inches of wire between the
input and the AC filter capacitor or if a battery input is used.
This capacitor may have to be increased If the regulator
Is wired for snap-on/snap-off output and the source Impedance is hIgh (see Snap-On/Snap-Off Operation section).

HEATSINK REQUIREMENTS
A heatsink may be required with the LP2957 depending on
the maximum power dissipation and maximum ambient temperature of the application. Under all possible operating
conditions, the junction temperature must be within the
range specified under Absolute Maximum Ratings.
To determine if a heatsink is required, the maximum power
dissipated by the regulator, P(max), must be calculated. It is
important to remember that if the regulator is powered from
a transformer connected to the AC line, the maxImum
specified AC Input voltage must be used (since this produces the maximum DC input voltage to the regulator), and
the maximum load current must also be used. Figure 1
shows the voltages and currents which are present in the
circuit. The formula for calculating the power diSSipated in
the regulator is also shown in Figure 1.
IN-

SHUTDOWN INPUT
A logic-level signal will shut off the regulator output when a
"LOW" « 1.2V) is applied to the Shutdown input.
To prevent possible mis-operation, the Shutdown input must,
be actively terminated. If the input is driven from open-collector logic, a pull-up resistor (20 ko. to 100 ko. recommended) must be connected from the Shutdown input to the regulator input.
If the Shutdown input is driven from a source that actively
pulls high and low (like an op-amp), the pull-up resistor is
not required, but may be used.

5V

TL/H/11340-7

'See EXTERNAL CAPACITORS
PrOTAL

If the shutdown function is not to be used, the cost of the
pull-up resistor can be saved by tying the Shutdown input
directly to the regulator input.

= (VIN -

S)IL + (VIN)IG
FIGURE 1. Basic 5V Regulator Circuit

The next parameter which must be calculated is the maximum allowable temperature rise, T R(Max). This is calculated by using the formula:

IMPORTANT: Since the Absolute Maximum Ratings state
that the Shutdown input can not go more than 0.3V below
ground, the reverse-battery protection feature which protects the regulator input is sacrificed if the Shutdown input is
tied directly to the regulator input.
If reverse-battery protection is required in an application, the
pull-up resistor between the Shutdown input and the regulator input must be used.

TR(Max) = TJ(Max) - TA(Max)
where: TJ(Max) is the maximum allowable junction temperature
TA(Max) is the maximum ambient temperature
Using the calculated values for T R(Max) and P(Max), the
required value for junction-to-ambient thermal resistance,
8(JA), can now be found:
8(JA) = T R(Max)/P(Max)
If the calculated value is 60"C/W or higher, the regulator
may be operated without an external heatsink. If the calculated value is below 60'C/W, an external heatsink is required. The required thermal resistance for this heatsink,
8(HA), can be calculated using the formula:

MINIMUM LOAD
It should be noted that a minimum load current is specified
in several of the electrical characteristic test conditions, so
the value listed must be used to obtain correlation on these
tested limits. The part is parametrically tested down to
100 ,...A, but is functional with no load.
DROPOUT VOLTAGE

8(HA) = 8(JAI - 8(JC) - 8(CHI
where:
8(JCI is the junction-to-case thermal resistance, which is
specified as 3'C/W for the LP2957.

The dropout voltage of the regulator is defined as the minimum input-to-output voltage differential required for the output voltage to stay within 100 mV of the output voltage measured with a 1V differential. The dropout voltages for various
values of load current are listed under Electrical Characteristics.

8(CHI is the case-to-heatsink thermal resistance, which is
dependent on the interfacing material (see Tables I and II).

If the regulator is powered from a transformer connected to
the AC line, the minImum AC line voltage and maximum
load current must be used to measure the minimum volt2-172

r-----------------------------------------------------------------------------, "tJ

~

Application Hints (Continued)

I\)

CD

Typical TO-220 Case-To-Heatslnk
Thermal Resistances In ·C/W
TABLE II.
(From Thermalloy)

TABLE I. (From AAVID)
Silicone Grease

1.0

Dry Interiace
Mica with Grease

If a single pull-up resistor is connected to the regulator output, the error flag may briefly rise up to about 1.3V as the
input voltage ramps up or down through the OV to 1.3V region.
In some cases, this 1.3V signal may be mis-interpreted as a
false high by a /LP which is still "alive" with 1.3V applied to
it.
To prevent this, the user may elect to use two resistors
which are equal in value on the error output (one connected
to ground and the other connected to the regulator output).
If this two-resistor divider is used, the error output will only
be pulled up to about 0.6V (not 1.3V) during power-up or
power-down, so it can not be interpreted as a high signal.
When the regulator output is in regulation (4.8V to 5V), the
error output voltage will be 2.4V to 2.5V, which is clearly a
high signal.

Thermasilill

1.3

1.3

Thermasilll

1.5

1.4

Thermalfilm (0.002)
with Grease

2.2

8(HA) is the heatsink-to-ambient thermal resistance. It is this

specification (listed on the heatsink manufacturers data
sheet) which defines the effectiveness of the heatsink. The
heatsink selected must have a thermal resistance which is
equal to or lower than the value of 8(HA) calculated from
the above listed formula.
This comparator produces a logic "LOW" whenever the output falls out of regulation by more than about 5%. This figure results from the comparator's built-in offset of 60 mV
divided by the 1.23V reference. An out-of-regulation condition can result from low input voltage, current limiting, or
thermal limiting.
Figure 2 gives a timing diagram showing the relationship
between the output voltage, the ERROR output, and input
voltage as the input voltage is ramped up and down to the
regulator without snap-on/snap-off output. The ERROR
signal becomes low at about 1.3V input. It goes high at
about 5V input, where the output equals 4.75V. Since the
dropout voltage is load dependent, the input voltage trip
pOints will vary with load current. The output voltage trip
point does not vary.

,

VIN
(6V-30V)

ERROR
OUTPUT

__

I
I

I
I

·_;_·~: ~I
I

•

LP2957

S7ii GND

TL/H/11340-8

'Minimum value (increase as required for smooth lurn·on characteristic).

FIGURE 3. Snap-On/Snap-Off Output
When connected as shown, the shutdown input holds the
regulator off until the input voltage rises up to the turn·on
threshold (VON), at which point the output "snaps on".
When the input power is shut off (and the input voltage
starts to decay) the output voltage will snap off when the
input voltage reaches the turn-off threshold, VOFF.

I

I
I

IN
R2

R3

,
------

c.n

):

Rl

1 ~r

~
I

I
I

CD

SNAP-ON/SNAP-oFF OPERATION
The LP2957 output can be wired for snap-on/snap-off operation using three external resistors:

The comparator has' an open-collector output which requires an external pull-up resistor. This resistor may be con·
nected to the regulator output or some other supply voltage.
Using the regulator output prevents an invalid "HIGH" on
the comparator output which occurs if it is pulled up to an
external voltage while the regulator input voltage is reduced
below 1.3V. In selecting a value for the pull-up resistor, note
that while the output can sink 400 /LA, this current adds to
battery drain. Suggested values range from 100k to 1 MO.
The resistor is not required if the output is unused.
'75V--

I\)

OUTPUT ISOLATION
The regulator output can be connected to an active voltage
source (such as a battery) with the regulator input turned
off, as long as the regulator ground pin Is connected to
ground. If the ground pin is left floating, damage to the
regulator can occur if the output is pulled up by an external
voltage source.

ERROR COMPARATOR

OUTPUT
VOLTAGE

~

"EO

__

I~ ~r_~_-_·
I
I

TL/H/11340-9

FIGURE 4. Snap-On/Snap-off Input
and Output Voltage Diagram

TUH/11340-14

'In shutdown mode. ERROR will go high if it has been pulled up to an
external supply. To avoid this invalid response, pull up to regulator output

It is important to note that the voltage VOFF must always be
lower than VON (the difference in these voltage levels is
called the hystereSis).

"Exact value depends on dropout voltage, which varies with load current.

FIGURE 2. ERROR Output Timing

2-173

•

Application Hints (Continued)
R1, R2 and RS are found by solving the node equations for
the currents entering the node nearest the shutdown pin
(written at the turn~on and turn-off thresholds).

Hysteresis is required when using snap-on/snap-off output,
with the minimum amount of hysteresis required for a specific application being dependent on the source impedance of
whatever is supplying VIN.
Caution: A type of low-frequency oscillation can occur if
VON and VOFF are too close together (Insufficient hysteresis). When the output snaps on, the
regulator must draw sufficient current to power
,the loa~ and charge up the output capacitor (in
most cases, the regulator will briefly draw the
maximum current allowed by, its internal limiter).
For this reason, it is best to assume the LP2957
may pull a peak current of about 600 rnA ,from the
source (which is the listed maximum short-circuit
load current of 530 rnA plus the ground pin current of 70 mAl.
'

The s/lutdown pin bias current (10 nA typical) is not included
in the calculations:
Turn-ON Transition

1.23V

~Rl :~R3

1

v:=bll~

1

I'

.. _--_ ..

1

,I

GN

'.

SV

LP2957

R2
1.23V

Rl

R3

.~

S7D GND

•

1

-b-

-

TLlH/11340-12

FIGURE 6. Equivalent Clrculta
( VON - 1.2S) = 1.2S
R2
R1
VOFF - 1.2S
'R2

I\OAO

+5-

+ 1.2S

(TURN-ON)

RS

1.2S = 1.2S
R1
RS

(TURN-oFF)

Since these two equations contain three unknowns (R1, R2
and RS) one resistor value must be assumed and then the
remaining two values can be obtained by solving the equations .
The node equations will be simplified by solving both equations for R2, a!1d then equating the two to generate an expression in terms of R1 and RS.

~. ~~
.........-

IN

V1N

+

~

TL/H/11340-11

Turn-OFF Transition

~~

1
1

1

-

+VIN

,~ ~

S7D GND

-b-

If the unregulated DC input ,voltage to the regulator comes
from a transformer, the required hysteresis is easily measured by loading the source with a resistive load:
TRANSFORMER

LP2957

R2

This high peak current causes VIN to drop by an amount
equal to the source impedance multiplied by the current. If
VIN drops below VOFF, the regulator will turn off and'stop
drawing current from the source. This will allow VIN to rise
back up above VON, and the cycle will sfart over. The regulator will stay in this oscillating mode and never come into
regulation.
HYSTERESIS IN TRANSFORMER-POWERED
APPLICATIONS:

r----"1

IN

V1N

....-oGND
TL/H/11340-10

FIGURE 5. Transformer Powered Input Supply
If the regulator is powered from a battery, the source impedance 'lllill probably be low enough that other considerations
will determine the optimum values for hysteresis (see De·
sign Example ;I' 2).
'

R2 = (R1

x RS) x (VON - 1.2S)
1.2S x (R1 + RS)

R2 = (R1 X R3) X (VOFF - 1.2S)
(1.2SR1 - S.77RS)

For ~est results, the load resistance used to test the transformer should be selected to draw about 600 mA for ,the
maximum load current test, since this is the maximum peak
current the LP2957 could be expected to draw from the
source.
The difference In Input voltage measured at no load and
full load defines the amount of hysteresis required for
proper snap-on/snap-off operation (the programmed
hysteresis must be greater than the difference in voltages).
CALCULATING RESISTOR VALUES:

(TURN-ON)
(TURN-OFF)

Setting these equal to each other and solving for R 1 yields:
R1 = RS X (VOFF + S.07VON -5)
VON - VOFF
The same equation solved for RS is:
RS = R1 X (VON - VOFF)
VOFF + S.07VON -5
A value for R1 or RS can be derived using either one of the
above equations, if the deSigner assumes a value for one of
the resistors.
The simplest approach is to assume a value for RS. Best
results will typically be obtained using values between about
20 kG and 100 kG (this keeps ,the current drain low, but
also generates realistic values for the other resistors).

The values of R1, R2 and RS can be calcula~ed assuming
the designer knows the hysteresis.
In most transformer-powered applications, it can be assumed that VOFF (the input voltage at turn-off) should be
set for about 5.5V. since this allows about 500 mV across
the LP2957 to keep'the output in regulation until it snaps off.
VON (the input voltage at tum on) is found by adding the
hysteresis voltage to VOFF.

There is no limit on the minimum value of RS, but current
should be minimized as it generates power that drains the
source and does not power the load.
2-174

.-----------------------------------------------------------------------------~

N

co
(II

SUMMARY: TO SOLVE FOR R1, R2 AND R3:

DESIGN EXAMPLE #2:

1. Assume a value for either R1 or R3.
2. Solve for the other variable using the equation for R 1 or
R3.
3. Take the values for R1 and R3 and plug them back into
either equation for R2 and solve for this value.
DESIGN EXAMPLE # 1:

A 5V regulated output is to be powered from a battery made
up of six NiCad cells. The cell data is:
cell voltage (full charged): 1.4V
cell voltage (90% discharged): 1.0V
The internal impedance of a typical battery is low enough
that source loading during regulator turn-on is not usually a
problem.

A 5V regulated output is to be powered from a transformer
secondary which is rectified and filtered. The voltage VIN is
measured at zero current and maximum current (600 mAl to
determine the minimum allowable hysteresis.

NO LOAD

~

r--- ....... l

/

FULL LOAD

7.BV

--...........

6.6V

TL/H/11340-13

FIGURE 7. VIN VOLTAGE WAVEFORMS

VOFF = 6.0V
Solving for R1:

The 1.2V differential between no-load and full-load conditions means that at least 1.2V of hysteresis is required for
proper snap-on/snap-off operation (for this example, we
will use 1.5V).
As a starting pOint, we will assume:
VOFF = 5.5V
5.5
R3 = 49.9k

+ HYST =

+ 1.5 =

R1 = R3

"'tJ
N

co

~

7V

VON = 7.2V

R3= 49.9k

x (VOFF + 3.07VON - 5)

R1 = 49.9k

x

VON - VOFF
(6 + (3.07 x 7.2) -5)
7.2 -6

R1 = 961k (standard size 953k)
Solving for R2:

Solving for R 1:

x R3) x (VON - 1.23)
1.23 x (R1 + R3)
R2 = (953k x 49.9k) x (7.2 - 1.23)
1.23 x (953k + 49.9k)
R2 = (R1

(VOFF + 3.07VON - 5)
VON - VOFF
R1 = 49.9k x (5.5 + (3.07 x 7) -5)
7 - 5.5
R1 = R3

r

For NiCad batteries, a good cell voltage to use to calculate
VON is about 1.2V per cell. In this application, this will yield a
value for VON of 7.2V.
We can now find R1, R2 and R3 assuming:

The full-load voltage waveform from a transformer-powered
supply will have ripple voltage as shown. The correct point
to measure is the lowest value of the waveform.

VON = VOFF

......
......

In a battery-powered application, the turn-off voltage VOFF
should be selected so that the regulator is shut down when
the batteries are about 90% discharged (over discharge can
damage rechargeable batteries).
In this case, the battery voltage will be 6.0V at the 90%
discharge pOint (since there are six cells at 1.0V each). That
means for this application, VOFF will be set to 6.0V.
Selecting the optimum voltage for VON requires understanding battery behavior. If a Ni-Cad battery is nearly discharged
(cell voltage 1.0V) and the load Is removed, the cell voltage will drift back up. The voltage where the regulator turns
on must be set high enough to keep the regulator from restarting during this time, or an on-off pulsing mode can occur.
If the regulator restarts when the discharged cell voltage
drifts up, the load on the battery will cause the cell voltage
to fall below the turn-off level, which causes the regulator to
shut down. The cell voltage will again float up and the on-off
cycling will continue.

VIN is measured using an oscilloscope (both traces are
shown on the same grid for clarity):

-- .......

r

"'tJ

Application Hints (Continued)

x

R2 = 230k (standard size 232k)

R1 = 731k (standard size 732k)
Solving for R2:
R2 = (R1

fI

x R3) x VON - 1.23)
1.23 x (R1 + R3)

R2 = (732k x 49.9k) x (7 - 1.23)
1.23 x (732k + 49.9k
R2 = 219k (standard size 221k)

2-175

Schematic Diagram

II

z
:>

I~
2-176

r-+--+---...,

~

N
CD
CD

t!lNational Semiconductor

Q

LP2980
Micropower SOT, 50 mA Ultra Low-Dropout Regulator
-General Description

Features
Ultra low dropout voltage
Output voltage accuracy 0.5% (A Grade)
Guaranteed 50 mA output current
Smallest possible size (SOT-23 Package)
Requires only 1 p.F external capacitance
< 1 p.A quiescent current when shutdown
Low ground pin current at all load currents
High peak current capability (150 mA typical)
Wide supply voltage range (16V max)
Fast dynamic response to line and load
Low ZOUT over wide frequency range
Overtemperature/overcurrent protection
-40·C to + 125·C junction temperature range

The LP2980 is a 50 mA, fixed-output voltage regulator designed specifically to meet the requirements of battery-powered applications.
Using an optimized VIPTM (Vertically Integrated PNP) process, the LP2980 delivers unequaled performance in all
specifications critical to battery-powered designs:
Dropout Voltage. Typically 120 mV @ 50 mA load, and
7 mV @ 1 mA load.
Ground Pin Current. Typically 375 p.A
80 ,.,.A @ 1 mA load.
.

@

50 mA load, and

Sleep Mode_ Less than 1 p.A quiescent current when
ON/OFF pin is pulled low. .
Smallest Possible Size. SOT-23 package uses an absolute
minimum of board space.
Minimum Part Count. Requires' only 1 p.F of external capacitance on the regulator output.
Precision Output. 0.5% tolerance output voltages available (A grade).
5.0V, 3.3V, and 3.0V versions available as standard products.

Applications
•
•
•
•

Cellular Phone
Palmtop/Laptop Computer
Personal Digital Assistant (PDA)
Camcorder, Personal Stereo, Camera

Block Diagram

GNO

TL/H/12078-1

Connection Diagram and Ordering Information

O
Q!!L

o:r

G:O

4

Hie

5·Lead Small Outline Package (M5)

v:"
~

. TLlH/12078-38

Actual Size
5

Your

TL/H/12078-3

Top View
For Ordering Inforynatlon See Table I In this Catasheet
See NS Package Number MA05A

2-177

I
.....

Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
-65·Cto + 150·C
Storage Temperature Range
Operating Junction Temperature Range -40·Cto + 125·C
Lead Temperature (Soldering, 5 sec.)
Power Dissipation (Note 3)

-0.3Vto +16V

Input Supply Voltage (Operating)
Shutdown Input Voltage (Survival)

2.Wto +16V
-0.3Vto +16V

Output Voltage (Survival, Note 4)

-0.3Vto +9V
Short Circuit Protected
lOUT (Survival)
-0.3Vto +16V
Input-Output Voltage (Survival, Note 5)

260"C
2kV

ESD Rating (Note 2)

Input Supply Voltage (Survival)

Internally Limited

Electrical Characteristics

Limits in standard typeface are for TJ 7' 25·C, and limits in boldface type apply
over the full operating temperature range. Unless otherwise specified: VIN = VO(NOM) + W, IL = 1 rnA, COUT = 1 ,..F,
VON/OFF = 2V.

Symbol

Vo

Parameter

Output Voltage
(5.0V Versions)

Output Voltage
(3.3V Versions)

Output Voltage
(3.0V Versions)

aVo
aVIN
VIN-VO

Conditions

Typ

5.0

VIN = VO(NOM) + W
1 rnA

< IL < 50 rnA

5.0
3.3

VIN = VO(NOM) + W
1 rnA

< IL < 50 rnA

3.3
3.0

VIN '= VOCNOM) + W
1 rnA

< IL < 50 rnA

Output Voltage
Line Regulation

VO(NOM) + 1V
~ VIN ~ 16V

Dropout Voltage
(Note 7)

IL = 0

3.0

5.025

4.950

5.050

4.962

5.038

4.925

5.075

4.875

5.125

4.825

5.175

3.283

3.317

3.267

3.333

3.275

3.325

3.250

3.350

3.217

3.383

3.184

3.41.

2.985

3.015

2.970

3.030

2.977

3.023

2.955

3.045

2.925

3.075

2_895

3.105

80
140

IL = 50 rnA

375

< 0.18V

0.014

0.014

0.032

0.032

3

3

5

5

10

10

15

15

60

60
90

90

65

IL = 10mA

ION/OFF

4.975

120

IL = 0

VON/OFF

Max

40

IL = 1 rnA

VON/OFF

Min

7

IL = 50 rnA
Ground Pin Current

Max

1

IL = 10mA

LP29801-XX
(Note 6)

Min

0.007

IL=1mA

IGND

LP2980AI-XX
(Note 6)

150

150

225

225

95

95

125

125

110

110

170

170

220

220

4.0

480

600

600

1200

1200

1

0

2.0

High = O/PON

1.4

Low = O/POFF

0.55

0.18

0.18

ON/OFF Input Current

VON/OFF = 0

'0

-1

-1

5

15

15

2-178

V

%IV

mV

,..A

1
2.0

ON/OFF Input Voltage
(Note 8)

VON/OFF = 5V

Units

V

p.A

Electrical Characteristics

Limits in standard typeface are for TJ

oyer the full operating temperature range. Unless otherwise specified: V,N
VON/OFF

=

=

=

25'C, and limits in

VO(NOM)

+

1V, IL

=

Parameter

Conditions

(Note

Typ

Min
IO(PK)

Peak Output Current

VOUT ~ VO(NOM) -

en

Output Noise

BW

Voltage (RMS)

COUT

Ripple Rejection

f

AVOUT

=

=

Short Circuit Current

RL

150

5%

300 Hz-50 kHz,

=

=

apply
1 ,...F,

=

(Note

=

LP29801·XX

6)

(Note

Max

Min

100

6)

Units

Max

100

mA

160

,...V

63

dB

150

rnA

10,...F

1 kHz

COUT

AV,N
IO(MAX)

1 rnA, COUT

2V. (Continued)
LP2980AI·XX

Symbol

boldface type

10,...F

0 (Steady State)

9)

Nate 1: Absolute maximum ratings Indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the
device outside of Its rated operating conditions.
Nole 2: The ESD rating of pins 3 and 4 Is 1 kV.
Nole 3: The maximum allowable power dissipation Is a fUnction of the maximum iunction temperature, TJ(MAX), the iunction.to·ambient thermal resistance, 8JA, and
the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using:
P(MAX) = TJIMAX)- TA
8JA

The value of 9JA for the SOT·23 package is 3000C/W. Exceeding the maximum allowable power dissipation will cause excessive die temperature. and the regulator
will go into thermal shutdown.
Nole 4: If used in a dual-supply system where the regulator load is returned to a negative supply, the lP2980 output must be diode·clamped to ground.
Nate 5: The output PNP structure contains a diode between the Y,N and YOUT terminals that is normally reverse-biased. Reversing the polarity from Y,N to VOUT
will turn !In this diode (see Application Hints).
Nole 6: UmRs are 100% production tested at 25"C. Umits over the operating temperature range are guaranteed through correlation using Statistical Ouality Control
(SOC) methods. The limits are used to calculate National's Averaging Outgoing level (AOOl).
Note 7: Dropout voltage is defined as the input to output differential at which the output voltage drops 100 mV below the value measured with a 1V differential.
Nate 8: The ON/OFF inputs must be properly driven to prevent misoperation., For details, refer to Application Hints.
Nate 9: See Typical Performance Characteristics curves.

Basic Application Circuit
c V,N

.

1

ON/OFF_

3

~J.

J
r-;~

REF

-,

I,

"'N/C-

4

~

~

OVER CURRENT/
OVER TEMP
PROTECTION

I

,.., YOUT

S

+1 ..
+
-r-

lj

>0

5.000

V r- i"-

:s

"

4.990
-50 -25

0

25

50

rl\

3.283

~

=>

"-

-

3.286

OUT

5.010

-

./

-r-

{

,;>

,....

3.280

3.278
-50 -25

75 100 125 150

a

TEMPERATURE (Oe)

25

50

75 100 125 150

TEMPERATURE (Oe)
TLlH/1207B-9

TL1H/12078-39

Output Voltage vs
Temperature
3.015

Dropout Characteristics

I

I
VOUT = 3V

3.010

:s

/

3.005

~

=>

,;>

//

3.000

5.0

I

4.0

/

:s

75 100 125 150

,"

RL = 100n-

A

~

2.0

50

r
ff

= 5k """"A

>0

0.0
25

~

3.0

=>

:--V

0

VOUT = 5.0V

-

.#

~

1.0

2.995
-50 -25

I
I
a

345
VIN (V)

TEMPERATURE (Oe)

TLlH/12078-16

TL/H/12078-40

Dropout Characteristics

Dropout Characteristics
4.0

~

=>

VOUT = 3.0V

VOUT = 3.3V

3.0

IQ

W

3.0

:s

RL = 3.3k
2.0

~

J

~ I<- RL

>0

:s

~

2.0

= 3k f--<

~

~

=>

= 66n

>0

J

1.0

1.0

111

0.0

o

#

~ f-- -RL =

60n

~

!J
0.0

00

o

Output Voltage vs
Temperature

Output Voltage vs
Temperature

:s

"co

a

11
2

II

3

VIN (V)
TLlH/1207B-14

TL/H/1207B-15

2-181

Typical Performance Characteristics (Continued)
Unless otherwise specified: TA = 25"C, V,N = VO(NOM)

+

,
'
1V, COUT = 2.2 p.F, all voltage options, ON/OFF pin tied to V,N.

Dropout Voltage VI '
Temperature

Dropout Voltage VI
Load Current

175

125

">

..5

..,.,. .".

...

100

D-

o

,,",

125

j

150

-

>""

-

25

100

I-?o mA
Lolad

">

..5

75
, 50

,. K

!i!

~~ad

>""

No

1 mA

o
-50 -25 0

25

50

50

:

/
I
o

25

LOj?_

LOrd

/

/

D-

10lmA

V

L

75

/

o

75 100 125 150

10

20

30

TEMPERATURE (Oe)

40

50

60

'L (mA)
TLlH/12078-11

TLlH/12D78-2D

Ground Pin Current vs
"Load Current

Ground Pin Current VI
Temperature
700
500

'"

600

\.

500

-:c
.3
ri1
£!

400

'-

400
300

.....

200

1~,

100

O~A ...

'0

--"r-

........

-

-50 -25 0

25 50

r50mA

~ ....
f...<

300

-'"

200

.3

Load

/

-:c

~,10mA

100

Load

I

o

75 100 125 150

, t...-'
~

'"

./

o

10

~

...

20

30

40

50

'L (rnA)

TEMPERATURE (Oe)

TL/H/12D78-19

TL/H/I2D78-1D

,Input Current VI V,N

Input Current vs V,N

1.6
VOUT = 5V

1.4
1.2

-:c

..5
..9

1.0
0.8

J

0.6

V

/

, 50

~

~ ~5~_ -:c

0.4

10

0.2
0.0

RL =00

"II

l
o

1

2

3

4

5

6

7

8

-

I

I
1/

I

o JI""
o 1 2

9 10

loon

1/

30

_0

20

\..~ =

I

I

40

..5

I

VOUT ,= 5V

~

-soon
I

1,..0-

I
3

4

5

6

7

8

9

10

Y,N (V)

Y,N (V)

TLlH/I2D78-18

TLlH/I2D78-17

2-182

Typical Performance Characteristics (Continued)
Unless otherwise specified: TA = 25°C, VIN = VO(NOM)

+

.
W, COUT = 2.2 /IoF, all voltage options, ON/OFF pin tied to VIN.

Line Transient Response
Your = 5V

Your (v)

It. = SOmA

5.02
I ...

,-

4099

7

-

-

5.02
5.01
5.00 f-I

111'1-

4.9B
7

II
II

VIN (v)
6

..,

."
'\iJ

4.99

I'

r

Your = 5V
II = lmA l -

Your (V)

,

5.0 1
5.00
4.9B

Line Transient Response

r

VIN (V)

20p.s/div-

20p.s/divTUH/12078-21

TUH/12078-22

Load Transient Response
3.01

Your (v) 3.00

-

~

1'-

3.01

Your (v) 3.00

Your = 3V
Cour = 2.2 p.F

2.99

50

Load Transient Response

I

~ --;

If

2.99

~

50

LOAD CURRENT

LOAD CU RRENT

(mA)

(mA)

Your = 3V
Cour = 10 p.F

:

o
10p../dlv-

10p.s/divTUH/12078-41

Tl/H/12078-42

Losd Transient Response

Load Transient Response
Your =5V I
Your (v) f- I-cour =10p.F

Your = 5V I
f- -cour = 2.2 p.J
5.01
4.99
50

Il (mA)

5.01

I\,

Your (v) 5.00

5.00
4.99~

~

50

40

40

30

30

It. (mA)

20
10

10 jJs/div-

'r

20
10

10 p.s/divTUH/12078-23

Tl/H112078-24

2·183

•

Typical Performance Characteristics (90ntinued)
Unless otherwise specified: TA = 25°C; VIN = VO(NOM)

+

.
'.
.
. ..,'
1V, COUTo =_2.2p.F, all voltage options, ON/OFF pin tied to VIN.

Instantaneous Sh~rt Circuit Current
vs Temperature

Short. Circuit Current

,

~

...

I I

'350

r-

"

200

.§.

-~

I I

VIN = 6V
OUTPUT SHORTED TO GND
AT TIME \ = O_

~

300

325
300

r

~

.§.
100

"- t\..

275

u

"\

_VI

250

o

.225
200
-50 -25

\ =0
500ms/div-

0

25

50

75 100 125 150

TEMPERATURE (Oc)

TL/H/I207B-32

TLlH/12078-12

Short Circuit Current

- r-.:.

...

~

400

.§. 300

1

1

VIN = 16V
OUTPUT SHORTED TO iND
AT TIME \ = O.
THERMAL
CYCLING

360
340
~

"'- r-

u
_VI

Instantaneous Short Circuit Current
vs Output Voltage

200

" " I"'

320

.§.

-~

100

o

,300

280

\ =0

260
20ms/div -

o

2

TL/H/I2078-33

Output Impedance
Frequency

0.03

o

0.01

,

4

5

Ripple Rejection
--rrmmr--r:-:nnnr----:o:'"TIIII

-;;:;

80

~

I-H-HHIII-H

z
0

...iJ>=
...'"

60

u

40

...J

O.l1-+ItHlfHtt

~

".

r'\

TL/H/I2078-43

vs

3I=*j;j;jlllll;;;~~

!;

3

"

VOUT (v)

30 I-HfttttIIl-H~':-'-:'10

~

~

a:

21)

I-+tltHUH+tH• .w

0.003 I-+ItIIHHtltHlII100
10

100

lk

10k

lOOk

1M

lk

10k

lOOk

1M

FREQUENCY (HZ)
TLlH/12D78-25

FREQUENCY (Hz)
TL/H/12D78-44

2-184

r-----------------------------------------------------------------------------, ."
r
Typical Performance Characteristics (Continued)
Unless otherwise specified:'TA = 25°C, V,N = VO(NOM) + W, COUT = 2.2 ,...F, all voltage options, ON/OFF pin tied to V,N.
Output Noise Density

Output Impedance vs
Frequency

10,------,------,-----,
I, = 50 rnA, <:OUT = IOI'F

30

~

10

...
z

3

~
....
::::>
....D..
::::>

0.1

'-'

...

...

a

:!

0.1

z

I, = 50 rnA, COUT = 2.2 I'F

0

0.0 1 " -____- L______- ' -____
100

1000

10000

0.3
0.03
0.01
0.003

~

100000
10

FREQUENCY (Hz)

100

lk

TUH/1207B-27

10k

lOOk

1M

FREQUENCY (Hz)
TUH/12078-26

Input to Output Leakage
vs Temperature

'<
-S

4

.....
'"

3

...~

1200

JI !

VON/OFF = 0
OUTPUT CONNECTED TO GND VIN = 6V.

5

Output Reverse Leakage vs
Temperature

t--

.3

....
""::::>""

...z

I
I

~

....
::::>

'-'

D..

....::::>

D..
....
::::>

LI

0

0
-50 -25

0

25

50

1000

800

\

1\

"

'"iiiz

~

....::::>

ON/OFF AND YIN PINS FLOATING.
VOUT CONNECTED TO 5V ACTIVE SOURCE.

'<

~ i'..

600

r-... r--....

0

400
-50 -25

75 100 125 "50

TEMPERATURE (DC)

0

25

50

75 100 125. 150

TEMPERATURE (DC)
TL/H/12078-29

Turn·On Waveform
5

-

Turn·Off Waveform

VOUT = 5V
~ = 5k

VOUT (v)

,

VOUT = 5V

VOUT (v)

\

I

II
o

~ =5k

\

r\.

I

VON/OFF (v)
5V

\

.......

~

.......

VON/OFF (v)

5

ov

ov
20I's/d;v-

U

I
10ms/d;v-

TUH/1207B-30

TL/H/12078-31

2·185

N

CD
CO

o

Q
CD
G)
('II

~

r-------------------------------------~----------------------------~

TABLE II_ Surface-Mount Tantalum capacitor
Selection Guide

Typical Performance
Characteristics (Continued)
Unless otherwise specified:
TA = 25°C, VIN = VO(N...QMl + 1V, COUT = 2.2 p.F,
all voltage options, ON/OFF pin tied to VIN.
ON/OFF Ph1 Current vs
VON/OFF
10

1 p.F Surface-Mount Tantalums
Manufacturer

Part Number

Kemet

T491A105M010AS

NEC

NRU105M10

Siemens

945196-E3105-K

Nichicon

F931C105MA

Sprague

2930105X0016A2T

2.2 p.F Surface-Mount Tantalums
Manufacturer

/'
/

7

o I
o

4

B

10

12

14

16

VON/orr (V) ,
TL/H/1207B-45

Application Hints
OUTPUT CAPACITOR
Like any low-dropout regulator, the LP29BO requires an output capacitor to maintain regulator loop stability. This capacitor must be selected to 'meet the requirements of minimum
capacitance and equivalent series resistance (ESR) range.
It is not difficult to find capaCitors which meet the' criteria of
the LP29BO, as the acceptable capacitance and ESR
ranges are wider than for most other LOOs.
In general, the capaCitor value must be at least 1 p.F (over
the actual ambient operating temperature), and the ESR
must be within the range indicated in Figures 1, 2, and 3. It
should be noted that, although a maximum ESR is shown in
these Figures, it is very unlikely to find a capacitor with ESR
that high.
Tantalum CapaCitors
Surface-mountable solid tantalum capaCitors offer a good
combination of small physical size for the capaCitance value, and ESR in the range needed by the LP29BO.
The results of testing ,the LP29BO stability with surfacemount solid tantalum capaCitors show good stability with
values of at least 1 p.F. The value can be increased to
2.2 p.F (or more) for even better performance, including
transient response and noise.
Small value tantalum capacitors that have been verified as
suitable for use with the LP29BO are shown in Table II. Capacitance values can be increased without limit.
Aluminum Electrolytic CapaCitors
Although probably not a good choice for a production design, because of relatively large physical size, an aluminum
electrolytic capaCitor can be used in the design prototype
for an LP29BO regulator. A value of at least 1 p.F should be
used, and the ESR must meet the conditions of Figures 1, 2,
and 3. If the operating temperature drops below OOC, the
regulator may not remain stable, as the ESR of the aluminum electrolytic capacitor will increase, and may exceed the
limits indicated in the Figures.

Part Number

Kemet

T491 A225M01 OAS

NEC

NRU225M06

Siemens

945196/2.2/10/10

Nichicon

F930J225MA

Sprague

2930225X0010A2T

Multilayer Ceramic CapaCitors
Surface-mountable multilayer ceramic capacitors may be an
attractive choiqe because of their relatively small physical
size and excellent RF characteristics. However, they sometimes have ESR values lower than the minimum required by
the LP29BO, and relatively large capaCitance change with
temperature. The manufacturer's datasheet for the capacitor should be consulted before selecting a value.
Test results of LP29BO stability using multilayer ceramic capaCitors show that a' minimum value of 2.2 p.F is usually
needed for the 5V regulator. For the lower output voltages,
or for better performance, a higher value should be used,
such as 4.7 p.F. '
Multilayer ceramic capacitors that have been verified as
suitable for use with the LP29BO are shown in Table III.
TABLE III. Surface·Mount Multilayer CeramiC CapaCitor
Selection Guide

:u p.F Surface-Mount Ceramic
Manufacturer

Part Number

Tokin

1E225ZY5U-C203

Murata

GRM42-6Y5V225Z16
4.7 p.F Surface·Mount Ceramic

Manufacturer
Tokin

Part Number
1E475ZV5U-C304

.-"tJ

Application Hints (Continued)

N

co

REVERSE CURRENT PATH
The power transistor used in the LP2980 has an inherent
diode connected between the regulator input and output
(see below).

100l11li

CD

o

r---I

u

=>
~
=>

,

.0

.9

z

0

'""

~

~

i'..

~

100

a

-50 -25

25

50

1. . . . .

"

I--

~,
~o

0.2

~z

..... ~ r'\

I
,
},

1.0
0.5

a

I"-~

1.00

0.951-+-1-+-1-+-1--l

o

a

0.9 L-..L-L-,-L-..L-L_L.....J
-50 -25 0
25 50 75 100 125

10 20 30 40 50 80 70 80 90 100
TA - AMBIENT TEMPERATURE (Oc)

TA - AMBIENT TEMPERATURE (OC)

Output Transistor Emitter
Voltage

Reference Transistor
Peak Output Current
125

VIN = 20V

I

I~UT = ~OO ~A

~

~ i---'"

~
t:

lS.6

I-- r-llJmA

,Je'

0

25

50

75

100

125'

'<

~

18.2

17.8

1-

l/

-50 -25

z

~

0

25

50

75

100

u

~

=>

~,
_0.

50

Standby Current
vsVoltage

o
-so

125

7.0

.I.

.-r.....

-25

a

25

50

6.0 I-+--t--If-+-+-I--l--l

V

5.0 I--II--I.......-l.....
~..--+-+-+-I
1"'- ......

Y,N = 40V -If-+-+""'!.........
::-+--i

4.0 'OUT REf = a mA +-+-jf-+.....
"'

..... 1---'"
...... ~E=-50mA
I

V

100

~

7

i3,

I

-50 -25

~

i5
mA

V
V

~

~

T

I
r'OUT = 20

RT = 5.6 kn
CT=O.OOI!'

1.05

19.0

1.5

0

3.30 rVcc'Ncc=f-2::-:0c.JV-+-+-+--+--l

i'1'-., r'\

Output Transistor
Saturation Voltage

2.0

°I::::t=j:::::j:;;:;;r't-j-l

3.35 f--t--t--t--t--t--t--I

0JA = B6°e/w, N PACKAGE

100 125

2.5

~

3. 4

f'.

0.6

TA - AMBIENT TEMPERATURE. (Oc)

~

1"-

0.8

0.4

3.45 r---,--,---,--,---,--,--,

= 125°C/W. M PACKAGE

~

75

Maximum & Minimum
Duty Cycle Threshold
Voltage

Maximum Average Power
Dissipation (N, M Packages)

75 100 125

TA- AMSIENT TE"PERATURE (OC)

~

200

~
~
~

z

·190

,

~

>u

. / I---'"

i---'"

./

l.- I--

I---'"

ISO
170
,-50 -25

a

25

50

75

100

125

TA-AMBIENT TEMPERATURE (OC)

TLiH/8650-3

3-14

r

s:
N

Test Circuit

CJ1
N

V,N

"'"

B-40V

2.
lW

~
02,.!!

Co

r

s:
w

"
} OUTPUTS

VIN

CA

LM2524D/LM3524D

OSC OUT

Nl

INV

2

INPUT

CQMP

-0'
2.

L...+

10k

2.

SHUT
DOWN

'Cl
SENSE

10

4

2k

-Cl

,

SENSE

.!!..

EA

.!!....

,

CT

AT
6

GNO
7

12

EO
VREF
INPUT

0.1 PF::::

C
......

2k
lW

CJ1
N

"'C"

AT

10k

:':=.CT

~1k ~

GNO

TLIH/8650-4

Functional Description
If two or more LM35240's must be synchronized together,
the easiest method is to interconnect all pin 3 terminals, tie
all pin 7's (together) to a single CT, and leave all pin 6's
open except one which is connected tei a single RT. This
method works well unless the LM35240's are more than 6"
apart. .

INTERNAL VOLTAGE REGULATOR
The LM35240 has an on-chip 5V, 50 mA, short circuit protected voltage regulator. This voltage regulator provides a
supply for all internal circuitry of the device and can be used
as an external reference.
For input voltages of less than SV the 5V output should be
shorted to pin 15, VIN, which disables the 5V regulator. With
these pins shorted the input voltage must be limited to a
maximum of 6V. If input voltages of 6V -SV are to be used, a
pre-regulator, as shown in Figure 1, must be added.

A second synchronization method is appropriate for any circuit layout. cine LM35240, deSignated as master, must
have its RTCT set for the correct period. The other slave
LM35240(s) should each have an RTCT set for a 10% longer period. All pin 3's must then be interconnected to allow
the master to properly reset the slave units.
The oscillator may be synchronized to an external clock
source by setting the internal free-running oscillator frequency 10% slower than the external clock and driving pin 3
with a pulse train (approx. 3V) from the clock. Pulse width
should be greater than 50 ns to insure full synchronization.

TL/H/8650-10

*Minimum Co of 10 p..F required for stability.

100
50

FIGURE 1
OSCILLATOR

The LM35240 provides a stable on-board oscillator. Its frequency is set by an external resistor, RT and capacitor, CT.
A graph of RT, CT vs oscillator frequency is shown is Figure
2. The oscillator's output provides the signals for triggering
an internal flip-flop, which directs the PWM information to
the outputs, and a blanking pulse to turn off both outputs
during transitions to ensure that cross conduction does not
occur. The width of the blanking pulse, or dead time, is controlled by the value of CT, as shown in Figure 3. The recommended values of RT are 1.S k!1 to 100 k!1, and for CT,
0.001 poF to 0.1 poF.

111_
CT - 0.001

~F

RCT =0.002 ~F
CT =0.005 ~F

1

2

5 10 20

50 100200 500 Ik

OSCILLATOR PERIOD {psi
TL/H/8650-5

FIGURE 2

3-15

•

cr-----------------------------------------------------------------,

&i

Functional Description

(Continued)

ell)

:5

10

;:.

i.....

The duty cycle is calculated as the percentage ratio of each
output's ON-time to the oscillator period. Paralleling the outputs doubles the observed duty cycle.

VCC'2DV
TA -2S·C

j

50

w

/.

.:Ii

;::

:&

'"cw
'"
!;
I!:
::0

i--'

40

§:

...........

DA

'"

>
>
I-

0.1

D.DOI

D.DD4

0.01

D.D4

::>

30
20

'"

0.1

cTIIIFI

10
TL/H/B650-6

FIGURE 3

D

ERROR AMPLIFIER
The error amplifier is a differential input, transconductance
amplifier. Its gain, nominally 86 dB, is set by either feedback
or output loading. This output loading can be done with either purely resistive or a combination of resistive and reactive components. A graph of the amplifier's gain vs output
load resistance is shown In Figure 4.

z
C

RL = lOOk.

'" .
....
·40

" ......
"

RL =30k

'".....c
CI

>

'.

~

I-

20

~

\
RL = RESISTANCE FRDM PIN 9,
TD GND
'

0
10

100

lk

10k

lOOk

FREQUENCy'IHz)'

~

1M

2

2.5

3

3.5

4
TL/H/6650-B

CURRENT LIMITING
The function of the current limit amplifier is to override the
error amplifier's output and take control of the pulse width.
The output duty cycle drops to about 25% when a current
limit sense voltage of 200 mV is applied between the + CL
and -CLsense terminals: Increasing the sense voltage approximately 5% results in a 0% output duty ·cycle. Care
should be taken to ensure the -0.7V to + 1.0V input common-mode range is not exceeded, .
In most applications, the current limit sense voltage is produced by a current through a sense resistor. The accuracy
of this measurement is limited by the accuracy of the sense
resistor, 'and by a small offset current, typically 100 p,A,
flowing from + CL to - CL.

RL = 1M ""
RL =~OOk

1.5

FIGURES
The amplifier's inputs have a common-mode input range of
1.5V-5.5V. The on board regulator is useful for biasing the
.
inputs to within this range.

80
60

/

VDL TAGE DN PIN 9 IV)

RL=CO
iii
:!!

/
1

/

/

10M·

OUTPUT STAGES
The outputs of the LM3524D are NPN transistors, capable
of a maximum current of 200 mAo These transistors are driven 180" out. of phase and have non-committed open collectors and emitters as shown in Figure 6.

TL/H/6650-7

FIGURE 4
The output of the .amplifier, or input to ttle pulse width modulator, can be overridden easily as its output impedance is
very high (Zo "" 5 MO). For this reason a DC voltage can
be applied to pin 9 which will override the error amplifier and
force a particular duty cycle to the: outputs. An example of
this could be a non-regulating motor speed control where a
variable voltage was applied to pin 9 to control motor speed.
A graph of the output duty cycle vs, the voltage on pin 9 is
shown in Figure 5.

OUTPUT _ ..._ _-\

ENABLE

',.

PWM--.......,

Ea
TLlH/B650-9

FIGURE 6

;

,:

:.'

3-16

r-----------------------------------------------------------------------------,
Typical Applications

~

iii:
N
en

.......
N

C

VINo----------------,

Design Equations

RF~ 5k(VO
-I)
2.5

PIN 1

fOSC .. - I-

5k

L1 ~ 2.5VIN2 (Vo - VIN)
fosclo Vo2

RM

5k
Lt.t3524D

I---1H~"+-""'OVO

Co~ lo(Vo-VIN)
fOSC~Vo Vo

VIN
lo(MAX) ~ liN Vo

------_+-.....--.....

....

_oGND

TUH/8650-11

FIGURE 7. Positive Regulator, Step-Up Basic Configuration (IIN(MAX) = 80 mAl

+

Co

GNDo-~~.....-

...
N

•

5k t----IINV

GNDo-~~.....-

~

iii:
Co)
en

------_+-.....

....- ....

____4~_+-

....

_oGND

FIGURE 8. Positive Regulator, Step-Up Boosted Current Configuration

3-17

TL/H/8850-12

C

C

~

r---~------------------------------~----------------~----------~----'

Typical Applications

(Continued)

Cf)

:!j

o...
C'\I

~

~

Design Equations

Rr

VINo-.....,-If----:---....:.......,----...,

= 5 kll

RF

PIN 1

(Va - 1)
2.5

Current Limit
SenseVol1

VR
VIN

LM35240

108C .. - 1-

RrCT

EB
CB

Ll

Vol

10 VIN10SC

Ll

CA
EA t-...-

= 2.5Vo (YIN -

Co = (YIN -

.....-rTTln-+--o Vo

SO
COMP

Vol VoT2

8 AVo VINL1
10(MAX) = liN VIN

Va

+

Co

01

~--~-...------~~-...---~__oGNO

TO -CL PIN

TO +CL PIN

TLIH18650-13

FIGURE 9. Positive Regulato'r, Step-Down Basic Conflgliratlon (iIN(MAX) = 80 mAl

Rr

VINo---+-------.:......--.....,_............~

_..J"'r't"Y"'-_-"

Vo

L1

01

+

Co

~_-.-~~-----~~~-----~---~-oGNO

FIGURE 10. Positive Regulator, Step-Down Boosted Current Configuration

3-18

TUH18650-14

r-----------------------------------------------------------------------------~r

i:

Typical Applications (Continued)

N
UI
N

RF
VINo----.....- - - - - . , ; . - - - -....-

....---.

" (1-....2.
V)

AF=5k

5k

"'o"
.....
r

Design EquatlDns

•

i:

Co)

2.5

PIN 1

UI
N

10SC",_I-

o"'"

AM

....--1-'-i---i INV
5k L..-...._-I

L1 =

"".""'0 V
o C=
o

Lt,435240

2,5VIN Vo

losc IV0 + VIN) 10
loVo

AVo losc (Vo

+ VIN)

GNO

GNOo-~~~~~-------------~~~--~--~_oGNO

TL/H/8650-15

FIGURE 11. Boosted Current Polarity Inverter
BASIC SWITCHING REGULATOR THEORY
AND APPLICATIONS
The basic circuit of a step-down switching regulator circuit is
shown in Figure 12, along with a practical circuit design using the LM35240 in Figure 15.
VA
VIN

L1

-

VO
10

IL

v~[

The circuit works as follows: 01 is used as a switcl), which
has ON and OFF times controlled' by the pulse width modulator: When 01 is ON, power is drawn' from VIN and supplied
to the load through L1; VA is at approximately VIN, 01 is
reverse biased, and Co is charging. When 01 turns OFF the
inductor L1 will force VA negative to keep the current flowing in it, 01 will start conducting and the load current will
flow through 01 and L1. The voltage at VA is smoothed by
the L1, Co filter giving a clean DC olitput. The current flowing through L1 is equal to the nominal DC load current' plus
some all which is due to the changing voltage across if A

good rule of thumb is to set ahp_p 's< 40%

01

x 10-

TUH/8650-16

FIGURE 12. Basic Step-Down Switching Regulator

... OV

I-I'--T~
FIGURE 13

3-19

. TUH/8650-17

Qr-------------------~--------------------------------------------,

~

Typical Applications (Continued)

~

From the relation Vl = L

(II)

e
N

an

N

:i

VlT
dj
dt'
all"" U

Solving the above for L1
L1 =2.5Vo (VIN-Vo)
10 VINf

al + = (VIN - Vo)tON. al _ = Vo toFF
,l L 1
'l
L1
Neglecting VSAT, Vo, and settling ~Il + = all, -;

V "" V (toN
o - IN tOFF + toN

where: L1 is in- Henrys
f is switching frequency in Hz
Also, see LM1578 data sheet for graphical methods of inductor selection.

= VIN (toTN);

where T = Total Period
The above shows the relation between VIN, Vo and duty
cycle.
IIN(OC) = IOUT(OC) (toN

CALCULATING OUTPUT FILTER CAPACITOR Co:
Figure 14 shows L1's current with respect to 01's toN and
tOFF times. This curent must flow to the load and Co. Co's
current will then be the difference between Il' and 10,
Ico = Il -10
From Figure 14 it can be seen that current will be flowing
into Co for the second half of toN through the first half of
tOFF, or a time, tON/2 + tOFF/2. The current flowing for this
time is all/4. The resulting aVe or aVo is described by:

~NtoFF)'

as 01 only conducts during toN'
PIN = IIN(OC) VIN = (lo(OC)(toN

~NtoFF) VIN

Po = 10Vo
The efficiency, 'II, of the circuit is:

aV
=.!. x all
oP-PC4

- Po .:..
10Vo
'II'MAX PIN
I (tON) V + (VSAT tON 'I- V01 t OFF) I
o'T' IN
T'
0
= I

Vo

VO '+

x

(toN +toFF)
22

= all (tON + tOFF)
4C
2
Since all = Vo(T,- tON) and' toN = VoT
L1
VIN

IforVSAT = V01 = 1V.
1
-

( T VoT)
V
= Vo
a op-p
4C L1 _

ViN

'IIMAX will be further decreased due to switching losses in
01. For this ~eaSon 01 should be selected to have the maximum possible fT, which implies very fast rise and fall times.

(!)2 = (VIN8VINC
- Vol VoT2 or
oL1

Co = (VIN - Vol Vo T2
8aVoVINL1

CALCULATING INDUCTOR L 1
(all +) x L1
(all -) x L1
toN'" (V
V),tOFF =
V
IN - 0
0
(all +) x L1
(all -) x L1
toN+tOFF=T=(V
V)+
V
IN - Q
0
= 0.410L1 + 0.410L1
(VIN - Vol
Vo
Since all + ,= all - = 0.41 0

1
. h' f
Ing requency
avo is p~p output ripple
For best regulation, the inductor's current cannot be allowed to fall to zero. Some minimum load current 10, and
thus inductor current, is required as shown below:

where: C is in farads, T is

10(MIN) =

VA

AIL·

(COUECTOR
or PNP)

=

SWltc

(VIN - Vo)tON
2L1

(VIN-VO)toN

I~

l1

~

O~~_Io(MIN)

TUH/8650-1a

FIGURE 14

TL/H/8650-1e

3-20

.-----------------------------------------------------------------------------'r
s:::

Typical Applications (Continued)

N

A complete step-down switching regulator schematic, using
the LM3524D, is illustrated in Figure 15. Transistors 01 and
02 have been added to boost the output to 1A. The 5V
regulator of the LM3524D has been divided in half to bias
the error amplifier's non-inverting input to within its common-mode range. Since each output transistor is on for half
the period, actually 45%, they have been paralleled to allow
longer possible duty cycle, up to 90%. This makes a lower
possible input voltage. The output voltage is set by:
Vo = VNI (1

where VNI is the voltage at the error amplifier's non-inverting input.

s:::

200 mV = 200 mV = 1.3A.
R3
0.15

Co)

Figure 16 and 17 show a PC board layout and stuffing diagram for the 5V, 1A regulator of Figure 15. The regulator's
performance is listed in Table I.

~

C

+ :~),

RIO
~ R9

R4
5k

r=~

""

~
r

Resistor R3 sets the current limit to:

LI

RI
5k

C4 n
10~
C3
0.1 ~r

en

N

R5
5k

I

R2
5k

~

15
16

'Y

2
I

R6
6.5k

6
CI
o·W· r

7

II

C2

500~H

VREF

VIN

NI

EA

INY

CB
LM3524D

Ry

EB

9

R7
30k

12

GND

-CL

f=20k Hz
Q2

R8
510
•••.1

.... ,

II

....

13

C5=:-1

o.l~r-~
500~r

14
~r DI

+CL ~

Cy

~ COMP

O.OI~F=~

CA

Vo=5 V

~ ~@lo=1 A

A~ MR850

~

8
GND
R3
0.15

RETURN
TLiH/8650-20

'Mounted to Staver Heatsink No. V5-1.

01

= 80344

02 = 2N5023
L1 = >40 turns No. 22 wire on Ferroxcube No. K300502 Torroid core.

FIGURE 15. 5V, 1 Amp Step-Down Switching Regulator

•
3-21

c ,-----------------------------------------------------------------------,

~
:::E
....

Typical Applications (Continued)

C")

Q
~
an
C"I

:s

TABLE I
Parameter
Output Voltage
Switching Frequency
Short Cifcuit
Current Limit
Load Regulation

Conditions

= 10V,Io = 1A
= 10V, 10 = 1A
VIN = 10V

VIN
VIN

= 10V
= 0.2 -1A
AVIN = 10 - 20V,
10 = 1A
VIN = 10V, 10 = 1A
VIN = 10V, 10 = 1A
VIN

10

Line Regulation
Efficiency
Output Ripple

Typical
Characteristics
5V
20kHz
1.3A
3mV
6mV
80%
10mVp-p

TLIH18650-21

FIGURE 16. 5V, 1 Amp Swl~chlng Regulator, Foil Side

TLlH18650-22

FIGURE 17. Stuffing Diagram, Component Side

3-22

,-----------------------------------------------------------------------------'r
s::
Typical Applications (Continued)

N

THE STEP-UP SWITCHING REGULATOR

N

en

"'C"
......

Figure 18 shows the basic circuit for a step-up switching
regulator. In this circuit 01 is used as a switch to alternately
apply VIN across inductor L 1. During the time, tON, 01 is ON
and energy is drawn from VIN and stored in L1; D1 is reverse biased and 10 is supplied from the charge stored in Co.
When 01 opens, toFF, voltage V1 will rise positively to the
point where D1 turns ON. The output current is now supplied through L 1, D1 to the load and any charge lost from Co
during toN is replenished. Here also, as in the step-down
regulator, the current through L 1 has a DC component plus
some all. all is again selected to be approximately 40% of
Il. Figure 19 shows the inductor's current in relation to 01 's
ON and OFF times.

!i:w

en
N

"'C"
t---~I+--'---~~Vo

10

TL/H/8650-23

FIGURE 18. Basic St~p-Up Switching Regulator

""'Vo- - -....

Vl

""'ov ______ b--:~N--~·I~·-~rr-1~

I.

·1

T

_________
TL/H/8850-24

FIGURE 19

II

3-23

Typical Applications (Continued)
From AIL =
an

VLT

T' AIL +

F~om Vo =

VINtoN
"'---u-

VIN ( 1 +

~;F.)'

......--,

,--'--

d AI - '" (Vo - VIN) toFF '
L
L1

Since AIL + = AIL -, VINtON,='VotoFF - VINtOFF,
This equation assum~s only 'DC losses, ,however '''IMAX is
further decreased because of, the ~wiii:hing time of 01 and
01." '
,
.

and neglecting VSAT and VOl
Vo ""VIN (1 + ttON)
,
OFF

In calculating the output capacitor Co it can be seen that Co
supplies 10 during tON. The voltage change on Co during this
time will be some AVe =, AVo or ,the output ripple of the
regulator. Calculation of Co is:

The above equation show~ 'the relationship betweeM VIN, Vo
and duty cycle.
In calculating input current IIN(06), which equals the inductor's DC current, assume first 100% efficiency:
,

AV = 10toN or C = 10toN
o
Co
0
AVo

PIN = 'iiN(oC) VIN'
From Vo = VIN (to:F): toFF =

POUT = 10Vo = 10 VIN (1 + toN)
"
tOFF
for "I = 100%,POUT ':'" P'IN,

where T = toN + tOFF =

10 VIN (1 + toN) .;, IIN(CC) VIN'
toFF
IIN(DC) = 10 ( 1 +

t:~~)

,

Volo

-V-ol-o-+~I~IN-(-lV)-

AVo

where: Co is in farads, f is the switching frequency,
AVo is the pop output ripple

(~)

Calculation of inductor L1 is as follows:
L1 = VINtO
+N, since during tON,
AIL
VIN is applied across L1
AILp.p = O.4IL = 0.41 liN = 0.41 0

(~~), therefore:

VINtON
T (VO - VIN)
L1=
(Vo) and since tON =
Vo
0.410 -V
IN

Volo
V 10 + 10 (1 + tON)
o

,loT(~)
Co =

So far it is assumed "I = 100%.. where the actual efficiency
or "IMAX will be somewhat less due to the saturation voltage
of 01 and forward on voltage of 01. The internal power loss
due to these voltages is the average IL current flowing, or
liN, through either VSAT or VOl. For VSAT = VOl = 1V this
power loss becomes IIN(OC) (1 V). "IMAX is then:
Po
AMAX = PIN =

f

toN = T - VIN T = T(VO - VIN) therefore:
Vo
Vo

This equation shows that the input, or inductor, current is .
larger than the output current by the factor (1 + toN/toFF).
Since this factor is the same as the relation between Vo and
VIN, liN (DC) can also be expressed as:
IIN(OC) = 10

~: T

1

tOFF

where: L1 is in henrys, f is the switching frequency in Hz

3-24

Typical Applications (Continued)
To apply the above theory, a complete step-up switching
regulator is shown in Figure 20. Since VIN is 5V, VREF is tied
to VIN. The input voltage is divided by 2 to bias the. error
amplifier's inverting input. The output voltage is:

Your = (1

+ :~)

x VINV = 2.5 X (1

circuit the inductor may saturate at turn-on because it has to
supply high peak currents to charge the output capacitor
from
It should also be noted that this circuit has no
supply rejection. By adding a reference voltage at the noninverting input to the error amplifier, see Figure 21, the input
voltage variations are rejected.

av.

+ :~)

The LM35240 can also be used in inductorless switching
regulators. Figure 22 shows a polarity inverter which if connected to Figure 20 provides a -15V unregulated output.

The network 01, C1 forms a slow start circuit.
This holds the output of the error amplifier initially low thus
reducing the duty-cycle to a minimum. Without the slow start

Ll

R2
12k

.....

~

00.510

'02'
MRS50

240

2k

VO=15V

~345

VREF

IN9148

VIN

CA

R4
Uk
NI

+

R3
Uk

Rl
2.4k

5/01F=:
==
O.lJo1F

INV

......
......

~2210
lk

CB~

+

LM35240

O.I/o1F:=

E"

== 5OO/olF

3k

Ea

RT

01

1~14

O.~~/oIF
II

Cr

GND

......

COMP
~50k

f

=~Cl
5/o1F

o.oOl/o1F

GNO

GND
TL/H/8650-25

L1 = > 251ums No. 24 wire on Ferroxcube No. K300502 Torrold core.

FIGURE 20. 15V. 0.5A Step-Up SWitching Regulator

100

FROM JUNcnON~I-"'-foI1II-_",,,,,,_-o-15V
OF Ll, 02~
@25mA

TO NON-INVERTING
INPUT OF LM3524

+100/olF
GNOo---....-----4~...-_oGND
TL/H/8650-27

FIGURE 22
TLlH/8650-26

FIGURE 21

3-25

Qr-------------------------------------------------------~
~

N

an
('I)
:E

Connection Diagram

,.,.,,'

'r"

....

Q

1&'

IN)/INPUT

~

N

an

~IINPUT:

:i

OSC OUTPUT

N

"

2

..

,.

i.'

,.

,

VREF ,
f

Order Number LM2524DN or LM3524DN
See NS Package Number N16E
"

'l

15 Y,N

Order Number LM3524DM
Stie NS Package Number M16A

';

+ CL SENSE
,.

COLLECTOR A

-CL SENSE

11 EMITTERA

RT
CT

COMPENSATION '

GNO

TL/H/B650-ii

Top VIew,

",

3-26

.

tfI Nat ion a I

S. em i con due to r

LM2574/LM2574HV Series
SIMPLE SWITCHERTM O.SA Step-Down Voltage Regulator
General Description

Features

The LM2574 series of regulators are monolithic integrated
circuits that provide all the active functions for a step-down
(buck) switching regulator, capable of driving a 0.5A load
with excellent line and load regulation. These devices are
available in fixed output voltages of 3.3V, 5V, 12V, 15V, and
an adjustable output version.
Requiring a minimum number of external components,
these regulators are simple to use and include internal frequency compensation and a fixed-frequency oscillator.
The LM2574 series offers a high-efficiency replacement for
popular three-terminal linear regulators. Because of its high
efficiency, the copper traces on the printed circuit board are
normally the only heat sinking needed.

• 3.3V, 5V, 12V, 15V, and adjustable output versions
II Adjustable version output voltage range,
1.23V to 37V (57V for HV version) ±4% max over line
and load conditions
• Guaranteed 0.5A output current
• Wide input voltage range, 40V, up to 60V
for HV version
• Requires only 4 external components
• 52 kHz fixed frequency internal oscillator
• TTL shutdown capability, low power standby mode
• High efficiency
• Uses readily available standard inductors
• Thermal shutdown and current limit protection

A standard series of inductors optimized for use with the
LM2574 are available from several different manufacturers.
This feature greatly simplifies the design of switch-mode
.power supplies.
Other features include a guaranteed ±·4 % tolerance on output voltage within specified input voltages and output load
conditions, and ± 10% on the oscillator frequency. External
shutdown is included, featuring 50 /LA (typical) standby current. The output switch includes cycle-by-cycle current limiting, as well as thermal shutdown for full proteeliol') under
fault conditions.

Typical Application

Applications
•
•
•
•

Simple high-efficiency step-down (buck) regulator
Efficient pre-regulator for linear regulators
On-card switching regulators
Positive· to negative converter (Buck-Boost)

(Fixed Output Voltage Versions)

GOY Max

Unreguillted -

" Regulated

......-...;;:.!

DC Input

~"""'~~....rlJlJ'IP"-+--- Output
O.5A Load

.......-:--r::--.,..;'

TL/H/11394-1

Nole: Pin numbers are for a·pin DIP package.

Connection Diagrams
8"Le~d

14..Lead Wide
Surface Mount (WM)

DIP (N)

Fa 1 •

8 ,

, . 4INo internal
connection, but

SIG GND 2

7 OUTPUT

should be soldered

ON/OFF 3

6 ,

.to PC board for

PWRGND '

5 VIN

best heat transfer.

.1.

14,

, 2

13,

Fa 3

12 OUTPUT
11,

SIGGND 4
TL/H/11394-2

II

10 VIN

ON/OFF 5

Top View

g. ,

PWRGND 6

8 ,

Order Number LM2574.. 3.3HVN, LM2574HVN.. 5.0,
LM2574HVN ..12, LM2574HVN .. 15, LM2574HVN..ADJ,
LM2574N ..3.3, LM2574N ..5.0, LM2574N.. 12,
LM2574N ..15 or LM2574N ..ADJ
See NS Package Number N08A

TUH/11394-3

Top View
Order Number LM2574HVM..3.3, LM2574HVM .. 5.0,
LM2574HVM ..12, LM2574HVM.. 15, LM2574HVM..ADJ,
LM2574M..3.3 LM2574M ..5.0, LM2574M .. 12,
LM2574M .. 15 or LM2574M ..ADJ
See NS Package Number M14B

Patent Pending

3-27

Absolute Maximum Ratings (Note 1)
Minimum ESD Rating
(C = 100 pF, R = 1.5 kn)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Maximum Supply Voltage
LM2574
LM2574HV
C>N/OFF Pin Input Voltage
Output Voltage to Ground
(Steady State)

45V
63V
-0.3V

~

~

V

2600C

Maximum Junction Temperature

1500C

Operating Ratings

+VIN

Temperature Range
LM2574/LM2574HV
Supply Voltage
LM2574
LM2574HV

-1V

Power Dissipation
Storage Temperature Range

2kV

Lead Temperature
(Spldering, 10 seconds)

Internally Limited
..,.65·C to + 150'C

-400C

~

TJ

~

+ 125'C
40V
SOV

LM2574-3.3, LM2S74HV-3.3
,

','

Electrical Characteristics Specifications with standard type face are for TJ = 25'C, and those with boldface
type apply over full Operating Temperature Range.

Symbol

Parameter

LM2574-3.3
. LM2574HV-3.3

Conditions

Typ

Limit
(Note 2)

Units
(Limits)

SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
VOUT

Output Voltage

VIN

= 12V,ILOAD ~

100 mA

3.3
3.234
3.366 .

VOUT

VOUT

'1/

~

VIN ~40V, 0.1A ~ ILOAD ~ O.SA

Output Voltage
LM2574

4.75V

Output Voltage
LM2574HV

4.75V ~ VIN ~ 60V, 0.1A ~ ILOAD ~ O.SA

Efficiency

VIN

= 12V,ILOAD = 0.5A

3.3

V
V(Min)
V(Max)

3.168/3.135
3.432/3.485

V
V(Min)
V(Max)

3.168/3.135
3.450i3.482

V(Min)
V(Max)

3.3

72

%

LM2574-5.0, LM2574HV-5.0
Electrical Characteristics Specifications with standard type face are for TJ
type apply over full Operating Temperature Range.
Symbol

Parameter

= 25'C, and those with boldface

LM2574-5.0
LM2574HV-5.0

Conditions
Typ

Limit
(Note 2)

Units
(Limits)

SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
VOUT

VOUT

VOUT

'1/

Output Voltage

VIN

=

12V,ILOAD

= 100 mA

Output Voltage
LM2574

7V ~ VIN ~ 40V, O.M ~ ILOAD ~ 0.5A

Output Voltage
LM2574HV

7V ~ VIN ~ 60V, O.IA ~ ILOAD ~ 0.5A

Efficiency

VIN

=

12V,ILOAD

= 0.5A

3-28

5
4.900
5.100

V
V(Mln)
V(Max)

4.800/4.750
5.200/5.250

V
V(Min)
V(Max)

4.800/4.750
5.225/5.275

V(Min)
V(Max)

5

5

77

%

r-

s:::
N

LM2574-12, LM2574HV-12

01

Electrical Characteristics

Specifications with standard type face are for TJ
type apply over full Operating Temperature Range.

Symbol

Parameter

=

25'C, and those with boldface

LM2574-12
LM2574HV-12

Conditions

Limit
(Note 2)

Typ

Units
(Limits)

~
rs:::

~::c
<

SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
VOUT

VOUT

VOUT

"1/

Output Voltage

VIN

=

25V, ILOAD

=

100 mA

Output Voltage
LM2574

15V,;; VIN ,;; 40V, 0.1A ,;; ILOAD';; 0.5A

Output Voltage
LM2574HV

15V ,;; VIN ,;; 60V, 0.1A ,;; ILOAD ,;; 0.5A

Efficiency

VIN

=

15V, ILOAD

=

0.5A

11.76
12.24

V
V(Min)
V(Max)

11.52/11.40
12.48/12.60

V
V(Min)
V(Max)

11.52/11.40
12.54/12.66

V(Min)
V(Max)

10

12

12

88

%

LM2574-15, LM2574HV-15

Electrical Characteristics

Specifications with standard type face are for TJ
type apply over full Operating Temperature Range.

Symbol

Parameter

=

25'C, and those with boldface

LM2574-15
LM2574HV-15

Conditions
Typ

Limit
(Note 2)

Units
(Limits)

SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
VOUT

VOUT

VOUT

"1/

Output Voltage

VIN

=

30V, ILOAD

=

100 mA

Output Voltage
LM2574

18V,;; VIN ,;; 40V, 0.1A ,;; ILOAD ,;; 0.5A

Output Voltage
LM2574HV

18V ,;; VIN ,;; 60V, 0.1A ,;; ILOAD ,;; 0.5A

Efficiency

VIN

=

18V, ILOAD

=

0.5A

15
14.70
15.30

V
V(Min)
V(Max)

14.40/14.25
15.60/15.75

V
V(Min)
V(Max)

14.40/14.25
15.68/15.83

V(Min)
V(Max)

15

15

88

%

•
3-29

LM2S74-ADJ, LM2S74HV-ADJ
Electrical Characteristics

Specifications with standard type face are for TJ = 2S'C, and those with boldface
type apply over full Operating Temperature Range. Unless otherwise specified, VIN = 12V, ILOAD = 100 mA.

Symbol

Parameter

LM2574-ADJ
LM2574HV-ADJ

Conditions

Limit
(Note 2)

Typ

Units
(Umlts)

SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
VFB

VFB

VFB

"'I

Feedback Voltage

1.230

VIN = 12V, ILOAD = tOO mA

Feedback Voltage
LM2S74

7V,;; VIN ,;; 40V, 0.1A,;; ILOAD';; O.SA
VOUT Programmed for SV. Circuit of Figure 2

1.230

Feedback Voltage
LM2S74HV

7V,;; VIN';; 60V,0.1A';; ILOAD';; O.SA
VOUT Programmed for SV. Circuit of Figure 2

1.230

Efficiency

VIN = 12V, VOUT = SV, ILOAD = O.SA

1.217
1.243

V
V(Min)
V(Max)

1.193/1.180
1.267/1.280

V
V(Min)
V(Max)

1.193/1.180
1.273/1.286

V(Min)
V(Max)

77

%

All Output Voltage Versions
Characterh:~tics Specifications with standard type face are for TJ = 2S'C, and those with boldface
type apply over full Operating Temperature Range. Unless otherwise specified, VIN = 12V for the 3.3V, SV, and
'Adjustable version, VIN = 2SV for the 12V version, and VIN = 30V for the 1SV version. ILOAD = 100 mA.

Electrical

Symbol

Parameter

Conditions

LM2S74-XX
LM2S74HV-XX

Units
(Limits)

Typ

Limit
(Note 2)
100/500

nA

47/42
S8/63

kHz
kHz(Min)
kHz(Max)

1.2/1.4

V
V(max)

93

%
%(Min)

0.7/0.65
1.6/1.8

A
A(Min)
A(Max)

DEVICE PARAMETERS
Ib '

Feedback Bias Current

Adjustable Version Only, VOUT = SV

SO

fo

Oscillator Frequency

(see Note 10)

S2

VSAT
DC
ICL

IL

10
ISTBY

Saturation Voltage
Max Duty Cycle (ON)
Current Limit

Output Leakage Current

Quiescent Current
Standby Quiescent
Current

Thermal Resistance
°JA
°JA
°JA
°JA
ON/OFF CONTROL Test Circuit Figure 2
VIH
VIL
IH
IlL

0.9

lOUT = O.SA (Note 4)
(NoteS)

98

Peak Current, (Notes 4, 10)

(Notes 6, 7)

Output = OV
Output = -1V
Output = -1V

(Note 6)

1.0

30

mA(Max)
mA
mA(Max)

10

mA
mA(Max)

200

p.A
p.A(Max)

2
7.S
S

ON/OFF Pin= 5V (OFF)

SO

N Package, Junction to Ambient (Note 8)
N Package, Junction to Ambient (Note 9)
M Package, Junction to Ambient (Note 8)
M Package, Junction to Ambient (Note 9)

92
72
102
78

ON/OFF Pin Logic
Input Level

VOUT = OV

1.4

2.2/2.4

V(Min)

VOUT = Nominal Output Voltage

1.2

1.0/0.8

V(Max)

ON/OFF Pin Input
Current

ON/OFF Pin = SV (OFF)

12
30

p.A
p.A(Max)

10

p.A
p.A(Max)

ON/OFF Pin = OV (ON)

3·30

'C/W

0

r-

==

Electrical Characteristics (Continued)

N

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: All limits guaranteed at room temperature (Standard type face) and at temperature extremes (bold type lace). All room temperature limits are 100%
production tested. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods. All limits are used
to calculate Average Outgoing Quality Level.
Note 3: External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the LM2574
is used as shown in the Figure 2 test circuit, system performance will be as shown In system parameters section of Electrical Characteristics.

Note 5: Feedback pin removed from output and connected to OV.
Note 6: Feedback pin removed from output and connected to +12V for the Adiustable. 3.3V, and 5V versions, and +25V for the 12V and 15Vversions, to force
the output transistor OFF.
Note 7: V,N = 40V (60V for high voltage version).
Note 8: Junction to ambient thermal resistance with approximately 1 square inch of printed circuit board copper surrounding the leads. Additional copper area will
lower thermal resistance further. See application hints in this data sheet and the thermal model in SWltchers Made SImple software.
Note 9: Junction to ambient thermal resistance with approximately 4 square inches of 1 oz. (0.0014 in. thick) printed circuit board copper surrounding the leads.
Additional copper area will lower thermal resistance further. (See Note a.)
Note 10: The oscillator frequency reduces to approximately 1a kHz in the event of an output short or an overload which causes the regulated output voltage to drop
approximately 40% from the nominal output voltage. This self protection feature lowers the average power dissipation of the IC by lowering the minimum duty cycle
from 5% down to approximately 2%.

Typical Performance Characteristics (Circuit of Figure 2)
Normalized Output Voltage

g
'"z

~

+0.8

+0.6
+0.4

-

=

ILOAD toO mA
Normalized at
_TJ =25 0 C

~

~

~

!5

~

-0.2
-0.4

~

.,.,.

+0.2

......

""

,

I---

1.2
1.0

~

0.8

D

0.6

-0.8
75

I

-o.~

o

Current Limit

I

10

YIN = 25Y

20

!5
1=
is

3D

1.2

--

0.9
0.8
0.7
-SO -25

0

25

50

~

40

SO

1.5

1.0

60

75

100 125

JUNCTION TEMPERATURE (OC)

.5

i
~

TJ =1 25OC

14

"

10

/

~OAD

~OAD

o

10

~

20

30

-

= 100 mA

o
-50 -25

0

25

50

75

100 125

INPUT VOLTAGE (V)

50

V,N = 40V

i

150

_i"'"'"

60

~

~

~

-

Viiil/OFF = 5V
100

!:i

~O

~

200

.3

~

= 500 mA

IWC= IOOmA
4

r- rr-

-r-4-.: -

0.5

JUNCTION TEWPERATURE (oC)

Ground PI"

~

= 500 mA

Standby
Quiescent Current

16

12

~OAD

I~I-

!5

~

-~8:~~:'~ !~

18
~

,.

15V

i5

~Nr = 0.211

Supply Current

1.3

1.0

a:

I
I

20

1.1

12V

~

m

,

L= 330 I'H

£

INPUT VOLTAGE (V)

1.4

i

r::;;:;:

3.3~. SV, ~ ADJ.

'r-- r-

I

JUNCTION TEMPERATURE (oC)

3:

I

V

-0.2

100 125

=25°C

~ 'd-

o
-0.6

50

TJ

~
~I

o.~

i
25

Dropout Voltage
2.0

_~OAD= 100m~

0.2

-0.6
-1.0
-50 -25 -0

Line Regulation
I.~

I

V,N =20V

50

1-

-

-

VIN = 12Y

o
-50 -25

0

25

SO

75

100 125

JUNCTION TEMPERATURE (Oc)

TLlH/11394-17

3-31

.......

r-

==

N
CJ't

.....
.a:o.

::J:

<

Note 4: Output pin sourcing current. No diode, inductor or capacitor connected to output pin.

+1.0

CJ't
.....
.a:o.

Typical Performance Characteristics (Circuit of Figure 2) (Continued)
Switch Saturation
Voltage

Oscillator Frequency
1.3

Normalized at 25°C

g

s~
~

I

/' 1\
-2

1.2

:E

1.1

~

1.0

§!
z
9

'\

~
~
UI

:\. Y,N = 4oV.I.

-4

N.A'

-6

0.9

040 0 C

0.8

25°C

0.7
0.6 '''DC
0.5

-8

0.3

-75 -50-25 0 25,50 75100125150

-- ----

o

:E

3.5

~

3.0

~

Q'

>,

i

......

'<

-5

~

I

2.5

u
~

2.0

-:-

VOUT I:f 1.23V

1.0

I
I

0.5

o

it:

~OAD= loomA

-50 -25

ill

I
I
25

~

0.5A

........

60

0.2

0.3

0.4

0.5

.........
o

10

20

3D,

40

o.IA

..........

50

80

INPUT VOLTAGE (V)

Feedback Voltage
vs Duty Cycle
20

Adjustable Version Only"';Y,N =7V

~

15.0
12.5

l#<

10.0
7.5

./

5.0

~

~OAo = 100 mA

"-

10

~
<

~

'5

"""l:: ~V'N=4oV

~

~

V,N'i4oV

~

'LOAD = 100 mA

49

15

-5

V

I
20

Adjust,able Version Onl)'

~

~

/'

o

100 125

-.....:: :!!i:i!

........

65

55

o
75

70

50

2.5
50

-

75 Vo-::5V

20.0
17.5

1.5

-~

0.5A

80

~
'0

Supply Current
vs Duty Cycle

Adjustable Version Only

4.0

g

~

SWITCH CURRENT (A)

Minimum Operating Voltage
4.5

VoUT~ 15V

85

.......

0.1

JUNCTION TEMPERATURE (DC)

5.0

90

,

004

Y,N = 12V

Efficiency
95

',60

'80

§!

-5

I

-10

V,N =7V ......

-15
-20

100

o

20

DUTY CYCLE (,,)

JUNCTION TEMPERATURE,(DC)

r::::::: ......

40

60

80

100

DUTY CYCLE (,,)

TL/HI11394-4

Feedback
Pin Current
100

Junction to Ambient
Thermal Resistance
150

IAdjustable Version Only

75

~
~

50
25

II

z

iL

~'

..

~

~

-25

~

<

-50

ffi

. -75

i!:

-100
-75 -50 -25 0 25 50 75 100125150

I I

140

I I I
I I

130
120
110
100
90
80
70

~\

50-14 (WM)

\' V
l'X

1·1
DlP-8 (N)

I" l' ./

.....

I I

60
0123456789
PC BOARD AREA (so. IN. OF 1 OZ. COPPER)

JUNCTION TEMPERATURE (DC)

TUH111394-5

3-32

Typical Performance Characteristics (Circuit of Figure 2) (Continued)
Continuous Mode Switching Waveforms
VOUT = 5V, 500 mA Load Current, L = 330 j.LH

Discontinuous Mode Switching Waveforms
VOUT = 5V, 100 mA Load Current, L = 100 j.LH

A{~

A{:~

B{~:::

B{ ~:::O

0.2A

o
cf20 mV

c{20mv

AC

lAC
TL/H/11394-6

TLlH/11394-7

A: Output Pin Voltage, 10VIdlv
B: Inductor Current, 0.2 A/div
C: Output Ripple Voltage, 20 mV/div,
AC·Coupled
Horizontal Time Base: 5,.s/dlv

A: Output Pin Voitage,10V/div
B: Inductor Current, 0.2 A/div
C: Output Ripple Voltage, 20 mY/dlv,
AC·Coupled
Horlzontai Time Base: 5 j.Ls/dlv

250 mA Load Transient Response for Discontinuous
Mode Operation. L = 68 ,.H, COUT = 470 j.LF

500 mA Load Transient Response for Continuous
Mode Operation, L = 330 j.LH, COUT = 300,.F

50mV

Af 50mV

AC

l

AC

200mA
{
B 100 mA

omA

TLlH/11394-6

TLlH/11394-9

A: Output Voltage, 50 mVIdlv.
ACCoupled
B: 100 mA to 500 mA Load Pulse
Horizontal Time Base: 200 j.Ls/div

A: Output Voltage, 50 mV/dlv.
ACCoupled
B: 50 mA to 250 mA Load Pulse
Horizontal Time Base: 200 ,.s/div

Block Diagram

Rl

= lk

3.3V. R2

•

= 1.7k

5V, R2 = 3.1k
12V, R2 = 8.84k
15V,R2 = 11.3k

For Adl. Version
Rl = Open, R2 =

011

Ha: PIn numbers are for the 8·pin DIP package.

FIGURE 1

3·33

TLlH/11394-10

Test Circuit and Layout Guidelines
Fixed Output Vol~ge Versions

CIN-

22 J.l.F,,75V
Aluminum Electrolytic
COUo- 220 J.l.F, 25V
Aluminum Electrolytic
D1-Schollky, 110006
L1- 330 J.l.H, 52627
(for 5V in, 3.3V out, use
100 J.l.H, !;iL-1284-100)
. R1-2k,0.1% .
R2- 6.12k,0.1%

reed Back

TL/H/11394-11

Adjusmble Output Voltage Version
Feed Back

VOUT
R2

220 J.lF

~ Rl

(VOUT - 1)
VREF
where VREF ~ 1.23V,

R2
6.12k

+ <:OUT

~ VREF ( 1 + ~ )

Rl

Rl between 1k & Sk.

2k

TLlH/11394-12

FIGURE 2
As in any switching regulator,layout is very important. Rapidly switching currents associated with wiring inductance
generate volmge transients which can cause problems. For
minimal inductance and ground loops, the length of the
leads indicated by heaVy lines should be kept as short as
possible. Single~point grounding (as indicated) or ground
plane construction' should be· used for best results. When
using tlie Adjustable version, physically locate the programming resisto.rs near the regulator, to keep the sensitive feedback wiring short.

Inductor
Value
68J.1.H
100J.l.H
150 J.l.H
220J.l.H·
330J.l.H
470J.l.H
680J.l.H
1000J.l.H
1500 J.l.H
2200J.l.H

Pulse Eng.
(Note 1)

··

52625
52626
52627
52628·
52629
52631

•

·

Renco
(Note 2)

NPI
(Note 3)

NP5915
RL-1284-68
RL-1284-100
NP5916
RL-1284-150
NP5917
NP5918/5919
RL-1284-220
RL-128.4-330 . NP5920/5921
NP5922
RL-1284-470
RL-1283-680
NP5923
RL-1283-1000
RL-1283-1500
RL-1283c2200

FIGURE 3. Inductor Selection by
Manufacturer's Part Number

··
·

European Source

U.S. Source

Note 3: NPiIAPC
+ 44 (0) 634290588
47 Riverside, Medway City Estate
. Strood, Rochester, Kent
ME24DP.
UK

Note 1: Pulse Engineering,
(619) 674-8100
P.O. Box 12236, San Diego, CA 92112
Note 2: Renco Electronics Inc.,
(516) 586·5566
60 Jeffryn Blvd. East, Deer Park, NY 11729

'Contact Manufacturer

'Contact Manufacturer

3-34

lM2574 Series Buck Regulator Design Procedure
PROCEDURE (Fixed Output Voltage Versions)

EXAMPLE (Fixed Output Voltage Versions)

Given:
VOUT = Regulated Output Voltage (3.3V, 5V,12V, or 15V)
VIN(Max) = Maximum Input Voltage
ILOAO(Max) = Maximurri Load Current
1. Inductor Selection (L 1)
A. Select the correct Inductor value selection guide from
Figures 4, 5, 6 or 7. (Output voltages of 3.3V, 5V, 12V or
15V respectively). For other output voltages, see the
design procedure for the adjustable version.
B. From the inductor value selection guide, identify the
inductance region intersected by VIN(Max) and
ILOAO(Max).
C. Select an appropriate inductor from the table shown in
Figure 3 . Part numbers are listed for three inductor
manufacturers. The inductor chosen must be rated for
operation at the LM2574 switching frequency (52 kHz) and
for a current rating of 1.5 x ILOAO. For additional inductor
information, see the inductor section in the Application
Hints section of this data sheet.
2.
Output Capacitor Selection (COUT)
A. The value of the output capacitor together with the
inductor defines the dominate pole·pair of the switching
regulator loop. For stable operation and an acceptable
output ripple voltage, (approximately 1% of the output
voltage) a value between 100 p.F and 470 p.F is
recommended.
B. The capacitor's voltage rating should be at least 1.5
times greater than the output voltage. For a 5V regulator,
a rating of at least 8V is appropriate, and a 10V or 15V
rating is recommended.
Higher voltage -electrolytic capacitors generally have lower
ESR numbers, and for this reasion it may be necessary to
select a capaCitor rated for a higher voltage than would
normally be needed.
3. Catch Diode Selection (01)
A. The catch·diode current rating must be at least 1.5
times greater than the maximum load current. Also, if the
power supply design must withstand a continuous output
short, the diode should have a current rating equal to the
maximum current limit of the LM2574. The most stressful
condition for this diode is an overload or shorted output
condition.
B. The reverse voltage rating of the diode should be at
least 1.25 times the maximum input voltage.
4. Input CapaCitor (CtN)
An aluminum or tantalum electrolytic bypass capaCitor
located close to the regulator is needed for stable
operation.

Given:
VOUT = 5V
VIN(Max) = 15V
ILOAO(Max) = 0.4A
1. Inductor Selection (L 1)
A. Use the selection guide shown in Figure 5.
B. From the selection guide, the inductance area
intersected by the 15V line and 0.4A line is 330.
C. Inductor value required is 330 pH From the table in
Figure 3, choose Pulse Engineering PE·52627, .
Renco RL·1284·330, or NPI NP5920/5921.

2.

Output Capacitor Selection (COUT)
A. COUT = 100 p.F to 470 p.F standard aluminum
electrolytic.
B. Capacitor voltage rating = 20V.

3.

Catch Diode Selection (01)
A. For this example, a 1A current rating is adequate.
B. Use a 20V 1N5817 or SR1 02 Schottky diode, or any of
the suggested fast·recovery diodes shown in Figure 9 .

4.

Input CapaCitor (CIN)
A 22 p.F aluminum electrolytic capacitor located near the
input and ground pins provides sufficient bypassing.

•
3·35

>

~

LM2574 Series Buck Regulator Design Procedure (Continued)

~

INDUCTOR VALUE SELECTION GUIDES (For Continuous Mode Operation)

:::E
....I

......
'Oil'

"'"

."
C'\I

~

...

:5

~
g

60
3D
20
15
12
10
9

~

...
'"'"~

.

....

0

>

....

::>
:;!;

~

,.
:;!;

'"::>
'"x
'"

::>

::Ii

X

::II

'"
::Ii

0.15

0.2

0.3

0.4

BV

0.5

MAXIMUM LOAD CURRENT (A)
TLlH/11394-26

MAXIMUM LOAD CURRENT (A)

FIGURE 4. LM2574HV-3.3Inductor Selection Guide

TLlH/11394-13

FIGURE 5. LM2574HV-5.0 Inductor Selection Guide

40V
30V

~

...
'"

~

20V

~

lBV

....>
:;!;
::Ii

17V

::>

::Ii

x

'"

16V

::II

MAXIMUM LOAD CURRENT (A)

MAXIMUM LOAD ,CURRENT (A)
TL/H/I1394-14

TLlH/11394-15

FIGURE 6. LM2574HV-12 Inductor Selection Guide
250
200
150

FIGURE 7. LM2574HV-15 Inductor Selection Guide

,

i,....--'"

.- .-

..--

.,... ....
rr- ....
....
Poo;r
.-i-"" ~ ..... ....
.-"',000-

2200>
1--""""1500

...

100
90
80
70
60
50

....

40

.'"
'"
:e.
....

30
20
15

----- ---- -....

680
I--"" 470

.-.-'"

.."....
0.15

----

330 •

~

.-

~

~

0.2

~

220

-;q1: ~ ....

I.,..-' -'00

~

\ ....

::t:!'8

0.3

0.4

0.5

MAXIMUM LOAD CURRENT (A)

FIGURE 8. LM2574HV-ADJ Inductor Selection Guide

3-36

'TLlH/I1394-16

LM2574 Series Buck Regulator Design Procedure (Continued)
PROCEDURE (Adjustable Output Voltage Versions)

EXAMPLE (Adjustable Output Voltage Versions)

Given:
VOUT = Regulated Output Voltage
VIN(Max) = Maximum Input Voltage
ILOAO(Max) = Maximum Load Current
F = Switching Frequency (Fixed at 52 kHz)
1.
Programming Output Voltage (Selecting R1 and R2, as
shown in Figure 2)

Given:
VOUT = 24V
VIN(Max) = 40V
ILOAO(Max) = 0.4A
F = 52kHz
1.
Programming Output Voltage (Selecting R1 and R2)

V~UT =

Use the following formula to select the appropriate
resistor values.
VOUT = VREF (1

+ :~)

1.23( 1

+ :~)

Select R1 = 1k

R2 = Rl (VOUT - 1) = 1k( .24V - 1)
VREF
.1.23V

where VREF = 1.23V

Rl can be between 1k and 5k. (For best temperature
coefficient and stability with time, use 1 % metal film
resistors)

R2 = 1k(19.51 -1) = 18.51k,closestl% value is 18.7k

R2 = Rl (VOUT - 1)
VREF

2.

2.

Inductor Selection (L 1)
A. Calculate the inductor Volt • microsecond constant,
E • T (V. p.s), from the following formula:

24 1000
E • T = (40 - 24) 0 40 •
= 185 V •

52

VOUT
1000
E • T = (VIN - VOUT) - - . - . - - (V. p.s)
VIN
F(mkHz)
B. Use the E • T value from the previous formula and
match it with the E • T number on the vertical axis of the
Inductor Value Selection Guide shown in Figure 8.
C. On the horizontal axis, select the maximum load
current.
D. Identify the inductance region intersected by the E • T
value and the maximum load current value, and note the
inductor value for that region.
E. Select an appropriate inductor from the table shown in
Figure 3. Part numbers are listed for three inductor
manufacturers. The inductor chosen must be rated for
operation at the LM2574 switching frequency (52 kHz)
and for a current rating of 1.5 x ILOAO. For additional
inductor information, see the inductor section in the
application hints section of this data sheet.

3.

Inductor Selection (L 1)
A. Calculate E • T (V • ",s)

"'S

B.E.T= 185V.",s
C. ILOAO(Max) = 0.4A
D. Inductance Region = 1000
E. Inductor Value = 1000 ",H Choose from Pulse
Engineering Part #PE·52631, orRenco
Part #RL· 1283· 1000.

3.

Output Capacitor Selection (COUT)

Output Capacitor Selection (COUT)
40

A. The value of the output capacitor together with the
inductor defines the dominate pole·pair of the switching
regulator loop. For stable operation, the capacitor must
satisfy the following requirement:
VIN(Max)
COUT ;;;, 13,300 VOUT. L(iL H) (",F)
'.

A. COUT

> 13,300 24 01000

= 22.2 ",F

However, for acceptable output ripple voltage select
COUT;;;' 100 ",F
COUT = 100 ",F electrolytic capacitor

The above formula yields capacitor values between 5 ",F
and 1000 ",F that will satisfy the loop requirements for
stable operation. But to achieve an acceptable output
ripple voltage, (approximately 1 % of the output voltage)
and transient response, the output capaCitor may need to
be several times larger than the above formula yields.
B. The capacitor's voltage rating should be at last 1.5
times greater than the output voltage. For a 24V regulator,
a rating of at least 35V is recommended.
Higher voltage electrolytic capaCitors generally have
lower ESR numbers, and for this reasion it may be
necessary to select a capaCitor rate for a higher voltage
than would normally be needed.

3·37

LM2574 Series Buck Regulator Design Procedure (Continued)
PROCEDURE (Adjustable Output Voltage Versions)

4. Catch Diode Selection (01)
A. The catch·diode current rating must be at least 1.5
times greater than the maximum load current. Also, if the
power supply design must withstand a continuous output
short, the diode should have a current rating equal to the
maximum current limit of the LM2574. The most stressful
condition for this diode is an overload or shorted output
condition. Suitable diodes are shown in the selection
guide of Figure 9.
B. The reverse voltage rating of the diode should be at
least 1.25 times the maximum input voltage.
5. Input Capacitor (CIN)
An aluminum or tantalum electrolytic bypass capacitor
located close to the regulator is needed for stable
operation.

EXAMPLE (Adjustable Output Voltage Versions)

4. Catch Diode Selection (01)
A. For this example, a 1A current rating is adequate.
B. Use a 50V MBR150 or 110005 Schottky diode, or any of the
suggested fast· recovery diodes in Figure 9.

5. Input Capacitor (CIN)
A 22 "F aluminum electrolytic capacitor located near the input
and ground pins provides sufficient bypassing.
1 Amp Diodes
VR
Schottky
20V

1N5817
SR102
MBR120P

30V

1N5818
SR103
110003
MBR130P
10J0030

40V

1N5819
SR104
"110004
11J004
MBR140P

50V

MBR150
SR105
110005
11J005

60V

MBR160
SR106
110006
11J006

90V

Fast Recovery

The
following
diodes
are all
rated to
100V
11OF1
10JF1
MUR110
HER102

110009
FIGURE 9. Diode Selection Guide

To further simplify the buck regulator design procedure, National
Semiconductor is making available computer design software to
be used with the Simple Switcher line of switching regulators.
Switchers Made Simple (version 3.3) is available on a (3% H)
diskette for IBM compaUble computers from a NaUonal
Semiconductor sales office in your area.

3·38

Application Hints
constant. As the load 'current rises or falls, the entire sawtooth current waveform also rises or falls. The average DC
value of this waveform is equal to the DC load current (in
the buck regulator configuration).
If the load current drops to a low enough level, the bottom
of the sawtooth current waveform will reach zero, and the
switcher will change to a discontinuous mode of operation.
This is a perfectly acceptable mode of operation. Any buck
switching regulator (no matter how large the inductor value
is) will be forced to run discontinuous if the load current is
light enough.
The curve shown in Figure 10 illustrates how the peak-topeak inductor ripple current (aIINO) is allowed to change as
different maximum load currents are selected, and also how
it changes as the operating point varies from the upper border to the lower border within an inductance' region (see
Inductor Selection guides). ,

INPUT CAPACITOR (CIN)
To maintain stability, the regulator input pin must be bypassed with at least a 22 JJ.F electrolytic capacitor. The capacitor's leads must be kept short, and located near the
regulator.
If the operating temperature range includes temperatures
below - 25D C, the input capaCitor value may need to be
larger. With most electrolytic capacitors, the capacitance
value decreases and the ESR increases with lower temperatures and age. Paralleling a ceramic or solid tantalum capacitor will increase the regulator stability at cold temperatures. For maximum capaCitor operating lifetime, the capacitor's RMS ripple current rating should be greater than
1.2 X

(~N)

X ILOAO

~

where tON = VOUT for a buck regulator
VIN
T

""<>:,
<>:
~

90.----,r-~-.----_.----_;
80~~~r---~----~-----l

c

g

and tON = I IViUTI
for a buck-boost regulator.
VOUT + VIN
T

70

z

'"~

INDUCTOR SELECTION
All switching regulators have two basic modes of operation:
continuous and discontinuous. The difference between the
two types relates to the inductor current, whether it is flowing continuously, or if it drops to zero for a period of time in
the normal switching cycle. Each mode has distinctively different operating characteristics, which can affect the regulator performance and requirements.
The LM2574 (or any of the Simple Switcher family) can be
used for both continuous and discontinuous modes of operation.

c

~

'"

50

t

Inductance
Region

0.2

0.3

0.4

0.5

MAXIMUM LOAD CURRENT (AI
TLlH/11394-18

FIGURE 10. Inductor Ripple Current (aIINO) Range'
'Based on Selection Guides from Figures 4-8. '

In many cases the preferred mode of operation is in the
continuous mode. It offers better load regulation, lower peak
switch, inductor and diode currents, and can have lower output ripple voltage. But it does require relatively large inductor values to keep the inductor current flowing continuously,
especially at low output load currents.

Consider the following example:
VOUT = 5V @ 0.4A
VIN = 10V minimum up to 20V maximum
The selection guide in Figure 5 shows that for a 0.4A load
current, and an input Voltage range between 10V and 20V,
the inductance region selected by the guide is 330 JJ.H. This
value of inductance will allow a peak-to-peak inductor ripple
current (aIINO) to flow that will be a percentage of the maximum load current. For this inductor value, the all NO will also
vary depending on the input voltage. As the input voltage
increases to 20V, it approaches the upper border of the
inductance region, and the inductor ripple current increases.
Referring to the curve in Figure 10, it can be seen that at the
0.4A load current level, and operating near the upper border
of the 330 JJ.H inductance region, the allNO will be 53% of
O.4A, or 212 mA pop.
'

To simplify the inductor selection process, an inductor selection guide (nomograph) was designed (see Figures 4
through 8). This guide assumes continuous mode operation, and selects an inductor that will allow a peak-to-peak
inductor ripple current (aIINO) to be a certain percentage of
the maximum design load current. In the LM2574 SIMPLE
SWITCHER, the peak-to-peak inductor ripple current percentage (of load current) is allowed to change as different
design load currents are selected. By allowing the percentage of inductor ripple current to increase for lower current
applications, the inductor size and value can be kept relatively low.

This allNO is important because from this number the peak
inductor current rating can be determined, the minimum
load current required before the circuit goes to discontinuous operation, and also, knowing the ESR of the output
capaCitor, the output ripple voltage can be c!!lculated, or
conversely, measuring the output ripple voltage and knowing the allNO, the ESR can be calculated.

INDUCTOR RIPPLE CURRENT
When the switcher is operating in the continuous mode, the
inductor current waveform ranges from a triangular to a
sawtooth type of waveform (depending on the input voltage). For a given input voltage and output voltage, the peakto-peak amplitude of this inductor current waveform remains

3-39

..

>
:c

.....

In
N

:;

~
N

:::I!!
-I

r-----------------------------------------------------------------------,
Application Hints (Continued)
From the previous example, the Peak-to-peak Inductor Ripple Current (aIINO) = 212 mA pop. Once the alNO value is
known, the following three formulas can be used to calculate additional information about the switching regulator circuit:
1. Peak Inductor or peak switch current

=

(ILOAO

(aIINO)' See the section on inductor ripple current in Application Hints.
The lower capacitor values (100 p.F- 330 p.F) will allow typically 50 mV to 150 mV of output ripple voltage, while largervalue capacitors will reduce the ripple to approximately
20 mV to 50 mV.

+ al~NO) = (0.4A + 2!2) = 506mA

Output Ripple Voltage = (aIINO) (ESR of COUT)
To further reduce the output ripple voltage, several standard
electrolytiC capacitors may be paralleled, or a higher-grade
capacitor may be used. Such capaCitors are often called
"high-frequency," "low-inductance," or "Iow-ESR." These
will reduce the output ripple to 10 mV or 20 mV. However,
when operating in the continuous mode, reducing the ESR
below 0.03n can cause instability in the regulator.

2. Mimimum load current before the circuit becomes discontinuous

= allNO = 212 = 106mA
2

2

3. Output Ripple Voltage = (aIINO) x (ESR of COUT)
The selection guide chooses inductor values suitable for
continuous mode operation, but if the inductor value chosen
is prohibitively high, the deSigner should investigate the possibility of discontinuous operation. The computer design
software Swltchers Made Simple will provide all component values for discontinuous (as well as continuous) mode
of operation.

Tantalum capaCitors can have a very low ESR, and should
be carefully evaluated if it is the only output capaCitor. Because of their good low temperature characteristics, a tantalum can be used in parallel with aluminum electrolytics, with
the tantalum making up 10% or 20% of the total capacitance.
The capacitor's ripple current rating at 52 kHz should be at
least 50% higher than the peak-to-peak inductor ripple current.

Inductors are available in different styles such as pot core,
toroid, E-frame, bobbin core, etc., as well as different core
materials, such as ferrites and powdered iron. The least expensive, the bobbin core type, consists of wire wrapped on
a ferrite rod core.' This type of construction makes for an
inexpensive inductor, but since the magnetic flux Is' not completely contained within the core, it generates more electromagnetiC interference (EM I). This EMI can cause problems
in sensitive circuits, or can give incorrect scope readings
because of induced voltages in the scope probe.

CATCH DIODE
Buck regulators require a diode to provide a return path for
the inductor current when the switch is off. This diode
should be located close to the LM2574 using short leads
and short printed circuit traces;
Because of their fast switching speed and low forward voltage drop, Schottky diodes provide the best efficiency, especially in low output voltage switching regulators (less than
5V). Fast-Recovery, High-Efficiency, or Ultra-Fast Recovery
diodes are also suitable, but some types with an abrupt turnoff characteristic may cause instability and EMI problems. A
fast-recovery diode with soft recovery characteristics is a
better choice. Standard 60 Hz diodes, (e.g., 1N4001 or
1N5400, etc.) are also not suitable. See Figure 9 for
Schottky and "soft" fast-recovery diode selection guide.

The inductors listed in the selection chart include powdered
iron toroid for Pulse Engineering, and ferrite bobbin core for
Renco.
An inductor should not be operated beyond its maximum
rated current because it may saturate. When an inductor
begins to saturate, the inductance decreases rapidly and
the inductor begins to look mainly resistive (the DC resistance of the winding). This can cause the inductor current to
rise very rapidly and will affect the energy storage capabilities of the inductor and could cause inductor overheating.
Different inductor types have different saturation characteristics, and this should be kept in mind when selecting an
inductor. The inductor manufacturers' data sheets include
current and energy limits to avoid inductor saturation.

OUTPUT VOLTAGE RIPPLE AND TRANSIENTS

a

The output voltage of switching power supply will contain
a sawtooth ripple voltage at the switcher frequency, typically
about 1% of the output voltage, and may also contain short
voltage spikes at the peaks of the sawtooth waveform.
The output ripple voltage is due mainly to the inductor sawtooth ripple current multiplied by the ESR of the output capaCitor. (See the inductor selection in the application hints.)

OUTPUT CAPACITOR

The voltage spikes are present because of the the fast
switching action of the output switch, and the parasitic inductance of the output filter capaCitor. To minimize these
voltage spikes, special low inductance capacitors can be
used, and their lead lengths must be kept short. Wiring inductance, stray capacitance, as well as the scope probe
used to evaluate these transients, all contribute to the amplitude of these spikes.

An output capaCitor is required to filter the output voltage
and is needed for loop stability. The capacitor should be
located near the LM2574 using short pc board traces. Standard aluminum electrolytics are usually adequate, but low
ESR types are recommended for low output ripple voltage
and good stability. The ESR of a capaCitor depends on
many factors, some which are: the value, the voltage rating,
physical size and the type of construction. In general, ,low
value or low voltage (less than 12V) electrolytiC capacitors
usually have higher ESR numbers.

An additional small LC filter (20 p.H & 100 p.F) can be added
to the output (as shown in Figure 16) to further reduce the
amount of output ripple and transients. A 10 x' reduction in
output ripple voltage and transients is possible with this filter.

The amount of output ripple voltage is primarily a function of
the ESR (Equivalent Series ReSistance) of the output capaCitor and the amplitude of the inductor ripple current

3-40

,-----------------------------------------------------------------------------, r
is:

Application Hints (Continued)

N

These thermal resistance numbers are approximate, and
there can be many factors that will affect the final thermal
resistance. Some of these factors include board size,
shape, thickness, position, location, and board temperature.
Other factors are, the area of printed circuit copper, copper
thickness, trace width, multi-layer, single- or double-sided,
and the amount of solder on the board. The effectiveness of
the pc board to diSSipate heat also depends on the size,
number and spacing of other components on the board.
Furthermore, some of these components, such as the catch
diode and inductor will generate some additional heat. Also,
the thermal resistance decreases as the power level increases because of the increased air current activity at the
higher power levels, and the lower surface to air resistance
coefficient at higher temperatures.

FEEDBACK CONNECTION
The LM2574 (fixed voltage versions) feedback pin must be
wired to the output voltage pOint of the switching power
supply. When using the adjustable version, physically locate
both output voltage programming resistors near the LM2574
to avoid picking up unwanted noise. Avoid using resistors
greater than 100 kn because of the increased chance of
noise pickup.
ON/OFF INPUT
For normal operation, the ON/OFF pin should be grounded
or driven with a lOW-level TTL voltage (typically below 1.SV).
To put the regulator into standby mode, drive this pin with a
high-level TTL or CMOS Signal. The ON/OFF pin can be
safely pulled up to +VIN without a resistor in series with it.
The ON/OFF pin should not be left open.

The data sheet thermal resistance curves and the thermal
model in Swltchers Made Simple software (version 3.3)
can estimate the maximum junction temperature based on
operating conditions. In addition, the junction temperature
can be estimated in actual circuit operation by using the
following equation.

GROUNDING
The B-pin molded DIP and the 14-pin surface mount package have separate power and signal ground pins. Both
ground pins should be soldered directly to wide printed circuit board copper traces to assure low inductance connections and good thermal properties.

Tj = Teu + (8j-eu x Po)
With the switcher operating under worst case conditions
and all other components on the board in the intended enclosure, measure the copper temperature (Teu ) near the IC.
This can be done by temporarily soldering a small thermocouple to the pc' board copper near the IC, or by holding a
small thermocouple on the pc board copper using thermal
grease for good'thermal conduction.

THERMAL CONSIDERATIONS
The B-pin DIP (N) package and the 14-pin Surface Mount
(M) package are molded plastiC packages with solid copper
lead frames. The copper lead frame conducts the majority
of the heat from the die, through the leads, to the printed
circuit board copper, which acts as the heat sink. For best
thermal performance, wide copper traces should be used,
and all ground and unused pins should be soldered to generous amounts of printed circuit board copper, such as a
ground plane. Large areas of copper provide the best transfer of heat (lower thermal resistance) to the surrounding air,
and even double-sided or multilayer boards provide better
heat paths to the surrounding air. Unless the power levels
are small, using a socket for the B-pin package is not recommended because of the additional thermal resistance ,it introduces; and the resultant higher junction temperature.

The thermal resistance (8j-eu) for the two packages is:
8j-eu = 42'C/W for the N-B package
8j-cu = 52'C/W for the M-14 package
The power dissipation (Po) for the IC could be measured, or
it can be estimated by using .the formula:
Vo)
,
Po = (VIN) (Is) + ( VIN (ILOAO) (VSAT)
Where Is is obtained from the typical supply current curve
(adjustable version use the supply current vs. duty cycle
curve).

Because of the 0.5A current rating of the LM2574, the total
package power dissipation for this switcher is quite low,
ranging from approximately 0.1 W up to 0.75W under varying
conditions. In a carefully engineered printed circuit board,
both the N and the M package can easily dissipate up to
0.75W, even at ambient temperatures of SO'C, and still keep
the maximum junction temperature below 125'C.

Additional Applications
INVERTING REGULATOR

Figure 11 shows a LM2574-12 in a buck-boost configuration
to generate Ii. negative 12V output from a positive input voltage. This circuit bootstraps the regulator's ground pin to the
negative output voltage, then by grounding the feedback
pin, the regulator senses the inverted output voltage and
regulates it to -12V.

A curve displaying thermal resistance vs. pc board area for
the two packages is shown in the Typical Performance
Characteristics curves section of this data sheet.

+8 to +25V
Unregulated
r------lJ:te!!e~d~ba!Sc~k_ _ _ _ _ _ _.,
DC Input +VIN
1
LM2574-12 Output
L1

~ GN

I

~ ~~~~

5....,._........_ ........ 7

4'1~Pwr

22)Jot

Gnd

21

Sig 3 -ON/Off
Gnd

C"":4
Dl 150
.. ..
- MBR

OUT
~T+~ C680)Jot
-::b-

-12V@100mA

Regulated
Output

Note: Pin numbers are for the 81'ln DIP package.

Tl/H/11394-19

FIGURE 11. Inverting Buck-Boost Develops -12V

3-41

~

.Po

r
is:
N
UI

......

.Po

:::J:

<

>
::J:

r---------------------------------------~----------~--~------------__,

'Of'

Additional Applications (Continued)

It)

For an input voltage of 8V or more, the maximum available
output current in this configuration is approximately 100 rnA.
At lighter loads, the minimum input voltage required drops to
approximately 4.7V.
The switch currents in this buck·boost configuration are
higher than in the standard buck·mode design, thus lower·
ing the available output current. Also, the start·up input cur·
rent of the buck·boost converter is higher than the standard
buck·mode regulator, and this may overload an input,power
source with a current limit less than 0.6A. Using a delayed
turn·on or an undervoltage lockout. circuit (described in the
next section) would allow the input voltage to, rise to a high
enough level before ,the switcher would be allowed to turn
on.

.....
N

:::E

....I

.....
'Of'
.....

It)

N

::i

Because of the boosting function of this type of regulator,
the switch current is relatively high, especially at low input
YoliSges. Output load current limitations are a result of the
maximum current rating of the switch. Also, boost regulators
riot provide current limiting load protection in the eyent
of 'a shorted load, so some other means (such as a fuse)
may be necessary:
' ,
'
.1:
'
.'
UNDERVOLTAGELOCKOUT
In some applications it is desirable to keep the regulator,off
until the, input voltage reaches a ,certain threshold. An un·
dervoitage'lockout circuit, which accomplishes, this 'task: is
shown' in Figure 13, while Figure 14 shows the same circuit
applied toa bucli·boost config'uration. These circuits keep
the regulator off Until the input voltage reaches a prede~er·
mined level.
'
,

can

Because of the structural differences between the buck and
the buck·boost regulator topologies, the buck regulator de·
sign procedure section can not be used to to select the
inductor or the output capacitor. The recommended range
of inductor values for the buck·boost ,design is between
68 ,..,H and 220 ,..,H, and the output capacitor values must be
larger than what is normally required for buck designs. Low
input voltages or high output currents require a large value
output capacitor (in the thousands of micro F!!rads).
The peak inductor ~urrent; which is the same 'a~ the peak
switch current, can be calculated from the following formula:

VTH :::: VZ1

+ 2VBE (Q1)

+VIN

....;;.;....--....-.....,....-+~

+

',t. ,"":

LM2574 - XX

ZI

I i:: ILOAD (VIN + IVol) + VIN Ivol 'x _1_,'
P
VIN
' VIN + Ivol ' 2L1 fosc
Where fosc = 52 kHz. Under normal continuous ind4cior
current operating conditions, tlie minim'um' VIN represents
the worst case. Select an inductor that is rated for'the peak
current anticipated.

TL/H111394-21

Also, the maximum voltage appearing across the regulator
is the absolute sum of the input' ahd output voltage; For' a
-12V output, the maximum input voltage for the LM2574 is
+ 28V, or + 48V for the LM2574HV.

Note: Complete circuit not shown.
Note: Pin numbers are for B-pin DIP package.

'FIGURE13. Undervoltage Lockout for Buck Circuit' ' '
"

The Swltchers Made Simple (version 3.3) design software
can be used to determine the feasibility of regulator desig(ls
using different topologies,' differ,ent input·output parameters,
different components, etc.
'
"

j

'+vlti'

"

•

•

-!,'

, +VIN

...;.;.;.....--.......--+...;:i
LM2574-XX
+ 5
20k ]SN

NEGATIVE BOOST REGULATOR
Another variation on the buck·boost topology is' the nega·
tive boost configuration. The circuit in Figure 12 iiccepts af!
input voltage ranging from -5V to -12V and provides a
regulated -12V output.,lnput voltages greater'than ':"12V
will cause the output to rise above "-'12V, but will not dam·
age the regulator.'
"
"

3 ON/OFF

2 &: 4' Gnds
pins

zi

-Your
TL/H/11394~22

Note: Complete circuit not shown (see Figure 11).
Note: Pin numbers are for B-pin DIP package.

FIGURE·14. Uridervoltage Lockout
for Buck·Boost Circuit

330 JlH

Load Current

-5 to -12V

60 rnA for VIN

=

120 rnA for VIN

-5.2V

= -7V
TLlH/I1394-20

Note: Pin numbers are for B-pin DIP package.

FIGURE 12. Negative Boost
3·42

AlPplilCa!~DtO>i1lS (Continued)

Additionai

DELAYED STARTUP
+VIN

The ON/OFF pin can be used to provide a delayed startup
feature as shown in Figure 15. With an input voltage of 20V
and for the part values shown, the circuit provides approximately 10 ms of delay time before the circuit begins switching. Increasing the RC time constant can provide longer delay times. But excessively large RC time constants can
cause problems with input voltages that are high in 60 Hz or
120 Hz ripple, by coupling the ripple into the ON/OFF pin.

O---<;---s:-il L M2 5 7 4 - XX

471<

ADJUSTABLE OUTPUT, LOW-RIPPLE
POWER SUPPL V

TL/H/11394-23

Note: Complete circuit not shown.

A 500 rnA power supply that features an adjustable output
voltage is shown in Figure 16. An additional L-C filter that
reduces the output ripple by a factor of 10 or more is included in this circuit.

SOV Max
Unregulated
DC Input

+VIN

LM2574HV
5
-ADJ

1'"

Pwr
Gnd

pacl~age.

FIGURE 15. Delayed Startup

"... _""'-"""""' .... _-L1

...

Output
Voltage

L2

+1.2 to

3

2

+ <1N

Feedback
1
Out ut
7

Note: Pin numbers are for a-pin DIP

Sig
Gnd

ssv

@ O.SA

ON/OFF

I100
Cl

JL F

r:. ... _""" .... .a .... _ _ _ _ _

R2 - Output voltage adjust

.:1

optional output ripple fIItor

Noto: Pin numbers are for a-pin DIP package.

FIGURE 16. 1.2V to 55V Adjustable 500 rnA Power Supply with Low Output Ripple
CAPACITOR EQUIVALENT SERIES RESISTANCE (ESR)
The purely resistive component of a real capacitor's impedance (see Figure 17). It causes power loss resulting in capacitor heating, which directly affects the capacitor's operating lifetime. When used as a switching regulator output
filter, higher ESR values result in higher output ripple voltages.

BUCK REGULATOR
A switching regulator topology in which a higher voltage is
converted to a lower voltage. Also known as a step-down
switching regulator.
BUCK-BOOST REGULATOR
A switching regulator topology in which a positive voltage is
converted to a negative voltage without a transformer.

TLlH/11394-25

DUTY CYCLE (D)

FIGURE 17. Simple Model of a Real Capacitor

Ratio of the output switch's on-time to the oscillator period.
for buck regulator

for buck-boost regulator

Most standard aluminum electrolytic capacitors in the
100 p.F-1000 p.F range have 0.5,n to 0.1,n ESA. Highergrade capacitors ("Iow-ESR", "high-frequency", or "low-inductance"') in the 100 p.F-1000 p.F range generally have
ESR of less than 0.15,n.

0= tON = VOUT

T
0= tON =

T

VIN

Ivol
Ivol + VIN

EQUIVALENT SERIES INDUCTANCE (ESL)
The pure inductance component of a capacitor (see Figure
17). The amount of inductance is determined to a large
extent on the capacitor's construction. In a buck regulator,
this unwanted inductance causes voltage spikes to appear
on the output.

CATCH DIODE OR CURRENT STEERING DIODE
The diode which provides a return path for the load current
when the LM2574 switch is OFF.
EFFICIENCY (-1)
The proportion of input power actually delivered to the load.
POUT

"1)

=

POUT

p;- = POUT + PLOSS

3-43

Definition of Terms (Continued)
OUTPUT RIPPLE VOLTAGE
The AC component of the switching regulator's output voltage. It is usually dominated by the output capacitor's ESR
multiplied by the inductor's ripple current (.1.IINO)' The peakto-peak value of this sawtooth ripple current can be determined by reading the Inductor Ripple Current section of the
Application hints.

CONTINUOUS/DISCONTINUOUS MODE OPERATION
Relates to the inductor current. In the continuous mode, the
inductor current is always flowing and never drops to zero,
vs. the discontinuous mode, where the inductor current
drops to zero for a period of time in the normal switching
cycle.
INDUCTOR SATURATION
The condition which exists when an inductor cannot hold
any more magnetic flux. When an inductor saturates, the
inductor appears less inductive and the resistive component
dominates. Inductor current is then limited only by the DC
resistance of the wire and the available source current.

CAPACITOR RIPPLE CURRENT
RMS value of the maximum allowable alternating current at
which a capacitor can be operated continuously at a specified temperature.
STANDBY QUIESCENT CURRENT (ISTBY)
Supply current required by the LM2574 when in the standby
mode (ON/OFF pin is driven to TIL-high voltage, thus turning the output switch OFF).

OPERATING VOLT MICROSECOND CONSTANT (E-Top)
The product (in Volt-p.s) of the voltage applied to the inductor and the time the voltage is applied. This E-Top constant
is a measure of the energy handling capability of an inductor
and is dependent upon the type of core, the core area, the
number of turns, and the duty cycle.

INDUCTOR RIPPLE CURRENT (.1.IIND)
The peak-to-peak value of the inductor current waveform,
typically a sawtooth waveform when the regulator is operating in the continuous mode (vs. discontinuous mode).

3-44

tflNational Semiconductor

lM1575/lM1575HVIlM2575/lM2575HV Series
SIMPLE SWITCHER® 1A Step-Down Voltage Regulator
General Description

Features

The LM2575 series of regulators are monolithic integrated
circuits that provide all the active functions for a step-down
(buck) switching regulator, capable of driving a 1A load with
excellent line and load regulation. These deyices are available in fixed output voltages of 3.3V, 5V, 12V, 15V, and an
adjustable output version.

• 3.3V, 5V, 12V, 15V, and adjustable output versions
• Adjustable version output voltage range,
1.23V to 37V (57V for HV version) ± 4 % max over
line and load conditions
• Guaranteed 1A output current
• Wide input voltage range, 40V up to 60V
for HV version
• Requires only 4 external components
• 52 kHz fixed frequency internal oscillator
• TTL shutdown capability, low power standby mode
• High efficiency
.. Uses readily available standard inductors
.. Thermal shutdown and current limit protection
• P+' Product Enhancement tested

Requiring a minimum number of externaf components,
these regulators are simple to use and include internal frequency compensation and a fixed-frequency oscillator.
The LM2575 series offers a high-efficiency replacement for
popular three:terminal linear regulators. It substantially reduces the size of the heat sink, and in many cases no heat
sink is required.
. A standard series of inductors optimized for use with the
LM2575 are available from several different manufacturers.
This feature greatly simplifies the design of switch-mode
power suppli!ls.
Other features include a guaranteed ± 4 % tolerance on output voltage within specified input voltages and output load
conditions, and ± 10% on the oscillator frequency. External
shutdown is included, featuririg 50 /LA (typical) standby current. The output switch includes cycle-by-cycle current limiting, as well as thermal shutdown for full protection under
fault conditions.

Applications
•
•
•
•

Simple high-efficiency step-down (buck) regulator
Efficient pre-regualtor for linear regulators
On-card switching regulators
Positive to negative converter (Buck-Boost)

Typical Application (Fixed Output Voltage Versions)
FEEDBACK
7V - 40V(60V)

+V,•

UNREGULATED
DC INPUT -_-~
G.

OUTPUT

Ll

+5V
REGULATED

L~;:~.".J-'--Ir.r3~!I~:=t-=---:,
OUTPUT
0,330 J.&H +
toUT I A. Load

I'OO}!F

IN5819

-=

Note: Pin numbers are for the T0-220 package.

I

330 J.'F'

TL/H/11475-1

Block Diagram and Typical Application

3.3V, R2 ~ 1.7k
5V, R2 ~ 3.1k
• 12V, R2 ~ 8,84k
15V, R2 ~ h3k
For ADJ. Version
'R1 ~ Open, R2 ~ 011
Note: Pin numbers are for
the TO-220 package.

TL/H/11475-2

Patent Pending

FIGURE 1

3-45

>
::I:

Absolute Maximum Ratings (Note 1)

II)

.....

II)

Minimum ESD Rating
(C = 100 pF, R = 1.5 kO)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications•

N

:::E

...I

"II)

.....

Maximum Supply Voltage
LM1575/LM2575
LM 1575HVILM2575HV

45V
63V

...I

ONIOFF Pin Input Voltage

-0.3V ~ V ~ +VIN

II)

Output Voltage to Ground
(Steady State)
Power Dissipation

II)

N

:::E

:>::I:
.....
.,...

II)

Operating Ratings
Temperature Range
LM1575/LM1575HV
LM2575/LM2575HV

-1V

it;

.....
.,...

-55'C ~ TJ ~ +150"C
-40'C ~ TJ ~ + 125'C

Supply Voltage
LM1575/LM2575
LM1575HV ILM2575HV

...I

II)

260"C
150'C

Maximum Junction Temperature

Internally Limited
- 65'C to + 150'C

Storage Temperature Range

:::E

2kV

Lead Temperature
(Soldering, 10 sec.)

40V
60V

LM 1575-3.3, LM 1575HV-3.3, LM2575-3.3, LM2575HV-3.3
Electrical Characteristics Specifications with standard type face are for TJ = 25'C, and those with boldface

:::E

...I

type apply over full Operating Temperature Range.
LM1575-3.3
Symbol

Parameter

Conditions

Typ

LM157~HV·3.3

Umit
. (Note 2)

LM2575-3.3
LM2575HV-3.3
Limit
. (Note 3)

Units
(Limits)

SYSTEM PARAMETERS (Note 4) Test Circuit Figure 2
VOUT

VOUT

VOUT

'1/

Output Voltage

VIN = 12V, ILOAD
Circuit of Figure 2

=

3.3

0.2A

Output Voltage
LM1575/LM2575

4.75V ~ VIN ~ 40V, 0.2A ~ ILOAD ~ 1A
Circuit of figure 2

3.3

Output Voltage
LM1575HVILM2575HV

4.75V ~ VIN ~ 60V, 0.2A ~ ILOAD ~ 1A
Circuit of Figure 2

3.3

Efficiency

VIN

=

12V, ILOAD

=

3.267
3.333

3.234
3.366

V
V(Min)
V(Max)

3.20013.168
3.400/3.432

3.168/3.135
3.432/3.465

V
V(Min)
V(Max)

3.200/3.168
. 3.416/3.450

3.168/3.135
3.45013.482

V
V(Min)
V(Max)

75

1A

%

LM1575-5.0, LM1575HV-5.0, LM2575-5.0, LM2575HV-5.0
Electrical Characteristics Specifications with standard type face are for TJ = 25'C, and those with boldface
type apply over full Operating Temperature Range.

Symbol

Parameter

Conditions

Typ

LM1575-5.0
LM1575HV-5.0

LM2575-5.0
LM2575HV-5.0

Limit
(Note 2)

Limit
(Note 3)

4.950
5.050

4.900
5.100

V
V(Min)
V(Max)

4.85014.800
5.150/5.200

4.800/4.750
5.200/5.250

V
V(Min)
V(Max)

4.850/4.800
5.175/5.225

4.800/4.750
5.225/5.275

V
V(Min)
V(Max)

Units
(Limits)

.SYSTEM PARAMETERS (Note 4) Test Circuit Figure 2
VOUT

VOUT

VOUT

'1/

Output Voltage

VIN = 12V, ILOAD
Circuit of Figure 2

=

0.2A

5.0

Output Voltage
LM1575/LM2575

0.2A ~ ILOAD ~ 1A,
8V ~ VIN ~ 40V
Circuit of Figure 2

5.0

Output Voltage
LM1575HVILM2575HV

O.?A ~ ILOAD ~ 1A,
8V ~ VIN ~ 60V
Circuit of Figure 2

5.0

Efficiency

VIN

=

12V, ILOAD

=

1A

3-46

77

%

r

LM1575-12, LM1575HV-12, LM2575-12, LM2575HV-12
Electrical Characteristics Specifications with standard type face are for T J = 25'C, and those with boldface
type apply over full Operating Temperature Range.

Symbol

Parameter

Conditions

Typ

LM1575-12
LM1575HV-12

LM2575-12
LM2575HV-12

Limit
(Note 2)

Limit
(Note 3)

Units
(Limits)

VOUT

VOUT

'1

=

12

0.2A

11.88
12.12

Output Voltage
LM1575/LM2575

0.2A ,;; ILOAD ,;; 1A,
15V ,;; VIN ,;; 40V
Circuit of Figure 2

12

Output Voltage
LM1575HV ILM2575HV

0.2A';; ILOAD ,;; 1A,
15V ,;; VIN ,;; 60V
Circuit of Figure 2

12

Efficiency

VIN

=

-.I

.......
r

....==

(II

.....
(II

r

VIN = 25V, ILOAD
Circuit of Figure 2

Output Voltage

(II

(II

::I:
<
.......

SYSTEM PARAMETERS (Note 4) Test Circuit Figure 2
VOUT

....==

=

15V, ILOAD

11.64111.52
12.36/12.48
11.64/11.52
12.42/12.54

11.76
12.24

11.52/11.40
12.48112.60

V
V(Min)
V(Max)

11.52/11.40
12.54/12.66

V
V(Min)
V(Max)

88

1A

V
V(Min)
V(Max)

==

N

(II

-.I

(II

.......

r

==

N

(II

-.I

(II

::I:

<

%

LM1575-15, LM1575HV-15, LM2575-15, LM2575HV-15
Electrical Characteristics Specifications with standard type face are for T J = 25'C, and those with boldface
type apply over full Operating Temperature Range.

Symbol

Parameter

Conditions

LM1575-15
LM1575HV-15

LM2575-15
LM2575HV-15

Limit
(Note 2)

Limit
(Note 3)

14.85
15.15

14.70
15.30

V
V(Min)
V(Max)

14.55114.40
15.45/15.60

14.40/14.25
15.60/15.75

V
V(Min)
V(Max)

14.55/14.40
15.525/15.675

14.40/14.25
15.68115.83

V
V(Min)
V(Max)

Typ

Units
(Limits)

SYSTEM PARAMETERS (Note 4) Test Circuit Figure 2
VOUT

VOUT

VOUT

'1

VIN = 30V, ILOAD
Circuit of Figure 2

Output Voltage

=

15

0.2A

Output Voltage
LM1575/LM2575

0.2A ,;; ILOAD ,;; 1A,
18V ,;; VIN ,;; 40V
Circuit of Figure 2

15

Output Voltage
LM1575HV ILM2575HV

0.2A';; ILOAD ,;; 1A,
18V ,;; VIN ,;; 60V
Circuit of Figure 2

15

Efficiency

VIN

=

18V, ILOAD

=

%

88

1A

LM 1575-ADJ, LM 1575HV-ADJ, LM2575-ADJ, LM2575HV-ADJ
Electrical Characteristics
Specifications with standard type face are for TJ
perature Range.

Symbol

Parameter

=

25'C, and those with boldface type apply over full Operating Tem-

Conditions

Typ

LM1575-ADJ
LM1575HV-ADJ

LM2575-ADJ
LM2575HV-ADJ

Limit
(Note 2)

Limit
(Note 3)

1.217
1.243

1.217
1.243

V
V(Min)
V(Max)

1.205/1.193
1.255/1.267

1.193/1.180
1.267/1.280

V
V(Min)
V(Max)

1.205/1.193
1.261/1.273

1.193/1.180
1.273/1.286

V
V(Min)
V(Max)

Units
(Limits)

SYSTEM PARAMETERS (Note 4) Test Circuit Figure 2
VOUT

VOUT

VOUT

'1

Feedback Voltage

VIN = 12V, ILOAD
VOUT = 5V
Circuit of Figure 2

=

1.230

0.2A

Feedback Voltage
LM1575/LM2575

0.2A ,;; ILOAD ,;; 1A,
8V,;; VIN';; 40V
VOUT = 5V, Circuit of Figure 2

1.230

Feedback Voltage
LM1575HVILM2575HV

0.2A ,;; ILOAD ,;; 1A,
8V,;; VIN';; 60V
VOUT = 5V, Circuit of Figure 2

1.230

Efficiency

VIN

=

12V, ILOAD

=

1A, VOUT

3-47

=

5V

77

%

II

All Output Voltage Versions
Electrical Characteristics Specifications with standard type face are for TJ =

25°C, and those with boldface
type apply over full Operating Temperature Range. Unless, otherwise specified, VIN = 12V for the 3.3V, 5V, and
Adjustable ve'rsion, VIN = 25V for the ,12Vversion, and Villi"" 30V for the 15V version.,ILOAD = 200 rnA.
"

Symbol

Parameter

"

Conditions

Typ

LM1575·XX
LM2575-XX
LM1575HV·XX LM2575HV·XX

Units
(Limits)

Limit
(Note 2)

Limit
(Note 3)

100/500

100/500

nA

47/43
58/62

47/42
58/63

kHz
kHz(Min)
kHz(Max)

1.2/1.4

1.2/1.4

V
V(Max)

93

93

%
%(Min)

1.7/1.3
3.0/3.2

1.7/1.3
3.0/3.2

A
A(Min)
A(Max)

2

2

30

30

mA(Max)
mA
mA(Max)

10/12

10

mA
mA(Max)

200/500

200

p.A
p.A(Max)

DEVICE PARAMETERS
Ib

Feedback Bias Current

VOUT == 5V (Adjustable Version Only)

50

fo

Oscillator Frequency

(Note 1'3)

52

VSAT
DC
ICL

Saturation Voltage
Max Duty Cycle (ON)
Current Limit

(Note 6)

Output Leakage Current (Notes 7 and 8)

10

Quiescent Curr~nt
Standby Quiescent
Current

98

Peak Current (Notes 5 and 13)

IL

ISTBY

0.9

lOUT = 1A (Note 5)

Output"" OV
Output = -W 7.5
Output = -W

(Note, 7)

5

ON/OFF Pin = 5V (OFF)

50

Thermal Resistance
K Package, Junction to Ambient
8JA
K Package, Junction to Case
8JC
; 8JA
T Package, Junction to Ambient (Note 9)
T Package, Junction to Ambient (Note 10)
8JA
T Package, Junction to Case
8JC
N Package, Junction to Ambient (Note 11)
8JA
M Package, Junction to Ambient (Note 11)
8JA
S Package, Junction to Ambient (Note 12)
8JA
'ON/OFF CONTROL Test Circuit Rgure2
VIH

ON/OFF Pin Logic

VIL

Input Level

IIH

ON/OFF Pin Input
Current

IlL

2.2

35
1.5
65
45
2
85
100
37

·C/W

VbUT = OV
VOUT = Nominal Output Voltage

1.4

2.2/2.4

2.2/2.4

V(Min)

1.2

1.0/0.8

1.0/0.8

V(Max)

ON/OFF Pin = 5V (OFF)

12
30

30

p.A
p.A(Max)

10

10

p.A
p.A(Max)

ON/OFF Pin = OV (ON)

0

Note I: Absolute Maximum Ratings indicate limns beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but do not guarantee specific performance limils. For guaranteed specificalions and tesl condnians. see the Electrical Characteristics.
Note 2: All limns guaranteed at room temperature (standard type face) and at temperature extremes (bold type face). Alillmts are used to calculate Average
Outgoing Quality Lasl, and all are 100% production tested',
Note 3: AlllimHs guaranteed at room temperatura (slandard type face) and at temperature extremes (bold type face). All room temperature limns ara 100%
production tested. All limns at tem,perature e~tremes are guarantasd via correlation using standard Statisllcal Quality Control (SOC) methods.
Note' 4: External components such as the catch diode, inductor, input and outpUt capacitors can affect switching regulator system performance. When the

LM1575/LM2575 Is used as shown In the Figure 2 test Circuit, system performance will be as shown In system parameters section of Electrical Charactaristics.
Note 5: Output (pin 2) sourcing current No diode, inductor or capacHor connected to output pin.
Note 6: Feedback (pin 4) removed from output and connected to OV.
Note 7: Feedback (pIn 4) removed from output and connected to + 12V for the Adjustable, 3.3V, and 5V versions, and +25V for the 12V and 15V versions, to
force the output transistor OFF. ,
" ' ,
Not. 8: VIN = 40V (BOV for the hl,gh yoltage, version).
"

"

3·48

r-

Electrical Characteristics (Notes) (Continued)
Note 9: Junction to ambient thermal resistance (no external heat sink) lor the 5 lead TO-220 package mounted vertically, with V. inch leads in a socket, or on a PC
board with minimum copper area.
Note 10: Junction to ambient thermal resistance (no external heat sink) lor the 5 lead TO-220 package mounted vertically, with Y. inch leads soldered to a PC
board containing approximately 4 square inches 01 copper area surrounding the leads.
Note 11: Junction to ambient thermal resistance with approxmlately 1 square inch 01 pc board copper surrounding the leads. Additional copper area will lower
thermal resistance further. See thermal model in Switchers made Simple software.

Note 12: lIthe TO-263 package is used, the thermal resistance can be reduced by increasing the PC board copper area thermally connected to the package: Using
0.5 square inches 01 copper area, BJA is 50'C/W; with 1 square inch 01 copper area, BJA is 37'C/W; and with 1.6 or more square inches 01 copper area, BJA is
3Z'C/W.
Note 13: The oscillator Irequency reduces to approximately 18 kHz in the event 01 an output short or an overload which causes the regulated output voltage to drop
approximately 40% lrom the nominal output voltage. This sell protection leature lowers the average power dissipation 01 the IC by lowering the minimum duty cycle
Irom 5% down to approximately 2%.

s::::
.....
en

......

en
.....
r-

s::::
.....

en
......
en

:z:

:::r-

s::::

I\)

Nota 14: ReIer to RETS LM1575K, LM1575HVK lor current revision 01 military RETS/SMO.

en
......
en
.....
r-

Typical Performance Characteristics (Circuit of Figure 2)

I\)

Normalized Output Voltage
+1.0

YIN

g

r--

+0.6

~

+0.4

t-- Normalized at
t-- f- TJ =25 C

i!i

+0.2

~

a

~
~

~

-0.2
-0.4

D

~

,

-.

i!i

0.6

~
g

0.4

!

-0.6
-0.6
-1.0
-50 -25 -0

~

WI

V

3.3J,, 5V &, ADJ
P 1-7'- 1--12V
& 15V

0.2

I

-0.4
-0.6

25

50

75

~

II"

-0.2

o

100 125

10

20

JUNCTION TEMPERATURE (DC)

40

30

ILOAD = lA

~

;
-<

S

1.5

I'"

e:

60

ILOAD

20

-:;-

..5

........

........

"

ii3
~

g

16
14

10

;;

-75 -50 -25 0

4
25 50 75 100 125 150

= 25°C

-:;-

ag;

VIN = 40V

r--

150

VOil/OFF =5V

~

15

11oOAO =lA

~
~

10

20

30

40

50

JUNCTION TEWPERATURE (CD)

INPUT VOLTAGE (V)

Oscillator Frequency

Switch Saturation
Voltage

100

~

~

= 200 mA

~

60

-

200

.3

:;;
o

25 50 75 100125 150

i3

/

~OAO

a

o

TJ

~

-

o

Standby
Quiescent Current

~

12

---- -

200 rnA

0.5

5%

JUNCTION TEMPERATURE (DC)

-~':~~I:~~
Ground Pin

,

18

=

=

= 0.2n

t-

~

1.0

5

&VOUT
~NO

-. -~

Quiescent Current
V,N =25V

-50 -25 0

E

INPUT VOLTAGE (v)

Current Limit

I ....

50

<

2.0

i

I
I

I

:z:

Dropout Voltage

200 m~
r-- r-- ~OAOTJ =
=25°C
g 1.2
~
1.0
J.'
0.8

= 200 rnA

10'

Line Regulation
1.4

=20V

+0.8

ILOAD

s::::

en
~

50

-

VIN = 12V

I--

r-

o

-50 -25

0

25

50

75

100 125

JUNCTION TEMPERATURE (DC)

TUH/11475-3

8

1.2
Normalized at 25°C

g

E

~
~
~

~
:::;
-<

~"

V
-2
-4

-6

~g

""\
I\,

i!i
\.. V,N = 40V

J.

~

V'N = 12V
-8
-75-50-250 255075100125150

JUNCTION TENPERATURE (DC)

1.0

0.8

~

~

0.6

0.4

o

I

-

-I---

25°C

r
150°C

0.2

... -

--

I

-55 0

rI

Efficiency

..........

-I---

-

100

TJ = 25°C

95

200mA.

~

§

85
80

-

5V

75

T::::::
T" I'...

..........

70

60
0.6

0.8

SWITCH CURRENT (A)

1.0

-

\

15V Out

...........

200mA

65
0.4

IA

90

g

o

10

20

30

40

50

60

INPUT VOLTAGE (V)

TUH/l T475-31

3-49

•

Typical Performance Characteristics

Quiescent Current
vs Duty Cycle

Minimum Operating Voltage
5.0
Adjustable Version Only

~
~
~
~

z

'"
-.5

1-

3.5

1"--1-

3.0

~

2.5

I---

1.5

z
w

VOUT Rj 1.23V
'LOAD = 200 rnA

u

~

~

1.0
0.5

o
-50 -25

0

25

50

75

100 125

-..../. / '

VIN = 7V

15.0
12.5

I#<

10.0

7.5

,/

5.0

Adjustable Version Only

-.5

IS

'"
'"

10

w
z

~

"

~

0

1

';l

40V

VIN

./

~

2.0

s:-

Adjustable Version Only/
17.5

4.0

§!

Feedback Voltage
vs Duty Cycle
20

20,0

4.5
>

(Continued)

ILOAD = 200 rnA

~

-5

'"

-10

0

'"

'LOAD = 200 rnA

~
~ ~VIN -40V
V,N = 7V .....

F==::::::

~

c

2.5

o
o

20

JUNCTION TEMPERATURE (Oe)

40

-20

ao

60

100

DUTY CYCLE (%)

--

-15

o

20

40

60

80

100

DUTY CYCLE (%)

TLlH/1147S-4

Maximum Power Dissipation
(TO-263) (See Note 12)

I

eJA -

N.

I

32oe/~

I

N..N

6JA=37OC/Vt........

........... I r-... :-...
~
o
o

"'"' ~~ ...... ~
t-...

I ~JA ~73fc7;':::; ;:;: ~
I i
'1'1

10 20 30 40 50 60 70

ao

90 100

AMBIENT TEMPERATURE (Oe)
TL/H/1147S-2a

3-50

r-----------------------------------------------------------------------------, r

...3:

Typical Performance Characteristics (Circuit of Figure 2) (Continued)

CI1

.......

Switching Waveforms

CI1
.....
r

Feedback Pin Current

...~3:

100
Adjustable Vorsion Only

1....

75
50

CI1

""""=>

25

<
.....
r

...

::I:

:z:

'"a:

II

:z:

><
~
CD

......'"...

./

-25

3:

IA

I\)

C.5:

.......

CI1

[

-50
-75
-100
-75 -50 -25 0

CI1

r
'"
3:

DC

I\)

CI1

25 50 75 100125150

TLiH/1147S-6
VOUT

JUNCTION TEMPERATURE (OC)

CI1

::I:

= 5V

A: Outpul Pin Voltage. 10Vldiv

TL/H/1147S-S

.......

<

B: Outpul Pin Current, lA1diy

Load Transient Response

C: Inductor Current, 0.5A1diY
0: Output Ripple Voltage, 20 mV/diy,

Output
Voltage
Change

Ac.Coupled

+100mV

Horizontal Time Base: 5 "s/dly

0

As in any switching regulator, layout is very important. Rapidly switching currents associated with wiring inductance
generate voltage transients which can cause problems. For
minimal inductance and ground loops, the length of the
leads indicated by heavy lines should be kept as short as
possible. Single-point grounding (as indicated) or ground
plane cOnstruction should be used for best results. When
using the Adjustable version, physically locate the programming resistors near the regulator, to keep the sensitive feedback wiring short.

-IOOmV

1.0A

~~nt

O.5A

o
100J.'sec/div.
TUH/1147S-7

Test Circuit and Layout Guidelines
Fixed Output Voltage Versions

CIN -

100 "F. 75V. Aluminum Electrolytic

CoUT- 330 "F, 25V, Aluminum ElectrolytiC
01- Schottky, 110006
L1 -

330 "H, PE·52627 (for 5V in, 3.3V out,
use 100 "H, PE-9210B)

Adjustable Output Voltage Version
FEEDBACK

VOUT
3 Oii/OFF 5

= VREF (1 +

R2 = Rl (VOUT VREF

1*)
1)

where VREF = 1.23V, Rl between 1k and 5k.
TL/Hl1l47S-9
Note: Pin numbers are for the T0-220 package.

FIGURE 2

3-51

Rl-2k,0.1%
R2-6.12k,0.1%

•

LM2575 Series Buck Regulator Design Procedure
PROCEDURE (Fixed Output Voltage Versions)

EXAMPLE (Fixed Output Voltage Versions)

Given:
VOUT = Regulated Output Voltage (3.3V, 5V,12V, or 15V)
VIN(Max) = Maximum Input Voltage
ILOAO(Max) = Maximum Load Current
1. Inductor Selection (L1)
A. Select the correct Inductor value selection guide from
Figures 3, 4, 5, or 6. (Output voltages of 3.3V, 5V, 12V or
15V respectively). For other output voltages, see the
design procedure for the adjustable version.
B. From the inductor value selection guide, identify the
inductance region intersected by VIN(Max) and
ILOAO(Max), and note the inductor code for that region.
C. Identify the inductor value from the inductor code, and
select an appropriate inductor from the table shown in
Figure 9. Part numbers are listed for three inductor
manufacturers. The inductor chosen must be rated for
operation at the LM2575 switching frequency (52 kHz) and
for a current rating of 1.15 X ILOAO. For additional
inductor information, see the inductor section in the
Application Hints section of this data sheet.
2. Output capaCitor Selection (COUT)
A. The value of the output capacitor together with the
inductor defines the dominate pole·pair of the switching
regulator loop. For stable operation and an acceptable
output ripple voltage, (apprOximately 1% of the output
voltage) a value between 100,...F and 470,...F is
recommended.
B. The capacitor's voltage rating should be at least 1.5
times greater than the output voltage. For a 5V regulator,
a rating of at least 8V is appropriate, and a 10V or 15V
rating is recommended.
Higher voltage electrolytic capacitors generally have lower
ESR numbers, and for this reasion it may be necessary to
select a capacitor rated for a higher voltage than would
normally be needed.
3. Catch Diode Selection (01)
A. The catch·diode current rating must be at least 1.2
times greater than the maximum load current. Also, if the
power supply design must withstand a continuous output
short, the diode should have a current rating equal to the
maximum current limit of the LM2575. The most stressful
condition for this diode is an overload or shorted output
condition.
B. The reverse voltage rating of the diode should be at
least 1.25 times the maximum input voltage.
4. Input CapaCitor (CIN)
An aluminum or tantalum electrolytic bypass capaCitor
located close to the regulator is needed for stable
operation.

Given:
VOUT = 5V
VIN(Max) = 20V
ILOAO(Max) = O.8A
1. Inductor Selection (L 1)
A. Use the selection guide shown in Figure 4.
B. From the selection guide, the inductance area
intersected by the 20V line and 0.8A line is La30.
C. Inductor value required is 330 ,...H. From the table in
Figure 9, choose AlE 415·0926, Pulse Engineering
PE·52627, or RL 1952.

2.

Output CapaCitor Selection (COUT)
A. COUT = 100,...F to 470 ,...F standard aluminum
electrolytic.
B. CapaCitor voltage rating = 20V,

3.

Catch Diode Selection (01)
A. For this example, a 1A current rating is adequate.
B. Use a30V 1N5818 orSR103 Schottky diode, or any of
the suggested fast·recovery diodes shown in Figure 8.

4.

Input CapaCitor (CIN)
A 47 ,...F, 25V aluminum electrolytiC capacitor located near.
the input and ground pins provides sufficient bypassing.

3·52

r-----------------------------------------------------------------------------, r
i:
....
LM2575 Series Buck Regulator Design Procedure (Continued)
en
......

INDUCTOR VALUE SELECTION GUIDES (For Continuous Mode Operation)

~
r
i:
en
......
en
:t:

....

~

'"'"
~

60
40
25
20

0

12

::I

10

...>
a..

a:

~

r
i:
I\)

15

en
......
en
......
r

::E

i:
I\)

::I

::E

en
......
en
:t:

~

::E

0.3

0.4

0.5 0.6

0.3

0.8 1.0

IotAXIt.lUt.l LOAD CURRENT (A)

FIGURE 4. LM2575(HV)-5.0

FIGURE 3. LM2575(HV)-3.3

'"~

60
50
40
30
25

~

'"
'"

'"~

~

0

>

20

a..

18
17

...=>
a:

::E

=>

16

x

15

60
50
40
35
30
25

0

>

...=>

22

a..

a:
=>

20
19

x

18

::E
::E

::E

'"

0.5 0.60.70.80.91.0
TLlH/11475-11

TL/H/11475-10

~

. 0.4

MAXIMUt.l LOAD CURRENT (A)

.",

::E

::E

0.3

0.4

0,3 .' 0.4

0.5 0.60.70.80.91.0

0.5 0.60.70.80.91.0

MAXIMUM LOAD CURRENT (A)

MAXIMUM LOAD CURRENT (A)

TLlH/11475-13

TL/H/11475-12

FIGURE 6. LM2575(HV)-15

FIGURE 5. LM2575(HV)-12

.

~
~

~

50

f7fj~--"1,=,':" ","'7IF-t--:YH-l

0.3

0.4

0.5 0.60.70.80.91.0

MAXIMUM LOAD CURRENT (A)
FIGURE 7. LM2575(HV)-ADJ

3-53

'TLlH/11475-14

<

LM2575 Series Buck Regulator Design Procedure (Continued)
EXAMPLE (Adjustable Output Voltage Versions)

PROCEDURE (Adjustable Output Voltage Versions)
Given:
VOUT = Regulated Output Voltage
VIN(Max) = Maximum Input Voltage
ILOAO(Max) = Maximum Load Current
F = Switching Frequency (Fixed at 52 kHz)
1.
Programming Output Voltage (Selecting R1 and R2, as
shown in Figure 2)

Given:
VOUT = 10V
VIN(Max) = 25V
ILOAO(Max) = 1A
F = 52 kHz
1.
Programming Output Voltage (Selecting R1 and R2)

Use the following formula to select the appropriate
resistor values.
VOUT = VREF (1

+ :~)

VOUT = 1.23( 1

+

:~)

Select R1 = 1k

R2 = R1 (VOUT -1) = 1k( 10V -1)
VREF
1.23V

where VREF = 1.23V

Rl can be between 1k and 5k. (For best temperature
coefficient and stability with time, use 1 % metal film
resistors)

R2 = 1k(8.13 -1) = 7.13k,closest1%valueis7.15k

R2 = R1 (VOUT - 1)
VREF

2.

Inductor Selection (L 1)
A. Calculate the inductor Volt. microsecond constant,
E • T (V • JoLs), from the following formula:

2.

10 1000
E • T = (25 - 10)· 25 • 52 = 115 V • JoLs

VOUT
1000
E • T = (VIN - VOUT) - - . - - .- - (V • JoLs)
VIN
F (mkHz)
B. Use the E • T value from the previous formula and
match it with the E • T number on the vertical axis of the
Inductor Value Selection Guide shown in Figure 7.
C. On the horizontal axis, select the maximum load
current.
D. Identify the inductance region intersected by the E • T
value and the maximum load current value, and note the
inductor code for that region.
E. Identify the inductor value from the inductor code, and
select an appropriate inductor from the table shown in
Figure 9. Part numbers are listed for three inductor
manufacturers. The inductor chosen must be rated for
operation at the LM2575 switching frequency (52 kHz)
and for a current rating of 1.15 x ILOAO. For additional
inductor information, see the inductor section in the
application hints section of this data sheet.

3.

Output Capacitor Selection (COUT)

Inductor Selection (L 1)
A. Calculate E • T (V • JoLs)

B.E.T= 115V.,...s
C.ILOAO(Max) = 1A
D.lnductance Region = H470
E.lnductor Value = 470,...H Choose from AlE
part #430·0634, Pulse Engineering
part #PE·53118, or Renco part #RL·1961.

3.

A. The value of the output capacitor together with the
inductor defines the dominate pole·pair of the switching
regulator loop. For stable operation, the capacitor must
satisfy the following requirement:
VIN(Max)
COUT;;' 7,785 VOUT. L(JoLH) (JoLF)

Output Capacitor Selection (COUT)
25
A. COUT > 7,78510.150 = 130,...F
However, for acceptable output ripple voltage select
COUT;;' 220 JoLF
COUT = 220 ,...F electrolytic capacitor

The above formula yields capacitor values between 10 JoLF
and 2000 JoLF that will satisfy the loop requirements for
stable operation. But to achieve an acceptable output
ripple voltage, (approximately 1% of the output voltage)
and transient response, the output capacitor may need to
be several times larger than the above formula yields.
B. The capacitor's voltage rating should be at last 1.5
times greater than the output voltage. For a 10V regulator,
a rating of at least 15V or more is recommended.
Higher voltage electrolytic capacitors generally have
lower ESR numbers, and for this reasion it may be
necessary to select a capacitor rate for a higher voltage
than would normally be needed.

3·54

r-

3:
.....
en

LM2575 Series Buck Regulator Design Procedure (Continued)
PROCEDURE (Adjustable Output Voltage Versions)

EXAMPLE (Adjustable Output Voltage Versions)

A. The catch-diode current rating must be at least 1.2
times greater than the maximum load current. Also, if the
power supply design must withstand a continuous output
short, the diode should have a current rating equal to the
maximum current limit of the LM2575. The most stressful
condition for this diode is an overload or shorted output.
See diode selection guide in Figure 8.
B. The reverse voltage rating of the diode should be at
least 1.25 times the maximum input voltage.
5. Input Capacitor (CIN)
An aluminum or tantalum electrolytic bypass capacitor
located close to the regulator is needed for stable
operation.

To further simplify the buck regulator
design procedure, National Semiconductor is making available computer
design software to be used with the
Simple Switcher line of switching regulators. Switchers Made Simple (version 3.3) is available on a (3]&#) diskette for IBM compatible computers
from a National Semiconductor sales
office in your area.

VR

A. For this example, a 3A current rating is adequate.
B. Use a 40V MBR340 or 310004 Schottky diode, or any of the
suggested fast-recovery diodes in Figure 8.

3:
.....

en
-...I
en

::I:

<
......
r-

3:
en
-...I
en
......
N

5. Input Capacitor (CIN)
A 100 /LF aluminum electrolytic capacitor located near the input
and ground pins provides sufficient bypassing.

Schottky
3A

20V

1N5817
MBR120P
SR102

1N5820
MBR320
SR302

30V

1N5818
MBR130P
110003
SR103

1N5821
MBR330
310003
SR303

.1N5819
MBR140P
110004
SR104

IN5822
MBR340
310004
SR304

50V

MBR150
110005
SR105

MBR350
310005
SR305

60V

MBR160
110006
SR106

MBR360
310006
SR306

r-

3:
en
-...I
en
N

::I:

<

Fast Recovery

1A

40V

-...I

en
......

r-

4. Catch Diode Selection (D1)

4. Catch Diode Selection (D1)

1A

3A

The following
diodes are all
rated to 100V

The following
diodes are all
rated to 100V

11OF1
MUR110
HER102

31OF1
MUR0310
HER302

FIGURE 8. Diode Selection Guide
Inductor
Code

Inductor
Value

Schott
(Note 1)

Pulse Eng.
(Note 2)

Renco
(Note 3)

L100

100/LH

67127000

PE-92108

RL2444

L150

150/LH

67127010

PE-53113

RL1954

L220

220/LH

67127020

PE-52626

RL1953

L330

330/LH

67127030

PE-52627

RL1952

L470

470/LH

67127040

PE-53114

RL1951

L6BO

680/LH

67127050

PE-52629

RL1950

H150

150/LH

67127060

PE-53115

RL2445

H220

220JloH

67127070

PE-53116

RL2446

H330

330/LH

67127080

PE-53117

RL2447

H470

470/LH

67127090

PE-53118

RL1961

H680

680JloH

67127100

PE-53119

RL1960

H1000

1000/LH

67127110

PE-53120

RL1959

H1500

1500 JloH

67127120

PE-53121

RL1958

H2200

2200/LH

67127130

PE-53122

RL2448

Note 1: Schott Corp., (612) 475·1173, 1000 Parkers Lake Rd., Wayzata, MN 55391.
Note 2: Pulse Engineering, (619) 674-6100, P.O. Box 12236, San Diego, CA 92112.
Note 3: Rence Electronics Inc., (516) 586-5566, 60 Jeffryn Blvd. East, Deer Park, NY 11729.

FIGURE 9_ Inductor Selection by Manufacturer's Part Number

3-55

•

> ,-----------------------------------------------------------------------,
::I:
Application Hints

c;
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..J

......

~

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..J

>
::I:

Ie
In
..-

:i

ie

In
:0-

pensive, the ,bobbin core type, consists of wire wrapped on
a ferrite rod core. This type of construction makes for an
inexpensive inductor, but since t~e magnetic flux is not completely contained within the core, it generates more electromagnetic interference (EM I). This.EMI can cause problems
in sensitive Circuits, or can give incorrect scope readings
because of induced voltages in the s!)ope 'prol>e.
'
The inductors listed in the selection chart include ferrite pot
core construction for AIE,powdered iron toroid for Pulse
Engineering, and ferrite bobbin core for Renco.
An inductor should not be operated beyond its maximum
rated current because it may saturate. When an inductor
begins to saturate, ihe inductance decreases rapidly and
the inductor begins to look mainly resistive (the DC resistance of the winding). This will cause the switch current to
rise very .rapidly. Different inductor types have different saturation characteristics, and this should be kept in mind when
selecting an inductor.
The inductor manufacturer's data sheets include current
and energy limits to avoid inductor saturation.
'

INPUT CAPACITOR (CIN)
To maintain stability, the regulator, input pin must be bypassed with at least a 47 ""F electrolytic capacitor. The capaCitor's leads must be kept short, 'and located near the
regulator.
If the operating temperature range includes temperatures
below -25°C, the input capacitor value may need to be
larger. With most electrolytic capacitors, the capacitance
value decreases and the ESR increases with lower temperatures and age. Paralleling a ceramic or solid tantalum capaCitor will increase the regulator stability at cold temperature.s. For maximum capacitor operating lifetime, the capacitor's RMS ripple current rating should be greater than
1.2 x

C~N)

where

t~N

:::IE

..J

=

X ILOAD

V~~T for a buck regulator

and toTN = Iv IViUTlv for a buck-boost regulator.
OUT + IN

INDUCTOR RIPPLE CURRENT'.
When the- switcher is operating' in the continuous'mode, the
inductor current waveform ranges from a triangular to a
sawtooth type of waveform (depending on the input voltage). For a given input voltage and output voltage, the peakto-peak amplit~de of this inductor current waveform remains
constant. As the load current rises or falls, the entire saw'tooth current waveform also rises or falls. The average DC
value of this waveform is equal to the DC load current (in
the buck regulator configuration).
!f the load current drops to a low enough level, the bottom
of the sawtooth current waveform will reach zero, and the
switcher will change to a discontinuous mode of operation.
This is a perfectly acceptable mode of operation. Any buck
switching regulator (no matter how large the inductor value
is) will be forced to run discontinuous if the load current is
light enough.

INDUCTOR SELECTION
All switching regulators have two basic modes of operation:
continuous and discontinuous. The difference between the
two types relates to the inductor current, whether it is flowing continuously, or.if it drops to zero for a period,of time in
the normal switching cycle. Each mode has distinctively different operating characteristics, which can affect the regulator performance and requirements.
The LM2575 (or any of the Simple Switcher family) can be
used for both continuous and discontinuous modes of operation.
The inductor value selection guides in Figures 3 through 7
were designed for buck regulator designs of the continuous
inductor current type. When using inductor values shown in
the inductor selection guide, the peak-to-peak inductor ripple current will be approximately 20% to 30% of the maximum DC current. With relatively heavy load currents, the
circuit operates in the continuous mode (inductor current
always flowing), but under light load conditions, the circuit
will be forced to the discontinuous mode (inductor current
falls to zero for a period of time). This discontinuous mode
of operation is perfectly acceptable. For light loads (less
than approximately 200 mAl it may be desirable to operate
the regulator in the discontinuous mode, primarily because
of the lower inductor values required for the discontinuous
mode.
The selection guide chooses inductor values suitable, for
continuous mOlde operation, but if the inductor value chosen
is prohibitively high, the designer should investigate the possibility of discontinuous operation. The computer design
software SiNltchers Made Simple will provide all component values for discontinuous (as well as continuous) mode
of operation..
Inductors are available in different styles such as pot core,
toriod, E-frame, bobbin core, etc., as well as different core
materials, such as ferrites and powdered iron. The least ex-

OUTPUT CAPACITOR
An output, capaCitor is required to filter the output voltage
and is needed for loop stability. The capacitor should be
located near the LM2575 using short pc board traces. Stan'dard aluminum ele!)trolytics are usually adequate, but low
ESR types are recommended for low output ripple voltage
and good stability. The ESR of a capaCitor depends on
many factors, some which are: the value, the voltage rating,
physical size and the type of construction. In general, low
value or low voltage (less than 12V) electrolytiC capacitors'
usually have higher ESR numbers.
The amount of output ripple voltage is primarily a function of
the ESR (Equivalent Series Resistance) of the output capacitor and the amplitude of the ihductor ripple current
(AIIND)' See the section on inductor ripple current in Appli, cation Hints.
The lower capaCitor values (220 ""F-680 ""F) will'allow typically 50 mV to 150 mV of output ripple voltage, while largervalue capaCitors will reduce the ripple to approximately
20 mV to 50 mV.
'
Output Ripple Voltage = (Allf.m) (ESR of COur)

3-56

r-----------------------------------------------------------------------,r
Application Hints (Continued)
FEEDBACK CONNECTION

To further reduce the output ripple voltage, several standard
electrolytic capacitors may be paralleled, or a higher-grade
capacitor may be used. Such capacitors are often called
"high-frequency," "low-inductance," or "Iow-ESR." These
will reduce the output ripple to 10 mV or 20 mY. However,
when operating in the continuous mode, reducing the ESR
below 0.050 can cause instability in the regulator.

The LM2575 (fixed voltage versions) feedback pin must be
wired to the output voltage point of the switching power
supply. When using the adjustable version, physically locate
both output voltage programming resistors near the LM2575
to avoid picking up unwanted noise. Avoid using resistors
greater than 100 kO because of the increased chance of
noise pickup.

Tantalum capacitors can have a very low ESR, and should
be carefully evaluated if it is the only output capacitor. Because of their good low temperature characteristics, a tantalum can be used in parallel with aluminum electrolytics, with
the tantalum making up 10% or 20% of the total capacitance.

ON/OFF INPUT
For normal operation, the ON/OFF pin should be grounded
or driven with a low-level TIL voltage (typically below 1.6V).
To put the regulator into standby mode, drive this pin with a
high-level TIL or CMOS Signal. The ON/OFF pin can be
safely pulled up to + Y,N without a resistor in series with it.
The ON/OFF pin should not be left open.

The capacitor's ripple current rating at 52 kHz should be at
least 50% higher than the peak-to-peak inductor ripple current.

GROUNDING

CATCH DIODE

3:
.....
en

c;l
......

r
3:
.....
en

c;l
::z::
~

r
3:
I\)
en
en
.......
r
3:
I\)
en
en

"'"

"'::z::"
<

To maintain output voltage stability, the power ground connections must be low-impedance (see Figure 2). For the
TO-3 style package, the case is ground. For the 5-lead
TO-220 style package, both the tab and pin 3 are ground
and either connection may be used, as they are both part of
the same copper lead frame.

Buck regulators require a diode to provide a return path for
the inductor current when the switch is off. This diode
should be located close to the LM2575 using short leads
and short printed circuit traces.
Because of their fast switching speed and low forward voltage drop, Schottky diodes provide the best efficiency, especially in low output voltage switching regulators (less than
5V). Fast-Recovery, High-Efficiency, or Ultra-Fast Recovery
diodes are also suitable, but some types with an abrupt turnoff characteristic may cause instability and EMI problems. A
fast-recovery diode with soft recovery characteristics is a
better choice. Standard 60 Hz diodes (e.g., 1N4001 or
1N5400, etc.) are also not sultable_ See Figure 8 for
Schottky and "soft" fast-recovery diode selection guide.

With the N or M packages, all the pins labeled ground, power ground, or signal ground should be soldered directly to
wide printed circuit board copper traces. This assures both
low inductance connections and good thermal properties.

HEAT SINKITHERMAL CONSIDERATIONS
In many cases, no heat sink is required to keep the LM2575
junction temperature within the allowed operating range. For
each application, to determine whether or not a heat sink
will be required, the following must be identified:

OUTPUT VOLTAGE RIPPLE AND TRANSIENTS

1. Maximum ambient temperature (in the application).

The output voltage of a switching power supply will contain
a sawtooth ripple voltage at the switcher frequency, typically
about 1 % of the output voltage, and may also contain short
voltage spikes at the peaks of the sawtooth waveform.

2. Maximum regulator power dissipation (in application).
3. Maximum allowed junction temperature (150·C for the
LM1575 or 125·C for the LM2575). For a safe, conservative deSign, a temperature approximately 15·C cooler
than the maximum temperature should be selected.

The output ripple voltage is due mainly to the inductor sawtooth ripple current multiplied by the ESR of the output capacitor. (See the inductor selection in the application hints.)

4. LM2575 package thermal resistances 8JA and 8JC.

The voltage spikes are present because of the the fast
switching action of the output switch, and the parasitic inductance of the output filter capacitor. To minimize these
voltage spikes, special low inductance capacitors can be
used, and their lead lengths must be kept short. Wiring inductance, stray capacitance, as well as the scope probe
used to evaluate these transients, all contribute to the amplitude of these spikes.

Total power dissipated by the LM2575 can be estimated as
follows:
Po = (V,N) (10) + (VoN,N) (I LOAD) (VSAT)
where 10 (quiescent current) and VSAT can be found in the
Characteristic Curves shown previously, Y,N is the applied
minimum input voltage, Vo is the regulated output voltage,
and ILOAD is the load current. The dynamic losses during
turn-on and turn-off are negligible if a Schottky type catch
diode is used.

An additional small LC filter (20 p.H & 100 p.F) can be added
to the output (as shown in Figure 15) to further reduce the
amount of output ripple and transients. A 10 x reduction in
output ripple voltage and transients is possible with this filter.

II

3-57

>r---------------------------------------------~------~----------~

::c
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Ii;
C'II

~
......

~

::E
....I

>:

::c
.."

....
....
:iii
.."

....I
......
.."

....
.."
....

....

::E

Application Hints (Continued)
When no heat sink is used, the junction temperature. rise
can be determined by the following: ' ..

Additional Applications
INVERTING REGULATOR
Figure 10 shows a LM2575-'12 in a buck-boost configuration
to generat~ a negaii've 12V output from a positive input volt~,
age. This circuit bootstraps the regulator's ground p'in to the
negative output voltage, then by grounding the feedback
pin, the regulator senses the inverted output voltage and
regulates it to -12V.
'

dTJ = (Po) (6JA)
To arrive at the actual operating junction temperature; add
the junction temperature rise to the maximum.ambient temperature.
TJ=dTJ+TA
If the actual operating junction temperature is greater than
the selected safe operating junction temperature deterIl'\ined in·step 3, then a heat sink is required. '
When using a heat sink, the junction temperature rise'can
be determined by the following:

For an input voltage of 12V or more, the maximum available
output current in this configuration is approximately 0.35A
At lighter loads, the minimum input voltage required drops to
'
,
approximately 4.7V.
The switch currents in' this buck.boost configuration' are
higher than in th~ standard buck-mode deSign, thus lowering the available output current. Also, the start-up input current of the buck-boost converter is higher thlin the standard
buck-mode regulator, and this may overload an input power
source with a current limit less than 1.5A. Using a delayed
turn-on or an undervoltage lockout circuit (described in the
next section) would allow the input voltage to rise to a high
enough level before the switcher woul,d 'be allowed to turn
on.
Because of the structural differences between the buck and
thebuck-b90st regulator topologies, ttie buck regulator design procedure section can not be used to to select the
inductor, or the (;U~put capaciior. The recommended range
of inductor values for the buck-boost design is between
68 /LH and 220 ,.H, and the ouiput capacitor values must be
larger than,what is normally required for buc,k'designs. Low
input voltages or high output currents reqUire a large value
output capacitor (in the thousands of micro Farads).
The peak inductor current,. which is the same as the peak
switch current, can be calculated from the following formula:

dTJ = (Po) (6JC + 6interface + 6HeatsiniJ
The operating junction temp~rature will be:
''
TJ = TA + dTJ
As above, if the actual operating junction temperature 'is
greater than the selected safe operating junction temperature, then a larger heat sink is required (one that has a lower
thermal resistance).
'
When using the LM2575 in the plastic DIP (N) or surface
mount (M)' packages, several items about'the thermal properties of the packages should be understood. The majority
of the heat is conducted out of the package through the
leads, with' a minor portion through the plastic parts of the
package. Since the lead frame is solid copper, heat from the
die is readily conducted through the leads to the printed
circuit board copper, whic!) is acting as a heat sink.
For best thermal performance, the ground pins and all the
unconnected pins should
soldered to generous 'amounts
qf printed circuit board copper, such as a ground pla!)e.
Large areas of copper provide the best transfer of heat to
the surrounding air. Copper on both sides of the board is
also helpful in getting the heat away from the package, even
if there is no direct copper contact between the two sides.
Thermal resistance numbers as low as 40'C/W for the SO
package, and 30'C/W for the N package can be realized
with a carefully engineered pc board,

be

I ::::: ILOAO(VIN -+- IVai) +'VIN Ivai x __1_,_
p
"
VIN
"
VIN + !vol
2 Ll fosc
Where fosc = 52 kHz. Under normal continuous inductor
current operating conditions, the minimum VIN represents
the worst case. Select an inductor thatis rated for the peak
current anticipated.
'

Included on the Swltchers Made Simple design software is
a more precise, (non-linear) thermal model ,that can be used
to determine junction temperature with different input-output
parameters or different component values. It can also calculate the heat sink thermal resistance required to maintain
the regulators junction temperature below the maximum operating temperature. '
'

+12 TO +25V
UNREGULATED
DC INPUT

+VIN
LM2575HV-12

Also, the maximum voltage appearing' across the' regulator
is the absolut(3 sum of the input and output Voltage. For a
-12V output, the maximum input voltage for the LM2575 is
+28V,'or +48V for the LM2575HV.
' ,
,'"
The SWitcheTfl Made Simple (versio!) 3.3) design software
can be,useq.to determine the feasibility of regulator designs
using different topologies, different input-output parameters,
different components, etc.

FEEDBACK
4
OUTPUT

L1

!.l l00P.F
GN
1.3""i"'---.......I2

I

GND

1

5 ON/OFF

"1

.... j..l 01
lN5819

+

-TI- 2200 p.F
COUT

-12V @O.35A
REGULATED
OUTPUT

FIGURE 10. Inverting Buck-Boost Develops -12V
3-58

TL/H/11475-15

r

is:
.....
U1

Additional Applications (Continued)
NEGATIVE BOOST REGULATOR

+VIN

Another variation on the buck-boost topology is the negative boost configuration. The circuit in Figure 11 accepts an
input voltage ranging from -5V to -12V and provides a
regulated -12V output. Input voltages greater than -12V
will cause the output to rise above -12V, but will not damage the regulator.

+VIN

.....;;.;.......-

......- -. . . .':'i,

+
20k

LM2575 - XX

......
U1
.......
r
is:
.....

U1
......

20k .J:SN

U1

::z::

Z,

:::r

Because of the boosting function of Hiis type of regulator,
the switch current is relatively high, especially at low input
Voltages. Output load current limitations are a result of the
maximum current rating of the switch. Also, boost regulators
can not provide current limiting load protection in the event
of a shorted load, so some other means (such as a fuse)
may be necessary.

:i:
N

U1

......

U1
.......
TL/H/11475-17

N

U1
......

Note: Complete circuit not shown.

U1

Note: Pin numbers are for the T0-220 package.

::z::

FIGURE 12. Undervoltage Lockout for Buck Circuit

+VIN

r
is:

+VIN

--.....-+--....
-,:-1 LM2575 +

<

XX
3

Gnd

150 J.lH

. ZI

Typical load Current
200 mA for VIN ~ -S.2V
SOOmAforVIN ~ -7V

-5 to -12V
TL/H/11475-16

Note: Pin numbers are for TO·220 package.

FIGURE 11. Negative Boost
-VOUT

UNDERVOLTAGELOCKOUT

TLlH/11475-16

In some applications it is desirable to keep the regulator off
until the input voltage reaches a certain threshold. An undervoltage lockout circuit which accomplishes this task is
shown in Figure 12, while Figure 13 shows the same circuit
applied to a buck-boost configuration. These circuits keep
the regulator off until the input voltage reaches a predetermined level.

VTH ::::; VZl

Note: Complete circuit not shown (see FIgure 10}.
Note: Pin n.umbers are for the T0-220 package.

FIGURE 13. Undervoltage Lockout
for Buck-Boost Circuit

+VIN

+ 2VSE (Q1)

+VIN

1

DELAYED STARTUP

0.1 p.~

The ON/OFF pin can be used to provide a delayed startup
feature as shown in Rgure 14. With an input voltage of 20V
and for the part values shown, the circuit provides approximately 10 ms of delay time before the circuit begins switching. Increasing the RC time constant can provide longer delay times. But excessively large RC time constants can
cause problems with input voltages that are high in 60 Hz or
120 Hz ripple, by coupling the ripple into the ON/OFF pin.

+

~Nl100

p.~

Ro

LM2575-XX
5 ON/O~~

47k

TLlH/11475-19

Note: Complete circuit not shown.
Note: Pin numbers are for the TO-220 package.

ADJUSTABLE OUTPUT, LOW-RIPPLE
POWER SUPPLY

FIGURE 14. Delayed Startup

A 1A power supply that features an adjustable output voltage is shown in Figure 15. An additional L-C filter that reduces the output ripple by l! factor of 10 or more is included in
this circuit.

II

3-59

>

:c
an

.....
an

r---------------------------------~----------------------------------__,

Additional Applications (Continued)
FEEDBACK

N

:;....
an
.....
an

60V·

UNREGULATED
DC INPUT

+V'N

4

-'---:-I'LM2575HV-ADJ

Ll

OUTPUT

........,..._ _~~2
3 GND 5 ON/OFF

N

:;
:>
:c

Dl
l1DQ06

an
.....
an

.....

OUTPUT
VOLTAGE

~~-~I-+"':"1.2 to
I @IA
I

55V

I""I
_-----"

....an

.. output ripple filter
optional

....I

:;

L2

I

:::as

.....
an
.....

r------.,

TLlH/11475-20

Note: Pin numbers are for the TO-220 package.
FIGURE 15. 1.2V to 55V Adjustable 1A Power Supply with Low Output Ripple

Definition of Terms
BUCK REGULATOR
A switching regulator topology in which a higher voltage is
converted to a lower voltage. Also known as a step-down
switching regulator.
BUCK-BOOST REGULATOR
A switching regulator topology in which a positive voltage is
converted to a negative voltage without a transformer.
DUTY CYCLE (D)
Ratio of the output switch's on-time to the oscillator period.
for buck regulator

for buck-boost regulator

D

= toN = VOUT
T

D = toN =

T

Y,N

Ivol
Ivol + VIN

CATCH DIODE OR CURRENT STEERING DIODE
The diode which provides a return path for the load current
when the LM2575 switch is OFF.
EFFICIENCY (1/)
The proportion of input power actually delivered to the load.
POUT

1/ =

"'PiN =

POUT
POUT + PLOSS

CAPACITOR EQUIVALENT SERIES RESISTANCE (ESR)
The purely resistive component of a real capacitor's impedance (see Figure 16). It causes power loss resulting in capacitor heating, which directly affects the capacitor's operating lifetime. When used as a switching regulator output
filter, higher ESR values result in higher output ripple voltages.

~1TLlH/11475-21

FIGURE 16. Simple Model of a Real CapaCitor
Most standard aluminum electrolytic capaCitors in the
100 p.F-1000 p.F range have 0.50 to 0.10 ESA. Highergrade capacitors ("Iow-ESR", "high-frequency", or "low-inductance"') in the 100 p.F-1000 p.F range generally have
ESR of less than 0.150.

EQUIVALENT SERIES INDUCTANCE (ESL)
The pure inductance component of a capacitor (see Figure
16). The amount of inductance is determined to a large
extent on the capacitor's construction. In a buck regulator,
this unwanted inductance causes voltage spikes to appear
on the output.
OUTPUT RIPPLE VOLTAGE
The AGcomponent of the switching regulator's output voltage. It is usually dominated by the output capacitor's ESR
multiplied by the inductor's ripple current (al'NO)' The peakto-peak value of this sawtooth ripple current can be determined by reading the Inductor Ripple Current section of the
Application hints.
CAPACITOR RIPPLE CURRENT
RMS value of the maximum allowable alternating current at
which a capacitor can be operated continuously at a specified temperature.
STANDBY QUIESCENT CURRENT (ISTBY)
Supply current required by the LM2575 when in the standby
mode (ON/OFF pin is driven to TTL-high voltage, thus tuming the output switch OFF).
INDUCTOR ,RIPPLE CURRENT (allNO)
The peak-to-peak value of the inductor current waveform,
typically a sawtooth waveform when the regulator is operating in the continuous mode (vs. discontinuous mode).
CONTINUOUS/DISCONTINUOUS MODE OPERATION
Relates to the inductor current. In the continuous mode, the
inductor current is always flowing and never drops to zero,
vs. the discontinuous mode, where the inductor current
drops to zero for a period of time in the normal switching
cycle.
INDUCTOR SATURATION
The condition which exists when an inductor cannot hold
any more magnetic flux. When an inductor saturates, the
inductor appears less inductive and the resistive component
dominates. Inductor current is then limited only by the DC
resistance of the wire and the available source current.
OPERATING VOLT MICROSECOND CONSTANT (EeTop)
The product (in Voltep.s) of the voltage applied to the inductor and the time the voltage is applied. This EeTop constant
is a measure of the energy handling capability of an inductor
and is dependent upon the type of core, the core area, the
number of turns, and the duty cycle.

Connection Diagrams
(XX indicates output voltage option. See ordering information table for complete part number.)
Straight Leads
5-Lead TO-220 (T)

Bent, Staggered Leads
5-Lead TO-220 (T)

(-"'
.-''''''''.
0"

i--'ii'O"

H ......
3- Ground
2- Output
I-V,N

3- Ground
2- Output
I-V,N

TLIH/11475-22 '

TL/H/11475-23

Top View

Top View

LM2575T-XX or LM2575HVT-XX
See NS Package Number T05A

_

CPin. 1,3 &: 5

~Pin'2&4
TLlH/11475-24

Side View
LM2575T-XX Flow LB03 or LM2575HVT-XX Flow LB03
See NS Package Number T05D
16-Lead DIP (N)

•

24-Lead Surface Mount (M)
16 V

PWR GND,

15 .'N

•

24

'.

OUTPUT

GND
GND

10 •

FB
8

9 ON/orr
TL/H/11475-25

FB

OUTPUT

SIG GND

OUTPUT

ON/orr

·No Internal Connection

Top View
PWR GND

LM2575N-XX or LM2575HVN-XX
See NS Package Number N16A

TLlH/11475-26

-No Intemal Connection

Top View
LM2575M-XX or LM2575HVM-XX
See NS Package Number M24B
4-Lead TO-3 (K)

OUTPUT

rEEDBACK

TLlH/11475-27

Bottom View
LM1575K-XX or LM1575HVK-XX/883
See NS Package Number K04A

3-61

Connection Diagrams (Continued)
(XX indicates output voltage option. See ordering information table for complete part number.)
T0-263(S)
5-Lead Surface-Mount Package

O

TAB IS
GND

S-ON/OFF
4- Feedback
3- Ground
2- Output

1- VIN
TLlH/11475-29

Top View

TLlH/11475-30

Side View
LM25758-XX or LM2575HVS-XX
See NS Package Number S05A

Ordering Information
Package
Type

NSC
Package
Number

Standard
Voltage Rating
(40V)

High
Voltage Rating
(60V)

5-Lead T0-220
Straight Leads

T05A

LM2575T·3.3
LM2575T·5.0
LM2575T·12
LM2575T-15
LM2575T·ADJ

LM2575HVT·3.3
LM2575HVT-5.0
LM2575HVT-12
LM2575HVT-15
LM2575HVT·ADJ

5-Lead TO·220
Bent and
Staggered Leads

T05D

LM2575T·3.3 Flow LB03
LM2575T·5.0 Flow LB03
LM2575T·12 Flow LB03
LM2575T·15 Flow LB03
LM2575T·ADJ Flow LB03

LM2575HVT-3.3 Flow LB03
LM2575HVT-5.0 Flow LB03
LM2575HVT-12 Flow LB03
LM2575HVT-15 Flow LB03
LM2575HVT·ADJ Flow LB03

16-Pin Molded
DIP

N16A

LM2575N·5.0
LM2575N-12
LM2575N·15
LM2575N-ADJ

LM2575HVN·5.0
LM2575HVN-12
LM2575HVN-15
LM2575HVN-ADJ

24-Pin
Surface Mount

M24B

LM2575M-5.0
LM2575M·12
LM2575M-15
LM2575M·ADJ

LM2575HVM-5.0
LM2575HVM-12
LM2575HVM-15
LM2575HVM-ADJ

5-Lead TO·236
Surface Mount

S05A

LM2575S-3.3
LM2575S-5.0
LM2575S·12
LM2575S-15
LM2575S·ADJ

LM2575HVS-3.3
LM2575HVS-5.0
LM2575HVS-12
LM2575HVS-15
LM2575HVS-ADJ

4-PinTO-3

K04A

LM1575K-3.3/BB3
LM1575K·5.0/BB3
LM1575K-12/BB3
LM1575K-15/BB3
LM1575K·ADJ/BB3

LM1575HVK-3.3/BB3
LM1575HVK·5.0/BB3
LM1575HVK-12/BB3
LM1575HVK·15/BB3
LM1575HVK-ADJ/BB3

3-62

Temperature
Range

-40"C :5: TJ :5: + 125·C

-55·C:5: TJ:5: +150·C

t!lNational Semiconductor

LM2576/LM2576HV Series
SIMPLE SWITCHER® 3A Step-Down Voltage Regulator
General Description

Features

The LM2576 series of regulators are monolithic integrated
circuits that provide all the active functions for a step-down
(buck) switching regulator, capable of driving 3A load with
excellent line and load regulation. These devices are available in fixed output voltages of 3.3V, 5V, 12V, 15V, and an
adjustable output version.

• 3.3V,5V, 12V, 15V, and adjustable output versions
• Adjustable version output voltage range,
1.23V to 37V (57V for HV version) ±4% max over
line and load conditions
• Guaranteed 3A output current
• Wide input voltage range, 40V up to 60V for
HV version
• Requires only 4 external components
• 52 kHz fixed frequency internal oscillator
• TTL shutdown capability, low power standby mode
• High efficiency
• Uses readily available standard inductors
• Thermal shutdown and current limit protection
• P + Product Enhancement tested

Requiring a minimum number of external components,
these regulators are simple to use and include internal frequency compensation and a fixed-frequency oscillator.
The LM2576 series offers a high-efficiency replacement for
popular three-terminal linear regulators. It substantially reduces the size of the heat sink, and in some cases no heat
sink is required.
A standard series of inductors optimized for use with the
LM2576 are available from several different manufacturers.
This feature greatly simplifies the design of switch-mode
power supplies.
Other features include a guaranteed ± 4 % tolerance on output voltage within specified input voltages and output load
conditions, and ± 10% on the oscillator frequency. External
shutdown is included, featuring 50 p.A (typical) standby current. The output switch includes cycle-by-cycle current limiting, as well as thermal shutdown for full protection under
fault conditions.

Typical Application

Applications
•
•
•
•

Simple high-efficiency step-down (buck) regulator
Efficient pre-regUlator for linear regulators
On-card switching regulators
Positive to negative converter (Buck-Boost)

(Fixed Output Voltage Versions)

7V - 40V
(60V for HV)

FEEDBACK

+V,.

UHR~~U~~:~~-""'--"'i,

I

G.

LU2576/
Lt.t2576HY-

~

Ll

:~;ULATED

L-:T~5.~O~=tf=t:~~;Jr::-OUTPUT
3A LOAD

IOO~F

TLlH/11476-1

FIGURE 1

Block Diagram

3.3V R2 ~ 1.7k
5V, R2 ~ 3.1k
12V, R2 ~ 8.84k
15V, R2 ~ ".3k
For ADJ. Version
R1 ~ Open, R2 ~

•
TLlH111476-2

on

Patent Pending

3-63

Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Maximum Supply Voltage
LM2576
LM2576HV
ON/OFF Pin Input Voltage
Output Voltage to Ground
(Steady State)
Power Dissipation
Storage Temperature Range

Minimum ESD Rating
(C = 100 pF, R = 1.5 kO)

2kV

Lead Temperature
(Soldering, 10 Seconds)
Maximum .Junction Temperature

45V
63V
-0.3V::;; V::;; +VIN

260"C
150"C

Operating Ratings
Temperature Range
LM2576/LM2576HV

-1V
Internally Limited
- 65'C to + 150'C

-40'C::;; TJ::;; +125'C

Supply Voltage
LM2576
LM2576HV

40V
60V

LM2576-3.3, LM2576HV-3.3
Electrical Characteristics Specifications with standard type face are for TJ =

25'C, and those ";"ith boldface

type apply over full Operating Temperature Range.

Symbol

Parameter

LM2576·3.3
LM2576HV·3.3

Conditions
Typ

Limit
(Note 2)

Units
(Limits)

SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
VOUT

VOUT

Output Voltage

VIN = 12V, ILOAD = 0.5A
Circuit of Figure 2

3.3

Output Voltage
LM2576

6V ::;; VIN ::;; 40V, 0.5A ::;; ILOAD ::;; 3A
Circuit of Figure 2

3.3

Output Voltage
LM2576HV

6V ::;; VIN ::;; 60V, 0.5A ::;; ILOAD ::;; 3A
Circuitof Figure 2

3:3

Efficiency

VIN = 12V, ILOAD = 3A

75

3.234
3.366
3.168/3.135

3.432/3.485
VOUT

3.168/3.135
3.450/3.482

'"

LM2576-5.0, LM2576HV-5.0
Electrical Characteristics Specifications with standard type face are fo~ TJ =

V
V(Min)
V(Max)
V
V(Min)
V(Max)
V
V(Min)
V(Max)
%

25'C, and those With boldface

type apply over full Operating Temperature Range.

Symbol

Parameter

LM2576·5.0
LM2576HV·5.0

Conditions
Typ

Limit
(Note 2)

Units
(Limits)

SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
VOUT

VOUT

VOUT

'"

Output Voltage

VIN = 12V,ILOAD = 0.5A
Circuit of Figure 2

5.0

Output Voltage
LM2576

0.5A ::;; ILOAD ::;; 3A,
8V::;; VIN::;; 40V
Circuit of Figure 2

5.0

Output Voltage
LM2576HV

0.5A ::;; ILOAD ::;; 3A,
8V::;; VIN::;; 60V
Circuit of Figure 2

5.0

Efficiency

VIN = 12V,ILOAD = 3A

77

3·64

4.900
5.100

V
V(Min)
V(Max)

4.800/4.750
5.200/5.250

V
V(Min)
V(Max)

4.800/4.750
5.225/5.275

V
V(Min)
V(Max)
%

LM2576-12, LM2576HV-12
Electrical Characteristics Specifications with standard type face are for TJ = 25'C, and those with boldface
type apply over full Operating Temperature Range.

Symbol

Parameter

LM2576-12
LM2576HV-12

Conditions

Limit
(Note 2)

Typ

Units
(Limits)

SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
VOUT

VOUT

VOUT

"I)

Output Voltage

VIN = 25V, ILOAD
Circuit of Figure 2

=

12

0.5A

Output Voltage
LM2576

0.5A :0: ILOAD :0: 3A,
15V :0: VIN :0: 40V
Circuit of Figure 2

12

Output Voltage
LM2576HV

0.5A :0: ILOAD :0: 3A,
15V :0: VIN :0: 60V
Circuit of Figure 2

12

Efficiency

VIN

=

15V, ILOAD

=

11.76
12.24

V
V(Min)
V(Max)

11.52/11.40
12.48/12.60

V
V(Min)
V(Max)

11.52/11.40
12.54/12.66

V
V(Min)
V(Max)

88

3A

%

LM2576-15, LM2576HV-15
Electrical Characteristics Specifications with standard type face are forTJ

=

25'C, and those with boldface

type apply over full Operating Temperature Range.

Symbol

Parameter

LM2576-15
LM2576HV-15

Conditions

Limit
(Note 2)

Typ

Units
(Limits)

SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
VOUT

VOUT

VOUT

"I)

Output Voltage

VIN = 25V, ILOAD
Circuit of Figure 2

=

15

O.5A

Output Voltage
LM2576

0.5A :0: ILOAD :0: 3A,
18V:O: VIN :0: 40V
Circuit of Figure 2

15

Output Voltage
LM2576HV

0.5A :0: ILOAD :0: 3A,
18V:o: VIN :0: 60V
Circuit of Figure 2

15

Efficiency

VIN

=

18V, ILOAD

=

14.70
15.30

V
V(Min)
V(Max)

14.40/14.25
15.60/15.75

V
V(Min)
V(Max)

14.40/14.25
15.68/15.83

V
V(Min)
V(Max)

88

3A

%

LM2576-ADJ, LM2576HV-ADJ
Electrical Characteristics Specifications with standard type face are for TJ = 25'C, and those with boldface
type apply over full Operating Temperature Range.

Symbol

Parameter

LM2576-ADJ
LM2576HV-ADJ

Conditions
Typ

VOUT

VOUT

VOUT

"I)

VIN = 12V, ILOAD
VOUT = 5V,
Circuit of Figure 2

=

1.230

0.5A

Feedback Voltage
LM2576

0.5A:O: ILOAD :0: 3A,
8V:O: VIN:O: 40V
VOUT = 5V, Circuit of Figure 2

1.230

Feedback Voltage
LM2576HV

0.5A :0: ILOAD :0: 3A,
8V:o: VIN:O: 60V
VOUT = 5V, Circuit of Figure 2

1.230

Efficiency

VIN

=

12V, ILOAD

Units
(Limits)

-

SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
Feedback Voltage

Limit
(Note 2)

=

3A, VOUT

3-65

=

5V

77

1.217
1.243

V
V(Min)
V(Max)

1.193/1.180
1.267/1.280

V
V(Min)
V(Max)

1.193/1.180
1.273/1.286

V
V(Min)
V(Max)

%

All Output Voltage Versions
Electrical Characteristics Specifications with standard type face are for TJ = 25·C, and those with boldface
= 12V for the 3.3V,
= 500 mAo

type apply over full Operating Temperature Range. Unless otherwise specified, VIN
version, VIN

Symbol

=

25V for the 12V version, and VIN

=

30V for the 15V version. ILOAD

Parameter

5V, and Adjustable

LM2576-XX
LM2576HV-XX

Conditions

Units
(Limits)

Typ

Limit
(Note 2)

50

100/500

nA

47/42
58/63

kHz
kHz (Min)
kHz (Max)

1.8/2.0

V
V(Max)

93

%
%(Min)

4.2/3.5
6.9/7.5

A
A(Min)
A(Max)

DEVICE PARAMETERS

=

Ib

Feedback Bias Current

VOUT

fa

Oscillator Frequency

(Note 11)

VSAT
DC
ICL

IL

10
ISTBY
8JA
8JA
8JC
8JA

Saturation Voltage
Max Duty Cycle (ON)
Current Limit

Outplll Le,akage Current

Quiescent Current

lOUT

=

5V (Adjustable Version Only)

52

1.4

3A (Note 4)

(Note 5)

98

(Notes 4 and 11)

5.8

Output = OV
Output = -1V
Output = -1V

(Notes 6 and 7)

(Note 6)

2
30

mA(Max)
mA
mA(Max)

10

mA
mA(Max)

200

p.A(Max)

7.5
5

=

Standby Quiescent
Current

ON/OFF Pin

5V (OFF)

Thermal Resistance

T Package, Junction to Ambient (Note 8)
T Package, Junction to Ambient (Note 9)
T Package, Junction to Case
S Package, Junction to Ambient (Note 10)

pA

50
65
45
2
50

·C/W

~/OFF CONTROL Test Circuit Figure 2
VIH
VIL
IIH
IlL

=
=

(jiij/OFF Pin
Logic Input Level

VOUT

ON/OFF Pin Input.
Current

ON/OFF Pin

VOUT

OV

1.4

2.2/2.4

V(Min)

Nominal Output Voltage

1.2

1.0/0.8

V(Max)

30

p.A
p.A(Max)

10

p.A
p.A(Max)

ON/OFF Pin

=
=

5V (OFF)
OV (ON)

12
0

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device Is
Intended to be functional, but do not guarantee specific performance limits. For guaranteed specHications and test condHions, see the Electrical Characteristics.
Note 2: All IImHs guaranteed at room temperature (standard type face) and at temperature extreme. (bold type face). All room temperature limits are t 00%
production tested. All limits at temperature extremes are guaranteed via correlation using standard Statistical aualRy Control (SaC) methods.
Note 3: External components such as the catch diode, inductor, input and output capacHors can affect switching regulator system performance. When the
LM2576/LM2576HV is used as shown in the F/{Jure 2 test circuit, system performance will be as shown in system parameters section of Electrical Characteristics.
Note 4:' Output pin sourcingcurfent No diode, Inductor or capacitor connected to output.
Note 5: Feedbeck pin removed from output and connected to OV.
Note 6: Feedbeck pin remoVed from output and connected to +12V for the Adjustable, 3.3V, and 5V versions, and +25V for the 12V and 15V versions, to force
the output transistor OFF.
Note 7: VIN = 40V (SOV for high voltage version).
Note 8: Junction to ambient thermal resistance (no external heat sink) for the 5 lead TO·220 package mounted vertically, with Y. inch leads in a socke~ or on a PC
board wHh minimum copper area.
Note 9: Junction to ambient thermal resistance (no external heat sink) for the 5 lead TQ.220 package mounted vertically, with Y. inch ieads soldered to a PC board
containing approximately 4 square inches of cOpper area surrounding the leads.
Note 10: If the TQ.2s3 packlige is lised, the thermal resistance can be reduced by increasing ihe PC board copper area thermally connected to the package. Using
0.5 square inches of copper area, 8JA is 511'C/W, with I square inch of copper area, 8JA is 37"C/W, and wHh 1.6 or more square inches of copper area, 8JA is
32'C1W.
Note 11: The oscillator frequency reduces to approximately t I kHz in the event of an output short or an overload which causes the regulated oulput voltage to drop
approximately 40% from the nominal output voltage. This self protection feature lowers the average power dissipation of the IC by lowering the minimum duty cycte
from 5% down to approximately 2%.

3-66

Typical Performance Characteristics (Circuit of Rgure2)

Normalized Output Voltage
+1.0

g
".,z
"'"
~

~

~
~

g

+0.8 t--

=
=

'LOAD 500 rnA
Normalized at
+0.4 t-- t-- TJ 25°C

I--

+0.6

+0.2
0

-

.,.,

......

-0.2

V

,

-0.4
-O.S
-0.8

-1.0
-50 -25

2.0

g

1.2

.,"z
"'"

0.8

~

f--

t-- ILOAD

~

0.4

!;

0

~

-0.2

25

50

75

.v

/
/- +

0.2

I

-0.4

100 125

o

10

20

.......

~

iB

5.5

~

5.0

'5

,

Y,N

20

= 25V
.5-

16

z

"/' ~

10

5

10

20

i

~
§!
~

h
NJ

\'V,N =40V

-6

~
~

-75 -50-25 0

1.2

0.6

25 0

4.0

o
o

25 50 75 100125150

~

~

~
40

50

3.0
2.5

~

0.5

I--

1.5

:;;;:: ".

,g

~

!:i

~
g

3.0

0

25

50

75

100 125

100 125

';1

........

=1 3A

I
o

--

;;;;;:::

10

20

/

'LOAD

=

30

40

...........

200 rnA
50

60

.INPUT VOLTAGE (V)

Feedback Voltage

vs Duty Cycle
20

YIN

Adjustable Version Onl1

15.0
12.5

~

10.0

~

i

o

-5

~

~

-10

-15
-20

20

40

""'l:: ~IN=40V
V'N=7V ...... ~ ......

40V

~OAO = 500 mA

./

5.0

VIN

~OAO = 500 mA

\.

10

~

~

7.5

15

=7V 1--........ V

o

JUNCTION TE~PERATURE (·c)

75

60
2.0. 2.5

2.5

-50 -25

75

.........

SVYr'

Adjustable Version Only/

~

50

T

I

80

65
1.5

25

,5V OUT

85

70 _'LIAO

~

I

o

0

I ~OAD = 3A TJ = 2S·C
I \ 'LOAD = 200 rnA

9.0

Quiescent Current
vs Duty Cycle

.5-

1.0
0.5

o

SWITCH CURRENT (A)

"<

YOUT ~ 1.23V
1LOAD = 500 mA

1-:..-

95

~

;;;

1.0

-

VIN = 12V
50

Efficiency

I
I

~

2.0

VON/OFF = SV
100

-50 ,-25

60

l.-

I

JUNCTION TEMPERATURE (·C)

~

17.5

-

I.......

3.5

150

g

CV

Adjustable Version Only

4.5

Y,N =40V

I--"

!!i

20.0

5.0

~

=3A

....150·C
0.4

Minimum Operating Voltage

~

~
~
~

15

-j/" /"

0.8

JUNCTION TE~PERATURE (·C)

E

z

100

-55°C

1.0

0.2

V,N =12V

-8

'LOAD

30

I
I

1.4
~

25 50 75 100125150

200

Switch Saturation
Voltage

Normalized at 25°C

-4

"<

INPUT VOLTAGE (V)

1.6

-2

~ND = O.ln

o

.3

~
o

Oscillator Frequency

~

at

~OAO - 200 mA

4

"\.

0.5

=>

25 50 75 100 125 150

1;

--

l- I-. 'LOAD = lA
l- I- I-. ~
'LOAD = 200 rnA r-

Standby
Quiescent Current

"

"~

E

-

~

~

= ISO},"

JUNCTION TEMPERATURE (·C)

14
12

L,

3AI

-75 -50 -25 0

60

Ground Pin
TJ = 25 0 C

JUNCTION TEMPERATURE (ac)

~

r1.0

i

~
~

B

4.0

0

50

~easured

0

/

40

~

z

4.5

~

I
I

LVour =5V

18

"<

r\

g

~

INPUT VOLTAGE (v)

",-

-75 -50 -25 0

30

I
I

ILO~D ~

1.5

is

3.3J.5V 8< ADJ

I

I-

~

Quiescent Current

6.5

".

E
.,

r- _12V & 15V

1/

Current Limit

3:

~

WI

0.6

JUNCTION TE~PERATURE (·C)

6.0

= 500 m~

TJ = 25°C

1.0

-0.6
-0

Dropout Voltage

Line Regulation
1.4

vlN = 20V

60

DUTY CYCLE (!II)

80

100

o

20

40

60

80

'DO

DUTY CYCLE (lI)

TUH/11478-3

3-67

•

>
:::E:

~

Typical Performance Characteristics (Circuit of Figure 2) (Continued)

1.1)

:s
C'I

Maximum Power Dissipation
(TO-263) (See Note 10)

.....

~

I

1.1)

9 JA = 32°C/~

C'I

::::is

4

~

...J

:z:

'I.

I

"'k~

0

;::

«

9 JA -37OC/v:.........

-

"-

...... ......

iii

III

is

-.

'"~
~

o
o

I ~ ::--.

~~ ....... ~
t'-...

I ~ ~73fci~ ;;;;: ~
I i JA I I

10 20 30 40 50 60 70 80 90 100
AMBIENT TEMPERATURE (Oc)

Feedback Pin Current

TL/H/11476-24

Switching Waveforms

100
Adjustable Version Only

75
50

4A

f

25

B 2A

J

a

l

,."

a

-25

r

-50

4A

C L2A

-75
0(0

-100

-75 -50 -25

a

25 50 75 100 125150
5 ",s/div

JUNCTION TEMPERATURE (OC)

TL/H/11476-6
TL/H/11476-4

VOUT

Load Transient Response

=

15V

A: Output Pin Voltage, 50V/div

B: Output Pin Current, 2A1div
Output

+ 1 00 mV

Voltage
Change

0

C: Inductor Current, 2A1div

0: Output Ripple Voltage, 50 mVIdiv,
AC-Coupled

Horizontal Time Base: 5 !'s/dlv

-100mV

As in any switching regulator, layout is very important Rapidly switching currents associated with wiring inductance
generate voltage transients which can cause problems. For
minimal inductance and ground loops, the length of the
leads indicated by heavy lines should be kept as short as
possible. Single-point grounding (as indicated) or ground
plane construction should be used for best results. When
using the Adjustable version, physically locate the programming resistors near the regulator, to keep the sensitive
feedback wiring short.

3A
Load
Current

2A
1A

o
100 ",s/div
TL/H/11476-5

3-68

Test Circuit and Layout Guidelines
Fixed Output Voltage Versions
rEEDBACK
GIN -

LM2576HV-

COUT -

FIXED OUTPUT
3

100 I'F, 7SY, Aluminum Electrolylic
1000 p.F, 25V, Aluminum Electrolytic

D, -

Schottky, MBR360

L, -

100 I'H, Pulse Eng. PE·92108

ON/orr

R,- 2k, 0.1%
R2- 6.12k, 0.1%
TL/H/11476-7

Adjustable Output Voltage Version
rEEDBACK

LM2576HV3 ON/orr

Your

L1

ADJ
S

Your

S.DDY

+ COUT

R2

R2

~ YREF ( 1 + ~ )
~

R, (Your -1)
YREF

IOOOl'r

Rl

rllH/11476-8

FIGURE 2

3-69

where YREF

~

1.23Y, R1 between 1k and Sk.

LM2576 Series Buck Regulator Design Procedure
PROCEDURE (Fixed Output Voltage Versions)

EXAMPLE (Fixed Output Voltage Versions)

Given:
VOUT = Regulated Output Voltage (3.3V, 5V, 12V, or 15V)
VIN(Max) = Maximum Input Voltage
ILOAO(Max) = Maximum Load Current
1. Inductor Selection (L 1)
A. Select the correct Inductor value selection guide from
Figures 3, 4, 5, or 6 . (Output voltages of 3.3V, 5V, 12V or
15V respectively). For other output voltages, see the
design procedure for the adjustable version.
B. From the inductor value selection guide, identify the
inductance region intersected by VIN(Max) and
ILOAO(Max), and note the inductor code for that region.
C. Identify the inductor value from the inductor code, and
select an appropriate inductor from the table shown in
Figure 3 . Part numbers are listed for three inductor
manufacturers. The inductor chosen must be rated for
operation at the LM2576 switching frequency (52 kHz) and
for a current rating of 1.15 x ILOAO. For additional
inductor information, see the inductor section in the
Application Hints section of this data sheet.
2. Output Capacitor Selection (COUT)
A. The value of the output capacitor together with the
inductor defines the dominate pole-pair of the switching
regulator loop. For stable operation and an acceptable
output ripple voltage, (approximately 1% of the output
voltage) a value between 100 ",F and 470 ",F is
recommended.
B. The capacitor's voltage rating should be at least 1.5
times greater than the output voltage. For a 5V regulator,
a rating of at least 8V is appropriate, and a 10V or 15V
rating is recommended.
Higher voltage electrolytic capacitors generally have lower
ESR numbers, and for this reason it may be necessary to
select a capacitor rated for a higher voltage than would
normally be needed.
3. Catch Diode Selection (01)
A. The catch-diode current rating must be at least 1.2
times greater than the maximum load current. Also, if the
power supply design must withstand a continuous output
short, the diode should have a current rating equal to the
maximum current limit of the LM2576. The most stressful
condition for this diode is an overload or shorted output
condition.
B. The reverse voltage rating of the diode should be at
least 1.25 times the maximum input voltage.
4.
Input Capacitor (CIN)
An aluminum or tantalum electrolytic bypass capacitor
located close to the regulator is needed for stable
operation.

Given:
VOUT = 5V
VIN(Max) = 15V
ILOAO(Max) = 3A
1. Inductor Selection (L 1)
A. Use the selection guide shown in Figure 4 .
B. From the selection guide, the inductance area
intersected by the 15V line and 3A line is L100.
C. Inductor value required is 100 ",H. From the table in
Figure 3. Choose AlE 415-0930, Pulse Engineering
PE921 08, or Renco Rl2444.

2.

Output Capacitor Selection (COUT)
A. COUT = 680 ",F to 2000 ",F standard aluminum
electrolytic.
B. Capacitor voltage rating = 20V.

3.

Catch Diode Selection (01)
A. For this example, a 3A current rating is adequate.
B. Use a 20V 1N5823 or SR302 Schottky diode, or any of
the suggested fast-recovery diodes shown in Figure 8 .

4.

Input Capacitor (CIN)
A 100 ",F, 25V aluminum electrolytic capacitor located
near the input and ground pins provides sufficient
bypassing.

3-70

LM2576 Series Buck Regulator Design Procedure (Continued)
INDUCTOR VALUE SELECTION GUIDES (For Continuous Mode Operation)
60
40
20
IS

~
~

~

...
~

10

!Ii!

!:l

!:;

0

0

>

>

~

~

~

~
~

~

'"=>
'"x

!:i

'"=>
::0;

'"

'"

::0;

TlIH/11476-10

TL/H/11476-9

FIGURE 4. LM2576(HV)-5.0

FIGURE 3. LM2576(HV)-3.3

~
~

'"'"

!:;

>

22

i

20

0

::0;

19

'"x
'"

18

=>

:I

.3

.4

.5.6.7.8

1.0

1.5

2.0

.3

2.5 3.0

.4

.5.6.7.8

1.0

1.5

2.0

2.5 3.0

MAXIMUM LOAD CURRENT (Al

MAXIMUM LOAD CURRENT(Al

TlIH/11476-12

TlIH/11476-11

FIGURE 6. LM2576(HV)-15

FIGURE 5. LM2576(HV)-12

.
....
~

.::.
l-

0.4

0.5 0.60.70.8 1.0
1.5
MAXIMUM LOAD CURRENT (A)
FIGURE 7. LM2576(HV)-ADJ

3-71

2.0

2.5 3.0
TlIH/11476-13

>
:::E:

CD

"'"
::i
....

r-----~----~~------------------------------------------------------__,

LM2576 Series Buck Regulator Design Procedure. (Continued)

II)

N

~
II)

N

::i

....

PROCEDURE (Adjustable Output Voltage Versions)

EXAMPLE (Adjustable Output Voltage Versions)

Given:
VOUT = Regulated Output Voltage
VIN(Max) = Maxim!Jm Input Voltage
ILOAD(Max) = Maximum Load Current
F = Switching Frequency (Fixed. at 52 kHz)
1. Programming Output Voltage (Selecting Rl and R2, as
shoWn in Figure.2)
.

Given:
VOUT = 10V
VIN(Max) = 25V
ILOAD(Max) = 3A
F = 52kHz
1.
Programming Output Voltage (Selecting Rl and R2)

Use the following formula to select ttie appropriate
resistor values.
.'
VOUT = VREF (1' +

:~)

. VOUT = 1.23( 1,

R2 = 1k(8.13 -1) = 7.13k,'closest1% value is 7.15k

Inductor Selection (L1)
A. Calculate the inductor Volt - microsecond constant,
.' E - T (V - /ls), f~om the following formula:
VOUT
1000 .
E - T = (VIN - VOUT) -.- - - - - . - . - (V - /ls)
.
.'. .
VIN . F (m kHz).
B. Use the E - T va.lue from the previous formula and
match it with the E - T number on the vertical axis of the
Inductor Value Selection Guide shown in Figure 7.
C.
the horizontal axis, select the maximum load
current.
D. Identify the inductance region intersected by the E - T
value and the maximum load current value, and note the
inductor code for that region:
E. Identify the inductor value from the inductor code, and
select an appropriate inductor from the table shown in
Figure 9. Part numbers are listed for three inductor
manufacturers. The inductor chosen must be rated for
operation at the LM2576 switching frequency (52 kHz)
and for a current rating of 1.15 x ILOAD. For additional
inductor information, see the inductor section in the
application hints section of this,data sheet.

2.

Output Capacitor Selection. (COUT)

3.

Inductor Selection (L 1)
A. Calculate E - T (V ~ /ls)
10 1000
E - T = (25 - 10) - 25 = 115 V -,/lS

52

B.E-T= 115V'-/ls
C. ILOAD(Max) = 3A
D.lnductance Region = H150
E; Inductor Value = 150 /lH Choose from AlE
part #415·0936 Pulse Engineering
psrt # PE·531115, or Renco part #RL2445.

On

3.

Select R1 = 1k

R2 = Rl(VOUT -1) = 1k( 10\1 -1)
VREF "
1.23V

where VREF = 1.23V

Rl can be between 1k and 5k. (For best temperature
coefficient and stability with time, use 1% metal film
resistors)
. (VOUT
.. )
R2 = Rl - - - 1
VREF
.

2.

+ :~)

A. The value of the output capacitor together with 'the
inductor defines the dominate pole·pair cif the switching
regulator loop. For stable operation, the capacitor must
satisfy the following requirement:
,
VIN(Max)
COUT;;' 13,300 VOUT _ L(/lH) (/IF)

Output Capacitor Selection (COUT)
25
A. GoUT> 13,300 10 _ 150 = 22.2/lF
However, for acceptable output ripple voltage select
GoUT;;' 680 /IF
COUT = 680 /IF electrolytic capacitor

The above formula yields capacitor va.lues between 10' ~F
and 2200 /IF that will satisfy the loop requirements for
stable operation. But to achieve an acceptable output
ripple voltage, (approximately 1 % of the output voltage)
and transient response, the output capacitor may need to
be several times larger than the above formula yields.,
B. The capacitor's voltage rating should be at last 1.5
times greater than the output voltage. For a 10V regUlator, .
a rating of at least 15V or more is recomlT]ended:
Higher voltage electrolytic capacitors generally have'
lower ESR numbers, and for this reason it may be
necessary to select a capacitor rate for a higher voltage
than would normally be needed.

3·72

r3:

LM2576 Series Buck Regulator Design Procedure (Continued)
PROCEDURE (Adjustable Output Voltage Versions)

EXAMPLE (Adjustable Output Voltage Versions)

4. Catch Diode Selection (01)
A. The catch-diode current rating must be at least 1.2
times greater than the maximum load current. Also, if the
power supply design must withstand a continuous output
short, the diode should have a current rating equal to the
maximum current limit of the LM2576. The most stressful
condition for this diode is an overload or shorted output.
See diode selection guide in Figure 8 .
B. The reverse voltage rating of the diode should be at
least 1.25 times the maximum input voltage.
5. Input Capacitor (CIN)
An aluminum or tantalum electrolytic bypass capacitor
located close to the regulator is needed for stable
operation.
Schottky

VR

3A

4. Catch Diode Selection (01)
A. For this example, a 3.3A current rating is adequate.
B. Use a 30V 31 0003 Schottky diode, or any of the suggested
fast-recovery diodes in Figure 8.

......

en
.......

r3:
N
UI

......
en

::::t

<

5. Input Capacitor (CIN)
A 100 /LF aluminum electrolytic capacitor located near the input
and ground pins provides sufficient bypassing.

Fast Recovery

4A-6A

20V

1N5820
MBR320P
SR302

1N5823

30V

1N5821
MBR330
310003
SR303

50W003
1N5824

1N5822
MBR340
310004
SR304

MBR340
50W004
1N5825

50V

MBR350
310005
SR305

50W005

60V

MBR360
0006
SR306

50WR06
50S0060

40V

N
UI

3A

4A-6A

The following
diodes are all
rated to 100V

The following
diodes are all
rated to 100V

50WF10
MUR410
HER602

31OF1
HER302

To further simplify the buck regulator
design procedure, National Semiconductor is making available computer
design software to be used with the
SIMPLE SWITCHER line of switching
regulators. Switchers Made Simple
(Version 3.3) is available on a (3MN)
diskeffe for IBM compatible computers
from a National Semiconductor sales
office in your area.

FIGURE 8. Diode Selection Guide
Inductor
Code

Inductor
Value

Schott
(Note 1)

Pulse Eng.
(Note 2)

Renco
(Note 3)

L47

47/LH

67126980

PE-53112

RL2442

L68

68/LH

67126990

PE~92114

RL2443

UOO

100/LH

67127000

PE-92108

RL2444

U50

150!-,H

67127010

PE-53113

RU954

L220

220!-,H

67127020

PE-52626

RU953

L330

330/LH

67127030

PE-52627

RU952

L470

470/LH

67127040

PE-53114

RU951

L680

680/LH

67127050

PE-52629

RU950

H150

150!-,H

67127060

PE~53115

RL2445

H220

220/LH

67127070

PE-53116

RL2446

H330

330/LH

67127080

PE-53117

RL2447

H470

470/LH

67127090

PE-53118

RU961

H680

680/LH

67127100

PE-53119

RU960

H1000

1000/LH

671 27110

PE-53120

RU959

H1500

1500/LH

67127120

PE-53121

RU958

H2200

2200/LH

67127130

PE-53122

RL2448

Note 1: Schott Corporation, (612) 475-1173, 1000 Parkers Lake Road, Wayzata, MN 55391.

Note 2: Pulse Engineering, (619) 674·6100. P.O. Box 12235, San Diego, CA 92112.
Note 3: Renco Electronics Incorporated, (516) 566-5566, 60 JeffJyn Blvd. East, Deer Park, NY 11729.

FIGURE 9. Inductor Selection by Manufacturer's Part Number
3-73

•

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....

Je

11)

N

::E
....I

r-----------------------------------------------------------------------,
Application Hints
Inductors are available in different styles such as pot core,
toriod, E-frame, bobbin core, etc., as well as different core
materials, such as ferrites and powdered iron. The least expensive, the, bobbin core type, cOrlsists of wire wrapped on
a ferrite rod core. This type of construction makes for an
inexpensive inductor, but since the magnetic flux is not completely contained within the core, it generates more' electromagnetic interference (EM I). This EMI can, cause problems
in sensitive Circuits, or can give incorrect scope readings
because of induced voltages in the scope probe.

INPUT CAPACITOR (CIN)
To maintain stability, the regulator input, pin must be bypassed with at least a 100 ,..F electrolytic capacitor. The
capacitor~s leads must be kept short, and located near the
regulator.
If the operating temperature range includes temperatures
below -25°C, the input capacitor value may need to be
larger. With most electrolytic capacitors, the capacitance
value decreases and the ESR increases with lower temperatures and age. Paralleling a ceramic or solid tantalum capacitor will increase the regulator stability at cold temperatures. For maximum capacitor operating lifetime, the capacitor's RMS ripple current rating should be greater than

1.2

The inductors listed in the selection chart include ferrite pot
core construction for AlE, powdered iron toroid for Pulse
Engineering, and ferrite bobbin core for Renco.
An inductor should not be operated beyond its maximum
rated current because it may saturate. When an inductor ,
begins to saturate, the inductance decreases rapidly and
the inductor begins to look mainly resistive (the DC ,reSistance of the winding). This will cause the switch current to
rise very rapidly. Different inductor types have different saturation characteristics, and this should be kept in mind when
selecting an inductor.
'

tON) X ILOAD
x (T

where

t~N = V~~T for a buck regulator

and toTN = Iv IV,uTl v for a buck-boost regulator.
OUT + IN

The inductor manufacturer's data sheets include current
and energy limits to avoid Inductor saturation.

INDUCTbR SELECTION
All switching regulators have two basic modes of operation:
continuous and discontinuous. The difference between the
two types relates to the inductor current, whether it is flowing continuously, or if it drops to zero for a period of time in
the normal switching cycle. Each mode has distinctively different operating characteristics, which can affect the regulator performance and requirements.
The LM2576 (or any of the SIMPLE SWITCHER family) can
be used for both continuous and discontinuous modes of
operation.

INDUCTOR RIPPLE CURRENT
When the switcher is operating in the continuous mode, the
inductor current waveform ranges from a triangular to a
sawtooth type of waveform (depending on the input voltage). For a given input voltage and output voltage, the peakto-peak amplitude of this inductor current waveform remains
constant. As the load current rises or falls, the entire sawtooth current waveform also rises or falls. The average DC
value of this waveform is equal to the DC load current (in
the buck regulator configuration).
If the load current drops to a low enough level, the bottom
of the sawtooth current waveform will reach zero, and the
switcher will change to a discontinuous mode of operation.
This is a perfectly acceptable mode of operation. Any buck
, switching regulator (no matter how large the inductor value
is) will be forced to run discontinuous if the load current is
light enough.

The inductor value selection guides in Figure 3 through Figure 7 were designed for buck regulator designs of the c,ontinuous inductor current type. When using inductor values
shown in the inductor selection guide, the peak-to-peak inductor ripple current will be approximately 20% to 30% of
the maximum DC current. With relatively heavy load currents, the circuit operates in the continuous mode (inductor
current always flowing), but under light'load conditions, the
circuit will be forced to the discontinuous mode (inductor '
current falls to zero for a period of time). This discontinuous
mode of operation is perfectly acceptable. For light loads
(less than approximately 300 mAl it may be desirable to
operate the regulator in the discontinuous mode, primarily
because of the lower inductor values required for the discontinuous mode.
The selection guide chooses inductor' values suitable for
continuous mode operation, but if the inductor value chosen
is prohibitively high, the designer should investigate the possibility of discontinuous operation. The computer deSign
software Swltchers Made Simple will provide all component values for discontinuous (as well as continuous) mode
of operation.

OUTPUT CAPACITOR

An output capacitor is required to filter the output voltage
and is needed for loop stability. The capacitor should be
located near the LM2576 using short pc board traces. Standard aluminum electrolytics are usually adequate, but low
ESR types are recommended for low output ripple voltage
and good stability. The ESR of a capaCitor depends on
many factors, some which are: the value, the voltage rating,
physical size and the type of construction. In general, low
value or low voltage (less than 12V) electrolytic capacitors
usually have higher ESRnumbers.
'
The, amount of output ripple voltage is primarily a function of
the ESR (Equivalent Series Resistance) of the output capacitor and the amplitude of the inductor ripple current
(aIIND)' See the section on inductor ripple current in Application Hints.
'
The lower capacitor values (220 ,..F-l000 ,..F) will allow
typically 50 mV to 150 mV of output ripple voltage, while
larger-value capaCitors will reduce the ripple to approximately 2ii mV to 50 mV.
'
,
,
Output Ripple Voltage = (aIIND) (ESR

3-74

of. COUT)

~------------------------------------------------------------------------------------,

Application Hints (Continued)
To further reduce the output ripple voltage, several standard
electrolytic capacitors may be parall!3led, or a higher-grade
capacitor may be used. Such capacitors are often called
"high-frequency," "low-inductance," or "Iow-ESR." These
will reduce the output ripple to 10 mV or' 20 mY. However,
when operating in the continuous mode, reducing the ESR
below 0.030 can cause instability in the regulator.
Tantalum capacitors can have a very low ESR, and should
be carefully evaluated if it is the only output capacitor. Because of their good low temperature characteristics, a tantalum can'be used in parallel with aluminum electrolytics, with
the tantalum making up 10% or 20% of the total capacitance.
The capacitor's ripple current rating at 52 kHz should be at
least 50% higher than the peak-to-peak inductor ripple current.

CATCH DIODE
Buck regulators require a diode to provide a return path for
the inductor current when the switch is off. This diode
should be located close to the LM2576 using short leads
and short printed circuit traces.
Because of their fast switching speed and low forward voltage drop, Schottky diodes provide the best efficiency, especially in low output voltage switching regulators (less than
5V). Fast-Recovery, High-Efficiency, or Ultra-Fast Recovery
.diodes are also suitable, but some types with an abrupt turnoff characteristic may cause instability and EMI problems. A
fast-recovery diode with soft recovery characteristics is a
better choice. Standard 60 Hz diodes (e.g., 1N4001 or
1N5400, etc.) are also not suitable. See Figure 8 for
Schottky and "soft" fast-recovery diode selection guide.

'oUTPUT VOLTAGE RIPPLE AND TRANSIENTS
The output voltage of a switching power supply will contain
a sawtooth ripple voltage at the switcher frequency, typically
about 1% of the output voltage, and may also contain short
voltage spikes at the peaks of the sawtooth waveform.
The output ripple voltage'is due mainly to the inductor sawtooth ripple current multiplied by the ESR of the output capaCitor. (See the inductor selection in the application hints.)
The voltage spikes are present because of the the fast
switching action of the output switch, and the parasitic inductance of the output filter capacitor. To minimize these
voltage spikes, special low inductance capaCitors can be
used, and their lead lengths must be kept short. Wiring inductance, stray capacitance, as well as the scope probe
used to evaluate these transients, all contribute to the amplitude of these spikes.
An additional small LC filter (20 J.LH & 100 J.LF) can be added
to the output (as shown in Rgure 15) to further reduce the
amount of output ripple and transients. A 10 x reduction in
output ripple voltage and transients is possible with this filter.

FEEDBACK CONNECTION
The LM2576 (fixed voltage versions) feedback pin must be
wired to the output voltage point of the switching power
supply. When using the adjustable version, physically locate
both output voltage programming resistors near the LM2576
to avoid picking up unwanted noise. Avoid using resistors
greater than 100 kO because of the increased chance of
noise pickup.

ON/OFF INPUT
For normal operation, the ON/OFF pin should be grounded
or driven with a low-level TTL voltage (typically below 1.6V).
To put the regulator into standby mode, drive this pin with a
high-level TTL or CMOS signal. The ON/OFF pin can be
safely pulled up to + VIN without a resistor in series with it.
The ON/OFF pin should not be left open.

r-

s:::

N
UI

~
r-

s:::
N
CJ'I
....,
G)

:::z:::

<

GROUNDING
To maintain output voltage stability, the power ground connections must be low-impedance (see Figure 2). For the
5-lead TO-220 and TO-263 style package, both the tab and
pin 3 are ground and either connection may be used, as
they are both part of the same copper lead frame.

HEAT SINK/.THERMAL CONSIDERATIONS
In many cases, only a small heat sink is required to keep the
LM2576 junction temperature within the allowed operating
range. For each application, to determine whether or not a
heat sink will be required, the following must be identified:
1. Maximum ambient temperature (in the application).
2. Maximum regulator power dissipation (in application).
3. Maximum allowed junction temperature (125'C for the
LM2576). For a safe, conservative deSign, a temperature
'approximately 15'C cpoler than the maximum temperatures should be selected.
4. 'LM2576 package thermal resistances 8JA and 8JC.
Total power dissipated by the LM2576 can be estimated as
follows:
Po = (VIN)(lO) + (VoIVIN)(ILOAO)(VSAT)
where 10 (quiescent current) and VSAT can be found in- the
Characteristic Curves shown previously, VIN is the applied
minimum input voltage, Vo is'the regulated output voltage,
and ILOAO is the load current. The dynamiC losses during
turn-ol) and turn-off are negligible if a Schottky type catch
diode is used. '
,
When no heat sink is used, the junction temperature rise
can be determined by the following:
ATJ = (Po) (8JA)
To arrive at the actual operating junction temperature, add
the junction temperature, rise to the maximum ambient temperature.
TJ=ATJ+TA
If the actual operating junction temperature is greater than
the selected safe operating junction temperature determined in step 3, then a heat sink is required.
When using a heat sink, the junction temperature rise can
be determined by the following:
, ATJ = (Po) (8JC + '8interface + 8Heatsinkl
The operating junction temperature will be:
TJ = TA + ATJ
As above, if the actual operating junction temperature is
greater than the selected safe operating junction temperature, then a larger heat sink is required (one that has a lower
'
thermal resistance).
Included on the Switcher Made Simple design software is
a more precise (non-linear) thermal model that can be used
to determine junction temperature with different input-output
parameters or different component values. It can also calculate the heat sink thermal resistance required to maintain
the regulators junction temperature below the maximum operating temperature.

•

Additional Applications
INVERTING REGULATOR

NEGATIVE BOOST REGULATOR
Another'variation on tlie buck-boost'lopology is the negative boost configuration. the circuit in F'igure 11 accepts an
input voltage ranging from -5V to -12V and provides a
regulated -12V output. Input voltages greater than '-12V
will cauSe the output to rise above -12V, but will not damage the regulator.
.

Figure 10 shows a LM2576-12 in a buck-boost configuration
to generate a negative 12V output from a positive input voltage. This circuit bootstraps the regulator's ground pin to the
negative output voltage, then by grounding the feedback
pin, the regulator senses the inverted output voltage and
regulates it to -12V.
For an input voltage of 12V or more, the maximum available
output current in this configuration is approximately 700 mAo
At lighter loads, the minimum input voltage required drops to
app~oximately' 4. 7V.
.
The switch currents in this buck-boost configuration are
higher than in the standard buck-mode design, thus lowering the available output current. Also, the start-up input current of the buck-boost converter is higher than the standard
buck-mode regulator, and this may overload an input power
source with a current limit less than 5A. Using a delayed
turn-on or an undervoltage lockout circuit (described in the
next section) would allow the input voltage to rise to a high
enough level before the switcher.would be allClwed to turn
on.

-5 10 -12V
NoterHeat sink may be required.

Because of the boosting function of this type of regulator,
the switch current is relatively high; especially at low input
voltages. Output load current limitations are a result of the
maximum current rating of the switch. Also, boost regulators
can not provide current limiting load protection in the event
of a shorted load, so SOme other means (such as a fuse)
.
may be necessary.
UNDERVOLTAGE LOCKOUT,
In some applications it is desirable to keep the regulator off
until the input voltage reaches a certain threshold., An undervoltage lockout circuit which accomlllishes this task ,is
shown in Figure 12, while Figure 13 shows the same circuit
applied to a buck-boost configuration. These circuits keep
the regulator off until the 'input voltage reaches a predeter. .
mined level.

. I :::: ILOAD (VIN + IVol) + VIN Ivol X _ 1 _
P
VIN
vlN+lvol
2Ll fose
Where fosc = 52 kHz. Under normal continuous inductor
current operating conditions, the minimum VIN represents
the worst case. Select an inductor that is rated for the peak
current anticipated.

VTH :::: VZl + 2VBE (01)

+VIN

FEEDBACK

4

! eND

TLlH/11476-15

FIGURE 11_ Negative Boost

Because of the structural differences between the buck and
the buck-boost regulator topologies, the buck regulator design procedure section can not be used to to select the
induetor or the output capacitor. The recommended range
of inductor values for the buck-boost design is between
68 /AoH and 220 /AoH, and the output capacitor values must be
larger than what Is normally required for buck designs. Low
input voltages or high output currents require a large value
output capacitor (in the thousands of micro Farads).
The peak inductor current,. which is the same as the.peak
switch current, can be calculated from the following formula:

1..r-_ _

Typical Lead Current
400 mA'forV,N = :"5.2V
750 rnA for V,N = -7V

~2

.,

+VIN

....;;.;..+--....- ....-1:'1 LM2576 - XX

LI

OUTPUT

+

68"H

1N5822

CoUT

Zl

2200p.r

-12Y 8MA
RECULAT[D
OUTPUT

TLlH/11476-14

FIGURE 10. Inverting Buck·Boost Develops -12V
Also, the maximum voltage appearing across the regulator
is the absolute sum of the input and output voltage. For a
-12V output, the maximum input voltage for the LM2576 is
+ 28V, or + 48V for the LM2576HV.
The SWltchers Made Simple (version 3.0) design software
can be used to determine the feasibility of regulator designs
using different topologies, different input-output parameters,
different components, etc.

TLlH/11476-16

Note: Complete clrcuR not shown.

FIGURE 12. Undervoltage Lockout for Buck CI~cult'

3-76

,-----------------------------------------------------------------------------, r
i!i:
I\)

Additional Applications (Continued)

U'I

ADJUSTABLE OUTPUT, LOW·RIPPLE
POWER SUPPLY
A 3A power supply that features an adjustable output volt·
age is shown in Figure 15. An additional L-C filter that reduces the output ripple by a factor of 10 or more is Included In
this circuit.

,+VIN

..;;;....--.....---..~ LM2576-XX
+

Rl

3 GND

~
......
r

i!i:

I\)

U'I

.....

a>
:::I:

<

ZI

+VIN

+VIN

..;;;..--.-.......-.....:;.;.!1

LM2576 - XX

R2
-VOUT
TL/H/11476-17

47k

Note: Complete circuit not shown (see Figure 10).

FIGURE 13. Undervoltage Lockout
for Buck·Boost Circuit
TLlH/11476-18

DELAYED STARTUP
The ON/OFF pin can be used to provide a delayed startup
feature as shown in Figure 14. With an input voltage of 20V
and for the part values shown, the circuit provides approxi·
mately 10 ms of delay time before the circuit begins switching. Increasing the RC time constant can provide longer delay times. But excessively large RC time constants can
cause problems with input voltages that are high in 60 Hz or
120 Hz ripple, by coupling the ripple into the ON/OFF pin.

55V
UNREGULATED DC INPUT

+VIN

r_-----.....,

.......--.;;~

LM25 76HV-ADJ

Note: Complete circuit not shown.

FIGURE 14. Delayed Startup

FEEDBACK

~--------------~
4
L1

-------.I
L2

OUTPUT

I VOLTAGE

OUTPUT

~~~_ _~~~2---1~.rIJOi~~-.-----+--~~--~~~~t----iI--+~1.2t050V
3 GND

5 liN/OFF

+ COUT

1'' '

+ Cl

I
I

@3A

1'"
i
------_.
--

I

op lonal output ripple filter
TL/H/11476-19

FIGURE 15. 1.2V to 55V Adjustable 3A Power Supply with Low Output Ripple

•
3-77

Definition of Terms
BUCK REGULATOR
A switching regulator topology in which a higher voltage is
converted to a lower voltage. Also known as a step-down
switching regulator.

EQUIVALENT SERIES INDUCTANCE (ESL)
The pure inductance component of a capaCitor (see Figure
16). The amount of inductance is determined to a large
extent on the capaCitor's construction. In a buck regulator,
this unwanted inductance causes voltage spikes to appear
on the output.

BUCK-BOOST REGULATOR
A switching regulator topology in which a positive voltage is
converted to a negative voltage without a transformer.

OUTPUT RIPPLE VOLTAGE
The AC component of the switching regulator's output voltage. It is usually dominated by the output capaCitor's ESR
multiplied by the inductor's ripple current (~IIND). The peakto-peak value of this sawtooth ripple current can be determined by reading the Inductor Ripple Current section of the
Application hints.

DUTY CYCLE (D)
Ratio of the output switch's on-time to the oscillator period.

for buck regulator

for buck-boost regulator

D = tON = VOUT
T
VIN
D = tON =
T

CAPACITOR RIPPLE CURRENT

Ivai
Ivai + VIN

RMS value of the maximum allowable alternating current at
which a capacitor can be operated continuously at a specified temperature.

CATCH DIODE OR CURRENT STEERING DIODE
The diode which provides a return path for the load current
when the LM2576 switch is OFF.

STANDBY QUIESCENT CURRENT (ISTBY)
Supply current required by the LM2576 when in the standby
mode (ONIOFF pin is driven to TTL-high voltage, thus turning the output switch OFF).

EFFICIENCY ("')
The proportion of input power actually delivered to the load.

'" =

POUT
POUT
PIN = POUT + PLOSS

INDUCTOR RIPPLE CURRENT (~IIND)
The peak-to-peak value of the inductor current waveform,
typically a sawtooth waveform when the regulator is operating in the continuous mode (vs. discontinuous mode).

CAPACITOR EQUIVALENT SERIES RESISTANCE (ESR)
The purely resistive component of a real capacitor's impedance (see Figure 16). It causes power loss resulting in capacitor heating, which directly affects the capaCitor's operating lifetime. When used as a switching regulator output
filter, higher ESR values result in higher output ripple voltages.

CONTINUOUS/DISCONTINUOUS MODE OPERATION
Relates to the inductor current. In the continuous mode, the
inductor current is always flowing and never drops to zero,
vs. the discontinuous mode, where the inductor current
drops to zero for a period of time in the normal switching
cycle.
INDUCTOR SATURATION

TL/H/11476-20

FIGURE 16. Simple Model of a Real Capacitor
Most standard aluminum electrolytic capacitors in the
100 /LF-l000 /LF range have 0.511 to 0.111 ESR. Highergrade capacitors ("Iow-ESR", "high-frequency", or "low-inductance"') in the 100 /LF-l000 /LF range generally have
ESR of less than 0.1511.

The condition which exists when an inductor cannot hold
any more magnetic flux. When an inductor saturates, the
inductor appears less inductive and the resistive component
dominates. Inductor current is then limited only by the DC
resistance of the wire and the available source current.
OPERATING VOLT MICROSECOND CONSTANT (EeTop)
The product (in Volte /Ls) of the voltage applied to the inductor and the time the voltage is applied. This EeTop constant
is a measure of the energy handling capability of an inductor
and is dependent upon the type of core, the core area, the
number of turns, and the duty cycle.

3-78

,-----------------------------------------------------------------------------, r

3:

Connection Diagrams

N
U1

......
Q)
......
r

(XX indicates output voltage option. See ordering information table for complete part number.)
Bent, Staggered Leads
5·Lead TO·220 (T)
Top View

Straight Leads
5·Lead TO·220 (T)
Top View

.-,......
(-''''''

3:
::J:

"OJ",'

<

3- Ground
2- Output

1-VIN

1-VIN
TLfHf11476-22

TLfHf11476-21

LM2576T·XX or LM2576HVT·XX
NS Package Number T05A

_

TO·263 (S)
5·Lead Surface·Mount Package
Top View

A

......
Q)

i.-.,- .......

3- Ground
2- Output

TAB IS
GND

N
U1

Side View

fL.

PINS 1,3,&:5

~PINS2&:4

S-ON/orr
4- r •• dback
3- Ground
2- Output
1- VIN

TLfHf11476-23

LM2576T·XX Flow LB03
or LM2576HVT·XX Flow LB03
NS Package Number T05D

TLfHf11476-25

Side View

TUHf11476-26

LM2576S·XX
NS Package Number TS5B

Ordering Information
Temperature
Range

Output Voltage

~---------r----------.-~----~~----------r_--------_1NSPackagePackage

3.3
LM2576S-3.3

5.0
LM2576S-5.0

12
LM2576S-12

15
LM2576S-15

ADJ
LM2576S-ADJ

LM2576HVT-3.3 LM2576HVT-5.0 LM2576HVT-12 LM2576HVT-15 LM2576HVT-ADJ
-40'C

S;

TA

S;

125'C LM2576T-3.3

LM2576T-5.0

LM2576T-12

LM2576T-15

LM2576T-ADJ

TS5B

TO-263

T05A

TO-220

T05A

TO-220

LM2576HVT-3.3 LM2576HVT-5.0 LM2576HVT-12 LM2576HVT-15 LM2576HVT-ADJ

T05D

TO-220

LM2576T-3.3

T05D

TO-220

LM2576T-5.0

LM2576T-12

3-79

LM2576T-15

LM2576T-ADJ

o

(II

r----------------------------------------------------------------------------,

';:
(II

U)

r-..
r-..

t!JNational Semic.onductor

It)

C'I

:::ill

LM 1577ILM2577 Series
.,... SIMPLE SWITCHER® Step-Up Voltage Regulator

...I

r-..
r-..
It)

:::ill

...I

General Description

Features

The LM1577 /LM2577 are monolithic integrated circuits that
provide all of the power and control functions for step-up
(boost), flyback, and forward converter switching regulators.
The device is available in three different output voltage versions: 12V, 15V, and adjustable.

•
•
•
•

Requiring a minimum number of external components,
these regulators are cost effective, and simple to use. Listed
in this data sheet are a family of standard inductors and
flyback transformers designed to work with these switching
regulators.
Included on the chip is a 3.0A NPN switch and its associated protection circuitry, consisting of current and thermal limiting, and undervoltage lockout. Other features include a 52
kHz fixed-frequency oscillator that requires no external components, a soft start mode to reduce in-rush current during
start-up, and current mode control for improved rejection of
input voltage and output load transients.

Requires few external components
NPN output switches 3.0A, can stand off 65V
Wide input voltage range: 3.5V to 40V
Current-mode operation for improved transient
response, line regulation, and current limit
• 52 kHz internal oscillator
• Soft-start function reduces in-rush current during
start-up
• Output switch protected by current limit, under-voltage
lockout, and thermal shutdown

Typical Applications
• Simple boost regulator
• Flyback and forward regulators
• Multiple-output regulator

Typical Application

O..ll' r

i

T

r-S.....
IV_IN_ _ _
4 ......
lsw""IITCH .

-

roMP

17.4k

2

L...---r__-...I BACK

R2

to- 2k

12V@:S800mA
REGULATED OUTPUT
VOUT = 1.23V (1 + Rl/R2)

+

R1

...---;- LM2577-ADJ t-r-EE- D--......
~
2.2k to-

1

lNS821
•

r
'-1-....,
....
- ....---.--0
T""'''

IOOI'H
+5V
INPUT 0 - - -....
1 _ _ _.......£

16

i

80 l'r

_
-

!ND
Note: Pin numbers shown
are for TO-220 (l) package.

TLlH/11468-1

Ordering Information
Temperature
Range
- 40'C

S;;

TA S;;

Package
Type

+ 125'C 24-Pin Surface Mount
16-Pin Molded DIP
5-Lead Surface Mount
5-Straight Leads
5-Bent Staggered Leads

- 55'C

S;;

TA S;;

+ 150'C 4-Pin TO-3

Output Voltage
12V

15V

ADJ

LM2577M-12
LM2577M-15
LM2577M-ADJ
LM2577N-12
LM2577N-15
LM2577N-ADJ
LM2577S-12
LM2577S-15
LM2577S-ADJ
LM2577T-12
LM2577T-15
LM2577T-ADJ
LM2577T-12
LM2577T-15
LM2577T-ADJ
Flow LB03
Flow LB03
Flow LB03
LM1577K-12/883 LM1577K-15/883 LM1577K-ADJ/883

3-80

NSC
Package Package
Drawing

M24B
N16A
TS5B
T05A
T05D

SO
N
TO-263
TO-220
TO-220

K04A

TO-3

Absolute Maximum Ratings

Operating Ratings

(Note 1)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Supply Voltage

Supply Voltage

Output Switch Voltage

Junction Temperature Range
LM1577
LM2577

65V
6.0A

Power Dissipation

OV

s:

s:

VIN

VSWITCH

Output Switch Current

45V

Output Switch Current (Note 2)

3.5V

Output Switch Voltage

ISWITCH
-55·C
-40·C

s: TJ s:
s: TJ s:

s: 40V
s: 60V
s: 3.0A

+ 150·C
+ 125·C

Internally Limited
-65·Cto + 150·C

Storage Temperature Range
Lead Temperature (Soldering, 10 sec.)

260·C

Maximum Junction Temperature

150·C

Minimum ESD Rating
(C = 100 pF. R = 1.5 kO)

2kV

E.lectrical Characteristics-LM1577-12, LM2577-12

Specifications with standard type face are for TJ = 25·C. and those in bold type face apply over full Operating Temperature
Range. Unless otherwise specified. VIN = 5V. and ISWITCH = O.
Symbol

Parameter

Conditions

Typical

LM1577·12
Umlt
(Notes 3, 4)

LM2577·12
Limit
(Note 5)

11.60/11.40
12.40/12.80

11.60/11.40
12.40/12.80

V
V(min)
V(max)

50/100

50/100

mV
mV(max)

50/100

50/100

mV
mV(max)

Units
(Limits) .

SYSTEM PARAMETERS Circuit of Figure 1 (Note 6)
VOUT

aVOUT

Output Voltage

Line Regulation

aVIN
aVOUT

Load Regulation

aLOAD
'Il

Efficiency

VIN = 5Vto 10V
ILOAD = 100 mA to 800 mA
(Note 3)

12.0

VIN = 3.5V to 10V
ILOAD = 300 mA

20

VIN = 5V
ILOAD = 100 mA to 800 mA

20

= 5V. ILOAD = 800 mA

80

VIN

0;.

DEVICE PARAMETERS
Is

Input Supply Current

VFEEDBACK

= 14V (Switch Off)

ISWITCH = 2.0A
VCOMP = 2.0V (Max Duty Cycle)
Vuv

fo

Input Supply
Undervoltage Lockout
Oscillator Frequency

ISWITCH

aVREF
aVIN

10.0/14.0

mA
mA(max)

50/85

50/85

mA
mA(max)

2.70/2.85
3.10/3.15

2.70/2.85
3.10/3.15

V
V(mln)
V(max)

48/42
56/82

48/42
56/82

kHz
kHz(min)
kHz(max)

11.76/11.84
12.24/12.38

11.76/11.84
12.24/12.38

V
V(min)
V(max)

25

52

= 100 mA

Output Reference
Voltage

Measured at Feedback Pin
VIN = 3.5V to 40V
VCOMP = 1.0V

putput Reference
Voltage Line Regulator

VIN

= 3.5V to 40V

12

7

mV

9.7

kO

RFB

Feedback Pin Input
Resistance

GM

Error Amp
Transconductance

ICOMP = -30 p.A to +30,.,.A
VCOMP = 1.0V

370

Error Amp
Voltage Gain

VCOMP = 1.1Vto 1.9V
RCOMP = 1.0 MO
(Note 7)

80

AVOL

10.0/14.0

2.90

Measured at Switch Pin
ISWITCH

VREF

= 100 mA

7.5

3-81

225/145
515/815

225/145
515/815

,.,.mho
,.,.mho(min)
,.,.mho(max)

50/25

50/25

VIV
VIV(min)

II

Electrical Characteristics~LM1577·12, LM2577·12 (Continued)
Specifications with standard type face are for TJ = 25'C, and those in bold type face apply overfull ,Operating Temperatur,e
Range. Unless otherwise specified, VIN =, 5V, and ISWITCH = O. '
Symbol

Parameter

Typical

Conditions

..

"

LM1577-12
Limit
(Notes 3, 4)

LM2577-12
Limit
(Note 5)

2.2/2.Q

2.2/2.0

V
V(min)

0.40/0.55

0.40/0.55

V
V(max)

Units
(Lllnlts)

DEVICE PARAMETERS (Continued)
Error Amplifier
Output Swing

Upper Limit
VFEEDBACK

2.4 '

= 10.0V

Lower Limit
VFEEDBACK
Error Amplifier
Output Current
Soft Start Current

Iss

Maximum Duty Cycle

D

0.3

= 15.0V
VFEEDBACK = 1O.OV to 15.0V
VCOMP = 1.0V

±200

' 5.0

"FEEDBACK = 10.0V
VCOMP = OV
YCOMP = 1.5V
ISWITCH = 100 mA

2.5/1.5
7.5/9.5

2.5/1.5
7.5/9.5

PIA
,...A(min)
,...A(max)

93/90

93/90

%
%(min)

95

I1ISWITCH
AVCOMP

'Switch
Transconductance

IL

S~i~ch Leakage
Current

VSWITCH = 65V
VFEEDBACK = 15V (Switch Off)

10

Switch Saturation
Voltage

ISWITCH = 2.0A
VCOMP = 2.0V (Max Duty Cycle)

O.p

VSAT

!J.A
±130(±90 , ,...A(min)
±300/±4bO ,...A(max)

±130/±90
±300/±400

12.5,

AN
,...A
,...A(max)

' 300/600

300/600
0.710.9

0.710.9

V
V(max)

3.713.0
5.3/6.0

3.7/3.0
5.3/6.0

A
A(min)
A(max)

4.5,

NPN Switch
: Current Limit
..

,.'

I

,

'

,

,',

'.

"

,
!l.

.

'.

,
..

r

,

,

;

..

'

,

.

,

'

;

,".'

I

3-82

,

'

Electrical Characteristics-LM1577-15, LM2577-15
Specificatiens with standard type face are fer TJ = 25'C, and those in bold type face apply over full Operating J"emperature
Range. Unless otherwise specified, VIN = 5V, and ISWITCH =; o.

Symbol

Parameter

Conditions

Typical

LM1577-15
Limit
(Notes 3, 4)

LM2577-15
Limit,
(Note 5)

14.50/14.25
15.50/15.75

14.50/14.25
15.50/15.75

V
V(min)
V(max)

50/1,00

50/100

mV
mV(max)

50/100

50/100

mV
mV(max)

Units
(Limits)

SYSTEM PARAMETERS Circuit of Figure 2 (Note 6)
VOUT

AVOUT

Output Voltage

VIN = 5Vto 12V
ILOAD = 100 rnA to 600 rnA
(Nete3)

Line Regulation

VIN
AVOUT

Lead Regulation

AILOAD
'Ij

"

'

Efficiency

15.0

VIN = 3.5Vto 12V
ILOAD = 300 rnA

20

VIN = 5V
ILOAD = 100 rnA te 600 rnA

20

VIN = 5V, ILOAD = 600 rnA

BO

%

DEVICE PARAMETERS
Is

Input Supply Current

' 7.5

VFEEDBACK = 1B.OV
(Switch Off)

fo

Input Supply
Undervoltage
Lockeut

ISWITCH = 100 rnA

Oscillater Frequency

Measured at Switch Pin
ISWITCH = 100 rnA

10.0/14.0

rnA
mA(max)

50/85

50/85

mA(max)

2.70/2.65
3.10/3.15

2.70/2.65
3.10/3.15

V
V(min)
V(max)

4B/42

48/42
56/62

kHz
kHz(min)
kHz(max)

14.70/14.55
1,5.30/15.45

V
V(min)
V(max)

25

ISWITCH = 2.0A
VCOMP = 2.0V
(Max Duty Cycle)
Vuv

10.0/14.0

rnA

2.90 '

52
56/62

VREF

AVREF
IlVIN

Output Reference
Voltage

Measured at Feedback Pin
VIN = 3.5V te 40V
VCOMP = 1.0V

Output Reference
Voltage Line Regulation

VIN = 3.5V to 40V

15

15,30/15.45
10

mV

12.2

kO

RFB

Feedback Pin Input
Voltage Line Regulator

GM

Error Amp
Transconductance

ICOMP = -30 JLA to +30 JLA
VCOMP = 1.0V

300

Error Amp
Veltage Gain

VCOMP = 1.1Vto 1.9V
RCOMP = 1.0 MO
(Note 7)

65

AVOL

14.70/14.55

170/110
420/500

170/110
420/500

p.mho
p.mho(min)
p.mho(max)

40/20

40/20

VIV
VIV(min)

II

3-83

Electrical Characteristics-LM1577-15, LM2577-15 (Continued)
Specifications with standard type face are for TJ = 25°C, and those in bold type face apply over full Operating Temperature
Range. Unless otherwise specified, VIN = 5V, and ISWITCH = o.
Symbol

Parameter

Conditions

Typical

LM1577-15
Limit
(Notes 3, 4)

LM2577-15
Limit
(Note 5)

2.2/2.0

2.2/2.0

0.4/0.55

0.40/0.55

±130/±90
±300/±400

±130/±90
±300/±400

p.A
p.A(min)
p.A(max)

2.5/1.5
7.5/9.5

2.5/1.5
7.5/9.5

p.A(min)
p.A(max)

93/90

93/90

%
%(min)

Units
(Limits)

DEVICE PARAMETERS (Continued)
Error Amplifier
Output Swing

Error Amp
, Output Current

ISS

D
~ISWITCH

aVCOMP
IL

Soft Start Current

Maximum Duty
, Cycle

2.4

Lower Limit
VFEEDBACK = 18.0V

0.3

VFEEDBACK = 12.0Vto 18.0V
VCOMP = 1.0V

. Switch Leakage
Current

±200

VFEEDBACK =.,12.0V
VCOMP = OV

5.0

VCOMP = 1.5V
ISWITCH = 100 mA

95

Switch
Transconductanpe

10

Switch Saturation
Voltage

ISWITCH = 2.0A
VCOMP = 2.0V
(Max Duty Cycle)

0.5

NPNSwitch
Current Limit

VCOMP = 2.0V

4.3

V
' V(max)

AN

p.A
300/800

300/800

p.A(max)
V

0.7/0.9

0.7/0.9

V(max)

3.7/3.0

3.7/3.0
5.3/8.0

A
A(min)
A(max)

5.3/8.0

3·84

V
V(min)

p.A

12.5
VSWITCH = 65V
VFEEDBACK = 18.0V
(Switch Off)

,
VSAT

Upper Limit
VFEEDBACK = 12.0V

Electrical Characteristics-LM1577-ADJ, LM2577-ADJ
Specifications with standard type face are for TJ = 25'C, and those in bold type face apply over full Operating Temperature
Range. Unless otherwise specified, VIN = 5V, VFEED8ACK = VREF, and ISWITCH = O.
Symbol

Parameter

Conditions

Typical

LM1577·ADJ
Limit
(Notes 3, 4)

LM2577·ADJ
Limit
(Note 5)

Units
(Limits)

SYSTEM PARAMETERS Circuit of Figure 3 (Note 6)
VOUT

t.vOUTI

Output Voltage

Line Regulation

I.WIN
AVOUTI
AI LOAD

Load Regulation

'1/

Efficiency

VIN = 5V to 10V
ILOAD = 100 mA to 800 mA
(Note 3)

12.0

VIN = 3.5V to 10V
ILOAD = 300 mA

20

VIN = 5V
ILOAD = 100 mAt0800 mA

20

= 5V, ILOAD = 800 mA

80-

VIN

:

11.60/11.40
12.40/12.60

11.60/11.40
12.40/12.60

V
V(min)
V(max)

50/100

50/100

mV
mV(max)

50/100

50/100

mV
mV(max)
%

DEVICE PARAMETERS
Is

Input Supply Current

VFEED8ACK

= 1.5V (Switch Off)

ISWITCH = 2.0A
VCOMP = 2.0V (Max Duty Cycle)
Vuv

fo

= 100 mA

Input Supply
Undervoltage Lockout

ISWITCH

Oscillator Frequency

Measured at Switch Pin
ISWITCH = 100 mA

AVREFI
AVIN

Reference Voltage
Line Regulation

VIN

18

Error Amp
Input Bias Current

VCOMP

Error Amp
Transconductance

ICOMP = -30 p.A to +30 p.A
VCOMP = 1.0V

Error Amp
Voltage Gain

VCOMP
RCOMP

Error Amplifier
Output Swing

Upper Limit
VFEED8ACK

= 1.0V

Lower Limit
VFEED8ACK

= 1.5V

AVOL

10.0/14.0

mA
mA(max)

50/85

50/85

mA
mA(max)

2.70/2.65
3.10/3.15

2.70/2.65
3.10/3.15

V
V(min)
V(max)

48/42
56/62

48/42
56/62

kHz
kHz(min)
kHz(max)

1.214/1.206
1.246/1.254

1.214/1.206
1.246/1.254

V
V(min)
V(max)

25

52

Measured at Feedback Pin
VIN = 3.5V to 40V
VCOMP = 1.0V

GM

10.0/14.0

2.90

Reference
Voltage

VREF

7.5

= 3.5V to 40V

1.230

0.5

= 1.0V

mV

100

= 1.1Vto 1.9V
= 1.0 M!l. (Note 7)

300/800

300/800

nA
nA(max)

2400/1600
4800/5800

2400/1600
4800/5800

p.mho
p.mho(min)
p.mho(max)

500/250

500/250

VIV
VIV(mln)

2.2/2.0

2.-2/2.0

.3700

800
2.4
0.3

.' 0.40/0.55

0.40/0.55

"

3·85

V
. V(min)
V
V(max)

II

~

~.....
.....

II)

Electrical Characteristics-LM1577-ADJ, LM2577-ADJ

N

::i!:
...I
.......

.....
.....
.,...

II)

(Continued)

Specifications with standard type face are for TJ = 25'C, and those in bold type face apply over full Operating Temperature
Range. Unless otherwise specified, VIN = 5V, VFEEDBACK = VREF, and ISWITCH = O.
Symbol

Parameter

Conditions

Typical

LM1577-ADJ
Limit
(Notes 3, 4)

LM2577-ADJ
Limit
(Note 5)

±130/±90
±300/±400

±130/±90
±300/±400

p.A
p.A(min)
p.A(max)

2.5/1_5
7.5/9.5

2.5/1_5
7.5/9.5

p.A
p.A(min)
p.A(max)

93/90

93/90

%
%(min)

Units
(Limits)

DEVICE PARAMETERS (Continued)

::i!:

...I

Iss

D

±200

Error Amp
Output Current

VFEEDBACK = 1.0Vto 1.5V
VCOMP = 1.0V

Soft Start Current

VFEEDBACK = 1.0V
VCOMP = OV

5.0

VCOMP = 1.5V
ISWITCH = 100 mA

95

Maximum Duty Cycle

alsWITCH/
aVCOMP

Switch
Transconductance

IL

Switch Leakage
Current

VSWITCH = 65V
VFEEDBACK = 1.5V (Switch Off)

10

Switch Saturation
Voltage

ISWITCH = 2.0A
VCOMP = 2.0V (Max Duty Cycle)

0.5

NPNSwitch
Current Limit

VCOMP

VSAT

12.5

= 2.0V

AIV

300/600

300/600

p.A
p.A(max)

0.7/0.9

0.7/0.9

V
V(max)

3.7/3.0
5.3/6.0

3.7/3.0
5.3/6.0

A
A(min)
A(max)

4.3

THERMAL PARAMETERS (All Versions)

°JC

K Package, Junction to Ambient
K Package, Junction to Case

35
1.5

OJA
OJC

T Package, Junction to Ambient
T Package, Junction to Case

65
2

OJA

N Package, Junction to
Ambient (Note 8)

85

OJA

M Package, Junction
to Ambient (Note 8)

100

OJA

S Package, Junction to
Ambient (Note 9)

37

OJA

Thermal Resistance

'C/W

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating ratings indicate conditions the device is intended to
be functional, but device parameter specifications may not be guaranteed under these conditions. For guaranteed specifications and test conditions. see the
Electrical Characteristics.

Note 2: Due to timing considerations of the LM1577/LM2577 current limit circuit. output current cannot be internally limited when the LMI577/LM2577 is used as a
step-up regulator. To prevent damage to the switch, its current must be externally limited to S.OA. However, output current is internally limited when the

LMI577/LM2577 is used as a flyback or forward converter regulator in accordance to the Application Hints.
Note 3: All limits guaranteed at room temperature (standard type lace) and at temperature extremes (boldface type). All limits are used to calculate Outgoing
Quality Level, and are 100% production tested.

Note 4: A military RETS electrical test specification is available on request. At the time of printing. the LMI577K-12/883. LMI577K·15/883. and
LMI577K-ADJ/883 RETS specifications complied fully with the boldface limits in these columns. The LMI577K-12/883. LMI577K-15/883. and LMI577K-ADJI
883 may also be procured to Standard Military Drawing specifications.
Note 5: All limits guaranteed at room temperature (standard type face) and at temperature extremes (boldface type). All room temperature limits are 100%
production tested. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SOC) methods.
Note 6: External components such as the diode, inductor, input and output capacitors can affect switching regulator performance. When the LM1577/LM2577 is
used as shown in the Test Circuit, system performance will be as specified by the system parameters.
Note 7: A 1.0 Mn resistor is connected to the compensation pin (which is the error amplifier's output) to ensure accuracy in measuring AVOL. In actual applications,
this pin's load resistance should be :?: 10 M!l, resulting in AVOL that is typically twice the guaranteed minimum limit.
Note 8: Junction to ambient thermal resistance with approximately 1 square inch of pc board copper surrounding the leads. Additional copper area will lower
thermal resistance further. See thermal model in "Switchers Made Simple" software.
Note 9: If the TO-263 package is used, the thermal resistance can be reduced by increasing the PC board copper area thermally connected to the package. Using
0.5 square inches of copper area, 6JA is 50"C/W; with 1 square inch of copper area, 6JA is 3rC/W; and with 1.6 or more square inches of copper area, 6JA is

3Z'C/W.

3-86

r-

i!i:
....
CI1

Typical Performance Characteristics
Reference Voltage
vs Temperature
1.240

E
Lt.I

i

12.1 0

ADJ VERSIONS

1.238

2

./

0

I--'"

8

:E

~

g

12.0 2

/

~

6

:E 15.0 6

12.0a

1-""'"

11.9 8
11.9 6

~

-50 -25

0

25

50

TE~PERATURE

g 15.0a
~

".9 2

1
w

~

g

0.4

.;'

0.3

!/

0.2

~
m
<2 -0.

1/

O. 1

I

1

-0.2

"

'"

/

1
....

~

e
"

[5

~
~

4000

.;'

3.0
2.0

~

1.0

15

20

25

30

35

40

!/

1/"

a

, r-...

3000

0

25 50

~
~

...... t-

g

450
400

g

800

5

w

-2.0
~

W

~

25

"
.......

,

,

300

~

40

400
~

~
~

~

t-,.,

~

g

10

15

a

so

25

" , ,
I........

50

75 100 125 150

TE~PERATURE

(Oe)

140

~

120

~

35

40

15V VERSIONS
350 \.
325

:'\..

300

~

275
250

"

r-...

.......

25

50

75 100 125 150

TEMPERATURE (Oe)

(Oe)

Error Amp Voltage
Gain vs Temperature
160

12V VERSIONS

z

30

375

Error Amp Voltage
Gain vs Temperature

'>

25

Error Amp Transconductance
vs Temperature

200
-50 -25 0

75 100 125 150

TE~PERATURE

~

20

225

(Oe)

Reo"p'" 10 Nil

25

a

SUPPLY VOLTAGE (V)

250

160

600
-50 -25 0

V

0.0

ADJ VERSIONS

!:; 1000

V

-1.0

180

1'\

./

2.0

1.0

350

Error Amp Voltage
Gain vs Temperature

1200

3.0

/'

1/

I. ,

V

200
-50 -25

1800

~

~

g

12V VERSIONS

75 100 125 150

TE~PERATURE

~

"

'"

4.0

500

.3
~

"-

3500

1400

15V VERSIONS
5.0

'>

.s

Error Amp Transconductance
vs Temperature

'>

75 lOa 125 150

vs Supply Voltage

SUPPLY VOLTAGE (V)

Error Amp Transconductance
vs Temperature

50

a Reference Voltage

<2

10

25

TEMPERATURE (oe)

4.0

-2.0

o

2500
-50 -25

~z

14.90
-50 -25 0

75 100 125 150

6.0

~ -1.0 I

i',

1600

50

12V VERSIONS

~g

15

A~J V~RSI~NS
4500

25

a Reference Voltage
vs Supply Voltage

SUPPLY VOLTAGE (V)

5000

a

5.0
ADJ VERSIONS

CD

o

~ 14.9 4

TEMPERATURE (Oe)

a Reference Voltage
vs Supply Voltage

en
CD
::::!-

/

....... ~

......
......

~ 14.9 6

(oe)

0.5

l-

I'

~ ' •.98 /

11.94
11.9a
-50 -25

75 100 125 150

15.04

~ 15.02

11.9 2

1.220

N
CI1

15V VERSIONS

15.0 8

,..-

12.0 4

~

ffi

15.10

-

12.0 6

.......
ri!i:

Reference Voltage
vs Temperature

12V VERSIONS

12.0 8

-....

1.23 6
1.234

......
......

Reference Voltage
vs Temperature

"'

1SV VERSIONS

140
RcO!.lpO::

i',

100

,

80
60
-50 -25 a

25

50

town

~
~

Reo.P'" 10MIl
120

z

~

'

~

!:;

g

.......

75 100 125 150

TEMPERATURE (oe)

100

,

I"-

80

r......

r...... ........

60
40
-50 -25 a

25

50 75 100 125 150

TEMPERATURE (Oe)
TL/H111468-2

3-B7

II

Typical Performance Characteristics
QuIescent Current
vs Temperature
50

.

.5

1"
§
!:l
5

'"

45
40
35
30
25
20
15
10

QuIescent Current
vs SwItch Current

ISWITCH

I

= 3A
I

ISWITCH

= 2A f-

ISWITCH

=

'SWITCH

."1
~

lA

= 100 mA

-50 -25 0

r\

o

25 50 75 100 125 150

--

0.5

TEMPERATURE (Oc)

~
'"0::
~

~

~
~

1.4

1.2
1.0

~ :""'"
~

0.8
0.6 -55
0.4
0.2

o

L

§

,..

1.0

1.5

......

B

2.0

3.0
-50 -25 0

3.0 (A)

2.5

:€

0.8

tl

0.7

~

I.

-

0.5

~

0.4

~

0.3

~

1
1

,

IP'"V

'~

~

12

~

11

'8

10

~

Z,

-55 0 C

.~

~

0.2

o

0.5

CURRENT LIMIT OVERDRIVE (mA)

1.0

1.5

2.0

220

2.5

100

"\
8
-50 -25 0

3.0

25 50 75 100 125 150

TEMPERATURE (Oc)

53

1 160 \
iii

I\.

54

180

120

" I'

Oscillator Frequency
vs Temperature

200

B
!:1

I'

SWITCH CURRENT (A)

Feedback PIn BIas
Current vs Temperature

140

i'- .........

~

~

O. 1

100 200 300 400 500 600 700 800

13

.A;t?

S
.~

V~

/ . /.

25 50 75 100 125 150

SwItch Transconductance
va Temperature

ISOOC

0.6

r-.,'

'TEMPERATURE (oc)

1.0

~

r-....

3.5

0= 0.2

0.9

~

.......

4.0

SwItch SaturatIon Voltage
vs SwItch Current

1
1

,\ 1/ '25
"'0..

3
!i:::;

4.5

SwiTCH CURRENT (A)

Current LImIt Response
TIme vs OverdrIve
2.0
1
1.8
6 \ 150
1.

D=~

/'

;'

15
V10
5

'"

/
./
0= 0.9

25
20

5

1 1 1

o

5.0

50
45
40
35
30

.5

1 1

....

'......

eyel~

Current LImIt
va Temperature

55

..

1 1 1
50" DUTY

(Continued)

N"

!

"

g

I'

8e:

"

V

I......

80
60
-50 -25 0

52

/

r'\

1/
V

ADJ VERSIONS

\
I\.

50

/

49

"I-'

48
47
-50 -25 0

25 50 75 100 125 150

TEMPERATURE (Oe)

25 50 75 100125 150

TEMPERATURE (Oe)

TL/H/I1468-S

MaxImum Power DIssIpation
(TO-263) (See Note 9)

~

9 JA

4

1'1..
1'1...:,.........

z
0
;::

...

9JA -37OC/YL...... i'oo...

"-

iii
en
is

= 32 o C/W

I""" ......

2

r...

ffi

~

0

"-

o

o

~

i"'-. :-...

~~ "...... ~

~JA ~73I;iw"":::: f;;: ~

i

'11

10 20 30 40 50 60 70 80 90 100

AMBIENT TEMPERATURE (OC)
TL/H/I1468-S1

3-88

Connection Diagrams
Bent, Staggered Leads
5-Lead TO-220 (T)

Straight Leads
5-Lead TO-220 (T)

~

~~:

~:5-VIN
3-

4- Switch
Ground
2- Feedback
1- Comp

5-VIN
4321-

Switch
Ground

Feedback
Comp

TLlHI11468-4

TL/H/11466-5

Top View

Top View

Order Number LM2577T-12, LM2577T-15,
or LM2577T-ADJ
See NS Package Number T05A

Order Number LM2577T-12 Flow LB03, LM2577T-15
Flow LB03, or LM2577T-ADJ Flow LB03
See NS Package Number T05D

16-Lead DIP(N)

24-Lead Surface Mount (M)

•

GND

COMP

COMP

FB

FB

GND

2

•

GND

SWITCH

SWITCH {

9 •

VIN

'No Internal
Connection
TLlH/1146S-6

Top View

14 •

Order Number LM2577N-12, LM2577N-15,
or LM2577N-ADJ
See NS Package Number N16A

13 •

'No Internal
Connection

Top View

TL/H/11466-7

Order Number LM2577M-12, LM2577M-15,
or LM2577M-ADJ
See NS Package Number M24B

TO-263(S)
5-Lead Surface-Mount Package

O

4-Lead TO-3 (K)

S-VIN

TAB IS
GND

4- Switch
3- Ground

2- Feedback
.

1- Comp
TLlH/11468·32

COIotP

Top View
TL/H/11468-8

Bottom View
Order Number LM1577K-12/883, LM1577K-15/883, or
LM1577K-ADJ/883
See NS Package Number K04A

TLlH/11468-33

Side View
Order Number LM25775-12, LM25775-15,
or LM25775-ADJ
See NS Package Number TS5B

3-89

II

Test Circuits
LM1577-12, LM2577-12
10k

+ 680 "F
CoUT

TLlH/11468-30
L = 415·0930 (AlE)
D = any manufacturer

CoUT

= Sprague Type 673D

Note: Pin numbers shown

Electrolytic 680 p.F, 20V

are for TO·22Q

en package

FIGURE 1. Circuit Used to Specify System Parameters for 12V'Versions

LM1577-15, LM2577-15
10 ko.

150/1

75/1

Your

50/1

TLlH/11468-28
L = 415-0930 (AlE)
D = any ma~ufacturer

CoUT

= Sprague Type 673D

Note: Pin numbers shown

Electrolytic 880 p.F, 20V

are for TO·220

en peckege

FIGURE 2; Circuit Used to Specify System Parameters for 15V Versions

LM1577-ADJ, LM2577-ADJ
V,N
10k

Note: Pin numbers shown
are for TO:220,

120

,

24

,

','

L = 415-0930 (AlE)
D = any manufa~~rer

60

Co';'

= Sprague Type 673D
Electrolytic 680 p.F, 20V

Rl
R2

TLlH/11468-9

= 4B.7k in series with 51111 (1%)
= 5.62k (1 %) .

FIGURE 3. Circuit Used to Specify System Parameters for ADJ Versions

3-90

en package

rs:::
......
U1
......
......

Application Hints

.....
rs:::

N
C'N

r - 4 1 I - - -__-o

U1
......
......

VOUT

...CDfC
en

Note: Pin numbers shown
aTe fOT TO·220
package

en

-Resistors are internal
to LM 15771LM2577 for
12V and 15V versions.

RIO

(1.23V)

R2 •

TL/H/11468-10

FIGURE 4. LM1577/LM2577 Block Diagram and Boost Regulator Application
STEP-UP (BOOST) REGULATOR

When the switch turns off, the lower end of the inductor flies
above VfN, discharging its current through diode (0) into the
output capacitor (COUT) at a rate of (VOUT - V'N)/L. Thus,
energy stored in the inductor during the switch on time is
transferred to the output during the switch off time. The out'put voltage is controlled by the amount of energy transferred which, in turn, is controlled by modulating the peak
inductor current. This is done by feeding back a portion of
the output voltage to the error amp, which amplifies the difference between the feedback voltage and a 1.230V reference. The error amp output voltage is compared to a voltage proportional to the switch current (i.e., inductor current
during the switch on time).

Figure 4 shows the LM1577-ADJ/LM2577-AOJ used as a
Step-Up Regulator. This is a switching regulator used for
producing an output voltage greater than the input supply
voltage. The LM1577-12/LM2577-12 and LM1577-15/
LM2577 -15 can also be used for step-up regulators with
12Vor 15Voutputs (respectively), by tying the feedback pin
directly to the regulator output.

A basic explanation of how it works is as follows. The
LM1577 ILM2577 turns its output switch 6n and off at a freCjuency of 52 kHz, and this creates energy in the inductor
(L). When the NPN switch turns on, the inductor current
charges up at a rate of V'N/L, storing current in the inductor.

3-91

Application Hints

(Continued)
The comparator terminates the switch on time when the two
voltages are equal, thereby controlling the peak switch current to maintain a constant output voltage.

Before proceeding any further, determine if the LMI577 /
LM2577 can provide these values of Your and ILOAO(max)
when operating with the minimum value of VIN. The upper
limits for Your and ILOAO(max) are given by the following
equations.

Voltage and current waveforms for this circuit are shown in
Figure 5, and formulas for calculating them are given in Figure6.

and
SWITCH
VOLTAGE
DIODE
VOLTAGE
INDUCTOR
CURRENT

VSW~FF) - r-1- -

"r-T - -._LL-....I __ L..-

SAT

OV - - - - - - - - - - - - -

~~

:0:: j--t :::

VR -

-

These limits must be grE3ater than or equal to the values
specified in this application.
1. Inductor Selection (L)

--

___ J_
~
'NO(AVE) - - -

A. Voltage Options:

- - - - TAINo

1. For 12Vor 15Voutput

0------------r--T --

SWITCH
CURRENT

ISW(PK) - - - -~--

DIODE
CURRENT

Io(PK)
'o(AVE) 0-

From FIgure 78 (for 12V output) or Figure 7b (for 15V
output), Identify Inductor code for region indicated by
VIN (min) and ILOAq (max). The shaded region indicates
conditions for which the LMI577/LM2577 output switch
would be operating beyond its switch current rating. The
minimum operating voltage for the LMI577/LM2577 is
3.5V.

o _--1 __ ..LL __ L_

-r:EF:E--------- - - - - - -

--

-lL/H/II468-11

From here, proceed to step C.

FIGURE 5. Step-Up Regulator Waveforms
Duty Cycle

0
IIND(AVE)

Inductor Current
Ripple

allND

0
VIN - VSAr
- - L - - 52,000

IIND(PK)

,ILoADcmaxl + allND
1 - O(meX)
2

Peak Inductor
Current
Peak Switch
Current

ILOAD

1-0

ISW(pK)

, ILDADCmaxl + allND
1 - O(max)
2

Switch Voltage
When Off

VSW(OFF)

Your + VF

Diode Reverse
Voltage

VR

Your -'VSAl

Average Diode
Current'

ID(AVE)

ILOAD

Peak Diode
Current

ID(PK) ,

Power Dissipation
of LM157712577

PD

2. For Adjustable version
Preliminary calculations:
The inductor selection is based on the calculation of the
following three parameters:

VOllT + VF - VIN ::: VOUT - VIN
Your + VF - VSAl
¥OllT

Average Inductor
Current

r0

D(max), the maximum switch duty cycle (0 S; D S; 0.9):
D
(max) -

Your + VF - VIN(min)
Your + VF - 0.6V

where VF = 0.5V for Schottky diodes and 0.8V for fast
recovery diodes (typically);
Ee T, the product of volts x 'time that charges the inductor:
EeT = D(max) (VIN(mln) - 0.6V)10B
52,000 Hz
,

+

(Vep.s)

I,ND,DC, the average inductor current under full load;

I
_ 1.05 x ILOAD(max)
IND,DC 1 - D(max)

~+"IIND
1 - O(max)
2

0250 ('LOAD
.
1-0

Your s; 60V
Your S; 10 x VIN(min)
2;IA x VIN(min)
I
LOAD(max)S;
V
our

.

B. Identify Inductor Value:
1. From Figure 7c, identify the inductor code for the region
indicated by the intersection of EeT and IIND,DC' This code
gives the inductor value in micro henries. The L or H prefix
signifies whether the inductor is rated for a maXimum EeT of
90 Vep.s (L) or 250 Vep.s (H).

ILOAD 0 VIN

"50(1-0)

VF = Forward Biased Diode Voltage
ILOAD = Output Load Current

2. If D < 0.85, go on to step C. If D ~ 0.85, then calculate
the minimum inductance needed to ensure the switching
regulator's stability:

FIGURE 6. Step-Up Regulator Formulas
STEP-UP REGULATOR DESIGN PROCEDURE
The following design procedure can be used to select the
appropriate external components for the circuit in Figure 4,
based on these system requirements.

LMIN = 6.4 (VIN(min) - 0.6V)(2D(max) - 1)
(p.H)
1 - D(max)
If LMIN is smaller than the inductor value found in step Bl,
go on to step C. Otherwise, the inductor value found in step
Bl is too low; an appropriate inductor code should be obtained from the graph as follows:
1. Find the lowest value inductor that is greater than LMIN.

Given:
VIN (min) = Minimum input supply voltage
= Regulated output voltage
ILOAO(max) = Maximum output load current

Your

2. Find where EeT intersects this inductor value to determine if it has an L or H prefix. If EeT intersects both the
Land H regions, select the inductor with an H prefix.

3-92

Application Hints

(Continued)

3~--~~~~WW~--~

0.1

0.2 0.30.4 0.60.81.0

1.75

0.2 0.30.4

MAXIMUM LOAD CURRENT (A)

0.60.81.0

1.7

MAXIMUM LOAD CURRENT (A)
TL/H/1146B-27

TLlH/1146B-2B

FIGURE 7a. LM2577·12 Inductor Selection Guide

FIGURE 7b. LM2577·15 Inductor Selection Guide

E'T (y. p.s)

11_ _

100
90
80

70~~-+~~~-r~~r-~~--~~~--~~~~

50~~~--~~~--~~-+-+~~--~~--+-~~~
45~~~~~~~~q-~-+~------~----+.~~~
40~.r~~~r-~~~-r~~~--~~--~~~-r~

35~~~~~~+-~~~~~~--~~~--~~
30~~~~~~~~~~-+~----~~----~~~~

20~~~~~--~~--~~L-----~----~--~~

0.3 0.350.4 p.45 0.5 0.6 0.7 0.80.91.0

1.5

2.0

2.5

3.0

IIND,DC (A)
TLlH/11466-12

FIGURE 7c. LM1577·ADJ/LM2577·ADJ Inductor Selection Graph
Note:
These charts assume that the inductor ripple current inductor is approximately 20% to 30% of the average inductor current (when the regulator is under full load).

Greater ripple current causes higher peak switch currents and greater output ripple voltage; lower ripple current is achieved with larger-value inductors. The factor
of 20 to 30% is chosen as a convenient balance between the two extremes.

3-93

Application Hints (Continued)
A. First calculate the maximum value for Ro

C. Select an inductor from the table of Figure 8 which crossreferences the inductor codes to the part numbers of three
different manufacturers. Complete specifications for these
inductors are available from 'the respective manufacturers.
The inductors listed in this table have the following characteristics:
AlE: ferrite, pot-core inductors; Benefits of this type are
low electro-magnetic interference (EM I), small physical
size, and very low power dissipation (core loss). Be careful not to operate these inductors too far beyond their
maximum ratings for EeT and peak current, as this will
saturate the core.
Pulse: powdered iron, toroid core inductors; Benefits are
low EMI and ability to withstand EeT and peak current
above rated value better than ferrite cores.

Rc ,,; .:..75.:..0,---X...:I!::LO;'!A""D",(m!!!ax~)_X_V",O""U",T_2
VIN(min)2
Select a resistor less than or equal to this value, and it
should also be no greater than 3 kO.
B. Calculate the minimum value forCOUT using the following
two equations.
COUT ;;, .:..O'.:..1.:..9_X:-:=-L_X_R.:..c",-X.,.,I:.:LO""A""D",(",m",ax,,)
VIN(min) x VOUT
and
C
;;, VIN(min) X Rc X (VIN(mln) + (3.74 X 105 X L»
OUT
487,800 X Vour3
The larger of these two values is the minimum value that
ensures stability.

Renco: ferrite, bobbin-core inductors; Benefits are low
cost and best ability to withstand EeT and peak current
above rated value. Be aware that these inductors generate more EMI than the other types, and this may interfere
with signals sensitive to noise.

Inductor
Code

C. Calculate the minimum value of Co
58.5 x Vour2 x COUT
C

c ;;, --=-;;-~:---"""":.!.
2

Rc x VIN(min)
The compensation capacitor is also part of the soft start
circuitry. When power to the regulator is turned on, the
switch duty cycle is allowed to rise at a rate controlled by
this capacitor (with no control on the duty cycle, it would
immediately rise to 90%, drawing huge currents from the
input power supply). In order to operate properly, the 50ft
start circuit requires Cc ;;, 0.22 JLF.

Manufacturer's Part Number
Schott

Pulse

Renco

L47
L68
L100
L150
L220
L330
L470
L680

67126980
67126990
67127000
67127010
67127020
67127030
67127040
67127050

PE - 53112
PE-92114
PE - 92108
PE-53113
PE- 52626
PE-52627
PE-53114
PE-52629

RL2442
RL2443
RL2444
RL1954
RL1953
RL1952
RL1951
RL1950

H150
H220
H330
H470
H680
H1000
H1500
H2200

67127060
67127070
67127080
67127090
67127100
67127110
67127120
67127130

PE-53115
PE - 53116
PE - 53117
PE - 53118
PE - 53119
PE-53120
PE- 53121
PE - 53122

RL2445
RL2446
RL2447
RL1961
RL1960
RL1959
. RL1958
RL2448

The value of the output filter capacitor is normally large
enough to require the use of aluminum electrolytic capacitors. Figure 9 lists several different types that are recommended for switching regulators, and the following parameters are used to select the proper capacitor.
Working Voltage (WVDC): Choose a capacitor with a working voltage at least 20% higher than the regulator output
voltage.
Ripple CUffent: This is the maximum RMS value of current
that charges the capaCitor during each switching cycle. For
step-up and flyback regulators, the formula for ripple current
is

I
ILOAD(max) x D(max)
RIPPLE(RMS) =
1 - D(max)
Choose a capacitor that is rated at least 50% higher than
this value at 52 kHz.
Equivalent Series Resistance (ESR): This is the primary
cause of output ripple voltage, and it also affects the values
of Rc and Cc needed to stabilize the regulator. As a result,
the preceding calculations for Cc and Rc are only valid if
ESR doesn't exceed the maximum value specified by the
following equations.

Schott Corp~ (612)475·1173
1000 Parkers Lake Rd., Wayza1a, MN 55391
Pulse Engineering, (619) 268·2400
P.O. Box 12235, San Diego, CA 92112
Renco Electronics Inc., (516) 586-5566
60 Jeffryn Blvd. Eas~ Deer Park, NY 11729

FIGURE 8, Table of Standardized Inductors and
Manufacturer's Part Numbers
2, Compensation Network (Re. Ce) and Output capacitor (COUT) Selection
.

ESR ,,; 0.01 X VOUT and ,,; 8.7 X (10)- 3 X VIN
IRIPPLE(P-P)
ILOAD(max)
where

Rc and Cc form a pole-zero compensation network that
stabilizes the regulator. The values of Rc and Cc are mainly
dependant on the regulator voltage gain, ILOAD(max), Land
COUTo The following procedure calculates values for Rc,
Cc, and COUT that ensure regulator stability. Be aware that
this procedure doesn't necessarily result in Rc and Cc that
provide optimum compensation. In order to guarantee optimum compensation, one of the standard procedures for
testing loop stability must be used, such as measuring VOUT
transient response when pulsing ILOAD (see Figure 13).

I
_ 1.15 X ILOAD(max)
RIPPLE(P-P) 1 - D(max)
Select a capaCitor with ESR, at 52 kHz, that is less than or
equal to the lower value calculated. Most electrolytiC capacitors specify ESR at 120 Hz which is 15% to 30% higher
than at 52 kHz. Also, be aware that ESR increases by a
factor of 2 when operating at - 20'C.

3-94

r-

s:
......

Application Hints (Continued)

U1

In general, low values of ESR are achieved by using large
value capacitors (C :
Do

::>
0

:E
...

15.140
15.120
15.100

60n

(-15V OUTPUT)
15.200

~ 15.180

f'.

!:i
0
15.160

...::>>

15.080

...
Do

::>

15.060

0

15.140

~

\

\

15.120

15.040

15.1001-+~t-+-t--lr-+-+-t-l

15.020 L-L_'--..L-.......---''--..L--'----''-'
4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0

15.080 L-L_'--..L-.......---''---'--'---'-'
4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0

INPUT VOLTAGE (V)

INPUT VOLTAGE (V)
TLlH/1146B-21

TLlH/1146B-22

FIGURE 21. Line Regulation (Typical) of Flyback
Regulator of Figure 20, + 15V Output

FIGURE 22. Line Regulation (Typical) of Flyback
Regulator of Figure 20, -15V Output

3-100

Application Hints

f

.-3:
......

(Continued)

U1

.......

.......
.......

r

.-3:

100mY

N
U1

.......

100mV

.......

At_100m:

en
CD

...iii'

At_100m:

.{

200mA
[

Bloom:

til

100mA
200mA
TUH/I1466-24

. FIGURE 24. Load Transient Response of Flyback
Regulator of Figure 20, -15V Output

TL/H/11468-23

FIGURE 23. Load Transient Response of Flyback
Regulator of Figure 20, + 15V Output
A: Oulput Voltage Change, 100 mVldiv
B: Output Current, 100 mAldiv
Horizontal: 10 ms/dlv

A

A: Output Voltage Change, 100 mVldiv
B: Output Current, 100 mAldiv
Horizontal: 10 ms/dlv

eo:

0(2:

cc:
TL/H/11468-25

FIGURE 25. Switching Waveforms of Flyback Regulator of Figure 20, Each Output Loaded with 60n
A:
B:
C:
D:

Switch pin voltage, 20 V Idiv
Primary current, 2 Aldlv
+ 15V Secondary current, 1 Aldiv
+15V Output ripple voltage, 100 mVldiv
Horizontal: 5 I's/dlv

3-101 .

tflNational Semiconductor

LM 1578A/LM2578A/LM3578A Switching Regulator
General Description

Features

The LM1578A is a switching regulator which can easily be
set up for such DC-to-DC voltage conversion circuits as the
buck, boost, and inverting configurations. The LM1578A
features a unique comparator input stage which not only
has separate pins for both the inverting and non-inverting
inputs, but also provides an internal 1.0V reference to each
input, thereby simplifying circuit design and p.c. board layout. The output can switch up to 750 rnA and has output
pins for its collector and emitter to promote design flexibility.
An external current limit terminal may be referenced to either the ground or the Vin terminal, depending upon the application. In addition, the LM1578A has an on board oscillator, which sets the switching frequency with a single external capacitor from <1 Hz to 100 kHz (typical).

•
•
•
•
•
•

Inverting and non-inverting feedback inputs
1.0V reference at inputs
Operates from supply voltages of 2V to 40V
Output current up to 750 rnA, saturation less than 0.9V
Current limit and thermal shut down
Duty cycle up to 90%

Applications
• Switching regulators in buck, boost, inverting, and
single-ended transformer configurations
• Motor speed control
• Lamp flasher

The LM1578A is an improved version of the LM1578, offering higher maximum ratings for the total supply voltage and
output transistor emitter and collector voltages.

Functional Diagram
PIN 8
REFERENCE·
REGULATOR

CURRENT
LIMIT
PIN 7
PIN 1
INPUTS
PIN 2

LATCH
GATES
AND DRIVER

PIN 6

EMITTER
PIN 5

TIMING CAPACITOR
PIN 3

3-102

GROUND
PIN 4
TL/H/8711-1

I

....s::

Absolute Maximum Ratings

(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Total Supply Voltage
50V
Collector Output to Ground
-0.3Vto +50V
-1Vto +50V
Emitter Output to Ground (Note 2)
Power Dissipation (Note 3)

U1

2kV

Operating Ratings
Ambient Temperature Range
LM157SA
LM2578A
LM357SA
Junction Temperature Range
LM157SA
LM257BA
LM357SA

Internally limited

Output Current
Storage Temperature
Lead Temperature
(soldering, 10 seconds)

150'C

Maximum Junction Temperature
ESD Tolerance (Note 4)

750mA
- 65'C to + 150'C
260'C

......
Q)

l>
.....
I,
s::
N
U1

......

-55'C,,; TA"; +125'C
-40'C"; TA ";+S5'C
O'C,,; TA"; +70'C

!:
.......

-55'C ,,; TJ ,,; + 150'C
-40'C"; TJ ";+125'C
O'C ,,; TJ ,,; + 125'C

U1

I

s::
Co)

......
Q)

l>

Electrical Characteristics
These specifications apply for 2V ,,; VIN ,,; 40V (2.2V ,,; VIN ,,; 40V for TJ ,,; -25'C), timing capacitor CT = 3900 pF, and 25%
,,; duty cycle,,; 75%, unless otherwise specified. Values in standard typeface are for T J = 25'C; values in boldface type apply
for operation over the specified operating junction temperature range.

Symbol

Parameter

Typical
(Note 5)

Conditions

LM1578A
Limit
(Notes 6, 11)

LM2578A/
LM3578A
Limit
(Note 7)

22.4
17.6

24
16

Units

OSCILLATOR
fose

afose/aT

Frequency

20

Frequency Drift with
Temperature
Amplitude

kHz
kHz (max)
kHz (min) "

-0.13

%rC

550

mVp_p

REFERENCE/COMPARATOR (Note 8)
VR

aVRlaVIN
IINV

Input Reference
Voltage

11 = 12 = OmAand
11 = 12 = 1 mA ± 1% (Note 9)

1.0

Input Reference Voltage Line Regulation

11 = 12 = OmAand
11 = 12 = 1 mA ±1% (Note 9)

0.003

Inverting Input
Current

11 = 12 = 0 mA, duty cycle = 25%

0.5

Level Shift Accuracy

Level Shift Current = 1 mA

1.0

1.035/1.050
0.965/0.950

1.050/1.070
0.950/0.930

0.01/0.02

0.01/0.02

%N

Input Reference
Voltage Long Term
Stability

%N(max)
/LA

5/8
aVR/at

V
V (max)
V (min)

10/13

100

%
% (max)
ppm/1000h

OUTPUT
Vc (sat)
VE(sat)
leES
BVCEO(SUS)

Collector Saturation
Voltage

Ie = 750 mA pulsed, Emitter
grounded

0.7

Emitter Saturation
Voltage

10 = SO mA pulsed,
VIN = Vc = 40V

1.4

Collector Leakage
Current

VIN = VeE = 40V, Emitter
grounded, Output OFF

0.1

Collector-Emitter
Sustaining Voltage

ISUST = 0.2A (pulsed), VIN = 0

60

3-103

0.85/1.2

0.90/1.2

V
V (max)

1.6/2.1

1.7/2.0

V
V (max)

50/100

200/250

50

50

/LA
/LA (max)
V
V (min)

•

Electrical Characteristics (Continued)
Symbol

Parameter

Conditions

.' (Note

LM2578A1

LM1578A

Typical

LM3578A

Limit

5)

. Units

Limit

(Notes 6, 11)

(Note 7)

CURRENT LIMIT
VCl

b.VCl/b.T

Sense Voltage

Referred to VIN or Ground

Shutdown Level

(Note 10)

110

mV

i

95

80

mV(min)

140

160

mV(max)

0.3

Sense Voltage

%I"C

Temperature Drift
ICl

Sense Bias Current

Referred to VIN

4.0

p.A

Referred to ground

0.4

p.A

DEVICE POWER CONSUMPTION
Is

Supply Current

'.

Output OFF, VE

= OV

2.0

mA

3.013.3
Output ON, Ic
VE

=:'

= 750 mA pulsed,

3.5/4.0

mA(max)

14

mA

OV

Note 1: Absolute Maximum Ratings Indicate limits beyond which damage 10 the device may occur. DC and AC electrical specifications do not apply when operating
the device beyond its rated operating conditions.
Note 2: For TJ ;, 100"C,lhe Emitter pin voltage should not be driven more than O.SV below ground (see Application Information).
Note 3: At elevated temperatures, devices must be derated based on package thermal resistance. The device in the TO-99 package must be derated at lSO'C/W,
junction to ambient, or 4S"C/W,/unction to case. The device in the B·pin DIP must be derated at 95"C/W, junction to ambient. The device in the surface·mount
package must be derated at 150"C/W, junction·to·amblent.
Nole 4: Human body model,l,S kG in series with 100 pF.
Note 5: Typical values are for TJ

= 2S"C and represent th'e most likely parametric norm_

Nole 6: All limits guaranteed and 100% production tested at room temperature (standard type lace) and at temperalure extremes (bold Iype lace). All limits are
used io calculate Average Outgoing Quality level (AOQl). .
Note 7: All limits guaranteed at room temperature (stsndard type lace) and at lemperalure exlremes (bold type lace). Room temperature limits are 100%
production tested. Limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SOC) methods. All limits are used to
calculate AOQL.
Nole II! Input terminals are protected Irom accidental shorts to ground but if external voltages higher than the reference voltage are applied, excessive current will
flow and should be limited 10 less than SmA.

Note 9: 11 and 12 are the external sink currents aUhe inputs (refer to Test Circuit).
Note 10: Connection of a 10 kG resistor from pin 1 to pin 4 will drive the duty cycle to its maximum, typically 90%. Applying the minimum Current Limit Sense
Voltage to pin 7 will not reduce the duty cycle to less than 50%. Applying the maximum Current Umit Sense Voltage to pin 7 is cerlain to reduce Ihe duty cycle
below SO%. Increasing this voltage by 15·mV may be required to reduce the duty cycle to 0%, when the Collector output swing is 40V or greater (see Ground-Re·
ferred Current limit Sense Voltage typical curve).
Nole 11: A military RETS specification Is available on request. AI the Ume
The LM157BAH may also be procured as a Standard Military Drawing.

oi printing; ttie LM1S7BA RETS spec complied with the boldface limits In this column.

Connection Diagram and Ordering Information
Metal Can

Dual-In-Line Package

VIN

--INPUT

+ INPUT

-INPUT- 1
8

7

1

2

+ INPUT-

CURRENT
LIMIT

6

2

'--"

8 ~VIN
7 ~CURRENT LIMIT

OSC- 3

6 ~COLLECTOR

GND- 4

5 ~EMITTER

COLLECTOR
TLlH/B711-29

OSC

3

5

Order Number LM3578AM, LM2578AN or LM3578AN
See NS Package Number M08A or N08E

EMITTER

4
GND
TL/H/B711-2B

Top View
Order Number LM1578AH/883 or SMD #5962-8958602
See NS Package Number H08C

3-104

.-3:
.....
U1

Typical Performance Characteristics
Oscillator Frequency Change
with Temperature
t.3

1>

t.2

ill

t.t

e:
e

t.o

8

'"

I
z

DB

t.D30

BOD

-

750

!..

r--.. .......

z

...........

.......

...... ......

~
III
~

!i!

DB

r

300

t.o2O

E
III

250

200

I--'"

-

-

0.990

Z

....

r--..

0.960

cr 4nF

0.950
-50 -25 0

25 50 75 tOO t25 t50

0.81--1---'

Emitter Saturation Voltage
(Sourcing Current,
Collector at Vln) .

g

"
:-...

~
l>
.......
3:

.-

N
U1

.....

;.....

.3:
Co)

U1

.....

co
l>

25 50 75 tOO t25 t50

TEMPERATURE (OC)

TEMPERATURE (OC)

Collector Saturation Voltage
(Sinking Current,
Emitter Grounded)

t-

-

0.980

m 0.970

I-LOWER UMIT

TEMPERATURE (OC)

1.000

g

.....

v

t.otO

!j
tJ

V

tOO
-50 -25 0

2S 50 75 tOO t25 t50

r- r--..

UPPER UMIT

700

t50

0.7
-50 -25 0

g

Input Reference Voltage
. Drift with Temperature

Oscillator Voltage Swing

Ground Referred
Current Limit Sense Voltage

t.or--'--~---.---r~

tOO

0.81-~--+--H~~~

80

0.6 f----I---I-:-It--I+-t--l

60

0.41-~---

<40

f=20kHz
C=40V SWING
E=GROUND
INV INPUT=
tOk.ll TO GND

20

o

O~~--~-~~~~

D.2

0.4

0.6

0.8

o

t.o

COLLECTOR-EMITTER VOLTAGE (V)

0.4

0.8

t.2

t.6

60

2.0

EMITTER-COLLECTOR VOLTAGE (V)

Current Limit Sense Voltage
Drift with Temperature

III
~

!i!

I

j,

vlH1=ty
GND REftRREO

t20

/'
80

t20

Current Limit Response Time
for Various Over Drives

~

/'

t:- ""

-:::I-

-

t5f---~r-l~~~~~~

Vs REFERRED

/

i

60
-50 -25 0

t5r-l~~-+-+-+~~~
to

I I

5

o

25 50 75 tOO t25 t50

4

-

OllTPUT orr

20

30

5UPPLY VOLTAGE (V)

100

<40

o

I OUTPUT
ON
fcoL = 0
-

I

-50 -25 0

25 50 75 tOO t25 t50

TEMPERATURE (OC)

TJ=25OC

I

IJ__1_
GND REFERREO

-

VIN REFERRED

TI I

80

-2.0

N-i-_
OUjUT10rr t -

t60

III

o

to

20

30

<40

SUPPLY VOLTAGE (V)

VIH =t5V
EMITTER = GND

""'"

to

~

3

I
o
o

t20

Supply Current

--

EMITTER = GND

-

~

TtNE (ps)

Supply Current

COLLECTOR OUTPUT
SWING=t5V
1

t<40

60

2

t

TEMPERATURE (OC)

OllTPUT ON
fcoL = 0

!

~

to

t<40

Current Limit Sense Voltage
vs Supply Voltage
t60

COLLECTOR OllTPUT
SWING =tav

t<40

tOO

tOO

SENSE VOLTAGE (mV)

t60

!

80

Collector Current with
Emitter Output Below Ground
COLLECTOR = ~IN =1 t 5V

E

~
!i!
~

ill

-t.6
-t.2
-0.8
-0.4

~ ......
........

i'- ......
...... i'- ~fcoLI=tOmA
...... ......
fcoL=tO':l: r-....

......

-0
-50 -25 0

25 50 75 tOO t25 t50

TEMPERATURE (OC)
TL/H/B7t 1-2

3-105

•

Test Circuit*
Parameter tests can be made using the test circuit shown.
Select the desired Vin, collector voltage and duty cycle with
adjustable power supplies. A digital volt meter with an input
resistance greater than 100 MO should be used to measure
the following:
Input Reference Voltage to Ground; SI in. either position.
'

The Current Limit Sense Voltage is measured by connecting
an adjustable O-to-1V floating power supply in series with
the current limit terminal and referring it to either the ground
or the Vin terminal. Set the duty cycle to 90% and monitor
test point TP5 while adjusting the floating power supply voltage until the LM1578A's duty cycle just reaches 0%. This
voltage is the Current Limit Sense Voltage. ,

Level Shift Accuracy (%) = (TP3(V)/IV) x 100%;SI at

The Supply Current should be measured with the duty cycle
at 0% and SI in the 11 = 12 = 0 mA position.

11 = 12 = 1 rnA

*LM1578A specifications are measured using automated
test equipment. This circuit ·is provided for the customer's
convenience when checking parameters. Due to possible
variations in testing conditions, the measured values from
these testing procedures may not match those of the
factory.

Input Current (mA) = (1V - Tp3 (V))/l MO: SI at 11 =

12 = 0 mAo

'

Oscillator parameters can be measured at Tp4 using a frequency counter or an oscilloscope.

VIII '
2TO:.tJv

VCCUECTOR
5TO-IOV

D, +15V
1"914

INPUT
RlFERENC£ R,
VOLTAGES 10k
Tpi
Tp2
R2
10k
~-----II---{JTp5

RS
1M
IX

RI3

DUlY
CYCLE

IDDk

SET

Tp3.D--'Ijo,fv----44-1-'--------+-<
LEVEL SHIrT ACCURACY
AND INPUT CURRENT

R,B
2k

.Tp4 D--'IIIfIt------i,.....
OSCILLATOR FREQUENCY.
AIIPUTUDE AND SCOPE SYNC
Note 1: Op amp supplies are ±,15V
'Note 2: DVM Input resistance> 100 Mil
Noi~ 3: 'LM1578 max duty cycle is 90%

TLlH/8711-3

Definition of Terms
Input Refe~nce Voltage: The voltage (referred to ground)
that must be applied to either the inverting or non-inverting
input to cause the regulator switch to change state (ON or
OFF).

Input Level Shift Accuracy: This specification determines
the output voltage tolerance of a regulator whose output
control depends on drawing equal currents from the inverting and non-inverting inputs (see the Inverting Regulator of
Figure 21, and the RS-232 Line Driver Power Supply of Figure23).

Collector Saturation Voltage: With the inverting input terminal grounded thru a 10 kO resistor and the output transistor's emitter connected to ground, the Collector SaturationVoltage is the collector-to-emitter voltage for a given collector current.
Emitter Saturation Voltage: With the inverting input terminal grounded thru a 10 kO resistor and the output transistor's collector connected to Vin. the Emitter Saturation Voltage is the collector-to-emitter voltage for a given emitter
current.
'Collector Emitter Sustaining Voltage: The collector-emitter breakdown voltage of the output transistor, measured at
, a specified current.

Level Shift Accuracy is tested by using two equal-value resistors to draw current from the inverting and non-invertirig
input terminals, then measuring the percentage differenqe in
the voltages across the resistors that produces a controlled
duty cycle at the switch output.

Current Limit Sense Voltage: The voltage. at the Current
Limit pin, referred to either the supply or the ground terminal, which (via logic circuitry) will cause the output transistor
to turn OFF and resets cycle-by-cycle at the oscillator frequency.

Input Reference Current: The current that must be drawn
from either the inverting or non-inverting input to ·cause the
regulator switch to change state (ON or OFF).

3-106

,-----------------------------------------------------------------------------'r
l!:
OUTPUT TRANSISTOR
....
Definition of Terms (Continued)
U1
The output transistor is capable of delivering up to 750 mA
with a saturation voltage of less than 0.9V. (see Col/ector
Saturation Voltage and Emiffer Saturation Voltage curves).

Current Limit Sense Current: The bias current for the Current Limit terminal with the applied voltage equal to the Current Limit Sense Voltage.
Supply Current: The IC power supply current, excluding the
current drawn through the output transistor, with the oscillator operating.

The emitter must not be pulled more than 1V below ground
(this limit is 0.6V for TJ ;;, 100·C). Because of this limit, an
external transistor must be used to develop negative output
voltages (see the Inverting Regulator Typical Application).
Other configurations may need protection against violation
of this limit (see the Emitter Output section of the Applications Information).

Functional Description
The LM1578A is a pulse-width modulator deSigned for use
as a switching regulator controller. It may also be used in
other applications which require controlled pulse-width voltage drive.

CURRENT LIMIT
The LM1578A's current limit may be referenced to either
the ground or the Vin pins, and operates on a cycle-by-cycle
basis.
The current limit section consists of two comparators: one
with its non-inverting input referenced to a voltage 110 mV
below Vin, the other with its inverting input referenced
110 mV above ground (see FUNCTIONAL DIAGRAM). The
current limit is-activated whenever the current limit terminal
is pulled 110 mV away from either Vin or ground.

A control signal, usually representing output voltage, fed
into the LM1578A's comparator is compared with an internally-generated reference. The resulting error signal and the
oscillator's output are fed to a logic network which determines when the output transistor will be turned ON or OFF.
The following is a brief description of the subsections of the
LM1578A.
COMPARATOR INPUT STAGE
The LM1578A's comparator input stage is unique in that
both the inverting and non-inverting inputs are available to
the user, and both contain a 1.0V reference. This is accomplished as follows: A 1.0V reference is fed into a modified
voltage follower circuit (see FUNCTIONAL DIAGRAM).
When both input pins are open, no current flows through Rl
and R2. Thus, both inputs to the comparator will have the
potential of the 1.0V reference, VA. When one input, for
example the non-inverting input, is pulled t. V away from VA,
a current of AV/Rl will flow through Rl. This same current
flows through R2, and the comparator sees a total voltage
of 2t. V between its inputs. The high gain of the system,
through feedback, will correct for this imbalance and return
both inputs to the 1.0\( level.

~

l>
......

r
l!:
N
U1

.....

;......
r

l!:
Co)
U1
.....

;

Applications Information
CURRENT LIMIT
As mentioned in the functional description, the current limit
terminal may be referenced to either the Vin or the ground
terminal. Resistor R3 converts the current to be sensed into
a voltage for current limit detection.
YIN

2
u.t1578A

This unusual comparator input stage increases circuit flexibility, while minimizing the total number of external components required for a voltage regulator system. The inverting
switching regulator configuration, for example, can be set up
without having to use an external op amp for feedback polarity reversal (see TYPICAL APPLICATIONS).
OSCILLATOR
TLlH/8711-15

The LM1578A provides an on-board oscillator which can be
adjusted up to 100 kHz. Its frequency is set by a single
external capacitor, C1, as shown in Figure 1, and follows the
equation
fosc = 8Xl0- 5/C1

FIGURE 2_ Current Limit, Ground Referred
YIN

The oscillator provides a blanking pulse to limit maximum
duty cycle to 90%, and a reset pulse to the internal circuitry.
LM1578A

l00~.

~
~

10

5

~~IUIII"I!IIIIIIIIIIII
~

TL/H/8711-16

~ 1»~~~I!~~~1!
FREQUENCY (kHz)

FIGURE 3. Current Limit, Vln Referred

TL/H/8711-4

FIGURE 1_ Value of Timing CapaCitor vs
OSCillator Frequency
3-107

•

Applications Information (Continued)
CURRENT LIMIT TRANSIENT SUPPRESSION
When noise spikes and switching transients interfere with
proper current limit operation, R1 and C1 act together as a
low pass filte~ to control the current limit circuitry's response
time.
Because the sense current of the current limit terminal varies according to where iUs referenced, R1 should be less
than 2 kO when referenced to ground, and less than 1000
when referenced to Vin.

Lt.t1578A

Rl

5

TL/H/8711-20

FIGURE 7. Current Limit Sense Voltage Multiplication,
Vln Referred

2

3

Lt.t1578A

UNDER-VOLTAGE LOCKOUT
Under-voltage lockout is accomplished with few external
components. When Vln becomes lower than the zener
breakdown voltage, the output transistor is turned off. This
occurs because diode 01 will then becorne forward biased;
allowing resistor R3 to sin~ a greater current from the nOninverting input than is sunk by the parallel combination of R1
and R2 at the inverting terminal. R3 should be one-fifth of
the ,value of R1 and R2 in parallel.

4

TL/H/8711-17

,FIGURE 4. Current Limit Transient Suppressor,
Ground Referred
VIN

8

3

Cl

8

7

2

Lt.t1578A

7

6

Lt.t1578A

Rl

5

6

5

TL/H/8711-18

FIGURE 5. Current Limit Transient Suppressor,
Vln Referred

TL/H/8711-22

FIGURE 8. Under-Voltage Lockout

C.L. SENSE VOLTAGE MULTIPLICATION

MAXIMUM DUTY CYCLE LIMITING
The maximum duty cycle can be extemaily limited by adjusting the charge to discharge ratio of the oscillator capacitor
with a single external resistor. Typical values are 50 "A for
the charge current, 450 /LA for the discharge current, and a
voltage swing from 200 mV to 750 mV. Therefore, R1 is
selected for the desired charging and discharging slopes
and C1 is readjusted to set the oscillator frequency.

When a larger sense resistor value' is desired, the voltage
divider network, consisting of R1 and R2, may be used. This
effectively multiplies the sense voltage by (1 + R1/R2).
Also, R1 can be replaced by a diode to increase current limit
sense voltage to about 800 mV (diode VI + 110 mV).
VIN

Lt.t1578A

4

TL/H/8711-19

FIGURE 6. Current Limit Sense Voltage Multiplication,
Ground Referred
3-108

r-

Applications Information

....
==
en

(Continued)

......
co

l>
......
r-

==

Rl

N

8

8

7

Lt.t1578A

7
Lt.t1578A

6

6

en
......
co

l>
......
r-

==

Co)

5

5

en
......
co

l>

YL

TL/H/8711-21

FIGURE 9. Maximum Duty Cycle Limiting
DUTY CYCLE ADJUSTMENT. ,
When manual or mechanical selection of the output transistor's duty cycle is needed, the cirucit shown below may be
used. The output will turn on with the beginning of each
oscillator cycle and turn off when the current sunk by R2
and R3 from the non-inverting terminal becomes greater
than the current sunk from the inverting terminal.
With the resistor values as shown, R3 can be used to adjust
the duty cycle from 0% to 90%.

TL/H/8711-24

FIGURE 11. Shutdown Occurs when VL Is High
EMITTER OUTPUT
When the LM157BA output transistor is in the OFF state, if
the Emitter output swings below the ground pin voltage, the
output transistor will turn ON because its base is clamped
near ground. The Collector Current with Emiffer Output Below Ground curve shows the amount of Collector current
drawn in this mode, vs temperature and Emitter voltage.
When the Collector-Emitter voltage is high, this current will
cause high power dissipation in the output transistor and
should be avoided.
This situation can occur in the high-current high-voltage
buck application if the Emitter output is used and the catch
diode's forward voltage drop is greater than 0.6V. A fast-recovery diode can be added in series with the Emitter output
to counter the forward voltage drop of the catch diode (see
Figure 2). For better efficiency of a high output current buck
regulator, an external PNP transistor should be used as
shown in Figure 16.

When the sum of R2 and R3 is twice the value of R1, the
duty cycle will be about 50%. C1 may be a large electrolytic
capacitor to lower the oscillator frequency below 1 Hz.
YIN

Lt.t1578A

, ,

TL/H/8711-23

FIGURE 10. Duty Cycle Adjustment
REMOTE SHUTDOWN
The LM1578A may be remotely shutdown by sinking a
greater current from the non·inverting input than from the
inverting input. This may be accomplished by selecting resistor R3 to be approximately one-half the value of R1 and
R2 in parallel.
TL/H/8711-30

FIGURE 12. 01 Prevents Output Transistor from
Improperly Turning ON due to D2's Forward Voltage

3·109

Component values are selected as follows:
R1 = (Vo - 1) x' R2 where R2 = 10 kO
R3 = V/lsw(max)
R3 = 0.150

Applications Information (Continued)
SYNCHRONIZING DEVICES
When several devices are to be operated at once, their oscillators may be synchronized by the application of an external signal. This drive signal should be a pulse waveform with
a minimum pulse width of 2 J.Ls. and an amplitude from 1.5V
to 2.0V. The signal source must be capable of 1.) driving
capacitive loads and 2.) delivering up to 500 J.LA for each
LM1578A.
Capacitors C1 thru CN are to be selected for a 20% slower
frequency than the synchronization frequency.

where:
V is the current limit sense voltage, 0.11V
Isw(max) is the maximum allowable current thru the output transistor.
L1 is the inductor and may be found from the inductance
calculation chart (Figure 16) as follows:
Given Vin = 15V

LM157BA

ALL DIODES ARE lN914

TOJUl

I.SY

Dl

2Y
~

-

Vo"; 5V

lo(max) = 350 mA foSC = 50 kHz
Discontinuous at 20% of lo(max)'
Note that since the circuit will become discontinuous at
20% of lo(max), the load current must not be allowed to fall
below 70 mA.
Step 1: Calculate the maximum DC current through the inductor, IL(max)' The necessary equations are indicated at
the top of the chart and show that IL(max) = lo(max) for the
buck configuration. Thus, IL(max) = 350 mAo
Step 2: Calculate the inductor Volts-sec product, E-ToP' according to the equations given from the chart. For the Buck:

o--4------~--------~

2 "•.
(min.)

E-Top = (Vln - Vol (VoNin) (1000/f080)
=(15 - 5)(5/15)(1000/50) , ,

TLlH/B711-25

FIGURE 13. Synchronizing Devices

= 66V-J.Ls.
with the oscillator frequency, fosc, expressed in kHz.

Typical Applications
The LM1578A may be operated in either the continuous or
the discontinuous conduction mode. The following applications (except for the Buck-Boost Regulator) are designed
for continuous conduction operation. That is, the inductor
current is not allowed to fall to zero. This mode of operation
has higher efficiency and lower EMI characteristics than the
discontinuous mode.

V'n

Rl

lose = 50 kHz
Rl = 40kll
R2 = 10 kll
R3 = 0.151l
R2

BUCK REGULATOR'
The buck configuration is used to step an input voltage
down to a lower level. Transistor 01 in Figure 14 chops the
input DC voltage into a squarewave. This squarewave is
then converted back into a DC voltage of lower magnitude
by the low pass filter consisting of L1 and C1. The duty
cycle, D, of the squarewave relates the output voltage to the
input voltage by the following equation:
Vou! = D X Vin = Vin X (Ion)/(lon

= 15V

Vo = 5V
Vrippl. = 10 mV
10 = 350 rnA

Cl

Cl

C2

= 1820 pF
= 220 "F

C3=2OpF

Ll = 470"H
01 = lN5818
TL/H/B711-6

FIGURE 15. Buck or Step-Down Regulator
Step 3: Using the graph with axis labeled "Discontinuous At
% lOUT" and "IL(max. DC)" find the point where the desired
maximum inductor current, IL(max, DC) intercepts the desired
discontinuity percentage.

+ tolfl.

L1

In this example, the point of interest is where the 0.35A line
in~ersects with the 20% line. This is nearly the midpoint of

the horizontal axis.
Step 4: This last step is merely the translation of the point
found in Step 3 to the graph directly below it This is accomplished by moving straight down the page to the point which
intercepts the desired E-Top. For this example, E-Top is
66V-J.Ls and the desired inductor value is 470 J.LH. Since this
example was for 20% discontinuity, the bottom chart could
have been used directly, as noted in step 3 of the chart
instructions.

TLlH/8711-5

FIGURE 14_ Basic Buck Regulator
Figure 15 is a 15V to 5V buck regulator with an output current, 10 , of 350 mA. The circuit becomes discontinuous at
20% of lo(max), has 10 mV of output voltage ripple, an efficiency of 75%, a load regulation of 30 mV (70 mA to
350 mAl and a line regulation of 10 mV (12 :5: Vin :5: 18V).

3-110

~

HOW TO USE THIS CHART

, 
BOOST
L = Yin (VO - Vin)/(all foscVo)
INVERT
L = Vin IVol/[all(Vin + IVolJfoscl
where all is the current ripple through the inductor. all is
usually chc;>sen based on the minimum load current expected of the circuit For the buck regulator, since the inductor
current Il equals the load current 10,

01 should be a Schottky type diode, such as the
,1N5818 or lN5819.
BUCK WITH BOOSTED OUTj)UT CURRENT
For applications requiring a large output current, an external
transistor may be used as shown in Figure 17. This circuit
steps a 15V supply down to 5V with 1.5A of output current.
The output ripple is 50 mV, with an efficiency of 80%, a load
regulation of 40 mV (150 mA to 1.5A), and a line regulation
of 20 mV (12V ,;: Yin ,;: 18V).
Component values are selected as outlined tor the buck
regulator with a discontinuity factor of 10%, with the addition of R4 and R5:

all = 2 - IO(min) ,
all = 140 mA for this circuit. all can alSo be interpreted !Is
all = 2 -(Discontinuity Factor) - Il
where the Discontinuity Factor is the ratio of the minimum
load current to the maximum load current. For this example,
the Discontinuity Factor.is 0.2.
'

R4 =10VeE1Bf/lp:
R5 = (Vin -, V - VeEI - Vsatl Bf/(Il(max, DC)
where:
.

+

IR4)

VeEI Is the VeE of transistor'QI.
,
Vsat ,is the saturation voltage of the LM 1578A output
tranSistor.
'
V is the current limit sense voltage.
Bf is the forced current gain ,of transistor 01 (Bf = 30
for Figure 17).
IR4 = VeEI/R4
Ip= Il(max, DC)

+

0.5all

= 15,V
= 5V
V'ipple = 50 mV
Vln

Vo

RI

10 = 1.5A

fose = 50 kHz
RI = 40 kO

C3

R2=10kO,
R3 = 0.050

R2
CI

TLlH/8711-8

FIGURE 17. Buck Conv~rter with Boosted Output Current

3-112

R4 ='2000
R5 = 3300
Cl = 1820 pF
C2 = 330 "F
'C3=20pF'
Ll = 220"H
01 = lN5819
",tl1=045

Typical Applications

(Continued)
C2 ~ 10 (Vo - Vin)/(fosc Vo Vripple).
D1 is a Schottky type diode such as a IN5818 or IN5819.

BOOST REGULATOR
The boost regulator converts a low input voltage into a higher output voltage. The basic configuration is shown in Figure
18. Energy is stored in the inductor while the transistor is on
and then transferred with the input voltage to the output
capacitor for filtering when the transistor is off. Thus,
Vo = Yin

L 1 is found as described in the buck converter section, using the inductance chart for Figure 16 for the boost configuration and 20% discontinuity.
INVERTING REGULATOR

+ Vin(ton/lott)·

L1

o0...-

Figure 20 shows the basic configuration for an inverting regulator. The input voltage is of a positive polarity, but the
output is negative. The output may be less than, equal to, or
greater in magnitude than the input. The relationship between the magnitude of the input voltage and the output
voltage is Vo = Yin X (ton/tott).

D1

.....-.1--"",--0 Vo

D1
TL/H/8711-9

FIGURE 18. Basic Boost Regulator
The circuit of Figure 19 converts a 5V supply into a 15V
supply with 150 mA of output current, a load regulation of
14 mV (30 mA to 140 mAl, and a line regulation of 35 mV
(4.5V ,;; Yin ,;; 8.5V).

TL/H/8711-10

Vin = 5V
Vo = 15V

FIGURE 20. Basic Inverting Regulator
Figure 21 shows an LM1578A configured as a 5V to -15V
polarity inverter with an output current of 300 mA, a load
regulation of 44 mV (60 mA to 300 mAl and a line regulation
of 50 mV (4.5V ,;; Yin ,;; 8.5V).

Vrippl9 = 10 mV

10 = 140 rnA

lose = 50 kHz
AI = 140 kll
A2 = 10kll

R1 = (IVel

r-I+. .I-+-OVo ~~ : ~;~~ll
Cl =
C2 =
C3 =
C4 =
Ll =
01 =

R3

1820 pF

R4

470 "F

20 pF
0.0022 "F
330"H
lNS818

+ 1) R2 where R2 =

V/(iL(max, DC)

10 kfi.

+ 0.5 dill·

10VSE1Bf/(IL (max, DC)

+ 0.5 dill

where:
V, VSE1, Vsat, and Bf are defined in the "Buck Converter
with Boosted Output Current" section.
dlL = 2(ILOAD(min))(Vin + IVol)IVIN
R5 is defined in the "Buck with Boosted Output Current" section.

TL/H/8711-11

FIGURE 19. Boost or Step-Up Regulator
R1 = (VO - 1) R2 where R2 = 10 kfi.
R3 = V /(iL(max, DC)
where:

=

=

+ 0.5 dill

R6 serves the same purpose as R4 in the Boost Regulator circuit and is typically 220 kfi.
C1, C3 and C4 are defined in the "Boost Regulator"
section.

dlL = 2(ILOAO(min))(VolVin)
dlL is 200 mA in this example.

C2 ~ 10 Ivol/lfosdlvol + Vin) Vripplel
L 1 is found as outlined in the section on buck converters, using the inductance chart of Figure 16 for the invert configuration and 20% discontinuity.

R4, C3 and C4 are necessary for continuous operation
and are typically 220 kfi, 20 pF, and 0.0022,..F respectively.
C1 is the timing capaCitor found in Figure 1.

Vln = 5V
Vo = -15V
VripPle = 5 mV
10 = 300 rnA, Imin = 60 rnA
fose = 50 kHz
AI = 160 kll A2 = 10 kll
A3 = 0.01 II A4 = 19011
RS = 8211 R6 = 220 kll
Cl = 1820 pF
C2 = 1000 "F
C3=20pF
C4 = 0.0022 "F
U=150"H
01 = lN5818
TLlH/8711-12

FIGURE 21. Inverting Regulator

3-113

Typical Applications (Continued)
BUCK·BOOST REGULATOR

RS-2S2 LINE DRIVER POWER SUPPLY

The Buck·Boost Regulator, shown in Figure 22, may step a
voltage up or down, depending upon whether or not the
desired output voltage is greater or less than the input voltage. In this case, the output voltage is 12V with an input
voltage from 9V to 15V. The circuit exhibits an efficiency of
75%, with a load regulation of 60 mV (10 mA to 100 mAl
and a line regulation of 52 mV.
R1 '7 (VA - 1) R2 where R2 = 10 kO

The power supply, shown in Figure '23, operates from an
input voltage as low as 4.2V (5V nominal), and delivers an
output of ± 12V at ± 40 mA with better than 70% efficiency.
The circuit provides a load regulation of ± 150 mV (from
10% to 100% of full load) and a line regulation of ±10 mV.
Other notable features include a cycle-by-cycle current limit
and an output voltage ripple of less than 40 mVp-p.
A unique feature of this circuit is its use of feedback from
both outputs. This dual feedback configuration results in a
sharing of the output voltage regulation by each output so
that neither side becomes unbalanped as in single feedback
systems. In addition, since both sides are regulated, it is not
necessary to use a linear regulator for output regulation.

RS = V/0.75A
R4,·C1, CS and C4 are defined in the "Boost Regulator"
section.
01 and 02 are Schottky type diodes such as the 1N5818 or
1N5819.
C2

~

The feedback resistors, R2 and RS, may be selected as
follows by assuming a value of 10 kO for R1;

(lolVripple) (VA + 2Vd)
.
[fosc (Vln + Va + 2Vd - Vsal - Vsat1)]

R2 = (VA - 1V)/45.8/LA = 240 kO

where:

RS = (IVai + 1V)/54.2;"A = 240 kO
Actually, the currents used to program the values for the
feedback resistors may vary from 40 /LA to 60 /LA, as long
as their sum is equal to the 100 /LA necessary to establish
the 1V threshold across R1. Ideally, these currents should
be equal (50 /LA each) for optimal control. However, as was
done here, they may be mismatched in order to use standard resistor values. This results in a slight mismatch of
regulation between the two outputs.

Vd is the forward voltage drop of the diodes.
VSal is the saturation voltage of the LM1578A output
transistor.
Vsall is the saturation'voltage of transistor Q1.
L1 ~ (Vin .:... VSal -:- VsallHton/lp)

The current limit resistor, R4, is selected by divi.ding the current limit threshold voltage by the maximum peak current
level in the output switch. For our' purposes R4
110 mV1750 mA..= 0.150. A value of 0.10 was used.
9V ,;: Vl n ,;: 15V
Vo = 12V
10 = 100 mA
Vripple = 50 mV
lose = 50 kHz
AI = 110k
A2 = 10 k
A3 = 0.15
A4=220k

A5 = 270
Cl = 1820 pF
C2 = 220 "F
C3=20pF
C4 = 0.0022 "F
Ll = 220"H
01.02 = lN5819
01 = D44

TL/H/8711-13

FIGURE 22. Buck·Boost Regulator

.r--"HH>+vo

R3

Vin = 5V
Vo = ±12V
10 = ±40 mA
lose = 80 kHz
Al=10kn
A2 = 240 kn
'A3 = 240kn
A4 = 0.15 n
Cl = 820 pF
C2 = 10 pF
C3 = 220 "F
01.02.03 = lN5819
T1 = PE·64287

• TL/H/8711-14

FIGURE 23. RS-232 Line Driver Power Supply
S-114

Typical Applications (Continued)
Capacitor C1 sets the oscillator frequency and is selected
from Figure 1.
Capacitor C2 serves as a compensation capaCitor for synchronous operation and a value of 10 to 50 pF should be
sufficient for most applications.
A minimum value for an ideal output capacitor C3. could be
calculated as C = 10 X tI AV where 10 is the load current. t
is the transistor on time (typically 0.4ffoscl. and AV is the
peak-to-peak output voltage ripple. A larger output capacitor
than this theoretical value should be used since electrolytics
have poor high frequency performance. Experience has
shown that a value from 5 to 10 times the calculated value
should be used.

For good efficiency. the diodes must have a low forward
voltage drop and be fast switching. 1N5819 Schottky diodes
work well.
Transformer selection should be picked for an output transistor "on" time of O.4ffosc• and a primary inductance high
enough to prevent the output transistor switch from ramping
higher than the transistor's rating of 750 mAo Pulse Engineering (San Diego. Calif.) and Renco Electronics. Inc.
(Deer Park. N.Y.) can provide further assistance in selecting
the proper transformer for a specific application need. The
transformer used in Figure 23 was a Pulse Engineering
PE-64287.

&I

3-115

~ .-~----------------------------------------------------------------------,

~

~

t!JNational Semiconductor

LM2S87
SIMPLE SWITCHER® SA Flyback Regulator
General Description

Features

The LM2587 series of regulators are monolithic integrated
circuits specifically designed for flyback, step-up (boost),
and forward converter applications. The device is available
in 4 different output voltage versions: 3.3V, 5.0V, 12V, and
adjustable.

•
•
•
•
•

Requiring a minimum number of external components,
these regulators are cost effective, and simple to use. Included in the datasheet are typical circuits of boost and flyback regulators. Also listed are selector guides for diodes
and capaCitors and a family of standard inductors and flyback transformers designed to work with these switching
regulators.
The power switch is a 5.0A NPN device that can stand-off
65V. Protecting the power switch are current and thermal
limiting circuits, and an undervoltage lockout circuit. This IC
contains a 100 kHz fixed-frequency internal oscillator that
permits the use of small magnetics. Other features include
soft start mode to reduce in-rush current during start up,
current mode control for improved rejection of input voltage
and output load transients and cycle-by-cycle current limiting. An output voltage tolerance of ±4%, within specified
input voltages and output load conditions, is guaranteed for
the power supply system.

•
•
•
•

Requires few external components
Family of standard inductors and transformers
NPN output switches 5.OA, can stand off 65V
Wide input voltage range: 4V to 40V
Current-mode operation for improved transient response, line regulation, and current limit
100 kHz switching frequency
Internal soft-start function reduces in-rush current during start-up
Output transistor protected by current limit, under voltage lockout, and thermal shutdown
System Output Voltage Tolerance of ±4% max over
line and load conditions

Typical Applications
•
•
•
•

Flyback regulator
Multiple-output regulator
Simple boost regulator
Forward converter

Flyback Regulator
+SV
(4V.~-6V)

INS822
....

r
~1t-+""'------.l"~::rL'--I"""".J~~10-00-!'-F±"""+-o +12V@O.3A
100!,F

22!'H·~::n
1 !,F

II

Dr

CA

5

mP
l

3k

1- -=

-

'1

L-......I - - I - - - _ - - o -12V@O.3A

YIN

Switch

LM2S87-12

04-

~:822

I

1000!'F J;+

II1i2~=,....-_...J
Feedback

~-GN~~D~3-~

TL/H/12316-1

Ordering Information
Package Type

NSCPackage
Drawing

5-Lead TO-220 Bent, Staggered Leads

T05D

Order Number
LM2587T-3.3, LM2587T-5.0, LM2587T-12, LM2587T-ADJ

5-Lead TO-263

TS5B

LM2587S-3.3, LM2587S-5.0, LM2587S-12, LM2587S-ADJ

5-Lead TO-263 Tape and Reel

TS5B

LM2587SX-3.3, LM2587SX-5.0, LM2587SX-12, LM2587SX-ADJ

3-116

Absolute Maximum Ratings

(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Input Voltage
-O.4V ~ VIN ~ 45V
Switch Voltage
-O.4V ~ Vsw ~ 65V
Switch Current (Note 2)
Internally Limited
Compensation Pin Voltage

-O.4V ~ VCOMP ~ 2.4V

Feedback Pin Voltage
Power Dissipation (Note 3)

-O.4V ~ VFB ~ 2 Your
Internally Limited

Storage Temperature Range
Lead Temperature (Soldering, 10 sec.)
Maximum Junction Temperature (Note 3)
Minimum ESD Rating (C

=

160 pF, R

=

-65·C to + 150·C
260·C
150·C

1.5 kG

2kV

Operating Ratings
4V ~ VIN ~ 40V
Vsw ~ 60V

Supply Voltage
Output Switch Voltage

OV·~

Output Switch Current
Junction Temperature Range

-40·C

~

TJ

Isw ~ 5.0A
~ +125·C

Electrical Characteristics
Specifications with standard type face are for TJ
Range. Unless otherwise specified, VIN = 5V.

=

25·C, and those in bold type face apply over full Operating Temperature

LM2587-3.3
Symbol

I

Parameters

I

I

Conditions

Typical

I

Min

I

I

Max

Units

SYSTEM PARAMETERS Test Circuit of Figure 2 (Note 4)
Your

Output Voltage

VIN = 4Vto 12V
ILOAD = 400 mA to 1.75A

3.3

I1Vour/
I1VIN

Line Regulation

VIN = 4Vto 12V
ILOAD = 400 mA

I1VOUT/
I1ILOAD

Load Regulation

VIN = 12V
ILOAD = 400 mA to 1.75A

11

Efficiency

VIN

=

12V, ILOAD

=

3.17/3.14

3.43/3.46

V

20

501100

mV

20

50/100

mV

0/0

75

lA

UNIQUE DEVICE PARAMETERS (Note 5)
VREF

Output Reference
Voltage

Measured at Feedback Pin
VCOMP = 1.0V

I1VREF

Reference Voltage
Line Regulation

VIN

GM

Error Amp
Transconductance

ICOMP = -30 /LA to +30 /LA
VCOMP = 1.0V

AVOL

Error Amp
Voltage Gain

VCOMP
RCOMP

=

3.3

4V to 40V

3.358/3.366 .

3.242/3.234

2.0

= 0.5V to 1.6V
= 1.0 MO (Note 6)

V
mV

1.193

0.678

260

151/75

2.259

mmho
VIV

LM2587-5.0
Symbol

I

Parameters

I

I

Conditions

Typical

I

Min

I

Max

I

Units

SYSTEM PARAMETERS Test Circuit of Figure 2 (Note 4)
Your

Output Voltage

VIN = 4Vto 12V
ILOAD = 500 mA to 1.45A

5.0

I1VOUT/
I1VIN

Line Regulation

VIN = 4Vto 12V
ILOAD = 500 mA

I1VOUTI
111 LOAD

Load Regulation

VIN = 12V
ILOAD = 500 mA to 1.45A

1j

Efficiency

VIN

=

12V, ILOAD

=

750 mA

3·117

5.20/5.25

V

20

501100

mV

20

50/100

mV

80

4.80/4.75

0/0

Electrical Characteristics
Specifications with standard type face are for T J = 25°C, and those in bold type face apply over full Operating Temperature
Range. Unless otherwise specified, VIN = 5V. (Continued)

LM2587-5.0 (Conti[lUed)
Symbol

I

Parameters

I

I

Conditions

Typical

I

Min

I

Max

I

Units

UNIQUE DEVICE PARAMETERS (Note 5)
VREF

Output Reference
Voltage

Measured at Feedback Pin

=

VCOMP

=

4.913/4.900

5.0

1.0V

.6.VREF

Reference Voltage
Line Regulation

VIN

GM

Error Amp
Transconductance

ICOMP = -30 p.A to +30 p.A
VCOMP = 1.0V

AVOL

Error Amp
Voltage Gain

VCOMP
RCOMP

4V to 40V

5.088/5.100

V

2.8

mV

0.750

0.447

165

99/49

Typical

Min

Max

Units

12.0

11.52/11.40

12.48/12.60

V

= 0.5Vto 1.6V
= 1.0 MO (Note 6)

1.491

mmho
VIV

LM2587-12
Symbol

Parameters

Conditions

SYSTEM PARAMETERS Test Circuit of Figure 3 (Note 4)
VOUT

Output Voltage

VIN = 4Vto 10V
ILOAD = 300 mA to 1.2A

.6.VOUT/
.6.VIN

Line Regulation

VIN = 4Vto 10V
ILOAD = 300 mA

20

100/200

mV

.6.VOUT/
.6.ILOAD

Load Regulation

VIN = 10V
ILOAD = 300 mA to 1.2A

20

100/200

mV

'1/

Efficiency

VIN

=

10V, ILOAD

=

%

90

1A

UNIQUE DEVICE PARAMETERS (Note 5)
Output Reference
Voltage

VREF

Measured at Feedback Pin
VCOMP

=

=

12.0

1.0V

.6.VREF

Reference Voltage
Line Regulation

VIN

GM

Error Amp
Transconductance

ICOMP = -30 p.A to + 30 p.A
VCOMP = 1.0V

AVOL

Error Amp
Voltage Gain

VCOMP
RCOMP

4V to 40V

11.79/11.76

12.21/12.24

V

1.0

mV

0.328

0.186

70

41/21

= 0.5Vto 1.6V
= 1.0 MO (Note 6)

0.621

mmho
VIV

LM2587-ADJ
Symbol

I

Parameters

I

I

Conditions

Typical

I

Min

I

Max

I

Units

SYSTEM PARAMETERS Test Circuit of Figure 3 (Note 4)
VOUT

Output Voltage

VIN = 4Vto 10V
ILOAD = 300 mA to 1.2A

.6.VOUT/
.6.VIN

Line Regulation

VIN = 4Vto 10V
ILOAD = 300 mA

.6.VOUT/
.6.ILOAD

Load Regulation

VIN = 10V
ILOAD = 300 mA to 1.2A

'1/

Efficiency

VIN

=

10V, ILOAD

=

1A

3-118

12.0

12.48/12.60

V

20

100/200

mV

20

100/200

mV

90

11.52/11.40

%

r-

:s::

Electrical Characteristics
Specifications with standard type face are for TJ = 25"C, and those in bold type face apply over full Operating Temperature
Range. Unless otherwise specified, VIN = 5V. (Continued)

LM2587·ADJ
Symbol

(Continued)

Parameters

Conditions

Typical

Min

Max

Units

1.230

1.208/1.205

1.252/1.255

V

UNIQUE DEVICE PARAMETERS (Note 5)
VREF

Output Reference
Voltage

Measured at Feedback Pin
VCOMP

=

=

1.0V

~VREF

Reference Voltage
Line Regulation

VIN

GM

Error Amp
Transconductance

ICOMP = -30 /-LA to +30 /-LA
VCOMP = 1.0V

AVOL

Error Amp
Voltage Gain

VCOMP
RCOMP

=
=

0.5Vto 1.6V
1.0 Mo. (Note 6)

18

Error Amp
Input Bias Current

VCOMP

=

1.0V

4V to 40V

1.5

mV

3.200

1.800

670

400/200

125

6.000

mmho
VIV

425/600

nA

Max

Units

15.5/16.5

rnA

COMMON DEVICE PARAMETERS for all versions (Note 5)
Symbol
Is

Parameters
Input Supply Current

Conditions
(Switch 011)
(Note 8)

= 3.0A
= 1000.

VUV

Input Supply
Undervoltage Lockout

RLOAD

fo

Oscillator Frequency

Measured at Switch Pin

fsc

VEAO

Short-Circuit
Frequency
Error Amplifier
Output Swing

=
=

1000.
1.0V

85

140

165

rnA

3.30

3.05

3.75

V

100

85/75

115/125

kHz

Measured at Switch Pin
RLOAD = 1000.
VFEEDBACK = 1.15V

25

Upper Limit
(Note 7)

2.8

Lower Limit
(Note 8)

0.25

Error Amp
Output Current
(Source or Sink)

(Note 9)

Iss

Soft Start Current

VFEED8ACK = 0.92V
VCOMP = 1.0V

D

Maximum Duty Cycle

RLOAD = 1000.
(Note 7)

IL

Switch Leakage
Current

IEAO

Min

11

ISWITCH

RLOAD
VCOMP

Typical

Switch 011

=

VSWITCH

=

VSUS

Switch Sustaining
Voltage

dV/dT

VSAT

Switch Saturation
Voltage

ISWITCH

ICL

NPNSwitch
Current Limit

2.6/2.4

5.0A

V

260/320

/-LA

11.0

8.0/7.0

17.0/19.0

/-LA

98

93/90

%
300/600

65
0.7
6.5

3-119

0.40/0.55

110/70

15

60V

V

165

1.5V/ns

=

kHz

5.0

/-LA
V

1.1/1.4

V

9.5

A

N
CJ1

CI)

.....

Electrical Characteristics
Specifications with standard type face are for TJ = 25·C, and those in bold type face apply over full Operating Temperllture
Range. Unless otherwise specified, VIN = 5V. (Continued)
COMMON DEVICE PARAMETERS (Note 4) (Continued)
Symbol
8JA
8JA
8JC
8JA
8JA
8JA
8JC

Parameters

Conditions

Typical

Thermal Resistance

T Package, Junction to Ambient (Note 10)
T Package, Junction to Ambient (Note 11)
T Package, Junction to Case

65
45
2

. S Package, Junction to Ambient (Note 12)
S Package, Junction to Ambient (Note 13)
S Package, Junction to Ambient (Note 14)
S Package, Junction to Case.

56
35
26
2

Min

,Max
",

Units
.'

':

·C/W

Note 1: Absolute Maximum Ratings Indicate limits beyond which damage to the device may occur, Operating ratings Indlcete cQndltions the device Is Intended to
be functional, but device parameter specifications may not be guaranteed under thesa conditions. For guaranteed specifications and test conditions, see the
EI~ctrical Characteristics,
Note 2: Note that switch current and output current are not Identical In a step-up regulator, Output current cannot be Internally IImHed when the LM2587 Is usad as
a Slep·up regulator. To prevent damage to the switch, the output current must be externally limited to 5A. However, output current Is Internally IIrnHed when the
LM2587 Is used as a flyback regulator (see the Application Hints section for mora Information).
Note 3: The Junction temperature of the device (TJ) Is a function of the ambient temperature (TN, the Junctlon·to·amblent thermal reslstence (9JN, and the power
dissipation of the device (Pol. A thermal shutdown w1l1 occur If the temperatura exceeds the maximum Junction temperature of the device: Po X 9JA + TA(MAX) ;,
TJ(MAX). For a safe thermal deSign, check that the maximum power diSSipated by the device Is less than: Po :<: [TJ(MAX) "7 TA(MAX)l1/9JA' When calculati~g the
maximum allowable power dlsslpetlon, derate the maximum Junction temperature-this ensures a margin of safety In the thermal design,
.
Note 4: External components such as the diode, inductor, input and output capacltors can affect swHching ragulator performance, When the LM2587 is used as
shown In Figures 2 and 3, system performance will be as specified by the system parameters.
Note 6: All room temperature limHs are 100% production tested, and all IImHs at temperature extremes are guaranteed via correlation using standard Statistic8J
Quality Control (SOC) methods,
Note s: A 1,0 Mil resistor Is connected to the compensation pin (which is the error amplijier output) to ensure accuracy In measuring AVOL.
Note 7: To measure this parameter, the feedbeck voltage is sat to a low value, depending on the output version of the device, to force the error ampllfler output
high. AdJ: VFB = 1.05V; 3.3V: VFB = 2.81V; 5.0V: VFB = 4.25V; 12V: VFB = 10,20V.
"
Note 8: To measure this parameter, the feedback voltage Is sat to a high value, depending on the output version of the device, to,force the error amplHier output
low, AdJ: VFB = t.41V; 3.3V: VFB = 3,80V; 5,OV: VFB = 5,75V; 12V: VFB = 13,BOV,
Note 9: To measure the worst·casa error amplifier output curren~ the LM2587Is tested with the feedback voltage set to Its low value (specifiad in Note 7) and at Hs
high value (specified in Note 8).
Note 10: Junction to ambient lhermal resistance (no external heat Sink) for the 5 lead TO·220 package mounted vertically, wHh Y.lnch leads In a i.ocket, or on a
PC board wHh minimum copper area,
Note 11: Junction to ambient thermal reslSlence (no external heat sink) for the 5 lead T0-220 package mounted vertically, with y. inch leads soldered to a PC
board containing approximately 4 square Inches of (1 oz.) copper area surrounding the leads.
:
Note 12: Junction to ambient thermal resistsnce for the 5 lead TO·263 mounted horizontally against a PC board area of 0,136 square Inches (the same size as the
TO·263 package) of 1 oz. (0.0014 in. thick) copper.
Note 13: Junction to ambient thermal resistence for the 5 lead TO·263 mounted horizontally against a PC board area of 0,4896 square Inches (3.6 times the area of
the TO·263 package) of 1 oz. (0,0014 in. thick) copper,
Note 14: Junction to ambient thermal reslstsnce for the 5 lead T0-263 mounted horizontally against a PC board copper area of 1,0064 square Inches (7.4 times the
area of the T0-263 package) of 1 oz. (0.0014 in. thick) copper. AddHlonal copper area will reduce thermal resistance further. See the thermal model in SwltchtIrs
Made Simp,," software.

3-120

Typical Performance Characteristics
Supply Current
vs Temperature
,.0
120

"'-

III

r--.

'C'

'SWITCH = SA

~ 100
~

z

80

!!lu

.....
60
.....
40

i

20

-

III

-

'SWITCH
'SWITCH

= 3A

ISWITCH

,.

1.24

1.238

:E 1.236
~

=2A

~

0.5

1.226

~

0.4

111

1.224

<

0.2

g

1.23

~

'I O. \ A

V

<

80

6.3

::;
~

/V

~

o
o

,..

100

1

20 40 60 80 100120 140

-40-200

E
~

0.7

~

0.6

g
6

~

0.5
0.4

a

I-"'"'

......

l- I-"'"'
l- I-

0.3

'SWITCH

=4A

~3
'SWITCH
'SWITCH

0.2

= 2A

= 1~-

1 I

0.1

16
14

tl

12

~

g

Oscillator Frequency
va Temperature
104

~

u

~

~

TEMPERATURE (c)

0.0025
..

r-.

~
~

z

0.002

700
600

il

500

~

400

g

300

~

0.001

800

92

/

II

TEMPERATURE (e)

Short Circuit Frequency
va Temperature
26

"'-

/

25.5

I'

......
j-...

200

0.0005

I

94

Error Amp Voltage
Gain va Temperature
900

...... fJ

88
-40 -20 0 20 40 60 80 100120140

1000

r-

98
96

90
-40 -20 0 20 40 60 80 100120140

1"'\

/

100

S

o

~ 0.0015

~

.......

TrwprRATURr (c)

t;
~

r.....

~
~

0.0035

.:!.

1Co

"'-

-40-20 0 20 40 60 80 100120140

'iii' 0.003
~

I"

10

Error Amp Transconductance
vs Temperature

II

102

'\

E

o

.......

TEwprRATURE (c)

Switch Transconductance
vs Temperature
~

~

20406080100120140

TEMPrRATURE (c)

ISWITCH=5~

~

o

-40 -20

18
0.8

~

20

SWITCH cURRrNT (A)

0.9

~

40

~
;;;

6

Switch Saturation
Voltage vs Temperature

~

'r-.

60

6. 1

0.5 1 1.5 2 2.5 3 3.5 4 4.5

,

i'-

80

I

6.2

...... ~

20

--

3

~

W

Feedback Pin Bias
Current vs Temperature
120

6.4
~

/

40

5

SUPPLY VOLTAGE

6.5

/

100

i

o

Current Limit
vs Temperature

120

60

V

o

TrMPrRATURr (c)

Supply Current
vs Switch Current

i13

/
J

0.1

1.22
-40 -20 0 20 40 60 80 100120140

TrwprRATURr (c)

/

1/

0.3

~

1.222

-40 -20 0 20 40 60 80 100120140

~

......

~

/

0.6

~

g

; - r-

/

0.7

~

1.234

~ 1.232

ei:

0.8

~

~ 1.228

ISWITCH = lA

o

AReference Voltage
vs Supply Voltage

Reference Voltage
vs Temperature

!,..

25

~

24

~ 24.5

- r-.

II

1/

\
I'J

II

23.5

100

o

o

-40 -20 0 20 40 60 80 100 120 140

-40-20 0 20406080100120140

TrMPrRATURr (c)

HMPERATURE (c)

23
-40 -20 0

20 40 60 80 100120 140
TEMPERATURE (e)

TLIH112316-2

3·121

•

Connection Diagrams
Bent, Staggered Leads
5-Lead TO-220 (T)
Top View
54321-

Bent, Staggered Leads
5-Lead TO-220 (T)
Side View
_

VIN
Switch
Ground
Feedback
Comp

E P i n s ,.,.3, &: 5

~PinS2&:4

TLlH/12316-4
Tl/H/12316-3

Order Number LM2587T-3.3, LM2587T-5.0,
LM2587T-12 or LM2587T-ADJ
See NS Package Number T05D
5-Lead TO-263 (S)
Top View

5-Lead TO-263 (S)
Side View

5- VIN
4- Switch
3- Ground
2- Feedback
1- Comp

TL/H/12316-6
TL/H/12316-5

Order Number LM2587S-3.3, LM25875-5.0,
LM25875-12 or LM2587S-ADJ
See NS Package Number TS5B

Block Diagram
Switch

4

INTERNAL SUPPLY
VOLTAGE

CURRENT LIMIT, .
THERMAL LIMIT, AND
UNDERVOLTAGE SHUTDOWN

5 A, 65 V
NPN
SWITCH

For FIXed Versions
= 3.4k, R2 = 2k
5V, Rl = 6.15k, R2 '" 2k
12V, Rl = B.73k, R2 = lk
For Adj. Version
Rl = Short (On), R2 = Open

3.3V, Rl

RSENSE
2 Feedback

R1

R2

Compensation

Ground
TLlH/12316-7

FIGURE 1

3-122

Test Circuits
o

Vour

+

100 p.F.
25V

"

II
II
II

+ 680 p.F.
16V

....

,,'-..;...---

L

o
A
o

CIN1-100 I'F. 25V Aluminum Elec1roly1ic
CINz-O.l I'F Ceramic .
T-22I'H. 1:1 Scholl #67141450

VIN

Switch

4

3

D-1N5820
Cour-680 I'F. 16V Aluminum Electrolytic

LM2587-XX

Feedback

Cc--O.47 p-F Ceramic
R~k

GND

TLlH/12316-6

FIGURE 2. LM2587-3.3 and LM2587-5.0

Your
VIN

0-.....- - - - - - -.......1
lN5820

+ 100 p.F.

Cour

CIN1-100 p-F. 25V Aluminum Electroly1ic

+ 680 p.F.

CINz-O.l I'F Ceramic

16V

25V
5

VIN

L

Switch

D-1N5820

o

Cour-680 p-F, 16V Aluminum Electroly1ic

A

LM2587-XX

L-15 p-H, Rence #RL·5472-5

o

Cc--O.47 p-F Ceramic

3

Rc-2k

GND

For 12V Devices: Rl
Open
For ADJ Devices: Rl
~ 5.62k, ±1%

TLlH/I2316-9

FIGURE 3. LM2587-12 and LM2587-ADJ

3·123

~
~

Short (On) and R2

~

48.75k, ±0.1% and R2

Flyback Regulator Operation
The LM2587 is ideally suited for use in the flyback regulator
topology. The flyback regulator can produce a single output
voltage, such as the one shown in Figure 4, or multiple output voltages. In Figure 4, the flyback regulator generates an
output voltage that is inside the range of the input voltage.
This feature is unique to flyback regulators and cannot be
duplicated with buck or boost regulators.

lapses, reversing the voltage polarity of the primary and secondary windings. Now rectifier D1 is forward biased and current flows through it, releasing the energy stored in the
.
transformer. This produces voltage at the output.
The output voliage is controlled by modulating the peak
switch current. This is done by feeding back a portion of the
output voltage to the error amp, which amplifies the difference between the feedback voltage and a 1.230V reference. The error amp output voltage is compared to a ramp
voltage proportional to the switch current (i.e., inductor current during the switch on time). The comparator terminates
the switch on time when the two voltages are equal, thereby
controlling the peak switch current to maintain a constant
output voltage.

The operation of a flyback regulator is as follows (refer to
Figure 4): when the switch is on, current flows through the
primary winding of the transformer, T1, storing energy in the
magnetic field of the transformer. Note that the primary and
secondary windings are out of phase, so no currentflows
through the secondary when current flows through the primary. When the switch turns off, the magnetic field colVIN
+12V
(8V-16V)

01

...--IM--....- ....--o

VOUT
+12V@1.2A

CC.I. 0.68 pF
Tl/H/12316-10

As shown in Figure 4, the LM2587 can be used as a flyback regulator by using a minimum number of external components. The switching waveforms of this
regulator are shOWn in Figure 5. Typical Performance Characteristics observed during the operation of this circuit are shown in Fl[Jure 6.

FIGURE 4. 12V Flyback Regulator Design Example

3-124

r-----------------------------------------------------------------------------,~

:s:::

Typical Performance Characteristics·

I\)

U'I

~

A

A: Switch Voltage, 10 Vld'rv
8: Switch Current, 5 Aldlv
C: Output Rectifier Current, 5 Aldiv
D: Output Ripple Voltage, 100 mVldlv
AC.Coupled

B

Horizontal: 21's/dlv

c
D
TL/H/12316-11

FIGURE 5. Switching Waveforms

Dutput

Voltage
Reaponse

Load
Current
Slap
Horizontal: 2 msldiv

FIGURE 6. VOUT Load Current Step Response

3·125

TL/H/12316-12

~ r-----------------------------------------------------~----------------------------------_,
CD

."

N

:=i

Typical Flyback Regulator Applications

Rgures 7 through 12 show six typical flyback applications,
varying from single output to triple output Each drawing
contains the part number(s) and manufacturer(s) for every
component except the transformer,' For the transformer part
numbers and manufacturers names, see the table in

Figure 13. For applications with different output voltages-requiring the LM2587-ADJ-or different output configura'tions that do not match the standard configurations, refer to
the SIMPLE SWITCHER~ Designer's Guide (AN-978) or
Swltchers Made Slmp/~ (Version 4.0) software.

Y,N
. +5V

(4-6V)

NiCh~~~

I

UPL1Al0lt.tRH _

01
'OO pF

VOUT

r--I"'-....--~~--o +3.3V@ 1.8A

2

TL/H112316-13

FIGURE 7. Single-Output Flyback Regulator

Y,N
+5V

(4-6V)

Nich~~~ .I,+100 pF

UPL lAl0lt.tRH _

01

VOUT

r--I"'-....--~~--o +5V@ 1.4A

TLlH/I2316-14

FIGURE 8. Single-Output Flyback Regulator

3-126

Typical Flyback Regulator Applications

(Continued)

Y,N
+12V
(8-16V)

NiCh~~~ I+100 p.F

UPL1El01MRH

_

01

VOUT

r---1. .- ....- - -...-------""I~_o
+

+ 12V@ lo2A

+

1200 P.FICOUTI

COUT2 I

Nichicon
UPL1VI22MRH

1200 p.F

TL/H/12316-15

FIGURE 9. Single-Output Flyback Regulator

Y,N
+5V
(4-6V)

01

VOUT

r---1..- ......t - - -...----o + 12V@ 0.3A
CIN1
Nichicon
UPL1Al01MRH

+

I I 00 p.F
_

II

II
II
II
II
II
II

VOUT

1:2.5

L...-+.---+--~~----o -12V@0.3A

+

I

330 p.F

C9UT.2

NtChlcon

UPL1V331MPH

Feedback

TL/H/12316-16

FIGURE 10. Dual-Output Flyback Regulator

3·127

to-

~

~

Typical Flyback Regulator Applications (Continued)
Y,N
+24V
(18-36V)

01

VOUT

r--t~--1~---1----~+12V@IA

.

NiCh~~~.I.+100 pf

UPL1Jl01MRH _

.

VOUT2

..........--+---...- - - 0 -12V@ lA
COUT2
Nichicon
"
-LUPL1VI82MRH

+r

1800 nf'
,rw

feedback

C0.I. 0.68 pf
TLIHII2316-17

FIGURE 11. Dual-Output Flyback Regulator

Y,N
+24V
(18-36V)

02

VOUT2

---o +12V@0.SA

r--I~----....

NiOh~~~

.I.+100 pf

UPL lJl01MRH _

VOUT3

&.--+.----....- - - 0 -12V@0.SA

Molorola Molorola

P6KE22A MUR 120

,

680

.

Pf+r~?~~~on
-LUPL1V681MRH

.':0.35

•
VOUT1
!• '----~H,....--....-----...- - - _ o +SV@2.SA

TLIH112316-1B

FIGURE 12. Triple-Output Flyback Regulator

3-128

Typical Flyback Regulator Applications (Continued)
Transformer Selection (T)
Figure 13 lists the standard transformers available for flyback regulator applications. Included in the table are the turns ralio(s)
for each transformer, as well as the output voltages, input voltage ranges, and the maximum load currents for each circuit.
Applications
Transformers
VIN

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

T1

T1

T1

T2

T3

T4

4V-6V

4V-6V

8V-16V

4V-6V

18V-36V

18V-36V

VOUTI

3.3V

5V

12V

12V

12V

5V

IOUT1 (Max)

1.8A

1.4A

1.2A

0.3A

1A

2.5A

1

1

1

0.35

Nl

2.5

0.8

VOUT2

-12V

-12V

12V

IOUT2 (Max)

0.3A

1A

0.5A

2.5

0.8

0.8

N2
VOUTS

-12V

IOUT3 (Max)

0.5A

Ns

0.8
FIGURE 13. Transformer Selection Table

Transformer
Type

Manufacturers' Part Numbers
Collcraft1

Collcraft1
Surface Mount

Pulse2
Surface Mount

Renco3

Schott4

T1.

04434·8

04435·8

PE·68411

RL·5530

67141450

T2

04337·8

04436·8

PE·68412

RL·5531

67140860

T3

04343·8

RL-5534

67140920

04344-8

-

PE-68421

T4

PE-68422

RL-5535

67140930

Note 1: Coilcra" Inc.•
1102 Silver Lake Road. Cary.IL60013
Note 2: Pulse Engineering Inc.•
12220 World Trade Drive, San Diego, CA 92128

Phone: (BOO) 322·2645
Fax: (708) 839·1469
Phone: (619) 674-8100
Fax: (619) 674-8262

Note 3: Rence Electronics Inc.,
60 Jeffryn Blvd. East, Deer Park, NY 11729

Phone: (800) 645·5828
Fax: (516) 586-5562

Note 4: Schott Corp.,
1000 Parkers Lane Road, Wayzata. MN 55391

Phone: (612)475·1173
Fax: (612) 475·1786

FIGURE 14. Transformer Manufacturer Guide

•
3-129

~

:5

Typical Flyback Regulator Applications (Continued)
Transformer Footprints
Figures 15 through 32 show the footprints of each transformer, listed in Figure N.

'T1

T2

1•
(:
1)
•
22~~

1~

~

•

••

4

(:

TL/H/12316-30

Top View

4

.;

~

8

5

TUH/12316-31

FIGURE 15. Colleraft 04434-B

Top View
FIGURE 16. Colleraft 04337-B

T3

T4
~,

•
•
•
•
•

lOe;)
854>1'~ 03
5

.~

10

lc>;g

•
•

85~~03

•

5

TL/H/12316-32

•

Top View
FIGURE 17. Colleraft 04343-B
TLlH/12316-33

Top View
FIGURE 18. Colleraft 04344-B

Tl

T2

~

2J~10

224>1'~

•

II~

11

~

•
•
•
•

•

12

4>

2J~8
&.09

221'~.

~10

~11

TUH112316-34

~

~

•
•
•
•
•

12

7

TL/H/12316-35

TOp View

Top View

FIGURE 19. Colleraft 04435-B
(Surface Mount)

FIGURE 20. Colleraft 04436-B
(Surface Mount)

3·130

Typical Flyback Regulator Applications (Continued)

T1

T2

lr;
•
•
•
•
•
•
•

22~~:JII(8
16

•
•
•
•
•
•
•
•

9

(7

16

~IJ
22~~

1

:;

•
•
•
•
•
•
•
•

•
•
•
•
•
•
•

(:

10

TLlH/12316-36

TL/H/12316-37

Top View

,

Top View

FIGURE 21. Pulse PE-68411
(Surface Mount)

FIGURE 22. Pulse PE-68412
(Surface Mount)

T3

T4

1~(4

"""C:"J (~
2.
9

1~

0

5

6

•
•
•
•

16

~

10

~

;J (;"

r;

""[:3
.' (5
10

2

TL/H/12316-36

(

•

•
•

7

9

Top View
FIGURE 23. Pulse PE-68421
(Surface Mount)

~

•
•

10

6
TLlH/12316-39

Top View
FIGURE 24. Pulse PE-68422
(Surface Mount)

T1

T2

1~

~

2-0--3 (5

22~H[~
3

•

8

4

~ :~(:

•
•

22~H[~
3·

..

'4

4

(7
•

•
4

•
g

8

TLlH/12316-40

TLlH/12316-41

Top View

Top View

FIGURE 25. Renco RL-5530

FIGURE 26. Renco RL-5531

3-131

~.---------------------------------------------------------~

CD

~

....
:&

Typical Flyback Regulator Applications (Continued)

T4

T3

::
•
•

'3~7
~9

Lp

85Jne fixed and three using the adjustable version
of the LM2587. Each drawing contains the part number(s)
and manufacturer(s) for every component. For the fixed 12V

output application, the part numbers and manufacturers'
names for the inductor are listed in a table in Figure 40. For
applications with different output voltages, refer to ,the SIMPLE SWITCHER~ Designer's Guide (AN-978) or Swltchers
Made Simple~ (Version 4.0) software.

01

+5V
(4.5-5.5V) C,Nl,
Nichicon
UPL1Al0lt.tPH

VOUT

'-....- ..

Y,N

....--o

+-~~--~~-----

I

+

-=

+

100 IlF
C,N2
0.1 I l f . I .

+12V@ !.2A

+

1200 IlFICoUTI

COUT2I'200 IlF

'Nichicon

UPL 1V 122t.tRH

5
Feedback

TL/H/12316-22

FIGURE 36.

+ 5V to + 12V Boost Regulator

Figure 37 contains a table of standard inductors, by part number and corresponding manufacturer, for the fixed output regulator
of Figure 36.
Renc03
RL-5472-5
Not. 1: Coilcraftlnc.•
1102 Sliver Lake Road. cary, IL 60013

Phone: (800) 322-2645
, Fax: (708) 639·1469

Not. 2: Pulse Engineering Inc.,
12220 World Trade Drive, San Diego, CA 92128

Phone: (619) 674-8100
Fax: (619) 674-8262

Note 3: Renco Electronics Inc..
60 Jeffryn Blvd. Easl, Deer park, NY 11729

Phone:, (800) 645·5828
Fax: (516) 586-5562

Nota 4: Schott Corp.,
,
'
1000 Parkers Lene Road, Wayzata, MN 55391

Phone: (612)47,5·1173
, Fax: (612) 475·1766

FIGURE 37. Inductor Selection Table

3-134

r---------------------------------------------------------------------------~,~

==

Typical Boost Regulator Applications (Continued)

~
(II

....

CD

D
VIN
+12V
(a-16V) <;Nl +
Nichicon
UPL IEIOIMPH

I

VOUT

~.---~+_~~----~~--~+24V@IA

+

laO jJF
<;N2
0.1 jJF.I.

I

1000 jJF
36.9k

COUT1
Nichicon
UPLtVI02MRH

2k

TL/H/12316-23

FIGURE 38.

+ 12V to + 24V Boost Regulator
D

VIN
+24V
(la-2av) <;NI +
Nichicon
UPL I H560MAH

I

VOUT

"-...- .....M--...- - -..- - O

+36V@2A

+

56 jJF
<;N2
0.1 jJF.I.

I

1200 jJF
56.3k

CoUT1
Nichicon
UPLt H 122MRH

TLlH/12316-24

,FIGURE 39.

+ 24V to + 36V Boost Regulator
D

VIN
+24V
(18-36V) <;Nl +
Nichicon
UPL I H560MPH

I

VOUT
~",--""*"-",----_,,,---o +48V@ t.5A

+

56 jJF
<;N2
0.1 jJF.I.

I

1200jJF

COUT1

75.7k

UPL 1J122MRH

Nichicon

TLlH/12316-25

FIGURE 40.

+ 24V to + 48V Boost Regulator

"The LM2587 will require a heat sink in these applications. The size of the heat sink will depend on the maximum ambient temperature. To calculate the thermal
resistance of the IC and the size of the heat sink needed, see the "Heat Sink/Thermal Considerations" section in the Application Hints.

3-135

•

~ r-~~------~--~~----~~~----~~~----~------~------------------------~

~
~

Application Hints
lN5822
+5V
Inputo--....- - - -.........r

:,100}'F

'-....- ..+-~~--~~--o

+12V@1.2A
Output

' '
I_ ; 0.1, }'F.I,

-

,

=r'5~:....._",",,",.,

2k

0.2}'F . I ,
TLlH/12316-26

FIGURE 41. Boost Regulator
PROGRAMMING OUTPUT VOLTAGE
(SELECTING Rl AND R2)

" '
Referring to the adjustable regulator in Figure 41, the output

voltage is programmed by the resistors Rl and R2 by the
,
"
following formula:

Your = VREF(1 + Rl/R2)
whereVREF = 1.23V
Resistors Rl and R2 divide the~utput voltag~ down so that
it can be compared with the 1.23Y internal reference. With'
R2 between 1k and 5k, R'l'is:',
'
Rl = R2(VOurIVREF -1)
wh~reVREF = 1.23V',
For best temperature. coefficient and stability with time, use
1 % metal film resistors.
", '

put with an external current limit circuit The external limit
, should be set to the maximum switch current of the device,
which is 5A.
In a flyback regulator application (Figure 42), using the stan"dard transformers, the LM2587 will survive a short circuit to
the 'main 'output. When the output voltage drops to 80% of
its nominal value, the frequency will drop to 25 kHz. With a
lower frequency, off times 'are larger. With the longer off
times, the ,transformer can release all of its stored energy
before the switch turns back on. Hence, the switch turns on
" initially with zero current at its collector. In this condition, the
switch current limit will limit the peak current, saving the
device.

'.' ":'

SHORT CIRCUIT CONDITION

FLYBACK REGULATOR INPUT CAPACITORS

Due to the inherent nature of boost regulators, when the
output is shorted (see Figure 41), current flows directly from
the input, through the inductor and the diode, to the output,
bypassing the switch. The current limit 'of the'switch does:
not limit the output current for the entire circuit. To protect
the load and prevent damage to the switch, the current must
be externally limited, either by the input supply or at the out-

A flyback

regulator draws discontinuous pulses of current
from the input supply. Therefore, there are two input capacitors needed in a flyback regulator; one for energy storage
and one for filtering (see Figure 42). Both are required due
to the inherent operation of a flyback regulator. To keep a
stable or constant voltage supply to the LM2587, a stor-

loon 0,.01 }'F

IN5822
+VOUT

~~-I~-t---~~--o+5V@1A

I

+
1000 }'F

-VOUT

' - - t 4 I - - t - - -.....-- Designer's Guide (AN-978).

Boost:
D = Your + VF - VIN ::: Your - VIN
Your + VF - VSAr
Your
Flyback:
D=

Your
N(V'N - VSAr)

+ VF
+ Vour + VF

where VF is the forward biased voltage of the diode and is
typically O.5V for Schottky diodes and O.8V for fast recovery
diodes. VSAr is the switch saturation voltage and can be
found in the Characteristic Curves.
When no heat sink is used, the junction temperature rise is:

HEAT SINK/THERMAL CONSIDERATIONS
In many cases, no heat sink is required to keep the LM2587
junction temperature within the allowed operating range. For
each application, to determine whether or not a heat sink
will be required, the following must be identified:

ATJ = PD X 8JA.
Adding the junction temperature rise to the maximum ambient temperature gives the actual operating junction temperature: '
,

1) Maxil!lum ambient temperature (in the application).

2) Maximum regulator power disSipation (in the application).
3) Maximum allowed junction temperature (125°C for the
LM2587). For 'a safe, conservative design, a temperature
approximately 15°C cooler than the maximum junction temperature should be selected (11 COC).
4) LM2587 package thermal resistances 8JA and 8JC (given
in the Electrical Characteristics).

TJ = ATJ + TA·
If the operating junction temperature exceeds the maximum
junction temperatue in item 3 above, then a heat. sink is
required. When using a heat sink, the junction temperature
rise can be determined by the following:

Total power dissipated (PD) by the LM2587 can be estimated as follows:

ATJ = PD X (8JC + 81nterface + 8HeatSlniJ
Again, the operating junction temperature will be:

Boost:

TJ = ATJ

P = 0 15!l.
D·

x(

ILOAD
1-D

)2 X D +

ILOAD
X Ox V
50X(1-D), IN

Flyback:
P = 0 15!l.
D·

x ( N X IILOAD)2 X D
1-D

+ ~O:~~L~~ x

D

Your
N(VIN) + Your

x VIN

3-138

+ TA

~----------------------------------------------------------------------------~

Application Hints (Continued)

European Magnetic Vendor
Contacts

As before, if the maximum junction temperature is exceeded"a larger heat sink is required (one that has a lower thermal resistance).
Included in the Switchers Made Simp/e@ (Version 4.0) design software is a more precise (non-linear) thermal model
that can be used to determine junction temperature with
different input-output parameters or different component
values. It can also calculate the heat sink thermal resistance
required to maintain the regulator junction temperature below the maximum operating temperature. .
.

r
3:

N
U1

Q)

.....

Please contact the following addresses for details of local
distributors or representatives:

Coilcraft
21 Napier Place
Wardpark North
Cumbernauld, Scotland G68 Oll
Phone: + 44 1236 730 595
Fax: +441236730627

To further simplify the f/yback regulator design procedure,
National Semiconductor is making available computer design software and an application note to be used with the
LM2587 SIMPLE SWITCHER@ line of switching regulators.
Swltchers Made Simp/e@ (Version 4.0) software is available on a (3~H) diskette for IBM compatable computers
from a National Semiconductor sales office in your area or
the National Semiconductor Customer Response Center
(1-800-272-9959). The SIMPLE SWITCHER@ Designer's
Guide (AN-978) is also available from the Customer Response Center.

Pulse Engineering
Dunmore Road
Tuam
Co. Galway, Ireland
Phone: +3539324107
Fax: + 353 93 24 459

•
3-139

9-

r-------------------------------------------------------------------------------------,

~d

:!5 pNational Semiconductor
LM3001 Primary-Side PWM Driver
General Description
The LM3001 is a primary-side PWM driver that provides all
the system start-up, switch control, and protection functions
needed on the primary side of an isolated offline converter.
It is primarily designed for pulse communication between
the primary and secondary controllers.
The LM3001 combined with the LM3101 secondary-side
controller forms an offline converter chip set which allows
electrical isolation between the high-power primary-side
switch and the precision secondary-side control. Secondary-to-primary communication is achieved using pulse communication, via a small pulse transformer.
The primary-side driver includes a 2.5A totem-pole output
switch with rise and fall times of less than 20 ns. This allows
the LM3001 to operate at frequencies from below 50 kHz to
beyond 1 MHz. The maximum duty cycle is programmable
for each application. There are two levels of current limit
within the LM3001, both of which are ground-referenced.
One is a cycle-by-cycle current limit which activates at
0.38V. The other is a secondary current limit that activates
at 0.6V. This current limit shuts down the LM3001 for a programmable deadtime, which is set with an extemal capaci-

tor. Although the LM3001 is optimized for pulse feedback
communication, it can also operate with conventional opta.
coupler feedback.

Features
•
•
•
•
•
•

2.5A peak high speed output driver
Low start-up current (typ. 190 p.A)
Dual-level current limit with programmable lockout time
Duty cycle clamp
Operation beyond 1 MHz
Soft-Start, undervoltage and overvoltage lockout with
hystereSiS
• Low output saturation voltage: Maximum of 1.5V at
400 mA sink current
• Active low output when in Undervoltage Lockout

Typical Applications
•
•
•
•

Isolated offline switching power supplies
Isolated Power DC/DC converters
Flyback converter
Forward converter

Block Diagram
RT

Cr

PIN

Vs

OVTH

12

10

PyS

14

RoL 2 0-+-.......--,

NC' 13

CSD

5 []o-----4......--1

11

6

GND

CUM

'Internal Test Point Leave Open.

3-140

TUH/11435-1

Operating Ratings

Absolute Maltimum Ratings (Note 1)
If Military/Aerospace specified devices are required,
. please contact· the National Semiconductor Sales
Office/Distributors for availability and specifications.
Supply Voltage (Vs, Pvs)
Vs-Pvs
Pulse Interface Input Current (lpIN)
ESD (Note 2)

8.5V ,;;: Vs ,;;: 20V

Supply Voltages

8.5V ,;;: PVS ,;;: 20V
Junction Temperature Range

-40'C ,;;: TJ ,;;:

20V
±O.SV
±4mA

+ 125'C

2kV

Electrical Characteristics

Specifications with standard type face are for TJ = 25'C, and those in bold type
face apply over full Operating Temperature Range. Unless otherwise specified, Vs = Pvs = 15V, CL = 1 nF,
RL = 10 kO, RT = 5.76 kO, CT = 200 pF (Fo = 500 kHz).
Parameter

Symbol

Conditions

Min

Typ

425

500

Max

Units

OSCILLATOR SECTION
Fo

Oscillator Frequency
(NoteS)

RT

=

5.76 kO, CT

=

200 pF

RT

=

5.29 kO, CT

=

100 pF

0.85

1.0

Peak-to-Peak Voltage (Pin 14)

ICT(SINK)

Timing Capacitor Sink Current

VCT

t..Folt..Vs

Line Regulation

9.BV ,;;: Vs ,;;: 20V

=

S.5V

1.15

1.20

0.80
VPP

575

600

400

kHz
MHz

1.0

V

S.O

mA

0.02

0.1

%IV

PULSE INTERFACE SECTION (Note 4)
IpIN(SINK)
IpIN(SQURCE)

Minimum Pulse Input
Sink Current Threshold

0.16

Minimum Pulse Input
Source Current Threshold

0.25

0.25

0.35
0.40

0.50

tpw

Minimum Pulse Width

15

SO

tdON

Pulse Rise
Delay-to-Output Time

28

42

Pulse Fall
Delay-to-Output Time

26

tdOFF

49
42

47

mA
mA
ns
ns
ns

PULSE-WIDTH MODULATOR SECTION
DMIN

S

Minimum Duty Cycle

4.75

5
DMAX

Maximum Duty Cycle

ROL

=

26.1 kO

78

85

91

97
ROL

=

22.6kO

42

50

58

60

%
%
%

CURRENT LIMIT SECTION
VCL1
VCL2
t..IdCL

0.S2

Pulse-by-Pulse Current
Limit Threshqld Voltage

0.28

Secondary Current Limit
Threshold Voltage

0.50

PUlse-by-Pulse Current
Limit Delay Time

0.55
200 mV overdrive

0.S8

0.44

0.46
0.60

0.67

0.70
50

70

85

S-141

V
V
ns

•

Electrical Characteristics Specifications with standard type face are for TJ = 25"C, and those in bold tvPe
face apply over full Operating Temperature Range. Unless otherwise specified, Vs = Pvs = 15V, CL = 1 nF,
RL = 10 kO, Rr. = 5.76 kO, CT = 200 pF (FO = 500 kHz). (Continued)
Symbol

I

Parameter

I

Conditions

I

Min

I

Typ

I

Max

I

Units

CURRENT LIMIT SECTION (Continued)

18

Current Limit Sense
Input Bias Current

ICSD

Secondary Current Limit
Restart Capacitor
Charge Current (Pin 5)

aVSD

-0.35
(Note 5)

58

65

42
1.30

Secondary Current Limit
Restart Hysteresis

p.A
70

84
1.40

1.55

1.85

1.20

p.A

V

OUTPUT SECTION
VOL

Output Low
Saturation Voltage

ISINK

tR

Output High
Saturation Voltage

Rise Time

1.3

400 mA

1.5

1.8
ISINK

VOH

=
=

20mA

1.0

1.2

ISOURCE

=

400 mA

2.0

2.4

ISOURCE

=

20 mA

1.6

1.9

11

22

CL

=

1000pF

25
tF

Fall Time

CL

=

8

1000pF

18

20

V
V
V
V
ns
ns

OVERVOLTAGE SHUTDOWN SECTION
VOVTH
VOVH

3.05

Overvoltage Shutdown
Comparator Threshold Voltage

2.80

Overvoltage Shutdown
Comparator Hysteresis

0.08

0.10

3.30

3.55

3.80
0.19

0.25

0.31

V
V

UNDERVOLTAGE LOCKOUT SECTION
VULTH

11.0

Turn-On Threshold Voltage

11.8

10.0
VULH

2.80

Undervoltage Lockout
Hysteresis

12.6

13.8
3.20

2.40

3.60

3.80

V
V

SOFT-START/DELAY SECTION
Iss

Soft-Start Current

(Note 5)

61

66

57
VSS

2.10

Soft-Start Threshold Voltage

2.30

1.90
VSI

Initial Soft-Start Voltage

71

75
2.60

2.80

(Note 6)

0.7

100% Duty Cycle and No Load
(Note 7)

21

p.A
V
V

SUPPLY AND START-UP SECTION
Is
IQ

Supply Current
Quiescent Current

Vs

=

9V (Note 7)

28

32
190

250

300

3-142

mA

p.A

Nole 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings Indicate conditions for which the device is
Intended to be functional, but do nol guarantee specific performance limits. For guaranteed specifications and lest conditions, see the Electrical Characteristics.
Note 2: Pins 6 and 10, the Current Llmillnput and the Overvoltage Threshold pins respectively, have an ESD rating of 1.8 kV.
Note 3: The oscillator frequency is set by RT and CT according to the equation:
1
= T = CT· (1.5 (RT)

Fa

+

728fi).

Nole 4: The internal oscillator will synchronize to the frequency of the feedback pulse.
Nole 5: These currents are set by RT according to the equation:
1= 1.4V/(2. RT).
The timing resistor during these tests is sel at 10.6 kfi.
Nole 6: The initial Soft-Start voltage is the voltage at the beginning of the start-up or re-start cycle.
Note 7: Total supply current drawn by Vs and

Pvs supply pins.

Typical Performance Characteristics
Supply Current
1
«

Vs = Pvs

23

= 15V

.s
~

z

u

i

.......

/

21

1100

210

!,ooo

200

z

r---

/'

~
~

:0

220

":i'

.3
22

~
~

-

190

:0

u

~

lBO

iii

20

0

25

50

75

1.5

350

~

~
g
........

~ 300

z

I'-..

r---

iii

0

25

50

75

-50 -25

100 125

250

~

.........

1.3

...............
1.2

_

1
1.
1.0

~

0.9

-50 -25

0

25

50

75

100 125

25

50

75

100 125

Output High Saturation
Voltage (Sourcing)
2.4

-

2.3

E

.400 mA

i

.......

z

~

........

r-

20f mA

~

2.2

I,

r-..

2.1
2.0

.......

1.9
I.B

r--...

........

I-

"-

1.7

........

200 mA

1.6

-

400 mA

I.........

1.5

........

1.4

D.B

200

0

JUNCT10N TEMPERATURE (oc)

Output Low Saturation
Voltage (Sinking)
1.4

pF

SOD

JUNCTION TENPERATURE (Oc)

450

= 200

CT

= 5.6 kn

400
-50 -25

500

" 'r--....

600

;:;
~

Current Sense Comparator
Input Bias Current

i

~

"-

160

JUNCT10N TEMPERATURE (Oc)

0400

RT

~ 700

f'.,

170

100 125

---

Cy = 100 pF

900

~ 800

.........

150
-50 -25

~

-

~

is

:0

:;;

19

":i'

Oscillator Frequency

Startup Supply Current

24

-50 -25

0

25

50

75

100 125

-50 -25

JUNCTION TENPERATURE (OC)

JUNCTION TEMPERATURE (Oc)

0

25

50

75

100 125

JUNCTION TEMPERATURE (Oc)

TLlH/11435-2

Overvoltage Comparator
Input Bias Current

Rise Time vs
Load Capacitance

0.090

":i'

.3

~
G
~

~

FaliTimevs
Load Capacitance
120

120

0.OB5 1\
"\
O.OBO

100

~

0.070
0.065
0.060
-50 -25

/"

.5

"' :--...
0

25

""

""- "\.
50

75

'"iE

60
40
20

!-.

100 125

JUNCTION TEMPERATURE (Oc)

o
o

TJ

= 2510 C

/""

-;: BO

\

0.075

TJ

/

]:

BO

I'

~

""~

/

60
40

/
o

10

15

20

V

/

20

LOAD CAPACITANCE (nF)

./'

= 1250C

100

o

J
5

10

15

20

LOAD CAPACITANCE (nF)

TL/H/11435-3

3-143

Connection. Diagram and Ordering Information
For DIP Package
Order Number LM3001N
See NS Package Number N14A

14-Lead Package
Rr .l
RoL 1
PIN 1.
css .i
CSD .2.
CUM ..2.
Pvs

0

'-./

~Cr

~NC·

For Surface Mount Package
Order Number LM3001M
See NS Package Number M14B

~Vs

~GND
~ oVrH

Consult your local National Semiconductor Sales
Office for Availability of this Device
In the Surface-Mount Package

~PGND
r§ Your

2

TLlH/11435-4

'00 not connect to this pin.

Top View

Pin-by-Pin Description
Pin No.
Pin 1

Symbol
RT

Description

Function
Timing Resisior

A resistor from this pin to ground and a capacitor from pin 14 to ground
, programs the oscillator frequency by'the following formula:
1/Fo = T = CT e (1.5 e RT

Pin2

ROL

Duty Cycle Limit

+ 728)

Is, F,OI

The duty cycle limit is set by connecting a resistor, from this pin to ground,
using the following formula:
ROL = RTI(DMAX e 1.71V)

+ 3.11V]

[0, V]

for'Ri ~ 5 kO and 3.37V ,;; ROL /RT ,;; 4.56. An internal current source
develops a voltage across this resistor which is compared to the oscillator
ramp voltage (see the block diagram and the Oscillator section of the
Functional Decriptions).
PinS

PIN

Pulse Input

Input for feedback pulses in pulse communication operating mode. The
peak current of these pulses can range from 0.3 mA to 4 mAo

Pin4

Css

Soft-Start Capacitor
and Delay

A capacitor, connected from this pin to ground, programs the Soft-Start
time delay. The Soft-Start time delay is made up of two parts: atime delay
during which the output is turned off (zero duty cycle), and a time period in
which the duty cycle goes from zero to its maximum value, set by the Duty
Cycle Limit.(see pin 2, description). The time delay equation is:
toss= 2 eCsseRT

"

Is, F,OI

The rate at which the duty cycle ramps up from zero to its maximum limit
follows the equation:
D/t = 0.58/(Css e RT)
Pin 5

CSO

Shutdown Delay Capacitor

A capacitor, conneCted from this pin to ground. provides a time delay,
before the device can restart from a second level current limit shutdown
,(see pin 6 description). This action is governed by the formula:
tso= 2eCsoeRT

Pin 6

Is, F,OI

Is, F,OI

CLiM

Current Limit Input

This provides a pulse·by-pulse current limit, with a voltage threshold of
0.S8V. If that is exceeded, a second level current limit, with a 0.60V
threshold voltage shuts down the chip completely for a programmed time
period (see pin 5 description).

Pin 7

Pvs

Driver Supply Voltage

Supply of the output driver.

Pin8

VOUT

Driver Output

Driver output. It can drive an external power MOSFET (in 11 ns typically)
with peak source or sink currents of up to 2.5A.

Pin 9

PGNO

Power Ground

Power ground.

3·144

r-

3:
w

Pin-by-Pin Description (Continued)
PinNa.

Symbol

Pin 10

OVTH

o

Function

o
.....

Description

Overvoltage Threshold

This monitors the supply voltage through an external resistor divider. It shuts
down the output driver if the threshold voltage is exceeded. The threshold
voltage is 3.3V typical.

Pin 11

GND

Ground

Signal ground.

Pin 12

Vs

Supply Voltage

Supply voltage of the control circuit.

Pin 13

NC

No Connect

Internal Test Point. Leave Open.

Pin 14

CT

Timing Capacitor

Inserting a capacitor from this pin to ground and a resistor from pin 1 to ground
programs the oscillator frequency by the following formula:

liFo = T = CT. (1.5 • RT

+ 728)

[s, F,OI

LM3001 Test Circuit
22.5 kll

5.29 kll

V 24. kll'.
V 20011

~'

SW2

2000 pI
___ SW5

100 pF

1 RT

,~ i~'"'"
~.
e.~
~~
15 VDci

l10

I'/~

6

CSD

OVTH
10

7 PVS

lOll

y82

Css

PGND

20011

-.l.:

SW1-'~

Vs 12
GND 11

CLiM

0

14

1.L

3 PIN
4

18 kll

Cr

2 RoL

500~~z

V2 SW

LM3001

VOUT

;+;0.1 I'F

9

•.•.L l+,

kll

15 VDC

n.

19.1kll

~

••

0.1 I'F~10 I'F

~15PI

V
4.711

10 Vs

11000 pF

TL/H/I143S-S

Initial Conditions:

SW1-Connects pin 14 10 100 pF capacitor.
SW2-Open.
SW3-Connects 20011 to ground.
SW4-Connects pin 5 to 100 pF capacitor.

SWS-Connects pin 4 to 2000 pF capacitor.

Bench Test Procedure*
'The LM3001 specifications are measured using automated
test equipment. This circuit is provided for the customer's
convenience when checking parameters. Due to possible
variations in testing conditions, the measured values from
these testing procedures may not match those of the facto-

1.55 VDC. Switch pin 14 from the 100 pF timing capacitor,
CT, to the 22.5 kO resistor. Measure the voltage across the
resistor. It should be about 2.5V. Switch pin 14 back to the
100 pF capacitor.
Step 2: Measure the peak-to-peak voltage at pin 14 (across
the timing capacitor CT). It should be approximately 1.0V.
Observe the waveform across the capacitor. The waveform
frequency should measure approximately 1 MHz, and the
shape of the waveform should be sawtooth.
Step 3: Measure the voltage at pin 2 (across the 24k resistor ROL). It should be approximately 2.65V.

ry.
Required Equipment: Voltmeter, Storage Oscilloscope,
Function Generator, Power Supply. Apply 15V between Pvs
and PGND. Then proceed with the following steps.
OSCILLATOR SECTION
Step 1: Measure the voltage at pin 1, across the 5.29 kO
timing resistor RT. It should range between 1.35 VDC and

3-145

.,...
o

o('I)

Bench Test Procedure*

==

SWITCHING OUTPUT SECTION

SHUTDOWN DELAYISOFT-START CONTROL SECTION

Step 4: Observe the waveform at pin 8 (VOUT). It should be
a pulse-width modulated waveform with a frequency of
about 1 MHz, the same frequency as the waveform of CT
(Step 2). Measure the duty cycle of the VOUT waveform. It
should be approximately 35%.

Step 12: Measure the shutdown time delay between when
the V2 voltage source is removed from the 200n resistor
and when the output starts up again. It should equal the
product of the following equation:

....I

(Continued)

TSO = 2· Cso 0 RT.
With a 100 pF shutdown delay capacitor (Cso) at pin 5 and
a 5.29 kn timing resistor (RT) at pin 1, the shutdown time
deiay should be approximately 1.3 flos.

Step 5: Measure the rise and fall times of the VOUT signal at
pin 8. They each should be typically 12 ns. Measure the
saturation voltage levels. The low saturation voltage level
should measure about 1.5V, arid the high .saturation voltage
level should be about 13.5V (15V-UjV).

Step 13: Switch SW4 from the shutdown delay capacitor to
the 18 kn resistor at pin 5. Measure the voltage across the
18 kn. It should measure about 2.0V. Return the switch to
the 100 pF capacitor.

Step 6: Close SW2 to apply VI, a 500 kHz 2VPK-to.PK
square wave, to pin 3 (the PIN input) through the 500n,
100 pF RC filter. The waveform at the VOUT output should
be a 500 kHz square wave. Measure the delay time from the
rising edge of the input signal to the rising edge of the output waveform. The delay time should measure about 20 ns.
The delay time between the falling edges of each signal
should be the same.

Step 14: Switch SW5 from the 2000 pF Soft-Start delay
capacitor to the 27 kn resistor at pin 4. Measure the voltage
across the 27 kn resistor. It should measure about 3.0V.
Return the switch to the 2000 pF capacitor. Turn off the
supply voltage. End of test.
For further information on the IC operation, see the Functional Section Descriptions in the Application Section.

Step 7: Open SW2 to disconnect the pulse waveform from
pin 3. Observe the VOUT waveform. It should also be off.
Turn off the supply voltage.

Functional Description

INTERNAL SUPPLY OPERATIONS
Step 8: Slowly turn on the supply voltage back up toward
15V, while observing the VOUT pin. Note the supply voltage
when the VOUT PWM waveform starts up-Le., when the
device turns on. The supply voltage should be about 11.8V.
Measure the current into the supply pins Pvs and Vs (pins 7
and 12 respectively). The Pvs supply current should range
from 13 mA to 23 mA, while the Vs supply current is about
12 mA. Decrease the supply voltage until the output shuts
down. The supply voltage should read approximately 8.6V.
Reset the supply voltage to 15V so that the device is back
on.

OSCILLATOR SECTION
The LM3001 oscillator can set the operating frequency from
50 kHz to over 1 MHz. The oscillator requires an external
resistor and capacitor to determine the operating frequency-the equation is:

liFo = T = CT • (1.5 • RT + 728).
With a 6 kn timing resistor and a 200 pF timing capacitor,
the formula calculates the operating frequency at 514 kHz.
At higher operating frequencies, the oscillator frequency deviates from this equation due to switching delays. Figure 1
shows the oscillator frequency for different combinations of
timing capacitors and resistors.

Step 9: Increase the supply voltage until the VOUT signal
turns off. The voltage at the Overvoltage Threshold pin (pin
10) should be between 3.0V and 3.6V. The supply voltage
should be approximately 20V. Return the supply voltage to
15V.

1000

\
B

800
C
N

CURRENT LIMIT SECTION

~

Step 10: Connect V2 (an adjustable voltage source set to
OV) through SW3 to the 200n resistor connected to pin 6,
the Current Limit Input. Raise the voltage from OV to 0.45V
into the 200n resistor while monitoring the VOUT signal.
Output driver VOUT should show a PWM waveform with a
minimum duty cycle of approximately 3%. The minimum
duty cycle waveform should start when tlie voltage source
reaches approximately 0.38V.

[

~

600
E

400

~

1\
\

\

1\

200

I'

CT(pF)
A 10
B 20
C 47
o 100
E 200
F 470
G 1000

,

-'" I'

o
1

Step 11: Increase the voltage at the source until the output
turns off completely. The voltage should measure approximately 0.6V. The output should remain completely off until
the shutdown time delay has expired and the voltage is removed.

10

100

1000

TLlH111435-6

FIGURE 1. Frequency vs RT and CT Graph

3-146

r-------------------------------------------------------------------------------------, r-

s::

Functional Description (Continued)

(,)

o

o
....

PWM
Flip-Flop

lockout
Camp

Pulse-byPulse Current
Camp

TL/H/11435-7

FIGURE 2. PWM Block Diagram
PULSE-WIDTH MODULATOR SECTION
The pulse-width modulator (PWM) section consists of the
PWM comparator and the PWM flip-flop (see Figure 2). During normal pulse feedback operation, the pulse interface circuit will set or reset the PWM flip-flop, which in turn, will
latch on or off the output driver (see the timing diagrams in
the pulse interface section of the Application Hints section).
During start-up, or opto-coupler feedback operation, the oscillator will set the PWM latch, and the PWM comparator will
reset the latch.

duty cycle of the regulator circuit. The maximum duty cycle
can be calculated using the following equation:
DMAX

=

[ROL/(1.71

0

RT)l - 1.82

For instance, if the ROL input had a 23.3 k!l resistor connected to it, and the timing resistor was 6 k!l, the maximum
duty cycle would be approximately 45%.
Conversely, if a known maximum duty cycle was desired,
the calculation .for ROL would be:
ROL = RT [(1.71

PWM COMPARATOR CIRCUIT
The PWM Comparator is fed by several different inputs. The
inverting inputs are the duty cycle limit input (Rm), and the
Soft-Start (Css). The non-inverting input comes from the
external timing capacitor, CT. The sawtooth waveform at CT
is adjusted up one' base-emitter junction voltage, and applied to the non-inverting input. Hence, this input is a sawtooth waveform oscillating between 2.32V to 3.3V. The level-shifted oscillator ramp voltage is compared to the two
inverting inputs. The lowest input determines the PWM comparator output and thus the state of PWM flip-flop. The
PWM flip-flop controls the output driver, driving it on or off.

0

DMAxl

+ 3.111

For example, a 30% duty cycle (and a 6 k!l timing resistor)·
would result in a ROL of 21-.7 k!l.
To disable the duty cycle limit, the voltage at the ROL pin
must be greater than 3.3V. The graph in Figure 3 shows the
maximum duty cycle for a range of ROL resistor values.
100

g
....
-'
u
>u

DUTY CYCLE LIMIT

Rt (kn)

A

8

C

A 6
8 12
C 24

I

I
II

I

80

&I

60

...>-

Duty cycle limit can be used for either pulse or opto-coupler
feedback systems. A current mirror delivers one-half of the
timing resistor current to the ROL input. Inserting a resistor
from this pin to ground will produce a voltage, that is compared to the oscillator ramp voltage. The result limits the

I

I
1

=0

C

40

20
10

100

TUH/11435-8

FIGURE 3. Maximum Duty Cycle vs ROL
3-147

~

!

~

r------------------------------------------------------------------------------------------,
Functional Description (Continued)
SOFT-START
The Soft-Start function limits the duty cycle at start-up. At
start-up, a current source charges the Soft-Start capacitor
with a current that is half the current that flows through the
timing resistor (see the PWM block diagram). Before the
Soft-Start voltage reaches 2.32V, the low voltage level of
the timing capacitor peak-to-peak voltage, the PWM comparator delivers a high signal to the reset input of the PWM
flip-flop (see the timing diagram in Figure 4). This forces it
and the output driver off. At the point where the Soft-Start
voltage reaches 2.32V, the PWM comparator changes its
output state, turning on the PWM flip-flop and the output
driver. However, the Soft-Start circuit still limits the duty cycle. The duty cycle will progressively get longer with each
cycle, until either the duty cycle limit is reached or the feedback signal takes control of the PWM circuil.

PULSE INTERFACE SECTION
Figure 5 shows the block diagram of the pulse interface
section. The pulse interface circuit will take AC coupled
feedback pulse signals and set or reset the PWM flip-flop,
depending upon whether the pulse signal is positive or negative-a positive pulse will set the flip-flop, a negative one
will reset il. In turn, the flip-flop will turn on or off the output
driver. Hence, the feedback signal through the pulse interface circuit will control the LM3001 operating frequency and
duty cycle (in steady-state operation).
The AC-coupled current pulses can be as low as 0.3 rnA
(guaranteed), and as narrow as 15 ns (typical). The minimum time between pulses is approximately 10 ns. The maximum current pulse that the feedback pin can handle is
4 rnA. Feedback signals beyond 4 rnA can either cause improper operation or catastrophic failure of the LM3001. The
time delay between when the feedback pulse signal is received and when the output gate drive signal changes state
is 28 ns typically.
During start-up of an isolated offline converter, once a positive AC-coupled feedback Signal is applied to the pulse interface circuit, the circuit will synchronize the internal oscillator to the feedback signal frequency. The same signal will
also turn on the output driver. If, after the pulse feedback
was established and for any reason it was terminated, the
output would deliver the Signal that was set by the last pulse
sent by the feedback circuil. For example, if the output driver was set high, and the LM3001 did not receive any further
feedback pulses, then the output driver would stay turned
on. Either the current limit circuit or the duty cycle limit circuit would shut down the output under these circumstances.

The formula for the Soft-Star! time delay (the time the voltage at the Soft-Start pin reaches the 2.32V level) is:
to = 2 e Css eRr.
After this time delay, the Soft-Start circuit limits the rise of
the duty cycle. The amount the duty cycle rises to, and the
time spent getting there, both depend on whether the duty
cycle limit voltage level (VROU or the current limit voltage
level (VCLlM) assumes control of the duty cycle first during
start-up. Assuming the duty cycle limit voltage level is the
Soft-Start voltage threshold during start-up, then the speed
at which the duty cycle achieves its maximum level is:
DMAX/tSS = 0.71 /(Css eRr).
And if the rise time is known, then the Soft-Start capacitor
can be calculated as:

OUTPUT DRIVER SECTION
The Output Driver is a totem pole output stage that can
supply or sink 2.5A peak currents at speeds less than 20 ns.
That is enough current to charge or discharge thousands of
picofarads of load capacitance, which is present when driving Power MOSFETs. The saturation voltages of the internal
power transistors are typically 1.5V from the rails when
sourcing or sinking 400 rnA.

Css = (0.71 elss)/(DMAX eRr).
The Soft-Start circuit has a clamp voltage of 4.2V. Leaving
the pin open will disable the Soft-Start function.

Ramp

Osc

Soft-Start
Voltage

':~~~~~~:::lZ~:z~fi=1i-

2.3_2V

PWM Comp
Output

I r ln
H

1"1

A demonstration of the drive capability of this output stage
is shown in Rgure 6. The drawings show the output stage
driving different values of load capacitance during .pulse
feedback operation. As shown, with a load capacitor value
of 1,000 pF, the rise time is typically 11 ns, and the fall time
is typically 8 ns. The supply voltage in all cases was 15V.

n I---l'
rl

1-1

1r--1nt---1nr-1n h

PWMrFD
Output

TUH/11435-9

FIGURE 4. Soft-Start Timing Diagram
15 ns

~I""

Output
Driver

PIN
3

PWM
Comp

15 ns
TL/H/11435-10

FIGURE 5. Pulae Interface Block Diagram

3-148

.-

Functional Description

iii:
Co)

(Continued)

g

OUTPUT VOLTAGE
100 mV

A

/\ -,.... rt(

0

100 mV

1 nF

15V

V

10V

5V

10

\

15V

\

a

/

100 mV

-5 nF

t-- t--

10V

'\
20

\

A a

"

B a

a

100 mV

ll'l

II

.....

OUTPUT VOLTAGE

20 nF

5V

B a

r-....
10

a

20

100

200

TIME (ns)

~~
300

400

500

TIME (ns)
TL/H/11435-11
A: Pulse Feedback Vollage, 100 mVldiv. (AC Coupled)
B: Oulpul Vollage, 5V1div.

FIGURE 6. Output Voltage Rise and Fall Times
CURRENT LIMIT SECTION
There are two circuits in the LM3001 that limit the peak
primary current. One executes pulse-by-pulse current limiting, and the other is a total shutdown current limit, which
shuts down the output driver (and thus, the Power MOSFET) for a programmable amount of time. Both current limit
circuits monitor the peak primary current by comparing the
voltage on the CUM input (pin 6) against two different voltage thresholds.
The voltage threshold for the pulse-by-pulse current limit is
0.38V (typical). When that threshold voltage is reached, the
pulse-by-pulse current comparator turns off the present
Power MOSFET gate drive by sending a high signal to the
clear input of the PWM flip-flop. The current limit circuit will
activate again during the next cycle, if the 0.38V threshold is
exceeded again.

The shutdown delay is controlled by an external capacitor
(on the Cso pin-pin 5) and an internal current source connected to the inverting input of the lockout comparator (the
current source delivers approximately half the current
through the timing resistor). The current source will charge
the capacitor until its voltage is internally clamped at about
3.0V. When the capacitor voltage reaches the reference
voltage, the Lockout Comparator will change its output from
a high to a low Signal. This action will release the PWM flipflop and the output driver, enabling them to resume normal
operation (assuming the problem causing the current limit
has been corrected. If,not, normal operation will be halted
again).
The time the PWM flip-flop and the output driver remain
shutdown is programmable, depending on the value of the
Cso capacitor. Rearranging the shutdown time delay equation, giving in the pin-by-pin description section, results in a
calculation of the capacitor value:

The voltage threshold for the total shutdown current limit is
0.6V. When that current limit comparator is activated, it
forces the inverting input of the lockout comparator low (to
about 0.7V) by driving a Darlington transistor into saturation.
With the other input connected to a 2. t V reference voltage,
the lockout comparator outputs a high signal to the PWM
flip-flop clear input (via the OR gate). A high signal at its
clear pin shuts down the PWM flip-flop and thus, the output
driver. The output driver will remain off until the voltage level
at the lockout comparator inverting input becomes larger
than the voltage at its non-inverting pin (because the shutdown delay has expired and the voltage at the CUM pin is
less than 0.6V).

Cso

=

tso/(2 • RT)·

For example, for a desired shutdown delay time of approximately 100 ,...s and a RT equal to 6 kG gives a Cso of
8200 pF. The shutdown delay circuit is temperature compensated, so the delay time is stable over temperature.
Also, after a total shutdown, the IC will repeat the Soft-Start
cycle when the shutdown delay time has elapsed.
If the shutdown delay feature is not desired, leaving the pin
open will disable the function (the pin voltage is internally
clamped to 3V, thereby holding the lockout comparator output low).

3-149

II

~

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r------------------------------------------------------------------------------------------,
Functional Description (Continued)

....I

Pulse-byPulse Current
Camp

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Output

Driver
Second
Level Current
Camp

TUH/II435-12

FIGURE 7. Current Limit Block Diagram
3.2V) is added to the circuit so that the supply voltage must
decrease to 8.6V (typical) before the UVL circuit shuts down
the IC. When the UVL circuit is activated, the rest of the IC
and the entire regulator are turned off, and the UVL and
bandgap reference voltage circuits are the only two inteinal
circuits left on. The UVL circuit will also discharge the SoftStart capacitor, so Soft-Start will commence at the next
start-up.

OVERVOLTAGE/UNDERVOLTAGE
SHUTDOWN SECTION
The Overvoltage and Undervoltage Lockout circuits protect
the LM3001 from deviations of the supply voltage. The
Overvoltage .Lockout (OVL) circuit monitors the supply voltage via an external resistor divider (for more information,
see the OVL section in the Application Hints section). The
Overvoltage Lockout Threshold voltage is 3.30V (typically).
When an overvoltage condition occurs, the OVL circuit
shuts down the Output Driver (the rest of the IC stays on)
until the fault causing it disappears. The Thermal Shutdown
protection circuit uses the same circuitry to shut down the
Output Driver and the entire regulator.
The Undervoltage Lockout (UVL) circuit monitors the supply
voltage from within the IC. At start-up, the UVL is turned on
when the supply voltage reaches approximately 2.0V. The
UVL circuits keeps the rest of the IC off until the supply
voltage reaches approximately 11.8V. The start-up supply
current during this period is about 190 pA Hysteresis (about

SIGNAL GROUND AND POWER GROUND
The LM3001 Primary-Side PWM Driver is designed with two
separate grounds inside that meet in one location-right at
the pins. One ground is for small signals-hence, it is very
clean (noise-free). The other ground is the power ground,
used by the large Signals of the Output Driver. The two
grounds are internally connected at the pins; pin 9 is a power ground and pin 11 is a signal ground. The grounds should
be isolated from each other on the board (see the PCB
Layout section in the Application Hints section).

OVTH
10

Pulse-by-

Pulse CUrrent

Css I--t-........J

t-i=t::==t~

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Lockout

Camp
TUH/II435-13

FIGURE 8. Overvoltage/Undervoltage Block Diagram

3-150

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Typical Application
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75k

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6k

2k
2000 pF
10k

4W

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82.5k

IN4937

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4W
3k
220 pF
100 pF 8

910 pF

Pvs
LM3001
PRIMARY
DRIVER Your

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SECONDARY
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TUH/11435-14

CAUTION: HIGH VOLTAGE
Handle with Extreme Care

FIGURE 9. Offline Voltage Mode Flyback Regulator
the output ripple voltage to SO mV. As shown in Rgure 10
the regulator can respond to a "step" change in load current from 1A to 10A in about 12 JLs. The efficiency of the
converter is approximately 80% at full load.

This SOO kHz Offline Converter delivers SOW (SV @ 10Al
from an input supply ranging from 90 VAC to 130 VAC
(130 VDC to 180 VDC). The regulator achieves a line regula·
tion of 0.06% and a load regulation of O.OS%. A O.S p.H
inductor and 100 JLF capacitor form an LC filter that reduces

SOOmV
A

0

1\

\
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-SOOmV
lOA

1

SA
0

TL/H/11435-15

A: Output Voltage, 500 mVldiv., AC Coupled
B: Load Current, SA/div.
Horizontal TIme Base: 20 ,",./div.

FIGURE 10. Load Step Response

3-151

~

!

~

r------------------------------------------------------------------------------------------,
Typical Application

(Continued)

POWER STAGE OPERATION
The LM3001 Primary-Side PWM Driver sends a pulse-widthmodulated signal (via pin 8) to a power switch, which in turn,
drives a power transformer.
The power switch used in this case is an IRF840 Power
MOSFET. It Is an N-Channel enhancement mode device
that has a drain-to-source voltage (Voss) rating of 500V and
a pulsed drain current (10M) rating of 32A. Even though the
Power MOSFET has a high Voss, snubber circuits are
needed to limit the drain voltage and damp out any ringing
that may occur.
The power transformer has a primary inductance of 87 fLH.
The primary-to-secondary turns ratio is 8.5 to 1 and the secondary-to-tertiary turns ratio is 1 to 2.5. The tertiary winding
delivers the LM3001 supply voltage (pins 7 and 12) to the
primary-side driver.

The LM3101 provides the fault protection in case of an output short circuit: During normal operation, the operating frequency of this circuit is determined by 25 kO resistor connected to pin 1 of the LM3101. However, during a short
circuit condition on the output, the frequency of the LM3101
, (and the entire circuit operating frequency) drops, yielding a
very low duty cycle. This short-circuit frequency is set by the
13 kO resistor connected to pin 5.
The LM3101 Mode Control and Current Mode Input pins
(pins 2 and 6 respectively) are for current mode control operation. The MCR pin determines which control mode is being used-the resistor tied to the supply voitage means voltage mode control (the resistor tied to ground would indicate
current mode conjrol).

START-UP OPERATION
When power is Initially applied to the regulator, the LM3001
Primary-Side PWM Driver receives its supply current
,through a 75 kO resistor connected to the input voltage (see
Figure 9). Once the supply pin voltage reaches the threshold of 11.8V (typical), the LM3001, turns on, sending pulse
signals (with an amplitude of approximately 10V) to the gate
of the Power MOSFET. Because the output is driving Power
MOSFETs, which need gate-to-source voltages greater
than 10V for hard turn-on (low RDS (ON» the threshold voltage of 11.8V was selected to insure sufficient output voltage.
At the beginning of the start-up process, the secondary side
of the regulator is still unbiased-hence the LM3001 does
not receive a feedback signal from the secondary side (see
the Start-Up Sequence in Figure 11). Before the LM3101
Secondary-Side PWM Controller is controlling the circuit,
the initial operating frequency of the gate drive is determined by the LM3001 internal oscillator. The oscillator uses
an external, capacitor and resistor, on pins 14 and 1 respectively. The initial operating frequency in this case is approxi,mately 500 kHz. During this time, ,he reg41!ltor is operating
in a "free-running" state,.
Also during the beginning, the LM3001 executes Soft-Start
by using the Soft-Start capacitor on pin 4. The voltage
across this capacitor is compared to the' oscillator ramp on
pin 14 (see the LM3001 block diagram). In the offline regulator, the Soft-Start time is 15 fLs approximately.

There is an Internal Overvoltage Threshold circuit (pin 10)
monitoring the input voltage via a resistor divider. The'overvoltage trip point is 3.3V typically. With the resistor values
shown, the maximum supply voltage is approximately 17.5V.
The output rectifier, an SR1606, delivers the secondary current to the output. The SR 1606 is specified for 16A forward
current, 60V reverse breakdown voltage, and comes in a
T0220-AB package. Since the SR1606 dissipates 7W to
8W at full load, it requires a heatsink. An RC snubber is
placed in parallel to reduce 'the ringing voltage caused by
the output rectifier turning off during the discontinuous
mode of operation.
Two Cornell Dubilier type 226 470 fLF, 25V high frequency
capacitors, with low ESRs of 0.250, are used as the output
capacitors.

OUTPUT VOLTAGE CONTROL
The output voltage is controlled by the LM3101 SecondarySide PWM Controller. The LM3101 uses its error amplifier to
compare the scaled-down output voltage against the internal precision 1.24V reference voltage. The error amplifier
provides compensation for the regulator frequency response, by way of an' RC feedback network.
The resulting error voltage is converted into a pulse-widthmodulated waveform at the system oscillator frequency of
approximately 500 kHz. This waveform is then differentiated
(using an external high-pass RC filter) into a series of positive and negative pulses representing the desired switch
duty cycle.

During this time, as the Soft-Start capacitor charges up, the
duty pycle increases with each progressive cycle, until finally the duty cycle reaches its maximum value set by the Duty
Cycle Limit circuit (ROL-pin 2) and the Current Limit circuit
(CUM-:-pin 6). The Soft-Start phase ends when the duty
cycle is limited by the ROL circuit. A resistor at this pin connects to an internal current source which together will generate a voltage that will be-Compared to the oscillator ramp
voltage. This comparison will determine the maximum duty
cycle during this phase of the start-up cycle. For the circuit
in Figure 9, the duty cycle is 'limited to 63% by the Rot
circuit.

The pulses are transferred through a pulse transformer to
the LM3001 Primary-Side Driver. The driver takes the feedback pulse signal and converts it into a PWM gate drive for
the Power MOSFET.

FAULT RECOVERY OPERATION
A 0.150 resistor sets the peak primary current limits to
2.28A for the pulse-by-pulse limiting, and to 3.6A for the
second-level limit. An RC network filters the current limit
voltage to prevent the current limit (pin 6) from being activated by the reverse recovery spike of the output rectifier.
When the second level current limit is triggered, the LM3001
shuts down and discharges the capacitor connected to pin 5
(the Shutdown Delay capacitor). After the capacitor is recharged to a voltage of approximately 2.1V, the device will
try to restart. If the overcurrent condition persists, the device
will shut down again.

The duty cycle will reach the ROL limit for several :cycles,
letting energy build up in the transformer-see the drain current waveform in Figure 11. When the residual energy builds
up enough, the duty cycle starts to decrease because it is
now determined by the CUM circuit. A voltage of 0.38V or
greater at this pin will toggle a pulse-by-pulse comparator
on every cycle (see the LM3001 block diagram). In the ap-

3-152

r-----------------------------------------------------------------------------'r"
i:
Typical Application (Continued)

Co)

plication circuit, a 0.1670 resistor will generate the current
limit threshold voltage when a 2.28A (peak) current flows
through it. With the CLiM circuit in control of the duty cycle,
the duty cycle will decrease with each sucessive cycle. The
duty cycle will continue to shrink until the pulse feedback
from the LM3101 takes control.

The method of Soft-Start used by the LM3101 ensures that
the error amplifier is in its linear region before the output
voltage reaches its nominal value, thus yielding a smooth
start-up of the output without any overshoot (see Figure 12).
\.

As the LM3001 switches the Power MOSFET on and off,
the Power Transformer starts delivering power to the secondary side of the circuit. This action will cause the supply
voltage of the LM3101 and the output voltage to gradually
rise. When the supply voltage reaches the Undervoltage
Lockout Threshold (of 3.9V), the LM3101 starts supplying a
pulse train to the differentiator circuit on pin 8. The resulting
PWM signals are fed back to the LM3001 via the pulse
transformer. The first pulse signal to the LM3001 will cause
it to disconnect its internal oscillator from its PWM and Output Driver circuits and trigger the Output Driver from the
pulse feedback Signals (of the LM3101). At this point, control of the frequency and the duty cycle changes from the
LM3001 to the LM3101.
The LM3101 also exercises Soft-Start capability (pin 3). An
RC network connected to this pin allows the LM3101 to
gradually increase the duty cycle to its nominal value (in the
example, the secondary Soft-Start time delay is 500 p,s approximately).

0.

LN3001
.SUPPLY

....

-

5V

I

TUH/11435-17

Output Voltage, tV/dlv.
Horizontal TIme Base: 500 ",s/div.

FIGURE 12. Output Voltage Start-Up
At the end of the start-up sequence. the circuit is in steadystate or normal PWM operation.

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(Representative not to scale)

FIGURE 11. Start-Up Timing Sequence

3-153

II

Typical Applications (Continued)
However, leakage inductance exists in the transformer,
causing a voltage spike immediately after the switch turns
off. This voltage spike will add to the res~ ·of ~he drain voltages, making VSW(OFF) even greater. With a leakage inductance that is 2% of the transformer primary inductance and
selecting a switch which has a fall time of 2% the total offtime, the added voltage will be:

DESIGN PROCEDURE
For the Offline Voltage Mode Flyback Regulator (Figure 9),
the specifications for the' power transformer, MOSFET
switch, the switch snUbber, and the output rectifier can be
calculated based on the system specifications:
System Specifications:
Vo = 5 VDC

. VLL = 2% • Lp elpRI(pK) e Fo/[2%. (1 - D(MAX)]'

VI Range = 90 VAC-132 VAC

10 Range = 0.5A-10A
Efficiency (-i!) = 80% '

The maximum duty cycle of 28% is·used for worst case
purposes. Thus, the leakage inductance voltage: spike is.: ..

Transformer Specifications

Fo = 500 KHz

VLL = 0.02 e B7 ,...H • 2.1 BA e 500 kHz/[0.02 e (1 - 0.28»)'
'=
~ 150V.

Manipulating the transfer function of a flyback regulator results in a calculation for the turns ratio of the power transformer, involving the minimum input voltage, the output voltage, and the maximum duty cycle (D):

This means the actual peak !;Irain voltage is approximately
400V. When choosing the Power MOSFET, add some margin to this number. A 500V MOSFET was used in this application.

Vo

+ VF =

139Y

Snubber Design

(VIN(MIN) - VSW(ON» • (Ns/Np).

A "snubber" circuit, conSisting of a 1N4937 fast recovery
diode and a parallel RC network, is inserted around the
transformer primary to clamp the voltage spike. This is to
the reduce the switch voltage stress when it .is' off. The
"snubber" components are calculated in the fOIl'owing'manner:

(D(MAX)/(1 - D(MAX))

.J.
+ VF)/(VIN(MIN) -

Ns/Np = [(Yo

VSW(ON»]·

«1 - D(MAX»)/D(MAX)'
Assume that the diode forward voltage (VF) is about 0.7V
and the drain-to-source voltage when the switch is on
(VSW(ON» is approximately 0.9V. Selecting a 2B% maximum
duty cycle results in a turns ratio of:

CSN :2: 0.02. Lp. Ip(PK)2/(VMAX2 - VSN2)
= 0.02 e B7 ,...H • (2.1 BA)21 [(255V)2 - (250V2] ::::

3.3nF

Ns/Np = (5.7V1126.1V). (1 - 0.28)/0.28 = 0.12

and

(Np/Ns' = 8.5/1).
RSN S; [(VMAX

Assuming an efficiency (-i!) of 80%, the average input current (at the maximnum load current andd for the entire peri"
od) is:
liN

=

(Vo) (lo)/(VIN(MIN)· -i!)

=

(50W)/(127V. O.BO)

=

IIN/D

=

(0.49A)/(0.28)

=

1.77A.

Selecting the primary inductance ripple current (alp) to be a
certain percentage of the IIN(TON), and combining that with
the duty cycle, the input voltage, and the operating frequency, gives the primary inductanc~ by the equation:

P = [(VMAX

Output Diode Parameters
The peak secondary current can be calculated using peak
primary current and the turns ratio (this equation is for single
output flyback regulators):

MOSFET Parameters
The peak current through the primary inductance and the
Power MOSFET is the average current when the. switch is
on plus one-half the primary inductance ripple current:

+ (alp/2) =

1.77A

ISEC(PK)

+ 185V =

233V -

IpRI(PK) e (Np/Ns)

=

2.18· 8.5

=

20A.

The maximum average current through the secondary and
the diode, when the switch is off, is the maximum load and
current divided by the inverse of the duty cycle:

2.1BA

+ VF) (Np/Ns) + VIN(MAX)

=

18.43A -

+ (0.81A12) =

Assuming ideal conditions, the maximum voltage at the
drain of the Power MOSFET when the switch is off is:
VSW (OFF) = (Vo

+

The fast recovery diode must have a reverse voltage rating
greater than VMAX. The 1N4937 has a 600V rating.

Lp = 126.1V. 0.28/(0.81 A .. 500 kHz) '" 87,...H.

IIN(TON)

VSN - VIN)/2]2/R = [(255V

To add some margin, a 4W resistor is chosen.

Assuming the percentage to be 46% in the example, then:

=

+

250V - 185V)/2)2/10 kO = 2.56W.

Lp = (VIN(MIN) ,.. VSW(ONi) • D(MAX)/(alp. Fo)

IpRI(PK)

185V)/2]2

In the Offline Flyback Regulator ap'plication, a 0.Q1 ,...F capacitor and a 10, kO resistor are used as the snubber components. VMAX is the selected maximum voltage at the drain
of the MOSFET. Usually the RC values are selected so that
VMAX is 5V to 10V higher than VSN. The power dissipation
of the resistor is:

The average current when the switch is on is the average
current over the entire period divided by the duty cycle:

=

VIN)/2]2 e [100/Fo e Lp

+ 250V -

• [100/(500 kHze 87,...H e (2.18A)2)) :::: 12kO.

0.49A.

IIN(TON)

+ VSN -

elp(PK)2)] = [(255V

ISEC(OFF)

= (5.7V) (8.5)

=

ILOAO/(1 - D(MAX)
:::: 15A.

250V.

3-154

=

10AlO.72

=

13.90A

r-----------------------------------------------------------------------------~

Typical Application
+3~D~72

:s::::

(Continued)

0-....,---.------..,.--..,

620pF'

c
c
.....

10n

2k
200pF'

13k

13

FBi---"
3.0k

LM3101
SECONDARY
CONTROLLER

14

EAOt--U-....

Your'

34.Sk

SFsTH-II-..,
12

1

4S.3k
25k

RtnQ----......

200n
SDk

TL/H/11435-18

FIGURE 13. Telecom Current Mode Flyback Regulator
The maximum average secondary current for the entire period is the maximum load current (lOA).
The maximum reverse-bias voltage on the output rectifier is:
VRV = VIN(MAX)· (NslNp)

+ 5.7V =

+ Vo + VF =

(185V) (1/8.5)

27.42V :::: 30V.

A suitable diode for this circuit is the SR1606, which has a
reverse voltage rating of 60V and an average current rating
of 16A.

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The most significant difference in the circuit design is the
change in the mode of operation-from voltge mode to current mode. For current mode operation, the LM3101 Mode
Control pin (MC-pin 2) is connected to ground by a 6 kO
resistor, and the Control Mode pin (CMI-pin 6) is connect, ed to the current sense transformer through a half-wave
, rectifier circuit and a low-pass filter. The filter is needed to
remove the leading edge spike on the current waveform,
caused by the rectifier recovery and interwinding capacitance of t~e power transformer.
Smaller component differences include reducing the current
sensing resistor in the primary side ground path (to allow for
the larger primary current), and removing a primary side
snubber circuit (due to smaller peak voltages at the drain).
Also, the output rectifier and Power MOSFET snubbers are
modified.

Application Hints
TELECOM CONVERTER
The schematic of a flyback regulator, used in Telecom Applications, is shown in Figure 19. The circuit has many of the
component values that are in the offline converter. Notable
exceptions are the power transformer, in which the turns-ratio and primary inductance has changed (due to the change
in the input voltage range), and the Power MOSFET, which
has a lower on-resistance and a lower breakdown voltage
rating.

3-155

~

o

~

:5

,------------------------------------------------------------------------------------------,
Application Hints (Continued)

LM3101
OSCILLATOR
RAMP
ERROR
AMP
OUTPUT

PULSE FEEDBACK SECTION
During steady-state operation, the LM3101 delivers pulsewidth modulated signals to the feedback circuit. The feedback circuit will convert that signal into a series of ACcoupled pulse signals and apply them to the LM3001 via the
pulse transformer (the first positive-edged pulse from the
LM3101 will cause the LM3001 to disconnect its internal
oscillator from its PWM and Output Driver circuits). The
feedback pulses will trigger the LM3001 Output Driver to
apply PWM drive signals to the Power MOSFET gate. The
timing diagram in Figure 14 demonstrates the feedback
communication.

LM310t
PWM
COMPo
OUTPUT

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LM3101
VOUT
PULSE fe
WAVEfORM
(LM3001
PIN INPUT)

PULSE INTERFACE CIRCUIT
The pulse Interface circuit provides isolation for the feedback circuit of the Offline Flyback Regulator. The differentiator circuit converts the PWM waveform into a pulse train.
The differentiator delivers to the pulse transformer a trBiri of
1 VPK, 15 ns wide pulses. The core should have ~Igh permeability (typically 10,000) at the switching frequency to allow the transfer of energy with a very small transformer
(size). This one-to-one transformer transfers the pulse train
to the LM3001 via a 2000 resistor, which is used mainly to
filter noise from the system.
.

LM3001
VOUT

. TLlH/II435-19

FIGURE 14. Pulse Feedback Timing Diagram

tOns S T S 95 I's

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500 ns S T S t 00 I'~

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~.3mA
Lt.l3001
PIN

TLlHI11435-20

FIGURE

1~.

Pulse Interface Circuit

3-156

~-----------------------------------------------------------------------------,

Application Hints (Continued)

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faster the output is turned off. The graph below demonstrates the relationship betWeen the overdrive voltage and
the speed of the current limit circuit. An overdrive of approximately 30 mV produces a response time of 58 ns, whereas
a 250 mV overdrive generates a response time of less than
50 ns.

CURRENT LIMIT
As previously mentioned, the primary current can be monitored by inserting a resistor between,the source of the Power MOSFET and ground (See General Circuit Operation section). This generates a voltage which is compared to the
reference voltages of the pulse-by-pulse current limit comparator (O.3BV) or the second level current limit comparator
(0.6). As an example, using a 0.1,{l will allow a peak primary
current of 3.8A to activate the pulse-by-pulse current limit. A
peak primary current of 6A will activate the total shutdown
current limit. Also mentioned before, after the second level
current limit threshold has been reached, there will be a
time delay before the circuit powers up again. This shutdown delay is controlled by the Shutdown Delay capacitor
(the equation for this is in the Current Limit section of the
Functional Description section). In the example, a shutdown
delay capacitor of 1 p.F and a timing resistor of 8 k,{l produces a time delay of 10 ms before the regulator starts up
again:
TSD = 1.25 e1 p.Fe 8 k,{l = 10ms

o
.....

OVERVOLTAGETHRESHOLD
The supply voltage is monitored by the Overvoltage Shutdown circuit through a resistor divider. The current needed
to bias the divider is delivered by the supply voltage. It is
stated in the Overvoltage/Undervoltage Shutdown section
that minimum bias current to insure proper operation is approximately 10 p.A. This minimum bias current Silts the maximum value of the resistor in the bottom leg of the divider.
While there is not' a maximum bias current limit as the
LM3001 is concerned, the bias current should be kept as
small as possible in order that the supply current is kept
small.
.
'

BYPASS CAPACITORS
Due to the high speed and currents of this IC, high frequen-

The voltage generated across the current-sensing resistor
needs to be filtered before it is applied to Current Limit circuit input. The filtering is needed because of current spikes,
caused by the transformer leakage inductance, during the
turn-on of the Power MOSFET. The filter that is used in the
regulator in the General Circuit Operation section is a RC
low pass filter with a 0.62 p.s time constant. This filter is fast
enough to allow proper operation of this function, but will
screen unwanted transient signals. Note that the lower the
leakage inductance the transformer has, the faster the filter
can be.
Usually, it is the filter that determines the response time of
the current limit activation. If the filter can be made fast
enough (less than 40 ns) due to low leakage inductance,
then the response time of the current limit circuit comes into
play. The Current Limit Delay Time is specified at 50 ns for
100 mV of "overdrive" (the term "overdrive" means the
amount of voltage over the comparator's threshold voltages). However, the speed or response time in which the
current limit circuit acts and shuts down the output depends
on the amount of "overdrive" caused by an excessive primary current. However, the amount of voltage, driving the
current limit input directly affects the speed or response
time of the current limit circuit. The higher the overdrive, the

cy noise can be generated very easily, causing erratic operation of the regulator. Hence, bypass capacitors must be
used to eliminate the high frequenci noise from interrupting
the operation of the circuit. Capacitor values of 0.1 J-LF and
10 p.F should be selected. The bypass capacitors should be
placed as near as possible to the IC.
60

.
0:

~

1

58

\

56

'"
:::E

i=
Ul
'"
Z

0

"-

Ul

'"'"

54

\ '\

52
50
48

o

50

['...

100

150

200

250

CURRENT LIMIT VOLTAGE (mV)
TL/H/11435-21

FIGURE 16. Current Limit Response Time

&I

3-157

~

~

:e
....I

r-------------------------------------------------------------------------------------,
Application Hints (Continued)
v

LM3001 WITH OPTo-COUPLER FEEDBACK
The LM3001 Primary-Side PWM Driver can also receive
opto-coupler feedback as shown in Figure 17. A LM4041ADJ Voltage Reference drives the opto-coupler's photodiode. The Error Amplifier of the LM4041 accepts a sample of
the output voltage, from the resistor divider of Rl and fl2'
and supplies a drive current to the opto-coupler. Resistor;
RD, limits the maximum photodiode current. The RC network (Cc and Rl R2) provides compensation to the circuit.
The feedback signal from the opto-coupler is injected into
the CUM pin (pin 6). The opto-coupler's phototransistor, in
an emitter follower configuration, supplies a current that
produces a DC offset voltage at pin 6. A resistor, Res, generates a voltage proportional to the primary or switch current. These voltages are summed at pin 6. Referring to the
LM3001 Block Diagram (on pg. 1), this summing voltage is
compared to a 380 mV reference by the Pulse-by-Pulse Current Limit Comparator (see Figure 18). The RF-CF network
provides filtering of the leading edge spikes.

380 mV Reference

Primllry Current
Analog Voltage
DC Offset Voltage

II

. OV L -__-,-__________________-,-___

T
Tl/HI11435-24

FIGURE 18. Opto-Coupler Feedback Waveforms

\----.-------..--4-I

12

Vs

LM3001
PRIMARY
DRIVER
PGND

GND

VOUT

CaVPASS

+

LM4041-ADJ
VOLTAGE ~F.;;..B_....._

R<;

8

VOUT

.....

REFERENCE

CUM
6

Rr

Rv

Cf

I

Res

Tl/H/11435-23

FIGURE 17_ Opto-Coupler Feedback Circuit

3-158

r-----------------------------------------------------------------------------~

Application Hints (Continued)
carrying the high di/dt currents, such as the input return and
the input capacitor negative lead.
High frequency bypassing is also a necessity. A 0.1 ",F ceramic capacitor should be inserted between the output driver supply pin (PvS - pin 7) and the PGND pin. The analog
signal supply pin (pin 12) should also be bypassed to Its
GND pin (Vs - pin 11) with a 0.1 ",F ceramic capacitor. The
bypass capacitors should be placed as near as possible to
the IC, with the shortest possible lead length.

LM3001 PCB LAYOUT

Due to the high speed of the LM3001 output driver, careful
layout of the printed circuit board is essential. The ground
plane should be divided into a power ground section (see
Figure 1{/), connected to the PGND pin (pin 9) and an analog signal ground region, connected to the GND pin (pin 11).
The separate ground sections are connected internally. The
power ground region should have connected to it all paths

r-----------,
Power

Ground

;t

r

3:
Co)
o
o.....

V,N

I
I
I
I
I
I
I

I:

r---------------

Rtn

Vs

I

13
1

LM3001
PRIMARY
DRIVER

PIN

Feedback

RoL

Cr

Ry

Signal
Ground

-----------------------~

TUH/11435-22

FIGURE 19. LM3001 PCB Layout

•
3-159

~

o

~

r--------------------------------------------------------------------------------,
tfI,N4 t i

0

n.4 I Sem i con due tor

LM3101 Secondary~Side PWM Controller
G~~eral Description

Featufes

The LM3101 is a precision high-speed PWM controller. It is
designed to provide secondary-side feedback for offline
Switch-Mode Power Supplies (SMPS) using pulse communication to the primary-side driver. The LM3101 is applicable
in all of the popular converter topologies such as flyback or
forward.
The LM3101 combined with its companion LM3001 PrimarySide Driver forms a regulator chip-set that provides precision control of offline or other isolated DC/DC converters.
The communication is realized between the two chips by a
small pulse transformer, with one or two turns on its primary
and secondary. This type of communication does not introduce any poles or zeroes in the control loop and yields the
fastest possible loop response for the isolated switching
regulator.
The secondary-side controller contains a precision 1.242V
reference, an error amplifier, and a trimmed oscillator which
is programmed with a single resistor. The LM3101 can realize voltage, current or charge mode control. Power supply
monitor features include power-on reset with programmable
delay and overvoltage protection.

• ± 2% precision voltage reference
•
•
.•
•
•
•
•
•

Wide-bandwidth (8 MHz) error amplifier .
Extemal synchronization
Frequency shift during an output short circuit
Power-on reset flag with programmable delay
Overvoltage crowbar trigger circuit
Ramped reference Soft-Start
Operation beyond 1 MHz
Voltage, current, or charge mode control

Typical Applications
•
•
•
•

Isolated offline switching power supplies
Isolated DC/DC power converters
Flyback regulator
Forward converter

Block Diagram
SFST

SYNC

3

4

RSC

INTERNAL BIAS Be
UNDERVOLTAGE
LOCKOUT

CMI

6

8

o-++---t

POWER-ON
RESET FLAG

FB 13 . .-

CROWBAR
DRIVER

.....--1

VOUT

1---l~U 11

POR

I -.....--L~ 12

~D

1---l~U

lOCO

ERROR AMP

14

7

EAO

GND
TL/HI11436-1

3-160

r-

Absolute Maximum Ratings (Note 1)

Operating Ratings

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
16V
Supply Voltage (Vs)
-65'C';; TJ';; +150'C
Junction Temperature Range

Supply Voltage
Junction Temperature Range

......==
Co)

4.5V,;; Vs ,;; 15V
-40'C';; TJ';; +125'C

«:)

1 kV

ESD
Lead Temperature (Soldering, 5 sec.)

260'C

Electrical Characteristics

Specifications with standard typeface are for TJ = 25'C, and those in bold typeface apply over full Operating Temperature Range. Pin 2, MC, is connected to Vs by a 5 kO resistor-this selects voltage
mode control operation. Unless otherwise specified, TA = 25'C, Vs = 5V, RFS = 25 kO (Fo = 500 kHz).
Symbol

I

Parameter

I

Conditions

I

Min

I

Typ

I

Max

I

Units

REFERENCE SECTION (Note 2)
VREF

Reference Voltage

1.230

1.242

1.217
AVREF/AVs

Line Regulation

4.5V ,;; Vs';; 15V

AVREF/AT

Temperature Stability
(Note 3)

-40'C';; TJ';; +125'C

1.254

1.266
0.01

0.03

0.003

V

%IV

%I'C

ERROR AMPLIFIER SECTION
AVOL

Open Loop Voltage Gain

Ie

Input Bias Current

75

90

-1.0

-0.5

dB
p.A

-2.0
GBW

Gain-Bandwidth Product

FTEST = 100 kHz

OM

Phase Margin

Av = 1

SR

Slew Rate

4.5

8

MHz

52

Deg

2.5

6

V/p.s

450

500

OSCILLATOR SECTION
Fo

Oscillator Frequency
(Note 4)

RT = 25kO
RT = 12.5 kO

0.88

1.0

0.8S
Fsc

Oscillator Frequency in
Output Short Circuit

MHz

120

187

260

kHz

RT = 12.5 kO
(Fo = 1 MHz),
Rsc = 6.34 kO (Note 5)

210

335

470

kHz

%I'C

0.1

Temperature Stability

(Note 3)

AFO/AVs

Line Stability

4.5V ,;; Vs ,;; 15V

VSYNC

Synch Signal Amplitude

AC Coupled, Negative Edge
Trigger (Note 6)

Compensation Current
Ramp Slope

1.12

1.1S

kHz

RT = 25kO
(Fo = 500 kHz),
Rsc = 13 kO (Note 5)

AFo/AT

AICOMP/At

550

S7S

42S

RT = 25kO
RMC = 5 kO (Note 7)

3-161

0.9
1.5

Vpp

2
155

%IV

208

260

p.A/p.s

•

Electrical Characte.ristics Specifications with standard typeface are for TJ .;,. 25°C, and those in bold typeface apply over full Operating Temperature Range. Pin 2, MC is connected to Vs by a 5 kO resistor-:-this selects voltage
mod~

control operation. Unless otherwise specified, T". ~ 25°C, Vs = 5V, RFS = 25 kO (Fo = 500 kHz). (Continued)

Symbol

Conditions

Parameter

Min

Typ

88

92

Max

Units

PULSE WIDTH MODULATOR SECTION
DMAX

Maximum Duty Cycle

Fo = 500kHz

%

84
Fo = 1 MHz

..

..
DMIN

Minimum Duty Cycle
(Note 8)

Fo

=;;

84

.%

500kHz

2.5

6

8
Fo = 1 MHz

..
tdCS

90

80

4

..

.Current Sense Time Delay·

10

12
75

100

%
%
ns

OUTPUT SECTION
tR

Rise Time

CL = 100pF

20

tF

Fall Time

CL = 100pF

30·

VOL

Output Voltage·· .

IL = 4 rnA Sinking
Fo = 100kHz

1.3

Output Voltage

ns
1.4

1.6

IL = 4 mA Sourcing
Fo = 100kHz

3.4

Relative Trigger
Threshold

Relative to Nominal Feedback
Pin Voltage (Note 10)

16

Ico

Crowbar Driver
Output Current

Rco = 100

tco

Crowbar Delay..

tc

Minimum Trigger Pulse Wi~th·

VOH

ns

3.6

3.8

V
V

OYER-YOLTAGE CROWBAR TRIGGER SECTION
%VTHC

.•

18

170

20

22

24

%

240

mA

Rco = 100, Vco = 1V

400

ns

(Note 11)

400

ns

POWER-ON RESET FLAG SECTION
-6

-4.5

-3

Relative POR Trigger
Threshold

Relative to Nominal
Feedback Pin Voltage (Note 10)

VPOR

POR Output Voltage

VFB = 1.11V
IpOR = 1.6 rnA

0.2

0.5

V

VSM

Minimum Supply Voltage
(Note 12)

:VPOR::;;: 0.5V
IpOR = 1.6mA

1

1.2

V

tOR

Power-On Res~t Delay

%VTHP

CRo=2nF

,

-6.5

65

-2.5

120

50

185

265

%

p.s

UNDER-YOLTAGE LOCKOUT SECTION
(Note 13)

Vuv

Start·Up Threshold

VUVH

Threshold Hysteresis.

SUPPLV SECTION
Is

3.65

3.92

4.20

300

I

Supply Current

Vs = 5V

11

16

20
4.5V::;;: Vs ::;;: 15V

15

24

28
ISFST

V
mV

Soft·Start Current (Note 14)

VSFST = OV

3·162

14.5

19.5

20.5

rnA
rnA
p.A

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: The reference voitage is measured at the error amplifier's output with the error amplifier connected as a non-inverting amplifier with a gain of one.

Note 3: The temperature coefficients of VREF or Fo are defined as the worst-case t. VREF or t.Fo measured at Specified Temperatures divided by the total span of
the Specified Temperture Range (see graphs). There is no guarantee that the Specified Temperatures are exactly at the minimum of maximum deviation.
Note 4: The frequency of the internal oscillator is set by connecting a resistor, AT, from pin 1 to ground. See detailed description of ,this feature in the Pin-by-Pin
Description section or the Functional Description of this datasheet.

Note 5: A resistor, RsC, is connected from pin 5 to the regulator's output. See detailed description of this feature in the Pin·by·Pin Descriplion section or the
Functional Description section of this datasheet.
Note 6: For this test, the frequency of synchronizalion, FSYNC, is 600 kHz, CSYNC is 220 pF, and RSYNC is 1 kil. The internal oscillator will synchronize to an AC
signal that is 1.1 to 1.5 times the free running oscillator frequency, Fa. See Functional Description section or Pin-by-Pin Description sectio~ for more detail on
synchronization.
'
Note 7: ICOMP is sourced from pin 6 (eM!). See Functional Description section or Pin-by-Pin Description section for more detail on current mode operation.

Note 8: Minimum duty cycle is the smallest duty cycle that can be produced by the LM31 01 in a given oscillator period. The controller can operate with effectively
zero duty cycle--it skips cycles if the regulation cannot be maintained with the minimum duty cycle. This means that the output voltage of the switching converter is
regulated down to no load.
Note 9: The current sense time delay is the lime span between an input applied to the CMI pin (pin 6) and the change of state of VOUT (pin 8) due to the input.
Note 10: Both these specifications, %VTHC and %VTHP, are relative to the nominal feedback voltage, VFB, by the factor. [(VTH-VFB)IVFB].
Note 11: An internal delay circuit prevents triggering of the overvoltage crowbar circuit, for pulse widths less than 400 ns, to ensure noise immunity.
Note 12: This is the minimum supply voltage for which the power-cn reset flag will continue to be valid (low).
Note 13: For Vs < Vuv, the output is off-it is in a high-impedance state.
Note 14: A reSistor/capacitor circuit is normally connected from the soft start circuit, pin 3, to ground. The circuit provides a slow or "soft" start of the IC by slowly
ramping the reference voltage from a lower initial value set by the resistor to its normal operating value. See detailed description of this feature in the Pin·by·Pin
Descriplion section or the Funclional Description seclion of this datasheet.

Connection Diagram and Ordering Information
14·Lead Package
Top View
R.

...!.

0

\....../

T 2

.!!.EAO
1l.FB

Me ....;;.

sf'ST2

.!1. C1lo

...!

.llPOR

SYNC

5

Rsc-

.1.2. CD

CMI.!

.!VS

GNO..!.

....!!.VOUT
TL/H/11436-2

For Sur1ace Mount Package
Order Number LM3101M
See NS Package Number M14B
For DIP Package' .
Order Number LM3101N
See NS Package Number N14A

•
3-163

Typical Performance Characteristics
For Fe
For Fe

= 500 kHz. RT = 25 kG
= 1· MHz. RT = 12.5 kG

,

Supply Current
vs Supply Voltage

Supply Current
15

1050

U

1/........

oC

.5

13

~

i5

~

i

12

,,/

Y'

/

9

8
-50 -25

Fa = 1 MHz

'<

.5

!

~ ~~

/"

10

Fo

= 500 kHz

i

20

16

~V

25

50

75

eeo

4

500

6

~

~

'¥

300

~

250

3

eeo

...

520

i"""

480
10

12

14

~

'"

140

15

200

100

~

-50 -25

0

25

50

17.5

r:
iii

17.0

s;

25

75

50

1.230
-50 -25

100 125

/'

./

'\

450
400

~

f' .......
0

!:l

--25

50

~
~

~

~

75

--

!:
::;

'"

~
u

1.1

,

'"

16.5

1.0
-25

0

25

50

75

100 125

JUNCTION TEMPERATURE (Oc)

.....
.......

50

75

100 125

3.8

.........

~

........ .......START UP

.......

"I's"

~/S"""""""'"
........ .....,

~

3.6

TURN OFF

3.4
3.2
-50 -25

100 125

TJ = -40°C

.---

.--- i1_ .--.--- =

1.2

>

/'

25

0

25

50

4

-- TJ

8

10

12

SUPPLY VOLTAGE (v)

100 125

Compensation Current
Ramp Slope

--

TJ=1~ I-

--

6

25°C

75

JUNCTION TEMPERATURE (Oc)

230

E
0

/

-so

4.0

Current Mode Input
Limit Voltage

.......

a

Undervoltage Lockout

1.3

./

.......

JUNCTION TEMPERATURE (Oc)

JUNCTION TEMPERATURE (oc)

19.0

Ii

a

E

300
-50 -25

100 125

.......

m

350

r75

,. ....

z

4.2

Soft-Start Current

18.0

u

4,4

JUNCTION TEMPERATURE (oc)

~
a

1.240

~

1.235

~

80

18.5

1.245

~

-r

ii

. . . r--., 1-0..

100 125

~

500

'\

120

~

:E
g

-;;-

\

75

l..- t--

Minimum Over-Voltage
Trigger Pulse Width

.=.

25 ·50

Reference Voltage

550

1\
160

a

JUNCTION TEMPERATURE (Oc)

JUNCTION TEMPERATURE (Oc)

180

;::

W)

Rsc = 13kfl
Fo = 500 kHz

100
-50 -25

18

200

~

450
-50 -25

16

A"'"

Power,On Reset Delay

..3

14

12

Rsc = 6.34 kn
Fa = 1 MHz ....-

SUPPLY VOLTAGE (V)

-;;-

10

1.250

150

8

8

Short Circuit
OSCillator Frequency

990

6

550

~

400
350

4

~

= 500 kHz

SUPPLY VOLTAGE

,

500

1;

12

100 125

I--"

1010

g

950

3

./

Oscillator FrequencY
vs Supply Voltage

3

Fa

1000

'¥

10

a

1020

1

:;0V

Fo=

14./

. /~

I I

18r-

JUNCTION TEMPERATURE (oc)

1000

Oscillator Frequency
1100

22

= 5V

Vs

14

~ 210
~ 200

~

RT = 25kn
""C = 5kn

-c:::

I-""

..3

190

16

-

220

L
II

180
-50 -25

0

25

50

75

100 125

JUNCTION TEMPERATURE (Oc)

TL/H/11436-3

3-164

r-

...o...

w
==

Typical Performance Characteristics (Continued)
Error Amplifier
Open Loop
Frequency Response

Error Amplifier
Step Response
0.5

~:;
:::~

0

<0

-0.5~

u~

>

~!

100
INPUT REFERENCED
TO VREr

400

1 1 1

200

1 1 1

~

"iD'
~

z

20k
0

~w

,,~

ffi*l1

0<

~i -zoo

'='

-400

-=

+

~

60
40

I' ""

C-

-40

180

GAIN

ZO

r-

1 1 1 1 1 1
TIME BASE (1

r---..

o
-zo

Cpr

225

80

135

I""'-....

-"':'!ASE -

lk

"./01,)

45

i"... ~

~

\

-60
10k

lOOk

1M

FREQUENCY (Hz)

10M

90

"-

0

0

~

<

il:

-45
-90

-135
lOON

TUH/11436-4

Pin-by-Pin Description
Description

Function

Pin '"

Symbol

1

RT

Frequency Setting
Resistor

Connecting a resistor, RT, between this pin and ground programs the frequencyfrom 50 kHz to 1 MHz-by the following equation:
[F, HZ,n].
. RT = 0.25/(Fo - 20 -10- 12)
RT also sets the intemal bias current, which affects the operation of several subcircuits within the IC.

2

MC

Mode Control

For voltage mode operation, connect a resistor, RMC, from this pin to the supply
voltage. For current mode operation, this pin is tied to ground via resistor RMC. A
current is sourced from the pin through the resistor such that it sets the slope of the
compen~ating ramp, ICOMP, according to the equation:
AICOMP/AT = 24-103/(RT- RMd
[IA-AlIA-S, nJ.

3

SFST

Soft-Start Control

A series resistor-capacitor network tied from this pin to ground provides Soft-Start
capability. The current charging the capaCitor is:
[A,V,nJ.
ISFST = 0.45/RT·
Leave this pin open if it is not used.

4

SYNC

Synchronization
Signal Input

An external negative pulse fed to this input will synchronize the internal oscillator.
The frequency range of the external signal should be between 1.1 to 1.5 times the
free-running frequency. Connect this pin to ground if it is not used.

5

Rsc

Short Circuit Frequency
Shift Control

A resistor, Rsc, connected from this pin to the regulator output, determines the
oscillator frequency during a short circuit by the formula:
[F,Hz,n].
Rsc = 0.OS/[(O.267/RT) - Fsc - 20 _-12J
or, alternately,
[F,Hz,nJ.
Fsc = (1/20 e10- 12) - [(O.2671RT) - (O.OS/Rse)]
The recommended minimum ratio of short circuit frequency to oscillator frequency is
one-third (nominal).

6

CMI

Current Mode Input

An analog voltage signal, proportional to the transformer primary current, fed to this
input results in current mode operation. Connect this pin directly to ground if
selecting voltage mode operation.

7

GND

Ground

Ground.

8

VOUT

Output

Output pin. It produces a PWM pulse train that is fed back to the primary side of the
regulator, via a pulse transformer.

S

Vs

Supply Voltage

Supply voltage.

10

CD

Crowbar Output
Driver

This pin delivers a current when an overvoltage condition occurs on the output. It can
be used to fire an external SCR to crowbar the output. Leave the pin open if not
used.

3-165

•

.,...
o
.,...
CO)

::ii5
-I

Pin-by-Pin Description (Continued)
Pin #

Symbol

11

paR

Power-On
Reset Flag

This open-collector output is driven low when either the supply voltage falls below the
Undervoltage Lockout Threshold Voltage or the output voltage is less than the Poweron Reset Threshold Voltage. Leave the pin open if not used.

12

CRD

Reset Delay Capacitor

Adding a capacitor between this pin and ground sets the power-on reset flag delay
time according to the following formula:
CRD = T DR/60. 103
IF, s, n].
Leave the pin open if not used. The paR flag will still operate if this function is not
used.

13

FB

Feedback Input

A sample of the output voltage, via a resistor divider, is fed back into this pin, which is
the inverting input of the error amplifier.

14

EAO

Error Amplifier Output

Error Amplifier Output. The output can source 1.5 mA typically and sink 300 p.A
typically. This pin is primarily used for loop compensation.

Function

Description

Note: Pins 1, 2, 4, 5, and 10 are internally clamped by a 5.6V zener diode. Do not force a voltage larger than 5V on these pins
without a resistor to limit the current to below 1 mAo All other pins are limited to the supply voltage.

Test Circuit

f)(EA

./"--"10
r-

OUT

14

EAO

I VMOOE

1---1'----'
22k 2.2k

'>S:.;W;.;I+-_ _ _ _'W'v_--__=_!

Ik

2 CMOO:!'

SYNC

0""_--1-_ _ _ _-111---,

IN"'"

22pF

~:.

1

LM3101

4

t-----'W'v_+--__1 SYNC
SW3

.P----_
...~
.....,....-'W'v_--__15 Rsc

-:=-

II

POR

2.2k
Ilk

~w7

-

LM3101 specifications are measured using automated
test equipment. This circuit is provided for the customer's convenience when checking parameters. Due to
possible variations in testing conditions, the measured
values from these testing procedures may not match
those of the factory.

Ik

10

CO

10k

lr-w......---t

t---..J\y"lv-------,
t---..J\y"lv---,

-::!::-

9

CMI

-

V

1,Cl

...n,

-"..

V

~~+i~
I~L-GN-O--------~-UT~~ ~ I ~IQ
S

7

8

~

~~

;"W5

Ik

Ik ~

3.3k

S

;::: OUT

j SW6

~

TLlH/11436-5

This test circuit is for exercising the LM3101 functions and
measuring its specifications. With the switch positions
shown, the supply current should measure 15 mA (typical)
for a supply voltage of 15V. Changing the supply voltage to
5V and opening SW6 on the VOUT pin should make the
supply current 11 mA (typical). Changing SW7 to the supply
voltage will shutdown the LM3101 output.

(typical). The maximum duty cycle of 92% typically can also
be measured. Closing SW3 on pin Rse and putting SW7 (pin
FB) in the open position will change the oscillator frequency
to approximately 180 kHz.
Switching the MC pin, SW1, to ground and opening SW4,
the CMI pin, will put the device in current mode control. To
measure the current sense time delay (typically 75 ns),
close SW5 (connected to the CMI pin) and open SW6.

To test the oscillator section, adjust the 5 kn potentiometer
at the RT pin such that the oscillator frequency is approximately 500 kHz. Switch SW2 to obtain a 1 MHz frequency

3-166

r-----------------------------------------------------------------------------, 3:
r
Functional Description

Co)

The oscillator frequency should range from 67% to 90% of
the synchronization frequency. In the above example, the
oscillator frequency can be between 400 kHz and 540 kHz.

OscillatorISynchronization Section
The operating frequency is set by a single resistor connected from the RT pin (pin 1) to ground, according to the equation:
Fa = 0.25/(RT· 20 pF)
[kHz, .oJ.
Inserting a 25 k.o for RT sets the oscillator frequency at
500 kHz.
The oscillator is capable of synchronizing to an external
source. To synchronize the oscillator, an external source is
connected to the SYNC pin (pin 4) via a differentiator (see
Figure 1). The external source delivers a pulse train to the
differentiator, which converts this signal into an AC-coupled
signal. The negative-edge of this signal, applied to the
SYNC pin, will control the oscillator, and thus set the operating frequency. The recommended values for RSYNC and
CSYNC are as follows:
RSYNC = a.o (typical)
and

VSYNC

.....
.....

C)

Il.I >-I t - - -..
CSYNC

CSYNC • RSYNC > 1/(8· FSYNcl .[F, .0, kHzJ.
To synchronize to a 600 kHz external source, and using a
RSYNC of 1 k.o, the CSYNC must be:
CSYNC

> 1/(8· RSYNC· FSYNcl = 1/(8· 1 k.o •

600 kHz)

TlIH/11436-6

= 208 pF ::::: 220 pF.

FIGURE 1. Simplified Version of the
Synchronization Circuit

~----~---.----.-------<~

IOSC

~ Iosc

N

TlIH/11436-7

FIGURE 2. Simplified Version of the Short
Circuit Frequency Shift Circuit

3-167

•

~~----------------------------------------~

....

<:)
('I)

==

...I

Functional Description

(Continued)

Frequency-Shift Circuit'

If RSC2 is omitted, the frequency starts to shift whim Your
drops below VREF.· The short circuit frequency equation
then becomes:

The LM31 01 has the ability to gradually reduce its operating
frequency during an output short circuit. The amount that
the frequency shifts and the output voltage threshold determining where the frequency starts to shift are both programmed by two external resistors, RSC1 and RSC2, connected to the pin Rsc (pin 5).

Fsc = (1/20 pF) • [(0.267/Rr) - (0.09/RsC1)1

nJ

" RSC1 = 0.09/[(0.267/Rr) - (Fsc· 20 pF)1
[0, kHzI.
Selecting a short-circuit frequency that is greater than onethird the operating frequency or 188 kHz leads to a resistor

A simplified internal schematic of the Frequency Shift Circuit
is shown in Figure 2. The oscillator operates at its nominal
frequency as long as the voltage at the emitter of the transistor 02 is higher than the internal reference voltage, VREF.
02 emitter voltage is the output voltage, Vour, scaled down
by the resistor divider:
VRSC = V02E = Vour· RSC2/(RSC1 + RSC2)
where V02 > VREF (1.24V) for normal operation.

[kHz,

!-

~oo~
RSC1

. " ,

= 0.09/[(0.267/25kO)

- (188 kHz· 20pF))

=

13kO.

Mode Control
The LM3101 can operate in voltage mode, current mode, or
charge mode control. Two multi-function pins are involved in
setting the operating mode, the Mode Control pin (Me - pin
2) and the Current Mode Input pin. (CMI - pin 6). Figure 3
shows the simplified schematic diagram of the mode control
circuit. To operate with voltage mode control, the MC pin is
pulled high with a resistor (typically 3 kn), and the CMI pin is
connected to ground. The mode comparator senses the MC
pin voltage and sets the mode control multiplexer to voltage
mode control. Notice that there is a 5.6V zener diode clamping the MC pin voltage.
.

[V, 01

If Your drops, due to an overload, a current starts to flow
through 02. A cascoded current mirror causes one-tenth of
this current to be subtracted from the timing capacitor
charge current. Reducing the timing capacitor charge current results in decreasing the oscillator frequency. The
breakpoint where the frequency-shift starts is programmed
by the ratio of the two resistors:
[V,OI.
Vour(sC) = 1.. 24V. [1 + (RSC1/,RSC2)1
The typical short circuit' frequency is. set' by the following
equations:
Fsc = [losc - 0.1 • {«1.24V - Vour(sC)/RSC1) +
(1.24V/RSC2)1l [1/(20 pF· 1.24V)1
[kHz, p.A, V, 01
where
losc = 0.25· (1.24V/Rr).
For example, say 140 kO and 100 kO were selected ,tor
RSC1 and RSC2, respectively, with Rr set to 25 kO. Then
the output voltage level where the frequency starts to decay
is:
VOUr(CL) = 1.24Vo [1

+

CMI

n.....----+--+ ;;,

D--+----I
~--_

The LM3101 provides two monitor functions, a power-on
reset flag with programmable delay, and a crowbar driver
output for overvoltage conditions.
.:'
.

_+'PWM
CaMP

POWER-ON RESET

The power-on reset (POR) flag monitors the output voltage
via the feedback pin (FB - pin 13). The POR flag will go low
after the output voltage reaches 95% of its nominal value,
and the subsequent programmed delay has passed. The
POR flag pin (pin 11) is an open-collector pin which needs
an external resistor to pull it up. This,pin is valid with supply
voltages as low as 1V while sinking 1.6 mA.
To program the reset delay, connect an external capacitor
to the ,CRO pin (pin 12). The practical range of delay is from
1.0 ,..s'to 5ms, and follows the equation:

EAO

14
R2

TRO=CRO e 60 e 103
[s,FJ.
For a power-on 'reset delay of 120 ,..S, the reset delay capaCitor must be 0.002 ,..F.

TLIH/11438-12

FIGURE 6. Soft"Start Block Diagram

CROWBAR DRIVER OUTPUT

Typically, ISFST starts to flow when the supply voltage is
raised above 3V.

The second monitor function is a crowbar driver output
(CD-pin 10). If the output voltage gets higher than 120% of
-its nominal value, the CD pin can supply more than 200 mA
to an external SCR trigger input. The SCR will fire, shorting
,the regulator output and saving the load circuitry from ex:cessive supply voltage.

As shown in Figure 6, at the beginning of start-up, CSFST is
not charged up, and the SFST pin pulls down the reference
voltage from its nominal value to:
VSFSTO = ISFST e Rl
[y, A, OJ.
VSFSTO is deSigned to be 85% of the nominal reference
voltage. The reference voltage rises smoothly from VSFSTO

3-170

r-------------------------------------------------------------------------------------~

r-

==
.....
.....

Typical Applications

Co)

<:)

VIN
+127-185

Vee

0.021'r 27.n

O-....~~--------_+--__.

100l'l

HER103

VOUT
+5V @ lOA

III- II
2000 pr

++------,

2k

IOl'r;r,

10k
4W

I
VIN

82.5k

lN4937

'I I

500.n

13k

4W

3k
220 pr
100 pr 8

Vs

, 6

910 pr

CMI

MC'

Rse

13

LM3101
SECONDARY
CONTROLLER

rSi---"
6k
14,
EAO

srST

34.5k

0.0051'r

O.331'r

4.7.n

R t n O - - -.....
200.n

CAUTION: HIGH VOLTAGE
Handle with Extreme Care

TLIH111436-13

FIGURE 7. Offline Voltage Mode Flyback ftegulator
output ripple voltage to 50,mV. As shown in Figure 8, the
regulator can respond to a "step" change in load current
from 1A':to 10A in about 12 /Jos. The efficiency of the converter, is approximately 80% at full load.

This 500 kHz Offline Converter delivers 50W (5V @ 10Al
from an input supply ranging from 90 VAC to 132 VAC (127
VOC to 185 VOC). The regulator achieves a line regulation
of 0.06% and a load regulation of 0.05%. A 0.5 /JoH induCtor
aild 100 /JoF capacitor form an LC filter that reduces the

SOOmY
A

0

1\

1

j

\i

-SOOmY
lOA
SA

I

0

I
TUH111436-14

A: Output Voltage, 500 mV/ciiv., Ac Coupled
B: Load Current, 5A/div.
Horizontal Time Base: 20 /Jos/div.
FIGURE 8. Load Step Response

3·171

....
....

C>
(I')

Typical Applications

....

POWER STAGE OPERATION

:::E

(Continued)
charged to a voltage of approximately 2.1V, the device will
try to restart. If the overcurrent condition persists, the device
will shut down again.

The LM3001 Primary-Side PWM Driver sends a pulse-widthmodulated signal (via pin 8) to a power switch, which in turn,
drives a power transformer.
The power switch used in this case is an IRF840 Power
MOSFET. It is an N-channel enhancement mode device
that has a drain-to-source voltage (Voss) rating of 500V and
a pulsed drain current (10M) rating of 32A. Even though the
Power MOFSET has a high Voss, snubber circuits are
needed to limit the drain voltage.
The power transformer has a primary inductance of 87 J-LH.
The primary-to-secondary turns ratio is 8.5 to 1 and the secondary-to-tertiary turns ratio is 1 to 2.5. The tertiary winding
delivers the LM3001 supply voltage (pins 7 and 12) to the
primary-side driver.

The LM3101 provides the fault protection in case of an output short circuit. During normal operation, the operating frequency of this circuit is determined by a 25 k!1 resistor connected to pin 1 of the LM3101. However, during a short
circuit condition on the output, the frequency of the LM3101
(and the entire circuit operating frequency) drops, yielding a
very low duty cycle. This short-circuit frequency is set by the
13 k!1 resistor connected to pin 5.
The LM3101 Mode Control and Current Mode Input pins
(pins 2 and 6 respectively) are for current mode control operation. The MC pin determines which control mode is being
used-the resistor tied to the supply voltage means voltage
mode control (the resistor tied to ground would indicate current mode control).

There is an internal Overvoltage Threshold circuit (pin 10)
monitoring the input voltage via a resistor divider. The overvoltage trip point is 3.3V typically. With the resistor values
shown, the maximum supply voltage is approximately 17.5V.

START-UP OPERATION

When power is initially applied to the regulator, the LM3001
Primary-Side PWM Driver receives its supply current
through a 75 k!1 resistor connected to the input voltage (see
Figure 7). Once the supply pin voltage reaches the threshold of 11.8V (typical), the LM3001 turns on, sending pulse
signals (with an amplitude of approximately 10V) to the gate
of the power MOSFET. Because the output is driving Power
MOSFETs, which need gate-to-source voltages greater
than 10V for hard turn-on (low ROS(ON»), the threshold voltage of 11.8V was selected to insure sufficient output voltage.

The output rectifier, an SR1606, delivers the secondary current to the output. The SR1606 is specified for 16A forward
current, 60V reverse breakdown voltage, and comes to a
T0220-AB package. Since the SR1606 dissipates 7W to
8W at full load, it requires a heatsink. An RC snubber is
placed in parallel to reduce the ringing voltage caused by
the output rectifier turning off during the discontinous mode
of operation.
Two Cornell Dubilier type 226 470 J-LF, 25V high frequency
capacitors, with low ESRs of 0.25!1, are used as the output
capaCitors.

At the beginning of the start-up process, the secondary side
of the regulator is still unbiased-hence the LM3001 does
not receive a feedback signal from the secondary side (see
the Start-up Sequence in Figure 9). Before the LM31 01 Secondary-Side PWM Controller is controlling the circuit, the
initial operating frequency of the gate drive is determined by
the LM3001 internal oscillator. The oscillator uses an external capacitor and resistor, on pins 14 and 1 respectively.
The initial operating frequency in this case is approximately
500 kHz. During this time, the regulator is operating in a
"free-running" state.
Also during the start-up, the LM3001 executes Soft-Start by
using the Soft-Start capacitor on pin 4. The voltage across
this capaCitor is compared to the oscillator ramp on pin 14
(see the LM3001 block diagram). In the offline regUlator, the
Soft-Start time is 15 J-Ls approximately.
During this time, as the Soft-Start capacitor charges up, the
duty cycle increases with each progressive cycle, until finally the duty cycle reaches its maximum value set by the Duty
Cycle Limit circuit (ROL - pin 2) or the Current Limit circuit
(CLIM - pin 6). The Soft-Start phase ends when the duty
cycle is limited by the ROL circuit. A resistor at this pin connects to an internal current source which together will generate a voltage that will be compared to the oscillator ramp
voltage. This comparison will determine the maximum duty
cycle during this phase of the start-up cycle. For the circuit
in Figure 7, the duty cycle is limited to 63% by the ROL
circuit.

OUTPUT VOLTAGE CONTROL

The output voltage is controlled by the LM3101 SecondarySide PWM Controller. The LM3101 uses its error amplifier to
compare the scaled-down output voltage against the internal precision 1.24V reference voltage. The error amplifier
provides compensation for the regulator frequency response, by way of an RC feedback network.
The resulting error voltage is converted into a pulse-widthmodulated waveform at the system oscillator frequency of
approximately 500 kHz. This waveform is then differentiated
(using an external high-pass RC filter) into a series of positive and negative pulses representing the desired switch
duty cycle.
The pulses are transferred through a pulse transformer to
the LM3001 Primary-Side Driver. The driver takes the feedback pulse signal and converts it into a PWM gate drive for
the Power MOSFET.
FAULT RECOVERY OPERATION

A 0.1670 resistor sets the peak primary current limits to
2.28A for the pulse-by-pulse limiting, and to 3.60A for the
second-level limit. An RC network filters the current limit
voltage to prevent the current limit (pin 6) from being activated by the reverse recovery spike of the output rectifier.
When the second level current limit is triggered, the LM3001
shuts down and discharges the capacitor connected to pin 5
(the Shutdown Delay capaCitor). After the capaCitor is re-

3-172

~------------------------------------------------------------------------------------,

Typical Applications (Continued)
The duty cycle will reach the ROL limit for several cycles,
letting energy build up in the transformer-see the drain current waveform in Figure 9. When the residual energy builds
up enough, the duty cycle starts to decrease because it is
now determined by the CLiM circuit. A voltage of 0.S8V or
greater at this pin will toggle a pulse-by-pulse comparator
on every cycle (see the LMS001 block diagram). In the application circuit, a 0.1670 resistor will generate the current
limit threshold voltage when a 2.28A (peak) current flows
through it. With the CLiM circuit in control of the duty cycle,
the duty cycle will decrease with each successive cycle.
The duty cycle will continue to shrink until the pulse feedback from the LMS101 takes control.

pulse train to the differentiator circuit on pin 8. The resulting
PWM signals are fed back to the LMS001 via the pulse
transformer. The first pulse signal to the LMS001 will cause
it to disconnect its internal oscillator from its PWM and Output Driver circuits and trigger the Output Driver from the
pulse feedback signals (of the LMS101). At this point, control of the frequency and the duty cycle changes from the
LMS001 to the LMS101.

I

I

Q

The method of Soft-Start used by the LMS101 ensures that
the error amplifier is in its linear region before the output
voltage reaches its nominal value, thus yielding a smooth
start-up of the output without any overshoot (see Figure UJj.

LM3001
VSUPPlY
I I

....

The LMS101 also exercises Soft-Start capability (pin S). An
RC network connected to this pin allows the LMS101 to
gradually increase the duty cycle to its nominal value (in the
example, the secondary Soft-Start time delay is 500 /Ls approximately).

As the LMS001 switches the Power MOSFET on and off,
the ,Power Transformer starts delivering power to the secondary side of the circuit. This action will cause the supply
voltage of the LMS101 .and the output voltage to gradually
rise. When the supply voltage reaches the Undervoltage
Lockout Threshold (of S.9V), the LMS101 starts supplying a

OV

rw
==
....

I

I

I

I

I

I

I
I

I
I

I
I
I

I
I

I
I

I
I

LM3001
VOUT
I

I

'DRAIN
OA

LM3101
VSUPPl Y

,
I
I

OV

LM3101 VOUT

OV

I
I

I
I

I

I

-------------------------------------------------------~
-------------------------------------------------------;~LjJ~~
..~rJ--.rJ--I
I

PULSE FB
WAVEFORM
LM3001
PIN INPUT

I
I
I

I
I

I
I

I
I

I
I

I
I

VOUT

(Representative not to scale)

OV

FIGURE 9. Start-Up Timing Sequence

TUH/11436-15

•
S-17S

~

o

~

C")

,-------------------------------------------------------------------------------------,
Typical Applications

(Continued)

:E
-I

~

5V

= lOA

MOSFET PARAMETERS
The peak current through the primary inductance and the
Power MOSFET is the average current when the switch is
on plus one-half the primary inductance ripple current:

-

.....

IpRI(PK) = IIN[TON) '+- (Alp/2) = 1.77A
= 2.18A

I

+ (0.81M2)"

Assuming ideal conditions, the maximum voltage at the
drain of the Power MOSFETwhen the switch is.off is:
VSW(OFF) = (Vo + VF) (Np/Ns) + VIN(MAX)
= (5.7V) (8.5) + 185V = 233V 250V.
However, leakage inductance exists in the transformer,
causing a voltage spike immediately after the switch turns
off. This voltage spike will add to the rest of the drain voltages, making VSW(OFF) even greater. With a leakage inductance that is 2% of the transformer primary inductance and
selecting a switch which has a fall time of 2% the total offtime, the added voltage will be:

TUH/11436-16

Output Voltage, 1VIdiv.
Horizontal Time Base: 500 ,...s/div.
FIGURE 10. Output Voltage Start-up
At the end of the start-up sequence, the circuit i~ in steadystate or normal P\I\IM operation.

Design Procedure

VLL = 2% • Lp .lpRI(PK)· Fo/[2% • (1-D(MAX)1l.
The maximum duty cycle of 28% is used for worst case
purposes. Thus, the leakage inductance voltage spike is:

For the Offline Voltage Mode Flyback Regulator (Figure 7),
the specifications for the power transformer, MOSFET
switch, the switch snubber, and the output rectifier can be
calculated based on the system specifications:
System specifications:
Vo = 5 VDC
VI Range = 90 VAC-132 VAC
10 Range = 0.5A-'10A
Efficiency ('l'/) :::: 80%
Fo = 500 kHz.

VLL = 0.02 • 87 ,...H • 2.18A • 500 kHz/[0.02. (1-0.28)1
= 130V 150V.
This means the actual peak drain voltage Is approximately
400V. When choosing the Power MOSFET, add some margin to this number. A 500V MOSFET was used in this application.

SNUBBER DESIGN

TRANSFORMER SPECIFICATIONS
Manipulating the transfer function of a flyback regulator results in a calculation for the turns ratio of the power transformer, involving the minimum input voltage, the output voltage, and the maximum duty cycle (D):
Vo

+ VF

A "snubber" circuit, consisting of a 1N4937 fast recovery
diode and a parallel RC network, is inserted around the
transformer primary to clamp the voltage spike. This is to
reduce the switch voltage stress when it is off. The "snubber" components are calculated in the following manner:
CSN :;" 0.02 • Lp • Ip(PK)2/(VMAX2 - VSN2)

= (VIN(MIN)-VSW(ON»)· (Ns/Np)·

(D(MAX)/(1-D(MAX)ll

= 0.02 • 87 ,...H • (2.18A)2/ [(255V)2 - (250V)21 :::: 3.3 nF

..j..

and

Ns/Np = [(Yo + VF)/(VIN(MIN)-VSW(ON»)I·
«1-D(MAX»)/D(MAX))
Assume that the diode forward voltage (VF) is about 0.7V
and the drain-to-source voltage when the switch is on
(VSW(ON») is approximately 0.9V. Selecting a 28% maximum
duty cycle results in a turns ratio of:

[(VMAX + VSN - VIN)/21 2 •
[100/(Fo· Lp .lp(PK)2JI
= [(255V + 250V -185V)/21 2 • [100/(500 kHz. 87,...H
• (2.18A)2)1 :::: 12 kG.
In the Offline Flyback Regulator application, a 0.01 ,...F capacitor and a 10 kG resistor are used as the snubber components. VMAX is the selected maximum voltage at the drain
of the MOSFET. Usually the RC values are selected so that
VMAX is 5V to 10V higher than VSN. The power dissipation
of the resistor is:
P = [(VMAX + VSN - VIN)/21 2/R =
[(255V + 250V - 185V)/212/10 kG = 2.56W.

Ns/Np

RSN

= (5.7V/126.1V). (1-0.28)/0.28 = 0.12
(Np/Ns = 8.5/1).

Assuming an efficiency ('l'/) of 80%, the average input current (at the maximum load current and for the entire period)
is:
liN = (Vo)(loll (VIN(MIN) • 'l'/) = (50W)/(127V· 0.80)
= 0.49A.

S;

To add some margin, a 4W resistor is chosen.

The average current when the switch is on is the average
current over the entire period divided by the duty cycle:

The fast recovery diode must have a reverse voltage rating
greater than VMAX. The 1N4937 has a 600V rating.

IIN[TON) = IIN/D = (0.49A)/(0.28) = 1.77A.
Selecting the primary inductance ripple current (Alp) to be a
certain percentage of IIN[TON), and combining that with the
duty cycle, input VOltage, and operating frequency, gives the
primary inductance by the equation:

The peak secondary current can be calculated using the
peak primary current and the turns ratio (thiS equation is for
single output flyback regulators):

OUTPUT DIODE PARAMETERS

ISEC(PK) = IpRI(PK)· (Np/Ns) = 2.18A·
8.5 = 18.43A 20A.

Lp = (VIN(MIN)-VSW(ON»). D(MAX)/ (Alp. Fo)
Assuming the percentage to be 46% in the example, then:
Lp = 126.1 V • 0.28/(0.81 A • 500 kHz) "" 87 ,...H.
3·174

Typical Applications (Continued)
exceptions are the power transformer, in which the turns
ratio and primary inductance has changed (due to the
change in the input voltage range), and the Power MOSFET, which has a lower on-resistance and a lower breakdown voltage rating.
The most significant difference in the circuit design is the
change in the mode of operation-from voltage mode to
current mode. For current mode operation, the LM3101
Mode Control pin (MC-pin 2) is connected to ground by a
6 kD. resistor, and the Control Mode pin (CMI- pin 6) is
connected to the current sense transformer through a halfwave rectifier circuit and a low-pass filter. The filter is needed to remove the leading edge spike on the current waveform, caused by the rectifier recovery and interwinding capacitance of the power transformer.

The maximum average current through the secondary and
the diode, when the switch is off, is the maximum load current divided by the inverse of the duty cycle:
ISEC(OFF) = ILOAD/(1-D(MAX)) = 10AlO.72
= 13.90A ::::: 15A.
The maximum average secondary current for the entire period is the maximum load current (10A).
The maximum reverse-bias voltage on the output rectifier is:
VRV = VIN(MAX) • (Ns/Np) + Vo + VF =
(185V) (1/8.5) + 5.7V = 27.47V ::::: 30V.
A suitable diode for this circuit is the SR1606, which has a
reverse voltage rating of 60V and an average current rating
of 16A.

Telecom Converter

Smaller component differences include reducing the current
sensing resistor in the primary side ground path (to allow for
the larger primary current), and removing a primary side
snubber circuit (due to smaller peak voltages at the drain).
Also, the output rectifier and Power MOSFET snubbers are
modified.

The schematic of a flyback regulator, used in Telecom applications, is shown in Figure 11. The circuit has many of the
component values that are in the offline converter. Notable

+3~D~72

0-,---....,------....,----,

620pF

10n

2k
200pF

13k

Vs

Rsc
13
FB

LM3001
PRIMARY
DRIVER
910pF

t--'MrlRoL

3.0k

LM3101
SECONDARY
CONTROLLER

1k

CLiM ~_---llJII'.---+

1.
EAO
0.001 }.'F

3
SfST

34.5k

Rr
1

RtnO-----+

'5.3k
25k

200n
60k

TLlH/11436-17

FIGURE 11. Telecom Current Mode Flyback Regulator

3-175

&I

~ ~-----------------------------------------------------------------------------------------,

CI
~

C")

~

Application Hints
LM3101
OSCILLATOR
RAMP.
ERROR
AMP
OUTPUT

Pulse Feedback Se~t,.on
During steady-state operation, tile LM3101 delivers pulsewidth modulated signals to the feedback circuil The feedback circuit will convert that signal into a series of AC-coupled pulse signals and apply them to the LM3001 via the
pulse transformer (the first positive-edged pulse from the
LM3101 will cause the LM3001 to disconnect its internal
oscillator from its' PWM and Output Driver circuits). The
feedback pulses wili trigger the LM3001 Output ,Driver to
apply PWM drive signals to the Power MOSFET gate. The
timing diagram' iii Figure 12 demonstrates the feedback
communication.
.
'

LM3101
PWM
COMPo
OUTPUT

1
1

1
1

1 1
1 1

1 1
1 1

1

1

1 1

1 1

1 1

1 1

1 1

1 1

,I
1

1
1

1
1

1
1

I' 1

LM3101
VOUT
PULSE Fa
WAVEFORM
(LM3001
PIN INPUT)

Pulse Interface Circuit,

',I
1

The pulse interface circuit provides isolation for the feedback circuit of the Offline Flyback Regulator. The differentiator circuit converts .the PWM waveform into, a pulse train.
Th,e differentiator delivers a train of 1VPK, .15 ns wide pulses
to the pulse transformer. The core should have high permeability (typically 10,000) at the switching frequency to allow
the transfer of energy with a very small transformer (Size).
This one-to-one transformer transfers the pulse train to the
LM3001 via a 200n resistor, which is used mainly to filter
noise from the system.

1

1

1

LM3001
VOUT

TL/H/II436-1B

FIGURE 12. Pulse Feedback Timing Diagram

IOns :S T :S 95 J .....yy'lr-4~

'0

lOa p.A/V

-v

-v

FIGURE 2. LM3411 Test Circuit

3-182

TL/H/11987-14

Applications Information
Input Voltage

+lOV to +20V

51k

Regulated
Output
+5V, 250 mA

Opto-coupler

4N28
TL/H/11987-15

FIGURE 3. Isolated 250 mA Flyback Switching Regulator
100

2 nF

Regula.ted
Output

L--oQ---O---~

_ _ _-+-__-£jComm.

470k
0.47 JAF

In
200
TUH/11987-16

FIGURE 4. Isolated 1.5A Flyback Switching Regulator Using a LM2577
An isolated DC/DC flyback converter capable of higher output current is shown in Figure 4. This circuit utilizes the
LM2577 SIMPLE SWITCHERTM voltage regulator for the
Pulse Width Modulation (PWM), power switch and protection functions, while the LM3411 provides the voltage reference, gain and opto coupler drive functions. In this circuit,
the reference and error amplifier in the LM2577 are not
used (note that the feedback pin is grounded). The gain is
provided by the LM3411. Since the voltage reference is located on the secondarY side of the transformer, this circuit
provides verY good regulation specifications.

The LM3411 regulator/driver provides the reference and
feedback drive functions in a regulated power supply. It can
also be used together with many different types of regulators. (both linear and switching) as well as other power
semiconductor devices to add precision and improve regulation specifications. Output voltage tolerances better than
0.5% are possible without using trim pots or precision resistors.
One of the main applications of the LM3411 is to drive an
opto-isolator to provide feedback signal isolation in a
switching regulator circuit. For low current applications, (up
to 250 mAl the circuit shown in Figure 3 provides good regulation and complete input! output electrical isolation.
For an input voltage of 15V, this circuit can provide an output of either 3.3V or 5V with a load current up to 250 mA
with excellent regulation characteristics. With the part values shown, this circuit operates at 80 kHz., and can be synchronized to a clock or an additional LM3578. (See LM1578
data sheet for additional information.)

The output of a switching regulator typically will contain a
small ripple voltage at the switching frequency and may also
contain voltage transients. These transient voltage spikes
can be sensed by the LM3411 and could give an incorrect
regulation voltage. An RC filter consisting of a 1n resistor
and a 100 nF capaCitor will filter these transients and minimize this problem. The 1n resistor should be located on the
ground side of the LM3411, and the capaCitor should be
physically located near the package.

3-183

&I

-

_r---------------------------------------------------------------------~

~

Applications Information

:=I

Input
+7V

+VIN

(Continued)

r"7':::::::-~~---:-:-:--:7--_,

to - ....---1
+40V
L;::.:.~t""-'--r

Output +5V, lA

~---r----------------~
51 k

+ 47
JLF

4.7
nF

470

+_-1

JLF "'_ _

lN5818

4.7k

TL/H/11987-17

FIGURE 5. Precision 1A Buck Regulator
lN5819

Output

+VIN
Lt.f2575-Adj

470

JLF

GND Fe

ON/OFF
+

0.1

47

IN

JLF

5819

JLF

.

Output
L~_j__..:=tti===~=~~:::~RgUlat.d
-5V, lA

47

lk

lk

JLF
-10V

to -20V
TLlH/11987-18

FIGURE 6. Negative Input, Negative or Positive Output Flyback Regulator
Improved output voltage tolerance and regulation specifications are possible by combining the LM3411 A with one of
the SIMPLE SWITCHER buck regulator IC's, such as the
LM2574, LM2575, or LM2576. The circuit shown in Figure 5
can provide a 5V, ± 0.5% Output (1 % over the operating
temperature range) without using any trim-pots or precision
resistors. Typical line regulation numbers are a 1 mV
change on the output for a 8V -18V change on the input,
and load regulation of 1 mV with a load change from
100 mA-1A.

negative or a positive output voltage. Although no isolation
is provided, with the addition of an opto-isolator and related
components, this circuit could provide input/output isolation.
Combining a LM3411 A-5.0 with a 1A low dropout linear regulator results in a 5V ±0.5% (1 % over the operating temperature range) regulator with excellent regulation specifications, with no trimming or 1 % resistors needed.
An added benefit of this circuit (and also true of many of the
other circuits shown here) is the high-side and low-sideremote output voltage sensing feature. Sensing the output
voltage at the load eliminates the voltage drops associated
with wire resistance, thus providing near perfect load regulation.
A 5V, 1A regulator circuit featuring low dropout, very good
regulation speCifications, self protection features and allows
output voltage sensing is shown in Figure 7. The regulator
used is a LM2941· adjustable low dropout positive regulator,
which also features an ON/OFF pin to' provide a shutdown
feature.

A DC-DC flyback converter that accepts a negative input
voltage, and delivers either a positive or negative output is
shown in Figure 6. The circuit utilizes a buck regulator (such
as the LM2574, LM2575, or LM2576, depending on how
much output current is needed) operating in a flyback configuration. The LM3411 provides the reference and the required level shifting circuitry needed to make the circuit
work correctly.
A unique feature of this circuit is the ability to ground either
the high or low side of the output, thus generating either a

3-184

r-

a:
olio
.....
.....

Applications Information (Continued)

Co)

Output
Voltage

+5V

lA

1 nF

+

22

J.lF

TL/H/11987-19

FIGURE 7. Precision 5V 1A Low Dropout Regulator
+VIN

04105

--~~~-1~-.

0.1

J.lF

Output +3.3V

increased and features are added. The circuit shown in Figure 9 provides much improved line and load regulation, lower temperature drift, and full remote output voltage sensing
on both the high and low side. In addition, a precise current
limit or constant current feature is simple to add.

r-------------~~500mA

(+l IN

Current limit protection in most IC regulators is mainly to
protect the IC from gross over-current conditions which
could otherwise fuse bonding wires or blow IC metalization,
therefore not much precision is needed for the actual current limit values. Current limit tolerances can sometimes
vary from ± 10% to as high as + SOO% over manufacturing
and temperature variations. Often critical circuitry requires a
much tighter control over the amount of current the power
supply can deliver. For example, a power supply may be
needed that can deliver 100% of its design current, but can
still limit the maximum current to 110% to protect critical
circuitry from high current fault conditions.

I nF

TL/H/11987-20

FIGURE 8. 3.3V O.5A Low Dropout Regulator
The circuit in Figure 8 shows a S.SV low dropout regulator
using the LMS411-S.S and several discrete components.
This circuit is capable of excellent performance with both
the dropout voltage and the ground pin current specifications improved over the LM2941/LMS411 circuit.
The standard LMS17 three terminal adjustable regulator circuit can greatly benefit by adding a LMS411. Performance is

The circuit in Figure 9 can provide a current limit accuracy
that is better than ± 4 %, over all possible variations, in addition to having excellent line, load and temperature specifications.

Output
Voltage +5V

1.25

~~~~~------------------~jQ ICL=-R-s-

-...,......

TLlH/11987-21

FIGURE 9. Precision Positive Voltage Regulator with Accurate Current Limit

3·185

I

Applications Information

V+

(Continued)
Like the positive regulators, the performance of negative
adjustable regulators can also be improved by adding the
LM3411. Output voltages of either 3.3V or 5V at currents up
to 1.5A (3A when using a LM333) are p()ssibie: Adding two'
resistors to the circuit in Figure 10 adds the precision current limit feature as shown in Figure 11. Current limit'-tolerances of ± 4 % over manufacturing and temperature variations are possible with this circuit. '

100 k >~I-"VV'o"...---t

lOOk

TUH/11987-25

FIGURE 13. ±50 mV External Trim
+

The LM3411 is guaranteed to drive a 15 mA load, but if
more current is needed, a NPN boost transistor can be added. The circuit shown in Figure 14 is a shunt regulator capable of providing excellent regulation over a very wide range
of current.

1 J'f
tan\.

V+

Output
I-------~ Voltage
-5V, 1.5A
, TL/H/11987-22

. - - - - - - - - - +5V

FIGURE 10. Preclsi,on Negative Voltage Regulator ,

1 }'F
300pF

-sv \0

Heat
Sink

tanto

,I--'IIVv-_--------"l)

-20V

-5V
Output Voltage

1.25

'CL:=T

TUH/II987-28

FIGURE 14. 250 mA Shunt Regulator

.

TL/H/II987"23

Perhaps one of the simplest applications for the LM3411 is
the vllitage detector circuit shown in Figure 15. The OUT pin
is low when the input voltage is less than VREG. When the
V(IN) pin rises above VREG, the OUT pin is pulled high by
the internal NPN output resistor.

FIGURE 11. PreclslonNegathie Voltage
'Regulator with Accurate CUrrent Limit
A simple 5V supply monitor circuit is shown in Figure 12.
Using the LM3411's voltage, reference, op:amp (as a, comparato~) and output driver, thi.s circuit provides a LED indi~­
tion of the presence of the 5V supply.

v+---,

V+

t-....-Output

100 mV Hysteresis

TL/H/II987-27

FIGURE 15. Voltage Detector

1.06t.!

2N2222

Also an overvoltage detector, the crowbar circuit shown in
Figure 16 is normally located at the output of a power supply
to protect the load from an overvoltage condition should the
power supply fail with an input/output short.

560

Ci rcu it Breaker

TL/H/11987 -24

FIGURE 12. 4.7V Power ON Detector with Hysteresis
The LM3411 initial room temperature tolerance is ±1 % ",nd
± 0.50/0 for the "An grade part. If a tighter tolerance is needed, a trim scheme is shown in Figure 13 that provides approximately ± 1 % adjustment range of the regulation voltage (VREG).

SCR

TUH/11987-28

FIGURE 16. Overvoltage Crowbar

3-186

Schematic Diagram
~~--~------~-----1~------'----1~---1~--~--------~----'--'---1~------~---1~[]+IN

Rl
30.75k

OONP.[]--+-----------t-~~_i

R15
lk

GNO[]--'_------------'_------------~--~~--------'_------------~

L..__.....__________....-I'] OUT

TL/H/11987-29

•
3-187

~ r-----------------------~--------------------------------------------_,

....

~

tfI Nat ion al S e m

i con

rJ ,U c tor

LM431A

Adjustable Precision Zener Sh,unt Regulator
General Description

Features

The LM431A is a 3-terminal adjustable shunt regulator with
guaranteed temperature stability over the entire temperature range 6f ope~ation. The output voltage may be se1 at
any level greater than 2.5V (VREF) up to 36V merely by
selecting two external resistors that act as a voltage divided
network. Due to the sharp turn-on characteristics this device
is an excellent replacement for many zener ,diode applications.

• Average temperature coefficient 50 ppml"C
• Temperature compensated for operation ,over the full
temperature range
'
• Programmable output voltag!'l
• Fast turn-on response
• Low outpu1' noise

Connection Diagrams

I

REF

II

8 ~REFERENC£

CATHODE- 1

3

2

ANODE II

I

2

7 I-ANODE

ANODE- 3

~-"-r'-SL CATHODE

6 I-ANODE

'NC- 4

51-NC
TUH/l0055-2

ANODE
TL/H/l0055-1

Top View

Top View
Order Number LM431ACM or LM431AIM
See NS Package Number MOBA

Order Number LM431ACZ or LM431AIZ
See NS Package Number Z03A

3-188

Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Storage Temperature Range
-65'Cto + 150'C
Operating Temperature Range
Industrial (LM431AI)
-40'Cto +B5'C
Commercial (LM431AC)
O'Cto +70'C
Lead Temperature
TO·92 Package/SO·B Package
(Soldering, 10 sec.)
265'C
Internal Power Dissipation (Notes 1, 2)
TO·92 Package
0.7BW
SO·B Package
0.B1W

Cathode Voltage
37V
Continuous Cathode Current
-10mAto +150mA
-0.5V
Reference Voltage
10mA
Reference Input Current
Operating Conditions
Min
Max
Cathode Voltage
37V
VREF
1.0mA
100mA
Cathode Current
Note t: TJ Max = 150'C.
Note 2: Aatlngs appy to ambient temperature at 25'C. Above this tempera·
ture, derate the TO·92 at 6.2 mWI'C, and the SO·8 at 6.5 mW I'C.

LM431A
Electrical Characteristics TA = 25'C unless otherwise specified
Symbol

Parameter

VREF

Reference Voltage

VOEV

Deviation of Reference
Input Voltage Over
Temperature (Note 3)

Min

Typ

Max

Units

2.440

2.495

2.550

V

B.O

17

mV

Vz from VREF to 10V

-1.4

-2.7

Vz from 1OV to 36V

-1.0

-2.0

Conditions

= VREF, I, = 10 mA (Figure 1)
Vz = VREF, I, = 10 mA,
TA = Full Range (Figure 1)
Vz

Ratio of the Change in
Reference Voltage to the
Change in Cathode
Voltage

Iz = 10mA
(Figure 2)

IREF

Reference Input Current

RI = 10 ko., R2 = 00,
I, = 10mA(Rgure2)

2.0

4.0

",A

cclREF

Deviation of Reference
Input Current over
Temperature

RI = 10 ko., R2 = 00,
I, = 10mA,
T A = Full Range (Figure 2)

0.4.

1.2

",A

Minimum Cathode Current
for Regulation

Vz

= VREF (Figure 1)

0.4

1.0

mA

Vz

= 36V, VREF = OV (Figure 3)

0.3

1.0

",A

AVREF
AVz

IZ(MIN)

Off·State Current

IZ(OFF)

mVIV

.

Dynamic Output
Vz = VREF,
0.75
0.
Impedance (Note 4)
Frequency = 0 Hz (Rgure 1)
Note 3: Deviation of reference Input voltage, VOEV, Is defined as the maxi·
The average temperature coefficient of the reference input voltage, ",VREF,
mum vartaUon of the reference Input voltage over the full temperature range.
i. defined as:

rZ

VIIAX -

VUltl

7
'"

± [ VMax - VMin ]
±[
VOEV
]
",VREF ppm =
VREF (at 25'C) 106 =
VREF (at 25'C) 106
'C
T2-Tl
T2-Tl
Where:
T2 - T1 = full temperature change.
'" VREF can be posiOVe or negative depending on whether the slope is posi·
tive or negative.

Example: VOEV = 8.0 mV, VREF = 2495 mV, T2 - T1 = 70'C, slope is
posijive.

I

VDEV

=VIIAX -

VIlIN

I
I
I
I
I

[ B.OmV ]
",VREF =

TEIotPERATURE

70'C

106

+46ppm/'C

Note 4: The dynamic output impedance, rz, is defined as:
rz = AVz
Alz
When the device Is programmed with two external resistors, AI and A2, (see
Figure 2), the dynamic output Impedance of the overall circuit, rz, Is defined
as:

I
1t

2495riiV

12
TLlH/l0055-7

AVz [ rzl+AI]
rz=-"
Alz
A2

3·1B9

Equivalent Circuit
, . . - - - - - - - - - - - - - - -....___4p-___4p--_p-- CATHODE
(Vi)

R3
2.5k~

R5

R2

R1

6"O~

1.0k~

3.3~

L------.....________4......- - - - _.....- -.....-

ANODE
(GND)
TL/HI10055-3

DC Test Circuits
1,..,..-

IN -'~W\r-""'- Vz

IN -""""VIr~~- Vz

TL/H/10055-4

TL/H/10055-5

FIGURE 1. Test Circuit for Vz = VREF

Note: Vz

= VREF (1 +

+ 'REF. R1
FIGURE 2. Test Circuit for Vz > VREF
R1/R2)

TL/H/10055-6

FIGURE 3. Test Circuit for Off·State Current

3·190

Typical Performance Characteristics
Input Current vs Vz
TA
500 Vz

~

150

Input Current vs Vz
TA
Vz

I
~

300

C>

:>

I

200

kI

0
0

Thermal Information

z

/IzYIN

100

1000

I

~«XJ

I

~

=250C
=vREF

z

~

1.0

~.
~

500

!i!
8
!!!

II

::II

lD

2.0

il

r-...

,

I

100

I

50

~

=250C
=VREF

i!!O

100
25

70

CATHODE VOLTAGE - V

0
0

125

85

ID

lD

2.0

CATHODE VOLTAGE - V
TLiH/l0055-8

TEYPERAnJRE - OC

Dynamic Impedance vs
Frequency
15

"

TA
Vz

=250(;
=VREF

I""'\.

1.0k~

I

~
~

i!

"

I

~~

10

5D

/

0
l.ok

/

50~

-'i'-

!z=
I

l.oy
10k
lOOk
FREQUENCY - Hz

""

•

•

10 mA

-:.:
-

lOY

TLiH/l0055-l0

TL/H/l0055-9
Note 1: The areas under the curves represent conditions that may cause the

Stability Boundary Conditions
100

90

....E
I
l-

....
'"'"::>u

:z

....
c
0
::t:

5

=VREF I
=5 V AT IZ =10 mA
=10V AT IZ =10mA
D Vz = 15 V AT IZ = 10 mA
A Vz
B Vz

(NOTE I)

80 C Vz
70

STABLE

i

60

A

50

B

",C

I

STABLE

40
30
20

TA

10

"

=25°C

l00pF

I

V

IIJ L

1\

D

V// r-.;~ \\

0
10pF

device to oscillate. For curves B. C. and D. R2 and V+ were adjusled to
establish the initial Vz and Iz conditions with CL = O. V + and CL were then
adjusted to determine the ranges of stability.

l000pF

O.D1pE

O.lpE

lpE

lOpE

LOAD CAPACITANCE
TLiH/l0055-ll

Test Circuit for Curve A Above

-l rr- r-

'K
CL :::

r:

'-:

-b
-

Test Circuit for Curves B, C and D Above

150.11

Rl ...

!,

~

~

CL';r:

VREF
R2 ),

olf

..

-l'K
I""":
....-r--

10k~

150.11

;-; ~V+
-b
-

TLlHI10055-l2

3-191

TL/H/l0055-l3

C
.,..
CO)

•~

r--------------------------------------------------------------------,
Typical Applications
Single Supply Comparator with
Temperature Compensated Threshold

Shunt Regulator

V+

V+--~~-.--~~~-----.,-----VO
I
I
I

..,..,

..L

,,
,,

....--'-OUT
IN ......W,.,.....-t...
VTH ... 2.5V

Tl/H/l0055-14 ..

'VON"" 2V
VOFF V+

=

--~----~~----GND

TUH/l0055-15

Series Regulator

~----.-------------------------..,

Output Control of iI Three
Terminal Fixed Regulator

V+------....,
IN
LM7805

OUT

t-...--- Vo

COMMON

TUH/l0055-16

Vo ,= ( 1 +
Vo MIN

3·192

~) VREF

= VREF +

5V

TUH/l0055-17

~------------------------------------------------------------------------------------~

Typical Applications (Continued)

~

Higher Current Shunt Regulator

CrowBar

V+--~~~~----~--------t----Vo

:J>

V+
R1

R2

TL/H/l0055-18

TLlH/l0055-19

VLlMIT:::: ( 1

+ ~)VREF

Over Voltage/Under Voltage
Protection Circuit
V+--~~-----------'-----'-------,

R1A

R1B

R2B

R2A

TLlH/l0055-20

R1B)
LOW LIMIT:::: VREF ( 1 + R2B
HIGH LIMIT:::: VREF ( 1

+ veE

R1A)
+ R2A

Voltage Monitor
V+--~------------t-~~~~--,

R1A

R1B

R2A

R2B

TLlHI10055-21

R1B)

LOW LIMIT:::: VREF ( 1

+ R2B

HIGH LIMIT:::: VREF ( 1

+ R1A)
R2A

r-

s:::
w
.....

LED ON WHEN
LOW LIMIT < V+ < HIGH LIMIT

3·193

~

..C")
~

~

.--------------------------------------------------------------------,
Typical Applications (Continued)
Delay Timer

Current Limiter or Current Source

v+-....--+.....

10

TUH/l0055-23
10 = VREF

RCL

TL/H/l0055-22

Constant Current Sink

v+

TL/H/l0055-24

3·194

r-------------------------------------------------------------------------.r

s:
.....
co

tflNational Semiconductor

en
0l:Io

(;)

LM78S40
Universal Switching Regulator Subsystem
General Description

Features

The LM78S40 is a monolithic regulator subsystem consisting of all the active building blocks necessary for switching
regulator systems. The device consists of a temperature
compensated voltage reference, a duty-cycle controllable
oscillator with an active current limit circuit, an error amplifier, high current, high voltage output switch, a power diode
and an uncommitted operational amplifier. The device can
drive extemal NPN or PNP transistors when currents in excess of 1.5A or voltages in excess of 40V are required. The
device can be used for step-down, step-up or inverting
switching regulators as well as for series pass regulators. It
features wide supply voltage range, low standby power dissipation, high efficiency and low drift. It is useful for any
stand-alone, low part count switching system and works extremely well in battery operated systems.

iii
II

II
g

II
•
•
111

Step-up, step-down or inverting switching regulators
Output adjustable from 1.25V to 40V
Peak currents to 1.5A without external transistors
Operation from 2.5V to 40V input
Low standby current drain
80 dB line and load regulation
High gain, high current, independent op amp
Pulse width modulation with no double pulsing

Block and Connection Diagrams
COMPARATOR
+IN

COMPARATOR
-IN

TIMING
CAPACITOR

DRIVER
SWITCH
COLLECTOR COLLECTOR

16-Lead DIP
DIODE
CATHODE
DIODE
ANODE
SWITCH

16
15

"

OP AWP OUT
OP AI.IP
SUPPLY

OP AMP
+IN

OP AMP
SUPPLY

OP AMP
OUT

---on-oj

SWITCH
EMInER

DIODE
ANODE

DIODE
CATHODE

TLlH/l00S7-2

Ordering Information
Part Number

NS Package

Temperature Range

LM78S40J/883

J16A Ceramic DIP

-55'Cto + 125'C

LM78S40N

N16E Molded DIP

-40'Cto + 125'C

LM78S40CN

N16E Molded DIP

O'Cto +70'C

3-195

V'N
TIMING CAPACITOR

OP AMP +IN

GND

OP AMP -IN
REFERENCE

CO!.lPARATOR -IN
COMPARATOR +IN

VOLTAGE

OP AMP
-IN

DRIVER
COLLECTOR
IpK SENSE

EMlnER

REFERENCE
VOLTAGE

SWITCH
COLLLECTOR

TL/H/l00S7-1

Top View

Absolute Maximum Ratings
Common Mode Input Range
(Comparator and Op Amp)
Differential Input Voltage
(Note 3)
Output Short Circuit
Duration (Op Amp)
Current from VREF
Voltage from Switch
Collectors to GND
Voltage from Switch
Emitters to GND
Voltage from Switch
Collectors to Emitter
. Voltage from Power Diode to GND
Reverse Power. Diode Voltage
Current through Power Switch
Current through Power Diode
ESD Susceptibility

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.

Storage Temperature Range
Ceramic DIP
Molded DIP
Operating Temperature Range
Extended (lM78S40J)
Industrial (lM78S40N)
Commercial (lM78S40CN)
lead Temperature.
Ceramic DIP (Soldering, 60 sec.)
Molded DIP (Soldering, 10 sec.)
Internal Power Dissipation (Notes 1, 2)
16l·Ceramic DIP
16l-Molded DIP
Input Vol1!ige from VIN to GND
Input Voltage from V+ (Op Amp) to GND

-65'C to + 175'C
-65'Cto + 150"C
-55'Cto + 125'C
-40'Cto + 125'C
O'Cto +70"C
300"C
265'C
1.50W
1.04W
40V
40V

-0.3toV+
±30V
Continuous
10mA
40V
40V
40V
40V
40V
1.5A
1·5A
(to be determined)

LM78S40
Electrical Characteristics
TA = Operating temperature range, VIN = 5.0V, V+(Op Amp) = 5.0V, unless otherwise specified. (Note 4)

SY~bOI

I

Parameter

I

Conditions

I Min I Typ I Max I Unlta

GENERAL CHARACTERISTICS

Icc
Icc

Supply Current
(Op Amp Disconnected)
Suppiy Current
(Op Amp Connected)

= 5.0V
= 40V
VIN = 5.0V
VIN = 40V
VIN

1.8

3.5

mA

VIN

2.3

5.0

mA

4.0

mA

5.5

mA

1.245

1.310

V

REFERENCE SECTION

VREF

Reference Voltage

IREF

= 1.0mA

Extend - 55'C <; TA < + 125'C,
CommO < TA < +70"C,
Indus -40"C < TA < +85'C

1.180

VRLlNE·

Reference Voltage
Line Regulation

VIN' = 3.0V to VIN = 40V,
IREF = 1.0mA, TA = 25'C

0.04

0.2

mVlV

VRLOAO

Reference Voltage
load Regulation

IREF = 1.0mAtoiREF
TA = 25'C

0.2

0.5

mV/mA

= 10mA,

OSCILLATOR SECTION

= 5.0V, TA = 25'C
= 40V, TA = 25'C
VIN = 5.0V, TA = 25'C
VIN = 40V, TA = 25'C
VIN = 5.0V, TA = 25'C

ICHG

Charging Current

VIN

20

50

p.A

ICHG

Charging Current

VIN

20

70

p.A

iOISCHG

Discharge Current

150

250

p.A

iOISCHG

Discharge Current

150

350

p.A

VOSC

Oscillator Voltage Swing

ion/tOil

Ratio of Charge/
Discharge Time

3-196

0.5

V

6.0

p.s/p.s

LM78S40
Electrical Characteristics (Continued)
TA = Operating Temperature Range, VIN = 5.0V, V+(Op Amp) = 5.0V, unless otherwise specified. (Note 4)
Parameter

Symbol I

Conditions

I

I

Min

I Typl

Max

I Units

I

250

I

350

I mV

CURRENT LIMIT SECTION
VCLS

I Current Limit Sense Voltage

ITA = 25'C

I

OUTPUT SWITCH SECTION
VSAT1

Output Saturation Voltage 1

Isw = 1.0A(FiguffJ 1)

1.1

1.3

V

VSAT2

Output Saturation Voltage 2

Isw = 1.0A (Figure 2)

0.45

0.7

V

hFE

Output Transistor Current Gain Ic = 1.0A, VCE = 5.0V, TA = 25'C

70

IL

Output Leakage Current

10

Va = 40V, TA = 25'C

nA

POWER DIODE
VFO

Forward Voltage Drop

Diode Leakage Current
lOR
COMPARATOR

1.25

10 = 1.0A
Vo = 40V, TA = 25'C

10

1.5

V
nA

Via

Input Offset Voltage

VCM = VREF

1.5

15

liB

Input Bias Current

VCM = VREF

35

200

nA

110

Input Offset Current

VCM = VREF

5.0

75

nA

VCM

Common Mode Voltage Range TA = 25'C

0

PSRR

Power Supply Rejection Ratio

70

VIN = 3.0V to 40V, TA = 25'C

VIN-2

96

mV

V
dB

OPERATIONAL AMPLIFIER
Via

Input Offset Voltage

VCM = 2.5V

4.0

15

mV

liB

Input Bias Current

VCM = 2.5V

30

200

nA

110

Input Offset Current

VCM = 2.5V

5.0

75

nA

Avs+

Voltage Gain+

RL = 2.0 kO to GND;
Va = 1.0Vt02.5V, TA = 25'C

25

250

VlmV

Avs-

Voltage Gain-

RL = 2.0 kO to V+ (Op Amp)
Va = 1.0Vt02.5V, TA = 25'C

25

250

VlmV

VCM

Common Mode Voltage Range TA = 25'C

0

CMR

Common Mode Rejection

VCM = OVt03.0V, TA= 25'C

76

100

Vcc- 2

V
dB

PSRR

Power Supply Rejection Ratio

V+ (OpAmp) = 3.0Vt040V, TA = 25'C

76

100

dB

10+

Output Source Current

TA = 25'C

75

150

mA

10

10-

Output Sink Currerit

TA = 25'C

SR

Slew Rate

TA = 25'C

VOL

Output Voltage LOW

IL = -5.0 mA, TA = 25'C

VOH

Output Voltage High

IL = 50 mA, TA = 25'C

35

mA

0.6

V//J-s
1.0

V+ (Op
Amp) - 3V

V
V

Note 1: TJ Max = 150"C for the Molded DIP, and 175'C for the Ceramlc.DIP.
Note 2: Ratings apply to ambient temperature at 25"'C. Above this temperature, derate the 16L-Ceramlc DIP at 10 mWrC, and the 16L-Molded DIP at 8.3 mW/'C.
Note 3: For supply voltages I.ss than 30V, the absolute maximum voltage Is equal to the supply voltage.
Note 4: A military RETS specification Is available on request. At the time of printing, the LM78S40 RETS specffication complied with the Min and Max limits in this
table. The LM78S40J may also be procured as a Standard Military Drawing.

3-197

Typical Performance Characteristics
,',

Reference Voltage vs
Junction Temperature

CT vs OFF Time
470

"

VI =5.0V
- TA =250(:

'li.I

...zu

47

~

:

(j

4.7,

0.47

/
I{

1.0

V

V

/

1.220

/

\

1.218
>1.216

..

VI = 5.0V

-

\.

~1.214

S1.212

~1.210
~1.208

~1:W6
~1.204

10

100

1.202
1.200
-75 -50 -25 0 25 50 75 100 125
JUNCTION TEMPERATURE - 0(:

1000

OFF TIME- J.lS

TL/H/10057-7

TLlH/10057-6

Current Limit Sense
Voltage vs Input Voltage

Discharge Current vs
Input Voltage
250

>350

1/

...is
...'"0

I-TA=250(:

/

1I
8l

400

/

f- TA =250(:

E

",
200

I
1=
:2

f-

:3300

",

15

'"~

--

.....

'"
'"
0250

u
en
Q

150

0

10

30
20
40
INPUT VOLTAGE - V

200

50

0

10

20
40
30
INPUT VOLTAGE - V

TLlH/1 0057-8

sO
TL/H/10057-9

Design Formulas
Characteristic

Step-Down

Step-Up

Inverting

ton

Vo + Vo
VI- VSAT - Vo

Vo +,Vo - VI
VI- VSAT

Ivol + Vb
VI- VSAT

loll
(ton + toll) Max

-1

-

1Min
CT

4X10- 5 ton

Ipk

2 lOMax

21

1

-1

1Min

1MIN

4 X 10-5 ton

4 X 10- 5 ton

ton + toll
o Max e - - toll

21

o Max

e ton +lo11
toll

Units

p.s
p.F

A

LMin

(VI- VSAT- Vo)
I
ton Max
pk

(VI- VSAT)
I
Ion Max
pk

(VI- VSAT)
I
ton Max
pk

p.H

,Rse

O.~3I1pk

0.3311 pk

0.3311 pk

n

Co

Ipk (Ion + toll)

:::::~elon

8V'ipPIe

Vripple

Note: VSAT = Saturation voltage of the switching element
Vo = Forward voltage of the flyback diode,

3-198

10

:::::--eton
V'ipple

p.F

Functional Description

Typical Applications

SWITCHING FREQUENCY CONTROL

VI
25V

The LM7BS40 is a variable frequency, variable duty cycle
device. The initial switching frequency is set by the timing
capacitor. (Oscillator frequency is set by a single external
capacitor and may be varied over a range of 100 Hz to
100 kHz). The initial duty cycle is 6: 1. This switching frequency and duty cycle can be modified by two mechanisms-the current limit circuitry (Ipk sense) and the comparator.
The comparator. modifies the OFF time. When the output
voltage is correct, the comparator output is in the HIGH
state and has no effect on the circuit operation. If the output
voltage is too high then the comparator output goes LOW.
In the LOW state the comparator inhibits the turn-on of the
output stage switching transistors. As long as the comparator is LOW the system is in OFF time. As the output current
rises the OFF time decreases. As the output current nears
its maximum the OFF time approaches its minimum value.
The comparator can inhibit several ON cycles, one ON cycle or any portion of an ON cycle. Once the ON cycle has
begun the comparator cannot inhibit until the beginning of
the next ON cycle.
The current limit modifies the ON time. The current limit is
activated when a 300 mV potential appears between lead
13 {Vee> and lead 14 (Iplll. This potential is intended to result when designed for peak current .flows through Rse.
When the peak current is reached the current limit is turned
on. The current limit circuitry provides for a quick end to ON
time and the immediate start of OFF time.
Generally the oscillator is free running but the current limit
action tends to reset the timing cycle.

Rsc
O.33tl

Cr

0.01 JAF

1.-

q=__ _

____ __L

Vo
10V
L
300J.'H

R2
12k.o.

Rl

Co
1500JAF

85k.ll
":'

Increasing load results in more current limited ON time and
less OFF time. The switching frequency increases with load
current.

'='
TL/H/l0057-3

FIGURE 1. Typical Step-Down Regulator and
Operational Performance (TA = 25°C)

USING THE INTERNAL REFERENCE, DIODE, AND
SWITCH
The internal 1.245V reference (pin 8) must be bypassed,
with 0.1 IlF directly to the ground pin (pin 11) of the
LM78S40, to assure its stability.

Characteristic

VFO is the forward voltage drop across the internal power
diode. It is listed on the data sheet as 1.25V typical, 1.5V
maximum. If an external diode is used, then its own forward
voltage drop must be used for VFO.
VSAT is the voltage across the switch element (output transistors 01 and 02) when the switch is closed or ON. This is
listed on the data sheet as Output Saturation Voltage.
"Output saturation voltage 1" is defined as the switching
element voltage for 02 and 01 in the Darlington configuration with collectors tied together. This applies to Figure 1,
the step down mode.

Condition

Typical
Value

Output Voltage

10 = 200mA

Line Regulation

20V ~ VI ~ 30V

1.5mV

Load Regulation

5.0mA ~ 10
10 ~ 300mA

3.0mV
500mA

10V

Max Output Current

Vo = 9.5V

Output Ripple

10 = 200mA

50mV

Efficiency

10 = 200mA

74%

Standby Current

10 = 200mA

2.8mA

Note A: For 10 ., 200 rnA use external diode to limit on-chip power dissipation.

"Output saturation voltage 2" is the switching element voltage for 01 only when used as a transistor switch. This applies to Figure 2, the step up mode.
For the inverting mode, Figure 3, the saturation voltage of
the external transistor should be used for VSAT.

3-199

•

Typical Applications (Continued)
L

RSC

--""-..

,

2N5003

300J,iH

0.33.0.

Rsc

0.334

180n.

02

Vo
25V

R2
12kn.

...

r...

O•1Jo1r

Vo
-15V'

Rl
230kn.

25 k4

TL/H/10057-4

Co

12oo Jol r

FIGURE 2. Typical Step-Up Regulator and
Operational Performance (TA = 25"C)

TLlH/10057-5

FIGURE 3. Typical Inverting Regulator and
Operational Performance (TA = 25"C)
Characteristic,

Condition

Output Voltage

10 = 50mA
' 5.0V S:VI

Line, Regulation

s:

15V"

,

Typical
, Value

Characteristic

Condition,

Typical
, Value
-15V

25V

Output VQltage

10 = 100mA

4.0mV

Line, Regulation

8.0V

Load Regulation

5.0mA,S: 10
10 s: 150 mA

3.0mV"

s: VI s: 18V

5.0mV

5.0mA s: 10
10 s: 100 mA

2.0,mV

Max Output Current

Vo = 23.75V

' 160mA

Max Output Current ,

Vo = 14.25V

160mA

Output Ripple

10 ~ 50mA

30rriV

Output Ripple

,10 = 100mA

20mV

Efficiency

10,= 50mA

,79%

Efficiency

10 = 100mA

70%

Standby Current

10 == 50mA-

2.6mA

Standby Current

10 = 100mA

2.3mA

Load Regulation

"

3-200

r---------------------------------------------------~--------------------------------,

Typical Applications (Continued)

r-

:s::
~

g;

....

CI
30VIN--._----------._------~._~~~~~~--_,

+
"'_ 100}lF
~------4-----~18~0~Op~F
•

B.2kll

MBR4030
SHOTTKY

+-....- -....~I------------.....-+- ~:g:

TL/H/l0057-10

FIGURE 4. Pulse Width Modulated Sfep-Down Regulator (fosc

3·201

=

20 kHz)

LMC7660 Switched Capacitor: Voltage Converter·
General Description

Features

The LMC7660 is a CMOS voltage converter capable of con- Operation over full temperature and voltage
verting a positive voltage in the range of + 1.5V to .+ 10V to
range without an external diode.
the corresponding negative voltage of -;-1.5V to -10V. The . _ Low supply current, 200 p.A maX
LMC7660 is a pin-for-pin replacement for the industry-stan- .. _ Pin-for-pin replacement for the 7660
dard 7660. The converter features: operation over full tem_ Wide operating range 1.5V to 10V
perature and voltage range without need for an external di_ 117 % Voltage Conversion Efficiency
_ :95%. Power Conversion Efficiency
ode, low quiescent current, and high power efficiency.
The LMC7660 uses its built-in oscillator to switch 4 power
_ Easy to use, only 2 externai components
MOS switches and charge two inexpensive electrolytic ca_ Extended temperature range
pacitors.

Block Diagram

TLlH/9136-1

Pin Configuration

Ordering Information
LMC7660

N/C08v+

Cap. 2
Gnd 3

Cap- 4

LMC7660MJ -55°C S; TA S; +125°C
LMC7660lN -400C S; TA S; +BSoC

7 Osc
6 LV

5 Vout
TLlH/9136-2

9·202

r

Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Supply Voltage
10.5V
Input Voltage on Pin 6, 7
(Note 2)
-0.3Vto (V+ + 0.3V)
for V+ < 5.5V
(V+ - 5.5V) to (V+ + 0.3V)
for V+ > 5.5V
Current into Pin 6 (Note 2)

Package
J
0.9W

Power Dissipation
(Note 3)
Tj Max (Note 3)
0ja (Note 3)
Storage Temp. Range

N
1.4W

en
c

150'C
150'C
140'C/W
90'C/W
-65'C ,;: T,;: 150'C

Lead Temp.
(Soldering, 5 sec)
ESD Tolerance (Note 8)

20 ",A

Output Short Circuit Duration
(V+ ,;: 5.5V)

o
==
......
en

260'C

260'C
±2000V

Continuous

Electrical Characteristics (Note 4)
LMC7660MJ
Symbol

Is

Parameter
Supply Current

Conditions
RL =

Typ
120

00

Tested
Limit
(Note 5)
200

400

LMC7660lN
Tested
Limit
(Note 5)

Design
Limit
(Note 6)

200

400

",A
max

Units
Limits

V+H

Supply Voltage
Range High (Note 7)

RL = 10 k!1, Pin 6 Open
Voltage Efficiency;;;' 90%

3to 10

3to 10

3to 10

3to 10

V

V+L

Supply Voltage
Range Low

RL = 10 k!1, Pin 6 to Gnd.
Voltage Efficiency ;;;, 90%

1.5 to 3.5

1.5 to 3.5

1.5 to 3.5

1.5 to 3.5

V

Rout

Output Source
Resistance

IL = 20mA

100

120

!1
max

200

300

!1
max

55

V = 2V, IL = 3 mA
Pin 6 Short to Gnd.
Fosc

Osciilator
Frequency

Pell

Power Efficiency

110

100

150
200

300

10
RL = 5k!1

97

kHz
95

90
Voell

Voltage Conversion
Efficiency

RL =

00

99.9

97

95

95

90

%
min

97

95

%
min

Pin 7 = Gnd. orV+
Oscillator Sink or
3
",A
Source Current
Note 1: Absolute Maximum ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating
the device beyond its rated operating conditions. See Note 4 for conditions.
Note 2: Connecting any input terminal to voltages greater than V+or tess than ground may cause destructive latchup. It is recommended that no Inputs from
sources operating from external supplies be applied prior to "power·up" of the LMC7660.
Note 3: For operation at elevated temperature, these devices must be derated based on a thermal resistance of Bja and Tj max, Tj = TA + 8ia PoNote 4: Boldface numbers apply at temperature extremes. All other numbers apply at TA = 2S'C, V+ = SV, Cose = 0, and apply for the LMC7660 unless

lose

otherwise specified. Test circuit is shown in Figure 1.

Note 5: Guaranteed and 100% production tested.
Note 6: Guaranteed over the operating temperature range (but not 100% tested). These limits are not used to calculate outgoing quality levels.
Note 7: The LMC7660 can operate without an external diode over the lull temperature and voltage range. The LMC7660 can also be used with the external diode
Ox, when replacing previous 7660 designs.

Note 8: The test circuit consists of the human body model of 100 pF in series with 1S00n.

3-203

•

IS

F8----~t=~ y+
~IL

(+ 5v)

RL
L..._ _ _ _ _. . ._Vo ut

C-

(-5v)

r~10J.'F
TLlH/9136-5

FIGURE 1. LMC7660 Test Circuit

Typical Performance Characteristics
osc Freq. vs OSC
lrP Capacitance

•
•

I

1

1

--

1

.....

80
70

ZI

1
14
12
10

/

60
50
40
50

1/
,/
,/

20

0/

V

...
-5

III

c:

:g
!:C

E
t;
is

II
~

:!

/

o

0

0123456789

4~

70
60
50
40
50
20
10

Unloaded Oscillator Frequency
as a Function of'Temperature
20

/-f.
~

1/
,I

1/

,I

o/
o

100
90
80
70
60 !:C
50
40
30
20
10

20

50

40

:z:

2"

50

6
-50 -25

0

.......

25

50

TEWPERATURE (OC)

100
50

~

--

I-'"

.1....Jv+=5V
lou\=20mA

0

25

75 100 125

50

Pen vs OSC Freq.
98
96
94

15_

92
90

e;

88
88

~
~

75 100 125

v+=2V

150

T[MPERATURE ("1:)

LV OPEN

......
........

200

100

LV TO ~
GROUND

"

250

-50 -25

t;

10

60

500

o

60

E

r'\

50

~

~
I:l
a ~
~ III
:! !;5<>

16

12

'iii'

Output R vs Supply Voltage

1=

18

40

Output Source Resistance as a
Function of Temperature

LOAD CURRENT (mA)

lrP

50

350

0
10

./
20

LOAD CURRENT (mA)

......

90
80

LOAD CURRENT (mA)

14 \

o -""'"
10

Supply Current & Power Efficiency
vs Load Current (V+ = 5V)
100

20

r---

/

-3

LOAD CURRENT (mA)

Supply Current & Power Efficiency
vs Load Current (V+ = 2V)
90

~

012345678
C... (pr)

100

I

1
-2

i--" I'""'"

i--"

-2

10

I

11111

II 111111

@

V+ = 5V

111111
1out=lmA

nlll I I 1111n-11
Cp=C,=1 01'1 I I
1out1=\!mA

64

o TA =25"1:

1

012345678
SUPPLY VOLTAGE (V")

OSCILLATOR FREQUENCY (Hz)
TLlH/9136-4

3-204

CIRCUIT DESCRIPTION

The LMC7660 closely approaches 1 and 2 above. By using
a large pump capacitor Cp, the charge removed while supplying the reservoir capacitor is small compared to Cp's total
charge. 5mall removed charge means small changes in the
pump capacitor voltage, and. thus small energy loss and
high efficiency. The energy loss by Cp is:
E = 1f2Cp (V12 - V22)

The LMC7660 contains four large CM05 switches which
are switched in a sequence to provide supply inversion You!
= -Vln. Energy transfer and storage are provided by two
inexpensive electrolytic capacitors. Figure 2 shows how the
LMC7660 can be used to generate -V+ from V+. When
switches 51 and 53 are closed, Cp charges to the supply
voltage V+. During this time interval, switches 52 and 54
are open. After Cp charges to V+, 51 and 53 are opened,
52 and 54 are then closed. By connecting 52 to ground, Cp
develops a voltage - V+ /2 on Cr. After a number of cycles
Cr will be pumped to exactly - V +. This transfer will be
exact assuming no load on Cr, and no loss in the switches.

By using a large reservoir capacitor, the output ripple can be
reduced to an acceptable level. For example, if the load
current is 5 mA and the accepted ripple is 200 mY, then the
reservoir capacitor can omit approximately be calculated
from:
dv
Is = Crdt

In the circuit of Figure 2, 51 is a P-channel device and 52,
53, and 54 are N-channel devices. Because the output is
biased below ground, it is important that the p- wells of 53
and 54 never become forward biased with respect to either
their sources or drains. A substrate logic circuit guarantees
that these p- wells are always held at the proper voltage.
Under all conditions 54 p- well must be at the lowest potential in the circuit. To switch off 54, a level translator generates VGS4 = OV, and this is accomplished by biasing the
level translator from the 54 p- well.

- CrX

~
4/Fosc

0.5mA

Cr

= 0.5V/ms = 10 p.F

PRECAUTIONS
1) Do not exceed the maximum supply voltage or junction
temperature.
2) Do not short pin 6 (LV terminal) to ground for supply voltages greater than 3.5V.

An internal RC oscillator and + 2 circuit provide timing signals to the level translator. The built-in regulator biases the
oscillator and divider to reduce power dissipation on high
supply voltage. The regulator becomes active at about V+
= 6.5V. Low voltage operation can be improved if the LV
pin is shorted to ground for V+ ,;:; 3.5V. For V+ ~ 3.5V, the
LV pin must be left open to prevent damage to the part.

3) Do not short circuit the output to V+.
4) External electrolytic capacitors Cr and Cp should have
their polarities connected as shown in Figure 1.
REPLACING PREVIOUS 7660 DESIGNS
To prevent destructive latchup, previous 7660 deSigns require a diode in series with the output when operated at
elevated temperature or supply voltage. Although this prevented the latchup problem of these deSigns, it lowered the
available output voltage and increased the output series resistance.

POWER EFFICIENCY AND RIPPLE
It is theoretically possible to approach 100% efficiency if the
following conditions are met:
1) The drive circuitry consumes little power.

The National LMC7660 has been designed to solve the inherent latch problem. The LCM7660 can operate over the

2) The power switches are matched and have low Ron.
3) The impedance of the reservoir and pump capacitors are
negligibly small at the pumping frequency.

or (pin 8)

SI./

(pin 2) S2./

o----- 7V, the output stays in regulation up to IL = 25
mA. The error flag on pin 5 of the LP2951 sets low when the
regulated output at pin 4 drops by about 5%. The LP2951
can be shutdown by taking pin 3 high; the LMC7660 can be
shutdown by shorting pin 7 and pin B.
The LP2951 can be reconfigured to an adjustable type regulator, which means the LMC7660 can give a regulated output from - 2.0V to -10V dependent on the resistor ratios
Rl and R2, as shown in Figure .12, V,el = 1.235V:

Thermometer Spans 180°C
Using the combined negative and positive multiplier of Figure 10 with an LM35 it is possible to make a /LPower thermometer that spans a 1BO°C temperature range. The LM35
temperature sensor has an output sensitivity of 10 mVrC,
while drawing only 50 /LA of quiescent current. In order for
the LM35 to measure negative temperatures, a pull down to
a negative voltage is required. Figure 10 shows a thermometer circuit for measuring temperatures from - 55°C to
+ 125°C and requiring only two 1.5V cells. End of battery life
can be extended by replacing the up converter diodes with
Schottky's.

Vou! = V,el (1

Regulating -Vou!
It is possible to regulate the output of the LMC7660 and still
maintain /LPower performance. This is done by enclosing.

+

:~)

8

*

+

Vo·

:!:L 1.5'(
1.5V

20j.lF

47k

~-------~~+------------.

Voul

V*
o

j-::~----+ OUTPUT

=10 mVjOe

-55°C to + 1250C
• For lower voltage operation, use Schottky rectifiers

TL/H/9136-15

FIGURE 10./LPower Thermometer Spans 180°C, and Pulis Only 150 /LA

3-209

~

Typical Applications (Continued)

:::E
...J

+V1n 6V
to 25V

O.022pF
8

7
6

330k

Error
Output

5

4

Regulated

-Vaut

TLlH/9136-16

FIGURE 11. Regulated - 5V with 200 p.A Standby Current

O.022pF

LMC7660

+V1ri 6V
to 25V

330k

4
5
Error
L_...JF1r-'-rL
__
.r-I~output
R2
Vout

~ Vref ( 1 + ~)

Vref

~

Rl

1.235V
TL/H/9136-17

'Low voltage operation

FIGURE 12. LMC7660 and LP2951 Make a Negative Adjustable Regulator

3-210

Section 4
Motion Control

Section 4 Contents
Motion Control and Motor Drive Selection Guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LM12 80W Operational Amplifier. .... ...... ... .. ... .. .... ....... ... ......... ... ......
LM628/LM629 Precision Motion Controller.. ................. .. ..... .... ............. .
LM 18293 Four Channel Push·Pull Driver. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LMD18200 3A, 55V H·Bridge ................................................•.......
LMD18201 3A, 55V H·Bridge ........................................................
LMD18245 3A, 55V DMOS Full·Bridge Motor Driver. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4-2

4-3
4-4
4-17
4-38
4-44
4-53
4-59

!!:

2o·

f}1National Semiconductor

:J

&>

-2:J

Motion Control and Motor Drive Selection Guide

AI
:J
C.

!!:

o
S"

Motor Drive Circuits-Bridges
Output
Current
(A)

Max Input
Voltage
(V)

3

55

- 40'C to + 125'C 11-Lead TO-220

4-44

DMOS H-Bridge

3

55

- 40'C to + 125'C 11-Lead TO-220

4-53

LMD18245

DMOS H-Bridge with Digital or Analog Control

3

55

- 40'C to + 125'C 15-Lead TO-220

4-59

LM18293

4-Channel Push-Pull Driver

1/Channel

36

- 40'C to + 125'C 16-Lead DIP

4-38

Device

Description

LMD18200 DMOS H-Bridge with Internal Current Sense
LMD18201

Operating
Temperature
(TJ)

Package
Availability

Page
No.

Motor Drive Circuits-Linear
Device
LM12

Description

Output
Current
(A)

Max Supply
Voltage
(V)

Operating
Temperature
(Te)

Package
Availability

Page
No.

Monolithic Power Op-Amp

±10

±30

O'Cto +70'C

4-LeadTO-3

4·4

Precision Motion Control Processor
Device

Features

Operating
Temperature
. (TA)

Max Clock
Speed
(MHz)

Package
Availability

Page
No.

LM628

32-Bit Position, Velocity, and Acceleration Registers; Position and
Velocity Modes; 16-Bit PID Filter with Programmable Coefficients;
8 or 12-Bit DAC Output Data; Quadrature Incremental
Encoder Interface; 8-Bit Asynchronous Host Interface

-40'Cto +85'C

60r8

28-Lead DIP

4-17

Same Features as LM628, but with 8-Bit
PWM Sign/Magnitude Output Data

-40'Cto + 85'C

60r8

28-Lead DIP

4-1"1

LM629

4-3

...c
...~.

en
CD

Ii"
n

o:J·

C)
C

a::
CD

.... r-------------------------------------------------------------------------,
:!i t!lNational Semiconductor
~

LM 12 SOW Operational Amplifier
General Description
The LM12 is a power op amp capable of driving ±25V at
±10A while operating from ±30V supplies. The monolithic
IC can deliver BOW of sine wave power into a 40 load with
0.01 % distortion. Power bandwidth is 60 kHz. Further, a
peak dissipation capability of BOOW allows it to handle reactive loads such as transducers, actuators or small motors
without derating. Important features include:
• input protection
• controlled turn on
• thermal limiting
• overvoltage shutdown
• output-current limiting
• dynamic safe-area protection
The IC delivers ± 10A output current at any output voltage
yet is completely protected against overloads, including
shorts to the supplies. The dynamiC safe-area protection is
provided by instantaneous peak-temperature limiting within
the power transistor array.
'
The turn-on characteristics are controlled by keeping the
output open-circuited until the total supply voltage reaches
14V. The output is also opened as the case temperature

exceeds 150·C or as the supply voltage approaches the
BVCEO of the output transistors. The IC withstands overvolt.
ages to BOV..
This monolithic op amp is compensated for unity-gain feedback, with a small-signal bandwidth of 700 kHz. Slew rate is
9V1 /J-s, even as a follower. Distortion and capacitive-load
stability rival that of the best designs using complementary
output transistors. Further, the IC. withstands large differential input voltages and is well behaved should the commonmode range be exceeded.
The LM12 establishes that monolithic ICs can deliver considerable output power without resorting to complex switching schemes. Devices can be paralleled or bridged for even
greater output capability. Applications include operational
power supplies, high-voltage regulators, high-quality audio
amplifiers, tape-head positioners, x-y plotters or other servo-control systems.
The LM12 is supplied in a four-lead, TO-3 package with Von the case. A gold-eutectiC die-attach to a molybdenum
interface is used to avoid thermal fatigue problems. The
LM12 is specified for either military or commercial temperature range.

Typical Application*

Connection Diagram
4-pln glass epoxy TO·3

1.5n

socket is available from

AUGATINC.

...-.....""""IIIIr-......IlJ1l1fl-. .

OUT

+---1

IN .......

lk
common

+IN

ground""
point

-=-

V""(CASE)

TL/H/8704-2

'Low distortion (0.01 %) audio amplifier

TUH/8704-1

BoHomVlew
Order Number LM12CLK
See NS Package Number K04A

4-4

Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
80V
Total Supply Voltage (Note 1)
(Note 2)
Input Voltage

Junction Temperature
Storage Temperature Range
Lead Temperature (Soldering, 10 seconds)

300'C

Operating Ratings
15Vto 60V

Total Supply Voltage
Case Temperature (Note 4)

Internally Limited

Output Current

(Note 3)
- 65'C to 150'C

O'Cto 70'C

Electrical Characteristics (Note 4)
Conditions

Parameter
Input Offset Voltage

± 10V:;;; Vs :;;; ±0.5 VMAX,
VCM = 0

Typ
25'C

LM12CL

2

15/20

mV(niax)

Limits

Units

Input Bias Current

V- + 4V:;;; VCM :;;; V+ -2V

0.15

0.7/1.0

p.A (max)

Input Offset Current

V

+4V :;;; VCM :;;; V+ -2V

0.03

0.2/0.3

p.A (max)

Common Mode
Rejection

V- +4V :;;; VCM ,;: V+ -2V

86

70/85

dB (min)

Power Supply
Rejection

V+ = 0.5 VMAX,
-6V ~ V- ~ -0.5 VMAX
V- = -0.5 VMAX,
6V :;;; V+ :;;; 0.5 VMAX

90

70/85

110

75170

dB (min)

tON = 1 ms,
aVIN = 5 (10) mV,
lOUT = 1A
8A
10A

1.8
4
5

2.2/2.5
517

V (max)
V (max)
V (max)

Large Signal Voltage
Gain

toN = 2ms,
VSAT = 2V,IOUT = 0
VSAT = 8V, RL = 40

100
50

30/20
15/10

V/mV(min)
V/mV(min)

Thermal Gradient
Feedback

POISS = 50W, tON = 65 ms

30

100

p.v/W(max)

Output·Current
Limit

tON = 10 ms, VOISS = 10V

13

16

A (max)

tON = 100 ms, VOISS = 58V

1.5
1.5

0.9/0.8
1.7

A (min)
A (max)

Power Dissipation
Rating

tON = 100 ms, VOISS = 20V
VOISS = 58V

100
80

80/55
52/35

W(min)
W(min)

DC Thermal Resistance

(Note 5)

2.3
2.7

2.9
4.5

'C/W(max)
'C/W(max)
'C/W(max)

Output Saturation
Threshold

VOISS = 20V
VOISS = 58V

AC Thermal Resistance

(Note 5)

1.6

2.1

Supply Current

VOUT = 0, lOUT = 0

60

120/140

dB (min)

mA(max)

Note 1: Absolute maximum ratings indicate limits beyond which damage to the device may occur. The maximum voltage for which the LM12 is guaranteed to
operate Is given in the operating ratings and in Note 4. With Inductive loads or output shorts, other restrictions described in applications section apply.
Note 2. Neither Input should exceed the supply voltage by more than 50 volts nor should the voltage between one Input and any other terminal exceed 60 volts.
Note 3. Operating junction temperature is internally limited near 225'C within the power transistor and 160'C for the control circuitry.
Note 4. The supply voltage is ±30V (VMAX = 60V). unless otherwise specified. The voltage across the conducting output transistor (supply to output) is VOISS and
intemal power dissipation Is POISS. Temperature range is O'C ,;: Tc ,;: 70'C where Tc is the case temperature. Standard typeface indicates limits at 25'C while
boldface type refera to limits or special conditions over full temperature range. With no heat sink. the package will heat at a rate of 35'C/sec per 100W of
Internal dissipetion.
Note 5. This thermal resistance is based upon a peak temperature of 200'C In the center of the power transistor and a case temperature of 25'C measured at the
center of the package bottom. The maximum iunction temperature of the control circuitry can be estimated based upon a dc thermal resistance of 0.9'C/W or an ac
thermal resistance of O.S'C/W for any operating voltage.
Although the output and supply leads are resistant to electrostatic discharges from handling, the Input leads are not.
The part should be treated accordingly.

4·5

N
....
:i

Output-Transistor Ratings (guaranteed)
. Pulse Thermal Resistance·

DC Thermal Resistance

Safe Area
10

3

70 o C--5.0

~

~

=l

8

"~

2.0

Tc=2SoC
TJ = 200 0 C

1.0

0.5

o

I--

......

" "'

~

i

VCE =40V-.- T~=250C I
58V---,TJ=200 a C

TC == 25 0 C- - TJ = 200 0 C

'oN=0.3m.

125OC -

1.0

"

20

-

/
/. '" '"

~

.............

0~~

40

-

60

~

20

COLLECTOR-EMITTER VOLTAGE (V)

'"

:.-

40

~

,

c..
I-

60

0.1

1.0

COLLECTOR-EMITTER VOLTAGE (V)

10

100

PULSE WIDTH (m')

TL/H/B704-3

Typical Performance Characteristics
Pulse Power Limit

Pulse Power Limit

120

80

~

60

Tc= 11Z5 O C

100

:g
~

~

o

Output Saturation Voltage

f- -

J.

-

-50

i== ..-

I

o
50

-

TC= lOQGe

=

D

o

20

40

60

CASE TEMPERTATURE (oC)

TC=25 0 C

-L

I
o

0.8

0.4

1.2

1.6

Follower Pulse Response
3D

§

~

=

Vs :I::30V
THD"5%
Rt. =40

~

5

£

20

'"z
10

~

~

\

150

-10

lOOk
FREQUENCY (Hz)

I

\

I

\

\I~

0

-20
-30

10k

r

lD

~

1\

o
100

rr-

TIME (ms)

Large Signal Response

:;
'-;

.5A

1/ 1

V1N =:l:15V

IOUT=:i:~

.\A

ioN = lOOms
TLiN 230 a C

2D

I

.8A

~

30

I II

Vour=O

r..:::: r--

COLLECTOR-EMITTER VOLTA~E (V)'

TIME (ms)

I

12

Peak Output Current
Vs =::I:30V

40
20

ioN = 1 m.

16

Tc=~5OC

~

1M

o

10

15

20

--

25

30

TIME (".)

TL/H/B704-4

4-6

Typical Performance Characteristics
Large Signal Gain

(Continued)

Thermal Response

Total Harmonic Distortion

50

~
~

-:-

30

.......

%

~.
~

~
~

g

S~URC~
--.+-

40

20

1,'
II"'
~PON=50W

VS;::: ±30V

Your = ±25V
10 I\. =411
f=100Hz

I

o

-I

-50

50

100

ISO

1 "I

o

1

20

40

Frequency Response
80

"I\.. GAiN

\

60

~

,~

40

PHASE

"

20

135
90

"\

45

',\:
100

Ik

10k lOOk 1M

fREQUENCY (Hz)

~
Ii'

3

80

.il
%

::II

~

~

~

I. '0

--

2!

-45
10M

I~

80

'01

'"

100

ISO

60

I"

40

""

20

o

o

10

"

60

r-..

iii
40

20
10

100

Ik

10k

Ik

lOOk

120

I
I

~
~

Tc=25 O C

Tc=-S5 0 C

I

I

I
I

I
I

20

SUPPLY VOLTAGE (tV)

'=<

.s

I

is

~

r-...

60

,

f-

;,.(, Vs • ,1t30V

20
-40

rVs=t20V

i

-20

I

20

:3

0.3

.."~

0.2
0.1

II I
II I

OUTPUT VOLTAGE (V)

rV~=tlJ

Vour=:!:2SY

~

40

30

0.4

I
I

80

1M

Cross-Supply Current
0.5

TC=2SoC
IoUT=O

100

lOOk

fREQUENCY (Hz)

Supply Current

I
I

10k

fREQUENCY (Hz)

Supply Current

.s

~

100

CASE TEMPERATURE (0 C)

-VO~T=O'

I.

...... 1=

50

80 -IoUT=O

"

3

>

lOOk

Common Mode Rejection
100

E

ill
~

10k

fREQUENCY (Hz)

10

-50

Ik

fREQUENCY (Hz)

~

r-.;:: ~

111111111

100

10M

"

NEGATIVE

Illim IIII

o
1M

0

I I

o

'=<

g

POSITIVE
40

20

0.1
lOOk

~

\ t\.VC" = 25V

111111

iii

IA

~.:s

~

VC" = -45V

100

0

Input Noise Voltage

Vs = t30V

0.2

"'01
3
z

,,

Ik

0.6

0.4

-I~

1.0

Input Bias Current

ii3

llill

60

:s

0.8

'=<
.5

Power Supply Rejection

10

"

-20
10

10k
fREQUENCY (Hz)

180 -;-

\

'01
3
z

80

Output Impedance
225

r-..
,

60

TI.E (m.)

CASE TEMPERATURE (0 C)

100

SINK

o
40

1.=0

I

,{

...
Ik

3k

1.=411
10k

30k

lOOk

fREQUENCY (Hz)

TLlH/8704-5

4·7

C'oI
.-

~

Application Information
The current in the supply leads is a rectified component of
the load currenl. If adequate bypassing is not provided, this
.distorted Signal can be fed back into internal circuitry. Low
distortion at high frequencies requires that the supplies be
bypassed with 470 IJ-F or more, at the package terminals.

GENERAL
Twenty five years ago the operational amplifier was a specialized design tool used primarily for analog computation.
However, the availability of low cost IC op amps in the late
1960's prompted their use in rather mundane applications,
replacing a few discrete components. Once a few basic
principles are mastered, op amps can be used to give exceptionally good results in a wide range of applications
while minimizing both cost and design effort.
The availability of a monolithic power op amp now promises.
to extend these advantages to high-power designs. Some
conventional applications are given here to illustrate op amp
design principles as they relate to power circuitry. The inevitable fall in prices, as the economies of volume production
are realized, will prompt their use in applications that might
now seem trivial. Replacing Single power transistors with an
op amp will become economical because of improved performance, simplification of attendant circuitry, vastly improved fault protection, greater reliability and the reduction
of deSign time.

LEAD INDUCTANCE
With ordinary op amps, lead-inductance problems are usually restricted to supply bypassing. Power op amps are also
sensitive to inductance in the output lead, particularly with
heavy capacitive loading. Feedback to the input should be
taken directly from the output terminal, minimizing common
inductance with the load. Sensing to a remote load must be
accompanied by a high-frequency feedback path directly
from the output terminal. Lead inductance can also cause
voltage surges on the supplies. With long leads to the power
source, energy stored in the lead inductance when the output is shorted can be dumped back into the supply bypass
capacitors when the short is removed. The magnitude of
this transient is reduced by increasing the size of the bypass
capaCitor near the IC. With 20 IJ-F local bypass, these voltage surges are important only if the lead length exceeds a
couple feet (> 1 IJ-H lead inductance). TWisting together the
supply and ground leads minimizes the effect.

Power op amps introduce new factors into the design equation. With current transients above lOA, both the inductance.
and resistance of wire interconnects become important in a
number of ways. Further, power ratings are a crucial factor
in determining performance. But the power capability of the
IC cannot be realized unless it is properly mounted to an
adequate heat sink. Thus, thermal design is of major importance with power op amps.
.

GROUND LOOPS
With fast, high-current circuitry, all sorts of problems can
arise from improper grounding. In general, difficulties can be
avoided by returning all grounds separately to a common
point. Sometimes this is impractical. When compromising,
speCial attention should be paid to the ground returns for
the supply bypasses, load and input signal. Ground planes
also help to provide proper grounding.
Many problems unrelated to system performance can be
traced to the grounding of line-operated test eqUipment
used for system checkout. Hidden paths are particularly difficult to sort out when several pieces of test equipment are
used but can be minimized by using current probes or the
new isolated oscilloscope pre-amplifiers. Eliminating any direct ground connection between the signal generator and
the oscilloscope synchronization input solves one common
problem.

This application summary starts off by identifying the Origin
of strange problems observed while using the LM12 in a
wide variety of designs with all sorts of fault conditions. A
few Simple precautions will eliminate these problems. One

would do well to read the section on supply bypassing,
lead inductance, output clamp diodes, ground loops
and reactive loading before doing any experimentation.
Should there be problems with erratic operation, blowouts,excesslve distortion or oscillation, another look at
these sections is in order.
The management and protection circuitry can also affect
operation. Should the total supply voltage exceed ratings or
drop below 15-20V, the op amp shuts off completely. Case
temperatures above 150·C also cause shut down until the
temperature drops to 145·C. This may take several seconds, depending on the thermal system. Activation of the
dynamic safe-area protection causes both the main feedback loop to lose control and a reduction in output power,
with possible oscillations. In ac applications, the dynamic
protection will cause waveform distortion. Since the LM12 is
well protected against thermal overloads, the suggestions
for determining power: dissipation and heat sink· requirements are presented lasl.

OUTPUT CLAMP DIODES
When a push-pull amplifier goes into power limit while driving an inductive load, the stored energy in the load inductance can drive the output outside the supplies. Although
the LM12 has internal clamp diodes that can handle several
amperes for a few milliseconds, extreme conditions can
cause destruction of the IC. The internal clamp diodes are
imperfect in that about half the clamp current flows into the
supply to which the output is clamped while the other half
flows across the supplies. Therefore, the use of external
diodes to clamp the output to the power supplies is strongly
recommended. This is particularly important with higher supply voltages.

SUPPLY BYPASSING
All op amps should have their supply leads bypassed with
low-inductance capacitors having short leads and located
close to the package terminals to avoid spurious oscillation
problems. Power op amps require larger bypass capaCitors.
The LM12 is stable with good,quallty electrolytic bypass capaCitors greater than 20 IJ-F. Other considerations may require larger capacitors.

Experience has demonstrated that hard-wire shorting the
output to the supplies clj-n induce random failures if these
external clamp diodes are not used and the supply voltages
are above ± 20V. Therefore it is prudent to use output-

4-8

Application Information

(Continued)

clamp diodes even when the load is not particularly inductive. This also applies to experimental setups in that blowouts have been observed when diodes were not used. In
packaged equipment, it may be possible to eliminate these
diodes, providing that fault conditions can be controlled.

>-_. . .

and expected nature of the load, but are not critical. A 4 JIoH
inductor is obtained with 14 turns of number 18 wire, close
spaced, around a one-inch-diameter form.

01

OUT

IN

-OUT

IN

- - - - - - - -......-v-

D2

TLIH18704-8

The LM12 can be made stable for all loads with a large
capaCitor on the output, as shown above. This compensation gives the lowest possible closed-loop output impedance at high frequencies and the best load-transient response. It is appropriate for such applications as voltage
regulators.

TLIH18704-6

Heat sinking of the clamp diodes is usually unimportant in
that they only clamp current transients. Forward drop with
15A fault transients is of greater concern. Usually, these
transients die out rapidly. The clamp to the negative supply
can have somewhat reduced effectiveness under worst
case conditions should the forward drop exceed 1.0V.
Mounting this diode to the power op amp heat sink improves
the situation. Although the need has only been demonstrated with some motor loads, including a third diode (03
above) will eliminate any concern about the clamp diodes.
This diode, however, must be capable of dissipating continuous power as determined by the negative supply current of
the op amp.

A feedback capaCitor, C1, is connected directly to the output
pin of the IC. The output capacitor, C2, is connected at the
output terminal with short leads. Single-point grounding to
avoid dc and ac ground loops is advised.
The impedance, 21, is the wire connecting the op amp output to the load capaCitor. About 3-inchesof number-18 wire
(70 nH) gives good stability and 18-inches (400 nH) begins
to degrade load-transient response. The minimum load capacitance is 47 JIoF, if a solid-tantalum capaCitor with an
equivalent series resistance (ESR) of 0.1 fi is used. Electrolytic capacitors work as well, although capacitance may
have to be increased to 200 JIoF to bring ESR below 0.1 fi.

REACTIVE LOADING
The LM12 is normally stable with resistive, inductive or.
smaller capacitive loads. Larger capacitive loads interact
with the open-loop output resistance (about 10) to reduce
the phase margin of the feedback loop, ultimately causing
oscillation. The critical capaCitance depends upon the feedback applied around the amplifier; a unity-gain follower can
handle about 0.01 JIoF, while more than 1 JIoF does not cause
problems if the loop gain is ten. With loop gains greater than
unity, a speedup capacitor across the feedback resistor will
aid stability. In all cases, the op amp will behave predictably
only if the supplies are properly bypassed, ground loops are
controlled and high-frequency feedback is derived directly
from the output terminal, as recommended earlier.
So-called capacitive loads are not always capacitive. A
hlgh-Q capacitor in combination with long leads can present
a series-resonant load to the op amp. In practice, this is not
usually a problem; but the situation should be kept in mind.

Loop stability is not the only concern when op amps are
operated with reactive loads. With time-varying Signals,
power dissipation can also increase markedly. This is particularly true with the combination of capacitive loads and
high-frequency excitation.
INPUT COMPENSATION
The LM12 is prone to low-amplitude oscillation bursts coming out of saturation if the high-frequency loop gain is near
unity. The voltage follower connection is most susceptible.
This glitching can be eliminated at the expense of smail-signal bandwidth using input compensation. Input compensation can also be used in combination with LR load isolation
to improve capacitive load stability.

L1
4).1
OUT

> ....- M..........-OUT
IN

R1

4.7
TUHI8704-7

TLIH18704-9

Large capacitive loads (including series-resonant) can be
accommodated by isolating the feedback amplifier from the
load as shown above. The inductor gives low output impedance at lower frequencies while providing an isolating impedance at high frequencies. The resistor kills the Q of series resonant circuits formed by capacitive loads. A low inductance, carbon-composition resistor is recommended.
Optimum values of Land R depend upon the feedback gain

An example of a voltage follower with input compensation is
shown here. The R2C2 'combination across the input works
with R1 to reduce feedback at high .frequencies without
greatly affecting response below 100 kHz. A lead capacitor,
C1, improves phase margin at the unity·gain crossover frequency. Proper operation requires that the output impedance of the circuitry driving the follower be well under 1 kfi
at frequencies up to a few hundred kilohertz.
4-9

II

-:i r---------------------------------------------------------------------------------,
~

Application Information (Continued)

equalization resistors. More output buffers, with individual
equalization resistors, may be' added to meet even higher
.
drive requirements. .

IN~I'V-4--.....- - I

R3
5k
C2
0.221'

OUT

>-....""',.,..-..... OUT

IN

RI
Ik

TLlH/8704-10

Extending input compensation to the integrator connection
is shown here. Both the follower and this integrator will handle 1 p.F capacitive loading without LR output isolation.

TL/H/8704-13

CURRENT DRIVE

RIO
10k

This connection allows increased output capability without
requiring a separate control amplifier. The output buffer, A2,
provides load current through A5 equal to that supplied by
the main amplifier, At, through A4. Again, more output buffers can be added.

R2°
10k

Current sharing among paralleled amplifiers can be affected
by gain error as the power-bandwidth limit is approached. In
the first circuit, the operating current increase will depend
upon the matching of high-frequency characteristics. In the
second circuit, however, the entire input error of A2 appears
across A4 and A5. The supply current increase can cause
power limiting to be activated as the slew limit is approached. This will not damage the LM12.lt can be avoided
in both cases by connecting At as an inverting amplifier and
restricting bandwidth with Ct.

>+-Ww-11-0UT
R3

500

°PRECISION RESISTORS
TLlH/8704-11

This circuit provides an output current proportional to the
input voltage. Current drive is sometimes preferred for servo
motors because it aids in stabilizing the servo loop by reducing phase lag caused by motor inductance. In applications
requiring high output resistance, such as operational power
supplies running in the current mode, matching of the feedback resistors to 0.Q1 % is required. Alternately, an adjustable resistor can be used for trimming.

SINGLE·SUPPLY OPERATION

CI
250p

R9
5k

PARALLEL OPERATION

+IN.JYVv--...----'\I'.(v-+-'

R4

0.1
IN

>-"'WIr'"4~IOUT

R5

-IN .JYVv--....---I>,f<.,.,.-I

0.1

TLlH/8704-14

Although op amps are usually operated from dual supplies,
single-supply operation is practical. This bridge amplifier
supplies bi-directional current drive to a servo motor while
operating from a single positive supply. The output is easily
converted to voltage drive by shorting A6 and connecting
A7to the. output of A2, rather than At.

TLlH/8704-12

Output drive beyond the capability of one power amplifier
can be provided as shown here. The power op amps are
wired as followers and connected in parallel with the outputs coupled through equalization resistors. A standard,
high-voltage op amp is used to provide voltage gain. Overall
feedback compensates for the voltage dropped across the
equalization resistors:

Either input may be grounded, with bi-directional drive provided to the other. It is also possible to connect one input to
a positive reference, with the Input signal varying about this
voltage. If the reference voltage is above 5V, R2 and A3 are
not required.

With parallel operation, there may be an increase in unloadedsupply current related to the offset voltage across the

4-10

r-

Application Information

.....
==

(Continued)

N

HIGH VOLTAGE AMPLIFIERS

-IN-+'WIr"e---"IIJ",""
Rl

IN .....JV.tIIr....---'w,,...,

lk

R3
lk

RS
lk

R7
lk

+IN ....--IW....---"IIJ!\,-J

TLlH/8704-15

TL/H/8704-16

The voltage swing delivered to the load can be doubled by
using the bridge connection shown here. Output clamping to
the supplies can be provided by using a bridge-rectifier assembly.

One limitation of the standard bridge connection is that the
load cannot be returned to ground. This can be circumvented by operating the bridge with floating supplies, as shown
above. For single-ended drive, either input can be grounded.

Cl
200p

=30V
R6
Sk

Rl
lk

>---4~I-OUT

TLlH/8704-17

This circuit shows how two amplifiers can be cascaded to double output swing. The advantage over the bridge is that the output
can be increased with any number of stages, although separate supplies are required for each .

...-Mo...._ _- - - _ Y+=8DV
Rll
3.9k
OUT
R13
3.3

+

Rl
lk
0.1%

RIO
47
CS
0.0221'

R12
3.9k

1...11+....- . . - - - -..... V"=

-8DV
TL/H/8704-18

Discrete transistors can be used to increase output drive to ± 70V at ± lOA as shown above. With proper thermal design, the IC
will provide safe-area protection for the external transistors. Voltage gain is about thirty.

4-11

•

....
:i

~ r---------------------------------------------------------------------------------~

Application Information (Continued)
OPERATIONAL POWER SUPPLY

Note: Supply voltages for the
,LM318s are ±15V

RI2
Ik

IN~~~------------------6_----------~~----~

TLlH18704-19

External current limit can be provided for a power op amp as shown above. The positive and negative current limits can be set
precisely and independently. Fast response is assured by 01 arid 02. Adjustment range can be set down to zero with potentiometers Rs and R7. Alternately, the limit can be programmed from a voltage supplied to'R2and Rs. This is the set up required for
an operational power supply or voltage-programmable power source.
SERVO AMPLIFIERS
When making servo systems with a power op amp, there is
a temptation to use it for frequency shaping to stabilize the
servo loop. Sometimes this works; other times there are
better ways; and occasionally it just doesn't fly. Usually it's a
matter of how quickly and to what accuracy the servo must
stabilize.

RI
10k

R3 C3
4.7k 0.221'

RI
160

03
7.SV

D4
7.SV

RS
10k

O.IX

,

,,

RS

Ik
TLIHIB704-21

This position servo uses an op amp to develop the rate
signal electrically instead of using a tachometer. In high-performance servos, rate signals must be developed with large
error signals well beyond saturation of the motor drive. Using a separate op amp with a feedback clamp allows the
rate signal to be developed properly with position errors
more than an order of magnitude beyond the loop-saturation level as long as the photodiode sensors are positioned
,with this in mind.

TLlHIB704-20

This motor/tachometer servo gives an output speed proportional to input voltage. A low-level op amp is used for frequency shaping while the power op amp provides currsnt
drive to the motor. Current drive eliminates loop phase shift,
due to motor inductance and makes high-performance servos easier to stabilize.
4-12

r-

Application Information

3:
.....
N

(Continued)

REMOTE SENSING

VOLTAGE REGULATORS
Rl

v+s. 55V

1.7k

R3

5Dk

C2
In
01
L~385

2.5V
R3

700
TL/H/8704-22

~

TLlH/8704-24

Remote sensing as shown above allows the op amp to correct for dc drops in cables connecting the load. Even so,
cable drop will affect transient response. Degradation can
be minimized by using twisted, heavy-gauge wires on the
output line. Normally, common and one input are connected
together at the sending end.

An op amp can be used as a positive or negative regulator.
Unlike most regulators, it can sink current to absorb energy
dumped back into the output. This positive regulator has a
0-50V output range.

Rl

AUDIO AMPLIFIERS

36k

OUT
R2

> .....~I----t-0UT

Uk

IN-+f---1
Rl
lk
common
Dl
LW329
7V
R3
4k

ground /.".-~ IH-+.........
point
V- y+

-=

C4

200!,

TL/H/8704-25

A power amplifier suitable for use in high-quality audio
equipment is shown above. Harmonic distortion is about
0.01-percent. Intermodulation distortion (60 Hzl7 kHz, 4:1)
measured 0.015-percent. Transient response and saturation
recovery are clean, and the 9 VI P.s slew rate of the LM12
virtually eliminates transient intermodulation distortion. Using separate amplifiers to drive low- and high-frequency
speakers gets rid of high-level crossover networks and attenuators. Further, it prevents clipping on the low-frequency
channel from distorting the high frequencies.

L -.....- ........- -...........- ..........- ......- _.... GND,
TUH/8704-23

Dual supplies are not required to use an op amp as a voltage regulator if zero output is not required. This 4V to 50V
regulator operates from a single supply. Should the op amp
not be able to absorb enough energy to control an overvoltage condition, a SCR will crowbar the output.

4-13

~ r-----------------------------------------------------------------------------~

.,...

:3

Application Information

(Continued)

DETERMINING MAXIMUM DISSIPATION

audio applications. The peak dissipation of each transistor is
about four times average. In ac applications, power capability Is often limited by the peak ratings of the power transistor.
The pulse thermal resistance of the LM12 is specified for
constant power pulse duration. Establishing an exact equivalency between constant-power pulses and those encountered in practice is not easy. However, for sine waves, reasonable estimates can be made at any frequency by assuming a constant power pulse amplitude given by:

It is a simple matter to establish power requirements for an
op amp driving a resistive load at frequencies well below
10 Hz. Maximum dissipation occurs when the output is at
one-half the supply voltage with high-line conditions. The
individual output transistors must be rated to handle this
power continuously at the maximum expected case temperature. The power rating is limited by the maximum junction
temperature as determined by
TJ = Tc + POISS8JC,
where TC is the case temperature as measured at the center of the package bottom, POISS is the maximum power
dissipation and 8JC is the thermal resistance at the operating voltage of the output transistor. Recommended maximum junction temperatures are 200"C within the power transistor and 150'C for the control circuitry.
If there is ripple on the supply bus, it is valid to use the
average value in worst-case calculations as long as the
peak rating of the power transistor is not exceeded at the
ripple peak. With 120 Hz ripple, this is 1.5 times the continuous power rating.
Dissipation requirements are not so easily established with
time varying output signals, especially with reactive loads.
Both peak and continuous dissipation ratings must be taken
into account, and these depend on the signal waveform as
well as load characteristics.
With a sine wave output, analysis is fairly straightforward.
With supply voltages of ±Vs, the maximum average power
dissipation of both output transistors is
P
=
MAX

2VS2
7T2 ZLcos8'

8

PPK ""

where  = 60' and 8 is the absolute value of the phase
angle of ZL. Equivalent pulse width is toN '" 0.4T for 8 = 0
and tON '" 0.2T for 8 ~ 20", where T is the period of the
output waveform.
DISSIPATION DRIVING MOTORS
A motor with a locked rotor looks like an inductance in series with a resistance, for purposes of determining driver
dissipation. With slow-response servos, the maximum signal
amplitude at frequencies where motor inductance is significant can be so small that motor inductance does not have
to be taken into account. If this is the case, the motor can
be treated as a Simple, resistive load as long as the rotor
speed is low enough that the back emf is small by comparison to the supply voltage of the driver transistor.
A permanent-magnet motor can build up a back emf that is
equal to the output swing of the op amp driving it. Reversing
this motor from full speed requires the output drive transistor to operate, initially, along a loadline based upon the motor resistance and total supply voltage. Worst case, this
loadline will have to be within the continuous dissipation
rating of the drive transistor; but system dynamics may permit taking advantage of the higher pulse ratings. Motor inductance can cause added stress if system response is
fast.
Shunt- and series-wound motors can generate back emf's
that are considerably more than the total supply voltage,
resulting in 'even higher peak dissipation than a permanentmagnet motor having the same locked-rotor resistance.

< 40";

and
PMAX =

~~: [ ; -

COS8],

8

~ 40",

where ZL is 'the magnitude of the load impedance and 8 its
phase angle. Maximum average diSsipation occurs below
maximum output swing for 8 < 40". '
'

100

r-""'T"....,.,..~....,.."""...,--.,--...,

VOUT =:t25V

9=400

80

~
z

II

iii

~

60

/'"

40
20
0

I 1""'\

VOLTAGE REGULATOR DISSIPATION
The pass transistor dissipation of a voltage regulator is easily determined in the operating mode. Maximum continuous
dissipation occurs with high line voltage and maximum load
current. As discussed earlier, ripple voltage can be averaged if peak ratings are not exceeded; however, a higher
average voltage will be required to insure that the pass transistor does not saturate at the ripple minimum.
Conditions during start-up can be more complex. If the input
voltage Increases slowly such that the regulator does not go
into current limit charging output capaCitance, there are no
problems. If not, load capacitance and load characteristics
must be taken into account. This is also the case if automatic restart is required in recovering from overloads.
Automatic restart or start-up with fast-rising input voltages
cannot be guaranteed unless the continuous dissipation rating of the pass transistor is adequate to supply the load
current continuously at all voltages below the regulated output voltage. In this regard, the LM12 performs much better
than IC regulators using foldback current limit, especially
with high-line input voltage above 20V.

/- \
I
'" ~\

VOUT =:l:19.1V
9=0_

0

!;;:
a..

/

/

V ""
0

30

\

Vs=:l:30V
ZL = 4 A/COS 9

60

90

120

150

~~: [ l-cos (<1>-8) ] ,

180

CONDUCTION ANGLE (DEGREES)
TLlH/8704-26

The instantaneous power dissipation over the conducting
half cycle of one output transistor is shown here. Power
dissipation is near zero on the other half cycle. The output
level is that resulting in maximum peak and average dissipation. Plots are given for a resistive and a series RL load. The
latter is representative of a 40 loudspeaker operating below
resonance and would be the worst case condition In most

4-14

,------------------------------------------------------------------------------, r
3:
....
Application Information (Continued)
~
case temperature is almost entirely dependent on heat sink
design and the mounting of the IC to the heat sink.

POWER LIMITING
40

Vs

30
~

20

~

10

~

g

I I/"' ..... Tc ; 30~C
V r\ 1"\ CURRENT
V

}/
V
-20

~ -10

6

= HOV

o

VOLTAGE

\/

-40
15

20

TIME

(m.l

25

30

.......

~

U'

a

~

...en
...ii:
...""=>
...'"""
......'"

-2 ~
~

~ "-

-30
10

2

\

1-

5

100

.. 3:

-.( is
-6

-8
35

0..

TUH/B704-27

Should the power ratings of the LM12 be exceeded, dynamic safe-area protection is activated. Waveforms with this
power limiting are shown for the LM12 driving ±26V at
30 Hz into 3n in series with 24 mH (0 = 4S'). With an
inductive load, the output clamps to the supplies in power
limit, as above. With resistive loads, the output voltage
drops in limit. Behavior with more complex RCL loads is
between these extremes.
Secondary thermal limit is activated should the case temperature exceed 1S0'C. This thermal limit shuts down the IC
completely (open output) until the case temperature drops
to about 14S'C. Recovery may take several seconds.

........
I'..

50

.........

i'.

.......
.........
20

10
200

~

r-..

P=80W

50

~

~

'~
500

~

1000

HEAT-SINK AREA

On 2)

2000
TL/H/B704-2B

The design of heat sink is beyond the scope of this work~
Convection-cooled heat sinks are available commercially,
and their manufacturers should be consulted for ratings.
The preceding figure is a rough guide for temperature rise
as a function of fin area (both sides) available for convection
cooling.
Proper mounting of the IC is required to minimize the thermal drop between the package and the heat sink. The heat
sink must also have enough metal under the package to
conduct heat from the center of the package bottom to the
fins without excessive temperature drop.
A thermal grease such as Wakefield type 120 or Thermalloy
Thermacote should be used when mounting the package to
the heat sink. Without this compound, thermal resistance
will be no better than O.S'C/W, and probably much worse.
With the compound, thermal resistance will be 0.2'C/W or
less, assuming under O.OOS inch combined flatness runout
for the package and heat sink. Proper torquing of the
mounting bolts is important. Four to six inch-pounds is recommended.
Should it be necessary to isolate V- from the heat sink, an
insulating washer is required. Hard washers like berylium
oxide, anodized aluminum and mica require the use of thermal compound on both faces. Two-mil mica washers are
most common, giving about 0.4'C/W interface resistance
with the compound. Silicone-rubber washers are also available. A O.S'C/W thermal resistance is claimed withoutthermal compound. Experience has shown that these rubber
washers deteriorate and must be replaced should the IC be
dismounted.
"Isostrate" insulating pads for four-lead TO-3 packages are
available from Power Devices, Inc. Thermal grease is not
required, and the insulators should not be reused.

POWER SUPPLIES
Power op amps do not require regulated supplies. However,
the worst-case output power is determined by the low-line
supply voltage in the ripple trough. The worst-case power
dissipation is established by the average supply voltage with
high-line conditions. The loss in power output that can, be
guaranteed is the square of the ratio of these two voltages.

Relatively simple off-line switching power supplies can provide voltage conversion, line isolation and S-percent regulation while reducing size and weight.
The regulation against ripple and line variations can provide
a substantial increase in the power output that can be guaranteed under worst-case conditions. In addition, switching
power supplies can convert low-voltage power sources
such as automotive batteries up to regulated, dual, highvoltage supplies optimized for powering power op amps.
HEAT SINKING

A semiconductor manufacturer has no control over heat
sink design. Temperature rating can only be based upon
case temperature as measured at the center of the package
bottom. With power pulses of longer duration than 100 ms,

4-15

~
..-

:I

r-------------------------------------------------------------------~

Definition of Terms
Input offset voltage: The absolute value of the voltage
between the input terminals with the output voltage and current at zero.
Input bias current: The absolute value of the average of
the two input currents with the output voltage and current at
zero.

Thermal gradient feedback: The input offset voltage
change caused by thermal gradients generated by heating
of the output transistors, but not the package. This effect is
delayed by several milliseconds and results in increased
gain error below 100 Hz.
Output-current limit: The output current with a fixed output
voltage and a large input overdrive. The limiting current
drops with time once the protection circuitry is activated.

Input offset current: The absolute value of the difference
in the two input currents with the output voltage and current
at zero.

Power dissipation rating: The power that can be dissipated for a specified time interval without activating the protection circuitry. For time intervals in excess of 100 ms, dissipation capability is determined by heat sinking of the IC package rather than by the IC itself.

Common-mode reJection: The ratio of the input voltage
range to the change in offset voltage between the extremes.
Supply-voltage rejection: The ratio of the specified supply-voltage change to the change in offset voltage between
the extremes.

Thermal resistance: The peak, junction-temperature rise,
per unit of internal power dissipation, above the case temperature as measured at the center of the package bottom.
The dc thermal resistance applies when one output transistor is operating continuously. The ac thermal resistance applies with the output transistors conducting alternately at a
high enough frequency that the peak capability of neither
transistor is exceeded.

Output saturation threshold: The output swing limit for a
specified input drive beyond that required for zero output. It
is measured with respect to the supply to which the output is
swinging.
Large signal voltage gain: The ratio of the output voltage
swing t,o the differential input voltage required to drive the
output from zero to either swing limit. The output swing limit
is the supply voltage less a specified quaSi-saturation voltage. A pulse of short enough duration to minimize thermal
effects, is used as a measurement signal.

Supply current: The current required from the power
source to operate the amplifier with the output voltage and
current at zero.

Equivalent Schematic (excluding active protection circuitry)

'Ri
3k

+

Ql

°Q14

01

, IN
R2
3k

~~----+------+--~~--~~--~--~OUT
02

R14
0.15

Q13

It!

IS},

12

IS}'!
°Q1S

°output clamps: hFE ~1
TL/H/8704-29

4-16

t;tINational Semiconductor

LM628/lM629 Precision Metion Controller
General Description

features

The LM628/LM629 are dedicated motion-control processors designed for use with a variety of DC and brush less DC
servo motors, and other servomechanisms which provide a
quadrature incremental position feedback signal. The parts
perform the intensive, real-time computational tasks required for high performance digital motion control. The host
control software interface is facilitated by a high-level command set. The LM628 has an 8-bit output which can drive
either an 8-bit or a 12-bit DAC. The components required to
build a servo system are reduced to the DC motor/actuator,
an incremental encoder, a DAC, a power amplifier, and the
LM628. An LM629-based system is similar, except that it
provides an 8-bit PWM output for directly driving H-switches.
The parts are fabricated in NMOS and packaged in a 28-pin
dual in-line package or a 24-pin surface mount package
(LM629 only). Both 6 MHz and 8 MHz maximum frequency
versions are available with the suffixes -6 and -8, respectively, used to designate the versions. They incorporate an
SDA core processor and cells designed by SDA.

32-bit position, velocity, and acceleration registers
Programmable digital PID filter with 16-bit coefficients
I:J Programmable derivative sampling interval
m 8- or 12-bit DAC output data (LM62B)
[J 8-bit sign-magnitude PWM output data (LM629)
[J Internal trapezoidal velocity profile generator
[J Velocity, target position, and filter parameters may be
changed during motion
c Position and velocity modes of operation
C Real-time programmable host interrupts
I!l 8-bit parallel asynchronous host interface
iii Quadrature incremental encoder interface with index
pulse input
[J Available in a 28-pin dual in-line package or a 24-pin
surface mount package (LM629 only)
[J

[J

LM628
HOST I/o PORT

1--14---1-_ TO HOST PROCESSOR

TL/H/9219-1

FIGURE 1. Typical System Block Diagram

Connection Diagrams
LM628N

LM629N

LM629M

iii

1

28

VDD

iii

28

VDD

'Ne

24

A

2

27

ffi

A

27

ffi

02

23

04

B

3

26

CLK

B

26

CLK

01

22

05

D7

4

25

DACO

07

25

NC

06

5

24

DACI

D6

24

NC

23

DAC2

05

6

23

NC

05

3

DO

21

06

cs

20

07

22

DAC3

04

7

22

NC

Ro

19

03

B

21

DAC4

03

8

21

NC

GNO

18

02

9

20

OACS

02

9

20

NC

17

01

10

19

OAC6

01

10

19

PWM NAG

ViR
Ps'

DO

II

18

DAC7

DO

11

18

PWM SIGN

HI

D4

cs

12

17

HI

iiii

13

16

GNO

14

15

PS
WR

cs

12

17

HI

iiii

13

16

GNO

14

15

PS
WR

TL/H/9219-2

TL1H/9219-3

iN

16

VOO

10

15

RST

PWM SIGN

II

14

eLK

'NC

12

13

PWN MAG

*00 not connect.

Order Number LM629M-6, LM629M-8, LM628N-6, LM628N-8, LM629N-6 or LM629N-8
See NS Package Number M24B or N28B
4-17

03

TL/H/9219-21

•

Absolute Maximum Ratings (Note 1)

Operating Ratings

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.

Temperature Range

Voltage at Any Pin with
Respect to GND

-0.3Vto +7.0V

Ambient Storage Temperature

-65·Cto + 150"C

+85·C

< felK < 6.0 MHz

1.0 MHz

< felK < B.O MHz
< Voo < 5.5V

4.5V

260·C
300·C

Maximum Power Dissipation (TA :s;; B5·C, Note 2)

=

< TA <

1.0 MHz

VooRange

Lead Temperature
2B-pin Dual In-Line
Package (Soldering, 4 sec.)
24-pin Surface Mount
Package (Soldering, 10 sec.)
ESD Tolerance
(CZAP = 120 pF, RZAP

-40·C

Clock Frequency:
LM628N-6, LM629N-6,
LM629M-6
LM628N-8, LM629N-8, '
LM629M-B

605mW
2000V

1.5k)

DC Electrical Characteristics (Voo and TAper Operating Ratings; felK = 6 MHz)
Symbol

Parameter

Tested Limits

Conditions

Min
Supply Current

100

Units

Max

Outputs Open

110

mA

O.B

V

10

IJ-A

0.4

V

10

IJ-A

INPUT VOLTAGES '
VIH

Logic 1 Input Voltage

Vil

Logic 0 Input Voltage

liN

Input Currents

2.0

V

-10

O:S;; VIN:S;; Voo

OUTPUT VOLTAGES

= -1.6mA
= 1.6mA

VOH

Logic 1

IOH

VOL

Logic 0

IOl

lOUT

TRI-STATE$ Output Leakage Current

O:S;; VOUT:S;; VOD

2.4

V

-10

AC Electrical Characteristics
(Voo and TAper Operating Ratings; felK

=

Timing Interval

6 MHz; ClOAO

=

50 pF; Input Test Signal tr

=

tf

=

10 ns)

Tested Limits

T#
Min

Units
Max

ENCODER AND INDEX TIMING (See Figure 2)
Motor-Phase Pulse Width

T1

-

16

-

B

felK

Dwell-Time per State

T2

felK

Index Pulse Setup and Hold
(Relative to A and BLow)

IJ-,s
IJ-s

T3

0

IJ-s

Clock Pulse Width
LM62BN-6, LM629N-6, LM629M-6
LM628N-B, LM629N-8, LM629M-B

T4
T4

7B
57

ns
ns

Clock Period
LM62BN-6, LM629N-6, LM629M-6
LM62BN-8, LM629N-8, LM629M-B

T5
T5

166
125

ns
ns

Res,et Pulse Width

T6

8
-felK

IJ-s

CLOCK AND RESET TIMING (See Figure 3)

4-18

AC Electrical Characteristics

(Continued)

(VDD and TA per Operating Ratings; fOLK = 6 MHz; CLOAD = 50 pF; Il')put Test Signal tr = tf = 10 ns)
Timing Interval

Tested Limits

T#
Min

Units
Max

STATUS BYTE READ TIMING (See Figure 4)
Chip-Select Setup/Hold Time

T7

0

ns

Port-Select Setup Time

T8

30

ns

Port-Select Hold Time

T9

30

Read Data Access Time

T10

Read Data Hold Time

T11

RD High to Hi-Z Time

T12

ns
180

0

ns
ns

180

ns

COMMAND BYTE WRITE TIMING (See Figure 5)

,

Chip-Select Setup/Hold Time

T7

0

ns

Port-Select Setup Time

T8

30

Port-Select Hold Time

T9

30

Busy Bit Delay

T13

WR Pulse Width

T14

Write Data Setup Time

T15

50

ns

Write Data Hold Time

T16

120

ns

ns
ns
(Note 3)

100

ns
ns

DATA WORD READ TIMING (See Figure 6)
Chip-Select Setup/Hold Time

T7

0

ns

Port-Select Setup Time

T8

30

ns

30

Port-Select Hold Time

T9

Read Data Access Time

T10

Read Data Hold Time

T11

RD High to Hi-Z TIme

T12

ns
180

0

ns
ns

180

ns

(Note 3)

ns

Busy Bit Delay

T13

Read Recovery Time

T17

120

ns

Chip-Selecl Setup/Hold TIme

T7

0

ns

Port-Select Setup Time

T8

30

ns

Port-Select Hold Time

T9

30

Busy Bit Delay

T13

WR Pulse Width

T14

100

ns

Write Data Setup Time

T15

50

ns

Write Data Hold Time

T16

120

ns

DATA WORD WRITE TIMING (See Figure 7)

ns
(Note 3)

ns

120
Write Recovery Time
ns
T18
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating
the device beyond the above Operating Ratings.
Note 2: When operating at ambient temperatures above 70'C, the device must be protected against excessive junction temperatures. Mounting the package on a
printed circuit board having an area greater than three square inches and sUlTOundlng the leeds and body w"h wide copper traces and large, uninterrupted areas of
copper, such as a ground plane, suffices. The 28-pin DIP (N) and the 24-pln surface mount package (M) are molded plastic packages with solid copper lead frames.
Most of the heat generated at the die flows from the die, through the copper lead frame, and into copper traces on the printed circuit board. The copper traces act
as a heat sink. Double-sided or mu"I-layer boards provide heat transfer charecteristics superior to those of single-sided boards.
Note 3: In order to read the busy bit, the status byte must first be read. The time required to read the busy bit far exceeds the time the chip requires to set the busy
bit. It Is, therefore, impossible to test actual busy bit delay. The busy bit Is guaranteed to be valid as soon as the user is able to read It.

4·19

en ,---------------------------------------------------------------------------------,
C'I

r-- T1

CD

::::!i

..J

~
CD

A~

::::!i

..J
B

-I- T1--1

tJI

I~T2J
i

I--T3-1

-;

I

L

\-T3--1
; - INDEX=A·ij·IN

TUH19219-4

FIGURE 2. Quadrature Encoder Input Timing

CLOCK

I----T6--1

TUH19219-5

FIGURE 3. Clock and Reset Timing

TLIH19219-6

. FIGURE 4. Status Byte Read Timing

4·20

r---------------------------------------------------------------------------------, r-

:s::::

en

~

r-

:s::::

en

N
CD

00-07

BUSY
. BIT ______________________________

~

TUH/9219-7

FIGURE 5. Command Byte Write Timing
17

T9

1'-.::...-----'lI-------TI7------+I ' - - - - - - - - '
--I
j-T12
.

00-07

-------------:~~O::.;.,l~O:l;.H.....:BYTEH;;.:1G:;.H_...;f_-~I:--------------~
(HI-I)

OL

_

BUSY
BIT
TUH/9219-8

FIGURE 6. Dl!ta Word Read Timing

TUH/921B-9

FIGURE 7. Data Word Write Timing

4·21

Pinout Description
1. LM628 (8-blt output mode): Outputs latched data to the
DAC. The MSB is Pin 18 and the LSB is Pin 25.
2. LM628 (12-blt output mode): Outputs two, multiplexed
6-bit words. The less-significant word is output first. The
MSB Is on Pin 18 and the LSB is on Pin 23. Pin 24 is used
to demultiplex the words; Pin 24 is low for the less-significant word. The positive-going edge of the signal on Pin
25 is used to strobe the output data. Figure 8 shows the
timing of the multiplexed signals.
3. LM629 (Sign/magnitude outputs): Outputs a PWM sign
Signal on Pin 18 (11 for surface mount), and a PWM magnitude signal on Pin 19 (13 for surface mount). Pins 20 to
25 are not used in the LM629. Figure 11 shows the PWM
output Signal format.

(See Connection Diagrams) Pin numbers for the 24-pin surface mount package are indicated In p~rentheses.
Pin 1 (17), Index (iN) Input: Receives optional Index pulse
from the encoder. Must be tied high If not used. The index
position is read when Pins 1, 2, and 3 are low.
Pins 2 and 3 (18 and 19), Encoder Signal (A, B) Inputs:
Receive the two-phase quadrature signals provided by the
incremental encoder. When the motor Is rotating in the positive ("forward") direction, the signal at Pin 2 leads the signal
at Pin 3 by 90 degrees. Note that the signals at Pins 2 and 3
must remain at each encoder state (See Figure 9) for a
minimum of 8 clock periods in order to be recognized. Because of a four-to-one resolution advantage gained by the
method of decoding the quadrature encoder signals, this
corresponds to a maximum encoder-state capture rate of
1.0 MHz (fCLK = 8.0 MHz) or 750 kHz (fCLK = 6.0 MHz).
For other clock frequencies the encoder signals must also
remain at each state a minimum of 8 clock periods.

Pin 26 (14), Clock (ClK) Input: Receives system clock.
Pin 27 (15), Reset (RST) Input: Active-low, positive-edge
triggered, resets the LM628 to the intemal conditions shown
below. Note that the reset pulse must be logic low for a
minimum of 8 clock periods. Reset does the following:
1. Filter coefficient and trajectory parameters are zeroed.

Pins 4 to 11 (20 to 24 and 2 to 4), Host 1/0 Port (00 to
07): Bi-directional data port which connects to host computer/processor. Used for writing commands and data to the
LM628, and for reading the status byte and data from the
LM628, as controlled by ~ (Pin 12), PS (Pin 16), AI) (Pin
13), and WR (Pin 15).
Pin 12 (5), Chip Select (CS) Input: Used to select the
LM628 for writing and reading operations.
Pin 13'(6), Read (RO) Input: Used to read status and data.

2. Sets position error threshold to maximum value (7FFF
hex), and effectively executes command LPEI.
3. The SBPAlSBPR interrupt is masked (disabled).
4. The five other interrupts are unmasked (enabled).
5. Initializes current position to zero, or "home" pOSition.

Pin 14 (7), Ground (GNO): Power-supply return pin.

6. Sets derivative sampling interval t6 2048/fCLK or 256 /JoS
for an 8.0 MHz clock.
.

Pin 15 (8), Write (Wl'i) Input: Used to write commands and
data.
'

7. DAC port outputs 800 hex to "zero" a 12-bit DAC and
then reverts to 80 hex to "zero" an 8-bit DAC.

Pin 16 (9), Port Select (PS) Input: Used to select command or data port. Selects command port when low, data
port when high. The following modes are controlled by Pin
16:
1. Commands are written to the command port (Pin 16 low),
2. Status byte is read from command port (Pin 16 low), and

Immediately after releasing the reset pin from the LM628,
the status port should read '00'. If the reset is successfully
completed, the status word will change to hex '84' or 'C4'
within 1.5 ms. If the status word has not changed from hex
'00' to '84' or '04' within 1.5 ms, perform another reset and
repeat the above steps. To be certain that the reset was
properly performed, execute a RSTI command. If the chip
has reset properly, the status byte will change from hex '84'
or '04' to hex '80' or 'CO'. If this does not occur, perform
another reset and repeat the above steps.

3. Data Is written and read via the data port (Pin 16 high).
Pin 17 (10), Host Interrupt (HI) Output: This active-high
signal alerts the host (via a host interrupt service routine)
that an interrupt condition has occurred.
Pins 18 to 25, OAC Port (OACO to OAC7): Output port
which is used in three different modes:

Pin 28 (16), Supply Voltage (VDD): Power supply voltage
(+5V).

2048

DATA:
(PINS 18 - 23)
SELECT:
(PIN 24)

STROBE:
(PIN 25)

I-f---,.Ixl-·----X~-:.6-:.H-IG-H-fBC-·ITSLK-

-f-(-~--I'X .

- - -------

)

6 LOW

B~

"'--------....JJ

~~i
----\1\

l,:'1-

\~

~

~f~~K ~
TLlH/9219-10

FIGURE 8. 12·Blt Multiplexed Output Timing

4-22

Theory of Operation
and an index pulse input. The quadrature signals are used
to keep track of the absolute position of the motor. Each
time a logiC transition occurs at one of the quadrature inputs, the LM62B internal position register is incremented or
decremented accordingly. This provides four times the resolution over the number of lines provided by the encoder.
See Figure 9. Each of the encoder signal inputs is synchronized with the LM62B clock.

INTRODUCTION

The typical system block diagram (See Figure 1) illustrates
a servo system built using the LM62B. The host processor
communicates with the LM62B through an I/O port to facilitate programming a trapezoidal velocity profile and a digital
compensation filter. The DAC output interfaces to an external digital-to-analog converter to produce the signal that is
power amplified and applied to the motor. An incremental
encoder provides feedback for clOSing the position servo
loop. The trapezoidal velocity profile generator calculates
the required trajectory for either position or velocity mode of
operation. In operation, the LM62B subtracts the actual position (feedback position) from the desired position (profile
generator position), and the resulting position error is processed by the digital·filter to drive the motor to the desired
pOSition. Table I provides a brief summary of specifications
offered by the LM62B/LM629:

The optional index pulse output provided by some encoders
assumes the logic-low state once per revolution. If the
LM62B is so programmed by the user, it will record the absolute motor position in a dedicated register (the index register) at the time when all three encoder inputs are logic low.
If the encoder does not provide an index output, the LM62B
index input can also be used to record the home position of
the motor. In this case, typically, the motor will close a
switch ~hich is arranged to cause a logic-low level at the
index input, and the LM62B will record motor position in the
index register and alert (interrupt) the host processor. Permanently grounding the index input will cause the LM62B to
malfunction.

POSITION FEEDBACK INTERFACE

The LM62B interfaces to a motor via an incremental encoder. Three inputs are provided: two quadrature signal inputs,

TABLE I. System Specifications Summary

Position Range

-1,073,741 ,B24 to 1,073,741 ,B23 counts

Velocity Range

o to 1,073,741 ,B23/2 16 counts/sample; ie, 0 to 16,3B3 counts/sample, with a resolution of 1/216
counts/sample

Acceleration Range

o to 1,073,741 ,B23/2 16 counts/sample/sample; ie, 0 to 16,3B3 counts/sample/sample, with a
resolution of 1/216 counts/sample/sample

Motor Drive Output

LM62B: B-bit parallel output to DAC, or 12-bit multiplexed output to DAC
LM629: B-bit PWM sign/magnitude signals

Operating Modes

Position and Velocity

Feedback Device

Incremental Encoder (quadrature signals; support for index pulse)

Control Algorithm

Proportional Integral Derivative (PID) (piUS programmable integration limit)

Sample Intervals

Derivative Term: Programmable from 204B/fCLK to (204B • 256)/fCLK in steps of 204B/fCLK (256
to 65,536 jJos for an B.O MHz clock).
Proportional and Integral: 204B/fCLK

4-23

-

Theory of Operation

(Continued)
STATES B A
1 1 0
pos
2 1 1
3 0 1
DIRECTION
400
1 1 0
NEG
2 1 1
3 0 1

1

!

TLlH/9219-11

FIGURE 9. Quadrature Encoder Signals
' \ " UMITING VELOCITY
YrLOCITY

STOPPING POSITION
IS INTEGRAL OF
TRAPEZOID

nME

(8)

VELOCITY

nME

(b)

TL/H/9219-12

FIGURE 10. Typical Velocity Profiles
VELOCITY PROFILE (TRAJECTORy) GENERATION
The trapezoidal velocitY profile generator computes the de·
sired position of the motor versus time. In the position mode
of operation, the host processor specifies acceleration,
maximum velocity, and final position. The LM628 uses this
information to affect the move by accelerating as specified
until the maximum velocity is reached or until deceleration
must begin to stop at the specified final position. The decel·
eration rate is equal to the acceleration rate. At any time
during the move the maximum velocity and/or the target
position may be changed, and the motor will accelerate or
decelerate accordingly. Figure 10 illustrates two typical trap·
ezoidal velocity profiles. Figure 10 (a) shows a simple trape·
zoid, while Figure 10 (b) is an example of what the trajectory
looks like when velocity and position are changed at differ·
ent times during the move.

condition goes undetected, and the impeding force on the
motor is subsequently released, the motor could reach a
very high velocity in order to catch up to the desired position
(which is still advancing as specified). This condition is easi·
Iy detected; see commands LPEI and LPES.
All trajectory parameters are 32·bit values. Position is a
signed quantity. Acceleration and velocity are specified as
16-bit, positive·only integers having 16·bit fractions. The in·
teger portion of velocity specifies how many counts per
sampling interval the motor will traverse. The fractional por·
tion designates an additional fractional count per sampling
interval. Although the position resolution of the LM628 is
limited to integer counts, the fractional counts provide in·
creased average velocity resolution. Acceleration is treated
in the same manner. Each sampling interval the command·
ed acceleration value is added to the current desired velocity to generate a new desired velocity (unless the command
velocity has been reached).
One determines the trajectory parameters for a desired
move as follows. If, for example, one has a 500-line shaft
encoder, desires that the motor accelerate at one revolution
per second per second until it is moving at 600 rpm, and
then decelerate to a stop at a position exactly 100 revolutions from the start, one would calculate the trajectory parameters as follows:

When operating in the velocity mode, the motor accelerates
to the specified velocity at the specified acceleration rate
and maintains the specified velocity until commanded to
stop. The velocity is maintained by advancing the desired
position at a constant rate. If there are disturbances to the
motion during velocity mode operation, the long-time aver·
age velocity remains constant. If the motor is unable to
maintain the specified velocity (which could be caused by a
locked rotor, for example), the desired position will continue
to be increased, resulting in a very large position error. If this
4-24

r

Theory of Operation

:s::
en

(Continued)

let P = target position (units = encoder counts)
let R = encoder lines • 4 (system resolution)
then R = 500 • 4 = 2000

a constant torque loading, the motor will still be able to
achieve zero position error.
The third term, the derivative term, provides a force proportional to the rate of change of position 'error. It acts just like
viscous damping in a damped spring and mass system (like
a shock absorber in an automobile). The sampling interval
associated with the derivative term is user-selectable; this
capability enables the LM628 to control a wider range of
inertial loads (system mechanical time constants) by providing a better approximation of the continuous derivative. In
general, longer sampling intervals are useful for low-velocity
operations.
In operation, the filter algorithm receives a 16-bit error signal
from the loop summing-junction.. The error signal is saturatedat 16 bits to ensure predictable behavior. In addition to
being multiplied by ,filter coefficient kp, the ,error signal is
added to an accumulation of previous errors (to form the
integral ,signal) and, at a rate determined by the chosen derivative sampling interval, the previous error i's subtracted
from it (to form the derivative signal). All filter multiplications
are 16-bit operations; only the bottom 16 bits of the product
are used.

and P = 2000 • desired number of revolutions
P ,;, 2000 • 100 revs = 200,000 counts (value to
load)
P (coding) = 00030D40 (hex code written to LM628)
let

V = velocity (units = counts/sample)

T = sample time (seconds) = 341 /Ls (with 6 MHz
clock)
let C = conversion factor = 1 minute/60 seconds
then V = R • T • C • desired rpm
let

and V = 2000' 341E-6 • 1/60' 600 rpm
V = 6.82 counts/sample
V (scaled) = 6.82 • 65,536 = 446,955.52
V (rounded) = 446,956 (value to load)
V (coding) = 0006D1 EC (hex code written to LM628)
let

A' = acceleration (units = counts/sample/sample)
A = R • T • T • desired acceleration (rev/sec/sec)

The integral signal is maintained to 24 bits, but only the top
16 bits are used. This scaling technique results in a more
usable (less sensitive) range of coefficient ki values. The 16
bits are right-shifted eight positions and multiplied' by filter
coefficient ki to form the term which contributes to the motor control output. The absolute magnitude of this product is
compared to coefficient ii, and the lesser, appropriately
signed magnitude then contributes to the motor control signal.
The derivative signal is multiplied by coefficient kd each derivative sampling interval. This product contributes to the
motor control output every sample interval, independent of
the user-chosen derivative'sampling interval.

then A = 2000' 341E-6 • 341E-6 • 1 rev/sec/sec
and A = 2.33E-4 counts/sample/sample
A (scaled) = 2.33E-4 • 65,536 = 15.24
A (rounded) = 15 (value to load)
A (coding) = OOOOOOOF (hex code written to LM628)
The above position, velocity, and acceleration values must
be converted to binary codes to be loaded into the LM628.
The values shown for velocity and acceleration must be
multiplied by 65,536 (as shown) to adjust for the required
integerlfraction format of the input data. Note, that after
scaling the velocity and acceleration values, literal fractional
data cannot be loaded; the data must be rounded and converted to binary. The factor of four increase in system resolution is due t,O the method used to decode the quadrature
encoder signals, see Figure 9.

The kp, limited ki, and kd product terms are summed to form
a 16-bit quantity. Depending on the output mode (wordsize),
either the top 8 or top 12 bits become the motor control
output signal.

PID COMPENSATION FILTER

LM628 READING AND WRITING OPERATIONS

The LM628 uses a digital Proportional Integral Derivative
(PID) filter to compensate the control loop. The motor is
held at the desired position by applying a restoring force to
the motor that is proportional to the position error, plus the
integral of the error, plus the derivative of the error. The
following discrete-time equation illustrates the control performed by the LM628:

The host processor writes commands to the LM628 via the
host I/O port when Port Select (PS) input (Pin 16) is logic
low. The desired command code is applied to the parallel
port line and the Write (WR) input (Pin 15) is strobed. The
command byte is latched into the LM628 on the rising edge
of the WR input. When writing command bytes it is necessary to first read the status byte and creck the state of a
flag called the "busy bit" (Bit 0). If the busy bit is logic high,
no command write may take place. The busy bit is never
high longer than 100 /Ls, and typically falls within 15 /Ls to
25/Ls.
The host processor reads the LM626 status byte in a similar
, manner: by strobing the Read (RD) input (Pin 13) when PS
(Pin 16) is low; status information remains valid as long as
_ RD is low.

n

u(n) = kp*e(n)

+ kiL

e(n)

+

N=O

kd[e(n') - e(n' - 1)1

(Eq.1)

where u(n) is the motor control signal output at sample time
n, e(n) is the position error at sample time n, n' indicates sampling at the derivative sampling rate, and
kp, ki, and kd are the discrete-time filter parameters
loaded by the users.

Writing and reading data to/from the LM628 (as opposed to
writing commands and reading status) are done with PS (Pin
16) logic high. These writes and reads are always an integral number (from one to seven) of two-byte words, with the
first byte of each word being the more significant. Each byte
requires a write (WR) or read (RD) strobe. When transferring
data words (byte-pairs), it is necessary to first read the
status byte and check the state of the busy bit. When the

The first term, the proportional term, provides a restoring
force porportional to the position error, just as does a spring
obeying Hooke's law. The second term, the' integration
term, provides a restoring force that grows with time, and
thus ensures that the static position error is zero. If there is
4-25

....,
co
.....
r

:s::
en
....,
CD

Theory of Operation (Continued)
The LM629 provides 8-bit, sign and magnitude PWM output
signals for directly driving switch-mode motor-drive amplifiers. Figure 11 shows the format of the PWM magnitude output signal.

busy bit is logic low, the user may then sequentially transfer
both bytes comprising a data word, but the busy bit must
again be checked and found to be low before attempting to
transfer the next byte pair (when transferring multiple
words). Data transfers are accomplished via LM628-internal
interrupts (which are not nested); the busy bit informs the
host processor when the LM628 may not be interrupted for
data transfer (or a command byte). If a command is written
when the busy bit is high, the command will be ignored.

PWM IIAGNllUDE WAVEFORMS (pin 19):

DUlY CYCLE:

o

1(ON)

(a) 128= OFF 0 _ _ _ _ _ _ _ _ _ _ __

:c:!

,
-ll-r--l
I-ClK. J L . . .
I JLL
I ..JL
( ) .L_ IIIN l IIJ L

The busy bit goes high immediately after writing a command
byte, or reading or writing a second byte of data (See Figures 5 thru 7).

,

b 128 -DRIVE

0

,

256

--t

c .M_ 50:! 1 I
()128-DRIVE

I- feLK

'

I

orLrLn-nJ

MOTOR OUTPUTS
The LM628 DAC output port can be configured to provide
either a latched eight-bit parallel output or a multiplexed
12;bit output. The 8-bit output can be directly connected to
a flow-through (non-input-Iatching) Df A converter; the 12-bit
output can be easily demultiplexed using an extemal '6-bit
latch and an input-latching 12-bit Of A converter. The DAC
output data is' offset-binary coded; the 8-bit code for zero is
80 hex and the 12-bit code for zero is 800 hex. Values less
than these cause a negative torque to be applied to the
motor and, conversely, larger values cause positive motor
torque. The LM628, when configured for 12-bit output, provides signals which control the demultiplexing process. See
Figure 8 for details.

508
"AX:1 fCLK
127 ~
(d) 128=POS
I
DRIVE 0

r-

1.---,..--,..--,..--,r
U
U
U
U
I---- 2048
.1

128 MAX

1CLK

1 ---......;;;;;.-------

(0) 128 =~~E 0 (OFF) ,

TL/H/9219-13

Nole: Sign output (pin 18) nbt'shown

FIGURE 11. PWM Output Signal Format

TABLE II. LM628 User Command Set
Command
RESET
PORT8
PORT12
DFH
SIP
LPEI
LPES
SBPA
SBPR
MSKI
RSTI
LFIL
UDF
LTRJ

sn
RDSTAT
RDSIGS
ROIP
RDDP
RORP
RDDV
RDRV
RDSUM

Type

Description

Hex

Initialize
Initialize
Initialize
Initialize
Interrupt
Interrupt
Interrupt
Interrupt
Interrupt
Interrupt
Interrupt
Filter
Filter
Trajectory
Trajectory
Report
Report
Report
Report
Report
Report
Report
Report

ResetLM628
Select 8-Bit Output
Select 12-Bit Output
Define Home
Set Index Position
Interrupt on Error
Stop on Error
Set Breakpoint, Absolute
Set BreakpOint, Relative
Mask Interrupts
Reset Interrupts
Load Filter Parameters
Update Filter
Load Trajectory
Start Motion
Read Status Byte
Read Signals Register
Read Index Position
Read Desired Position
Read Real Position
Read Desired Velocity
Read Real Velocity
R,ead Integration Sum

00
05
06
02
03
lB
lA
20
21
lC

10
lE
04
lF
01
None
OC
09
08
OA
07
OB
OD

Nole 1: Commands may be executed "On the Fly" during motion.
Note 2: Commands not applicable to execution during motion.
Note 3: Command may be executed during motion if acceleration parameter was not changed.
Nole 4: Command needs no code because the command port status-byte read is totally supported by hardwara.

4-26

Data
Bytes

Note

0
0
0
0
0
2
2
4
4
2
2
2 to 1,0
0
2 to 14'
0
1
2
4
4
4
4
2
2

1
2
2
1
1
1
1
1
1
1
1
1
1
1
3
1,4
1
1
1
1
1
1
1

mediately executed. This command must not be issued
when using an 8-bit converter or the LM629, the PWM-output version of the LM628.

User Command Set
GENERAL

The t6ilowing: p~ragraphs describe the user command set of
the LM628: Some,of the commands can be issued alone
and some require a supporting data structure. As examples,
the command STT (STarT motion) does not require additional data; command LFIL (Load Filter parameters) requires additional data (derivative-term sampling interval
and/or filter parameters).

DFH COMMAND: DeFine Home
02 Hex
Command Code:
Data Bytes:
None
Executable During Motion: Yes
This command declares the current position as "home", or
absolute position 0 (Zero). If DFH is executed during motion
it will not affect the stopping position of the on-going move
unless command STT is also executed.

Commands are categorized by function: initialization, interrupt control, filter control, trajectory control, and data reporting. The commands are listed in Table II and described in
the following paragraphs. Along with each command name
is its command-byte code, the number of accompanying
data bytes that are to be written (or read), and a comment
as to whether the command is executable during motion.

Interrupt Control Commands
The following seven LM628 user commands are associated
with conditions which can be used to interrupt the host computer. In order for any of the potential interrupt conditions to
actually interrupt the host via Pin 17, the corresponding bit
in the interrupt mask data associated with command MSKI
must have been set to logic high (the non-masked state).

Initialization Commands
The following four LM628 user commands are used primarily to initialize the system for use.

The identity of all interrupts is made known to the host via
reading and parsing the status byte. Even if all interrupts are
masked off via command MSKI, the state of each condition
is still reflected in the status byte. This feature facilitates
polling the LM628 for status information, as opposed to interrupt driven operation.

RESET COMMAND: RESET the LM62a
00 Hex
Command Code:
Data Bytes:
None
Executable During Motion: Yes
This command (and the hardware reset input, Pin 27) results in setting the following data items to zero: filter. coefficients and their input buffers, trajectory parameters and
their input buffers, and the motor control output. A zero motor control output is a half-scale, offset-binary code: (80 hex
for the 8-bit output mode: 800 hex for 12-bit mode). During
reset, the DAC port outputs 800 hex to "zero" a 12-bit DAC
and reverts to 80 hex to "zero" an 8-bit DAC. The command
also clears five of the six interrupt masks (only the SBPAI
SBPR interrupt is masked), sets the output port size to
8 bits, and defines the current absolute position as home.
Reset, which may be executed at any time, will be completed in less than 1.5 ms. Also see commands PORT8 and
PORT12.

SIP COMMAND: Set Index Position
Command Code:
03 Hex
Data Bytes:
None
Executable During Motion: Yes
After this command is executed, the absolute position which
corresponds to the occurrence of the next index pulse input
will be recorded in the index register, and bit 3 of the status
byte will be set to logic high. The position is recorded when
both encoder-phase inputs and the index pulse input are
logic low. This register can then be read by the user (see
description for command RDIP) to facilitate aligning the definition of home pOSition (see description of command DFH)
with an index pulse. The user can also arrange to have the
LM62a interrupt the host to signify that an index pulse has
occurred. See the descriptions for commands MSKI and
RSTI.
.

PORTa COMMAND: Set Output PORT Size to a Bits
Command Code:
05 Hex
Data Bytes:
. None
Executable During Motion: Not Applicable
The default output port size of the LM628 is a bits; so the
PORTa command need not be executed when using an
a-bit DAC. This command must not be executed when using
a 12-bit converter; it will result in erratic, unpredictable motor behavior. The 8-bit output port size is the required selection when using the LM629, the PWM-output version of the
LM628.

LPEI COMMAND: Load Position Error for Interrupt
Command Code:
Data Bytes:
Data Range:
Executable During Motion:

1B Hex
Two
0000 to 7FFF Hex
Yes

An excessive position error (the output of the loop summing
junction) can indicate a serious system problem; e.g., a
stalled rotor. Instruction LPEI allows the user to input a
threshold for position error detection. Error detection occurs
when the absolute magnitude of the position error exceeds
the threshold, which results in bit 5 of the status byte being
set to logic high. If it is desired to also stop (turn off) the
motor upon detecting excessive position error, see command LPES, below. The first byte of threshold data written
with command LPEI is the more significant. The user can
have the LM628 interrupt the host to signify that an excessive position error has occurred. See the descriptions for
commands MSKI and RSTI.

PORT12 COMMAND: Set Output PORT Size to 12 Bits
Command Code:
06 Hex
Data Bytes:
None
Executable During Motion: Not Applicable
When a 12-bit DAC is used, command PORT12 should be
issued very early in the initialization process. Because use
of this command is determined by system hardware, there is
only one. foreseen reason to execute it later: if the RESET
command is issued (because an 8-bit output would then be
selected as the default) command PORT12 should ·be im-

4-27

II

~ r-----------------------------------------------------------------------------~

~

::i
....I

~
CD
~

Interrupt Control Commands (Continued)
LPES COMMAND: Load Position Error for Stopping

6-bit field will mask the corresponding interrupt(s); any
one(s) enable the interrupt(s). Other bits, comprising fhe two
bytes have no effect. The mask controls only the host interrupt process; rea~ing the status byte will still reflect the actual conditions independent of the mask byte. See Table III.

Command Code:
lA Hex
Data Bytes:
Two
0000 to 7FFF Hex
Data Range:
Executable During Motion: Yes
Instruction LPES is essentially the same as command LPEI
above, but adds the feature of turning off the motor upon
detecting excessive position error. The motor drive is not
actually switched off, it is set to half-scale, the offset-binary
code for zero. As with command LPEI, bit 5 of the status
byte is also set to logic high. The first byte of threshold data
written with command LPES is the more significant. The
user can have the LM628 interrupt the host to signify that an
excessive position error has occurred. See the descriptions
for commands MSKI and RSTI.

TABLE III. Mask and Reset Bit Allocations for Interrupts

SBPA COMMAND:
cOmmand Code:
20 Hex
Datil Bytes:
Four
COOOOOOO to 3FFFFFFF Hex
Data Range:
Executable During Motion: Yes
This command enables the user to set a breakpoint in terms
of absolute position. Bit 6 of the status byte is set to logic
high when the breakpoint position is reached. This condition
is useful for signaling trajectory and/or filter parameter updates. The user can also arrange to have the LM628 interrupt the host to signify that a breakpoint position has been
reached. See the descriptions for commands MSKI and
RSTI.

Bit Position

Function

Bits 15thru 7,
Bit 6
Bit 5
Bit4
Bit3
Bit 2
Bit 1
Bit 0

Not Used
Breakpoint Interrupt
Position-Error Interrupt
Wrap-Around Interrupt
Index-Pulse Interrupt
Trajectory-Complete Interrupt
Command-Error Interrupt
Not Used

RSTI COMMAND: ReSeT Interrupts
Command Code:
10 Hex
Data Bytes:
Two
See Text
Data Range:
Executable During Motion: Yes
When one of the potential interrupt conditions of Table III
occurs, command RSTI is used to, reset the corresponding
interrupt flag bit in the status byt,e. The host may reset one
or all flag bits. Resetting them one at a time allows the host
to service them one at a time 'according to a priority programmed by the user. As in the MSKI command, ,bits ,I
through 6 of the second (less significant) byte correspond to
the potential interrupt conditions shown in Table III. Also
see description of RDSTAT command. Any zero(s) in this
6-bit field reset the corresponding interrupt(s). The remaining bits have no effect.

SBPR COMMAND:
Command Code:
21 Hex
Data Bytes:
Four
See Text
Data Range:
Executable During Motion:' Yes
This command enables the user to set a breakpoint in terms
of relative position. As with command SBPA, bit 6 of the
status byte is set to logic high when the breakpoint position
(relative to the current commanded target position) is
reached. The relative breakpoint input value must be such
that when this value is added to the target position the result
remains within the absolute position range of the system
(COOOOOOO to 3FFFFFFF hex). This condition is useful for
signaling trajectory and/or filter parameter updates. The
user can also arrange to have the LM628 interrupt the host
to signify that a breakpoint position has been reached. See
the descriptions for commands MSKI and RSTI.

Filter Control Commands
The following two LM628 user commands are used for setting the derivative-term sampling interval, for adjusting the
filter parameters as required to tune,the system, and to control the timing of these system changes.

LFIL COMMAND: Load Filter Parameters
Command Code:
lE Hex
Data Bytes: '
Two to Ten
Data Ranges ...
Filter Control Word:
See Text
Filter Coefficients:
0000 to 7FFF Hex (Pos Only)
Integration Limit:
0000 to 7FFF Hex (Pos Only)
Executable During Motion: Yes"
The filter parameters (coefficients) which are written to the
LM628 to control loop compensation are: kp, ki, kd, and iI
(integration limit). The integration limit (iI) constrains the
contribution of the integration term

MSKI COMMAND: MaSK Interrupts
Command Code:
1C Hex
Data Bytes:
Two
See Text
Data Range:
E~ecutable Durin'g Motion:' Yes
The MSKI command lets the user determine which potential
interrupt condition(s) will interrupt the host. Bits 1 through 6
of the status byte are indicators of the six conditions which
are candidates for host interrupt(s). When interrupted, the
host then reads the status byte to learn which condition(s)
occurred. Note that the MSKI command is immediately followed by two data bytes. Bits 1 through 6 of the s~cond
(less significant) byte written determine the masked/unmasked status of each potential interrupt. Any zero(s) in this

. [ k i . ! e(n)]

N=O
(see Eq. 1) to values equill to or less than a user-defined
maximum value; this capability minimizes integral or reset
"wind-up" (an overshooting effect of the integral action).
The positive-only input value is compared to the absolute

4-28

Filter Control Commands (Continued)
magnitude of the integration term; when the magnitude of
integration term value exceeds ii, the iI value (with appropriate sign) is substituted for the integration term value.
The derivative-term sampling interval is also programmable
via this command. After writing the command code, the first
two data bytes that are written specify the derivative-term
sampling interval and which of the four filter parameters
is/are to be written via any forthcoming data bytes. The first
byte written is the more significant. Thus the two data bytes
constitute a filter control word that informs the LM628 as to
the nature and number of any following data bytes. See
Table IV.

The data bytes specified by and immediately following the
filter control word are written in pairs to comprise 16-bit
words. The order of sending the data words to the LM628
corresponds to the descending order shown in the above
description of the filter control word; i.e., beginning with kp,
then ki, kd and il. The first byte of each word is the more-significant byte. Prior to writing a word (byte pair) it is necessary to check the busy bit in the status byte for readiness.
The required data is written to the primary buffers of a double-buffered scheme by the above described operations; it
is not transferred to the secondary (working) registers until
the UDF command is executed. This fact can be used advantageously; the user can input numerous data ahead of
their actual use. This simple pipeline effect can relieve potential host computer data communications bottlenecks,
and facilitates easier synchronization of multiple-axis controls.
UDF COMMAND: UpDate Filter
Command Code:
04 Hex
Data Bytes:
None
Executable During Motion: Yes

TABLE IV. Filter Control word Bit Allocation
Bit Position

Function

Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0

Derivative Sampling Interval Bit 7
Derivative Sampling Interval Bit 6
Derivative Sampling Interval Bit 5
Derivative Sampling Interval Bit 4
Derivative Sampling Interval Bit 3
Derivative Sampling Interval Bit 2
Derivative Sampling Interval Bit 1
Derivative Sampling Interval Bit 0
Not Used
Not Used
Not Used
Not Used
Loading kp Data
Loading ki Data
Loading kd Data
Loading il Data

ren
==
N
co
.....
ren
==
N
CD

The UDF command is used to update the filter parameters,
the specifics of which have been programmed via the LFIL
command. Any or all parameters (derivative-term sampling
interval, kp, ki, kd, and/or II) may be changed by the appropriate command(s), but command UDF must be executed to
affect the change in filter tuning. Filter updating is synchronized with the calculations to eliminate erratic or spurious
behavior.

Trajectory Control Commands
The following two LM628 user commands are used for
setting the trajectory control parameters (position, velocity,
acceleration), mode of operation (position or velocity), and
direction (velocity mode only) as required to describe a desired motion or to select the mode of a manually directed
stop, and to control the timing of these system changes.
LTRJ COMMAND: Load TRaJectory Parameters

Bits 8 through 15 select the derivative-term sampling interval. See Table V. The user must locally save and restore
these bits during successive writes of the filter control word.
Bits 4 through 7 of the filter control word are not used.
Bits 0 to 3 inform the LM628 as to whether any or all of the
filter parameters are about to be written. The user may
choose to update any or all (or none) of the filter parameters. Those chosen for updating are so indicated by logic
one(s) in the corresponding bit position(s) of the filter control word.

Command Code:
Data Bytes:
Data Ranges .•.
Trajectory Control Word:
Position:
Velocity:

1F Hex
Two to Fourteen

See Text
COOOOOOO to 3FFFFFFF Hex
00000000 to 3FFFFFFF Hex
(PosOnly)
Acceleration:
00000000 to 3FFFFFFF Hex
(PosOnly)
Executable During Motion: Conditionally, See Text

TABLE V. Derivative-Term Sampling Interval Selection Codes
Bit Position

thru

15

14

13

12

11

10

9

8

0
0
0
0

0
0
0
0

0
0
0
0

0
0
0
0

0
0
0
0

0
0
0
0

0
0
1
1

0
1
0
1

1

1

1

1

1

1

1

1

Selected Derivative
Sampling Interval
256p.s
512p.s
768p.s
1024 p.s, etc ...
65,536 p.s

Note: Sampling intervals shown are when using an 8.0 MHz clock. The 256 corresponds to 2048/8 MHz; sample intervals must be scaled for other clock
frequencies.

4-29

•

en ,---------------------------------------------------------------------------------,

~

~

:5

Trajectory Control Commands (Continued)
The, trajectory control' parameters' which are written to the
LM628 to control motion are:, acceleration, velocity, and position. In addition, Indications as to whether these three parameters are to be considered,as absolute or relative inputs,
selection of.velocity mode and, direction, and manual stopping mode selection and execution are programmable via
this command. After writing the command code, the first ,two
data bytes that are written specify which parameter(s) is/are
being changed. The first byte written is the more significant.
Thus the two data bytes constitute a trajectory control word
that informs the LM628 as to the nature and number of any
following data bytes., See Table VI.
.
.. '
,
.
TABLE VI. Trajectory Control Word Bit Allocation

none) of ,the trajectory parameters. Those chosen for updating are so indicated by logic one(s) in the corresponding bit
position(s). Any parameter may be changed while the motor
is in motion; however, ,if acceleration is changed then the
next
command must not be issued until the LM628 has
completed the current move or has been manually stopped.

sn

The data bytes specified by and immediately following the
trajectory control word are written in pairs which comprise
16-bit words. Each data item (parameter) requires two 16-bit
words; the word and byte order is most-to-Ieast significant.
The order of sending the parameters to the' LM628 corresponds to the descending order shown in the above description of the trajectory control word; i.e., beginning with
acceleration, then velocity, and finally position.
Acceleration and velocity are 32 bits, positive only, but
range,only from 0 (00000000 hex) to [230]-1 (3FFFFFFF
hex). The bottom'16 bits of both acceleration and velocity
are scaled as fractional data; therefore, the least-significant
inte'ger data bit for these parameters is bit 16 (where the bits
are numbered 0 through 31). To determine the coding for a
given velocity, for example, one multiplies the desired velocity (in counts per sample intel'l(al) times 65,536 and converts
the result to binary. The units of acceleration are counts per
sample per sample. The value loaded for acceleration must
not exceed the value loaded for velocity. Position is a
signed, 32-bit integer, but ranges only from - [230]
(COOOOOOO hex) to [230]-1 (3FFFFFFF Hex).

'

Bit Position

Function

Bit1S

Not Used

Bit 14

Not Used

Bil13

NolUsed.

'.',

Bit12

Forward Direction (Velocity Mode Only)

Bit11

Velocity Mode

B~10

Stop ,SmQothly (Decelerate as, Programmed)

B~

9,

Stop Abruptly (Maximum, Deceleration)

Bit 8

Turn Off Motor (Output Zero Drive)

Bit 7

Not Used

Bit 6
Bit

Not Lised'

5

Accel~ration wiil Be Loaded,

Bit 4

Acceleration Data Is Relative

Bit 3

Veloc~ Will

Bit 2

Velocity Data ,Is Relative

The required data is written to the primary buffers of a double-buffered scheme by the above described operations; it
is not transferred to the secondary (working) registers until
command is executed. This fact can be used adthe
vantageously; the user can Input numerous data ahead of
their actual use. This simple pipeline effect can relieve potential host computer data communications bottlenecks,
and facilitates easier synchronization of multiple-axis controls.
,
'

Be Loaded

Bit 1

Posilion Will Be Loaded

Bit 0

PosHion Data

sn

'I

IS:R~lalive

Bit 12 determines the motor direction when in the velocity
mode. A logic one indicates forward direction. This bit has
no effect when in position, mode.

STT COMMAND: STarT Motion Control

Bit 11 determines whether'the LM628 operates in velocity
mode (Bit ,11 logic one) or position mode (Bit 11 logic zero).

Command Code:'
01 Hex
None
Data Bytes:
Executable During Motion: Yes, if acceleration has not
,
, ,
, been changed'
'

Bits 8 through 10 are used to select the method of manually
stopping the motor. These bits are not provided for,one to
merely specify the desired mode of stopping, in position
mode operations, normal stopping is always smooth and
occurs automatically 'at.the end of the specified trajectory.
Under excepti6nal circumstances it may be desired to manually intervene with the trajectory generation process to affect a premature stop. In velocity mode operations, however, the normal means of stopping is via bits 8 through 10
(usually bit 10). Bit 8 is set to logic one to stop the 'motor by
turning off motor drive output (outputting the appropriate offset-binary code to apply zero drive to the motor); bit 9 is set
to one to stop the motor, abruptly (at maximum available
acceleration, by setting the target position equal to the cur,rent position); and bit 10 is set to one to stop the motor
smoothly by using the current user-programmed acceleration value. Bits 8 through 10 are to be used exclusively; only
one bit should be a logic one at any time.
Bits 0 through 5 inform the LM628 as to whether any or all
of the trajectory contrOlling parameters are about to be written, and whether the data should be interpreted as absolute
or relative. The 'user may choose to update any or all (or,

T~e sn command is used to execute the desired traje'ctory, 'the specifics of which have been programmed'via the
LTRJ command. Synchronization of mUlti-axis control (to
within one sample interval) can be arranged by loading the
required trajectory parameters for each (and every) axis and
then simultaneously issuing a single
command to all
axes. This command may be executed at any time, unless
the acceleration value has been changed and a trajectory
has not been completed or the motor has not been manually stopped. If SIT is issued during motion and acceleration
has been changed, a command error interrupt will be generated and the command will be ignored.

sn

Data ,Reporting Commands
The following seven LM628 user commands are used to
obtain data from various registers in the LM628. Status, position, and velocity information are reported. With the exception of RDSTAT, the data is read from the LM628 data port
, after first writing the cQrresponding command to the command port~

4-30

,-----------------------------------------------------------------------------, r
!!:
G)

Data Reporting Commands (Continued)

I\,)

RDSTAT COMMAND: ReaD STATus Byte

Bit 2, the trajectory complete interrupt flag, is set to logic
one when the trajectory programmed by the LTRJ command and initiated by the STT command has been completed. Because of overshoot or a limiting condition (such as
commanding the velocity to be higher than the motor can
achieve), the motor may not yet be at the final commanded
position. This bit is the logical OR of bits 7 and 10 of the
Signals Register, see command RDSIGS below. The flag
functions independently of the host interrupt mask status.
Bit 2 is cleared via command RSTI.

Command Code:
None
Byte Read:
One
Data Range:
See Text
Executable During Motion: Yes
The RDSTAT command is really not a command, but is listed with the other commands because it is used very frequently to control communications with the host computer.
There is no identification code; it is directly supported by the
hardware and may be executed at any time. The single-byte
status read is selected by placing CS, PS and RD at logic
zero. See Table VII.

Function

Bit7
Bit 6
Bit 5
Bit 4
Bit3
Bit 2
Bit 1
Bit 0

Motor Off
Breakpoint Reached [Interrupt]
Excessive Position Error [Interrupt]
Wraparound Occurred [Interrupt]
Index Pulse Observed [Interrupt]
Trajectory Complete [Interrupt]
Command Error [Interrupt]
Busy Bit

!!:
G)
I\,)

CD

Bit 1, the command-error interrupt flag, is set to logic one
when the user attempts to read data when a write was appropriate (or vice versa). The flag is functional independent
of the host interrupt mask status. Bit 1 is cleared via command RSTI.

TABLE VII. Status Byte Bit Allocation
BltPoslUon

CD
.....
r

Bit 0, the busy flag, is frequently tested by the user (via the
host computer program) to determine the busyI ready status
prior to writing and reading any data. Such writes and reads
may be executed only when bit 0 is logic zero (not busy).
Any command or data writes when the busy bit is high .will
be ignored. Any data reads when the busy bit is high will
read the current contents of the 1/0 port buffers, not the
data expected by the host. Such reads or writes (with the
busy bit high) will not generate a command-error interrupt.
RDSIGS COMMAND: ReaD SIGnalS Register
Command Code:
OC Hex
Bytes Read:
Two
Data Range:
See Text
Executable During Motion: Yes
The LM628 internal "signals" register may be read using
this command. The first byte read is the more significant.
The less significant byte of this register (with the exception
of bit 0) duplicates the status byte. See Table VIII.

Bit 7, the motor-off flag, is set to logic one when the motor
drive output is off (at the half-scale, offset-binary code for
zero). The motor is turned off by any of the following condi·
tions: power-up reset, command RESET, excessive position
error (if command LPES had been executed), or when command LTRJ is used to manually stop the motor via turning
the motor off. Note that when bit 7 is set in conjunction with
command LTRJ for producing a manual, motor-off stop, the
actual setting of bit 7 does not occur until command STT is
issued to affect the stop. Bit 7 is cleared by command STT,
except as described in the previous sentence.

TABLE VIII. Signals Register Bit Allocation

Bit 6, the breakpoint-reached interrupt flag, .is set to logic
one when the position breakpoint loaded via command
SBPA or SBPR has been exceeded. The flag is functional
independent of the host interrupt mask status. Bit 6 is
cleared via command RSTI.
Bit 5, the excessive-position-error interrupt flag, is set ·to
logic one when a position-error interrupt condition exists.
This occurs when the error threshold loaded via command
LPEI or LPES has been exceeded. The flag is functional
independent of the host interrupt mask status. Bit 5 is
cleared via command RSTI.
Bit 4, the wraparound interrupt flag, is set to logic one when
a numerical ''wraparound'' has occurred. To "wraparound"
means to exceed the position address space of the LM628,
which could occur during velocity mode operation. If a wraparound has occurred, then position information will be in
error and this interrupt helps the user to ensure position
data integrity. The flag is functional independent of the host
interrupt mask status. Bit 4 is cleared via command ASTI.

Bit Position

Function

Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0

Host Interrupt
Acceleration Loaded (But Not Updated)
UDF Executed (But Filter Not yet Updated)
Forward Direction
Velocity Mode
On Target
Turn Off upon Excessive Position Error
Eight-Bit Output Mode
Motor Off
Breakpoint Reached [Interrupt]
Excessive Position Error [Interrupt]
Wraparound Occurred [Interrupt]
Index Pulse Acquired [Interrupt]
Trajectory Complete [Interrupt]
Command Error [Interrupt]
Acquire Next Index (SIP Executed)

Bit 15, the host interrupt flag, is set to logic one when the
host interrupt output (Pin 17) is logiC one. Pin 17 is set to
logiC one when any of the six host interrupt conditions occur
(if the corresponding interrupt has not been masked). Bit 15
(and Pin 17) are cleared via command RSTI.

Bit 3, the index-pulse acquired interrupt flag, is set to logic
one when an index pulse has occurred (if command SIP had
been executed) and indicates that the index positiol") register has been updated. The flag is funCtional independent of
the host interrupt mask status. Bit 3 is cleared by command
RSTI.

Bit 14, the acceleration-loaded flag, is set to logic one when
acceleration data is written to the LM628. Bit 14 is cleared
by the STT command.

4-31

•

en ,---------------------------------------------------------------------------------,
~
Data Reporting Commands (Continued)

==

...I
......
CD

'"
CD

==
...I

Bit 13; the UDF-executed flag, is set to logic one when the
UDF command is executed. Because bit 13 is cleared at the
end of the sampling interval in which it has been set, this
signal is very short-lived and probably not very profitable for
monitoring.
Bit 12, the' forward direction flag, is meaningful only when
the LM62B is in velocity mode. The bit is set to logic one to
indicate that the desired direction of motion is "forward";
zero indicates "reverse" direction. Bit 12 is set and cleared
via command LTRJ. The actual setting and clearing of bit 12
does not occur until command STT is executed.
Bit 11, the velocity mode flag, is set to logic one to indicate
that the user has selected (via command LTRJ) velocity
mode. Bit 11 is' cleared when position mode is selected (via
command LTRJ). The actual setting and clearing of bit 11
does not occur until command STT is executed.

This command reads·the current actual pOSition of the 'motor. This is the feedback input to the loop summing junction.
The bytes are read in most-to-Ieast significant ord.er.
RDDV COMMAND: ReaD Desired Velocity
Command Code:
Bytes Read:
Data Range:
Executable During Motion:

This command reads the Integer and fractional portions of
the Instantaneous desired (current temporal) velocity, as
used to generate the desired position profile. The bytes are
read in most-to-Ieast significant order. The: value read 'is
properly scaled for numerical comparison with the user-supplied (commanded) velocity; however, because the two
least-significant bytes represent fractional velocity, only ,the
two most-significant bytes are appropriate for comparison
with the data obtained via command RDRV (see below).
Also note that, although the velocity input data is constrained to positive numbers (see command LTRJ), the data
returned by command RDDV represents a signed quantity
where negative numbers represent operation in the reverse
direction.

Bit 10, the on-target flag, is set to logic one when the trajectory generator has completed its functions for the last-issued STT command. 'Bit lOis cleared by the next STT command.
Bit 9, the turn-off on-error flag, is set to logic one when
command LPES.is executed. Bit 9 is cleared by command
~a

07 Hex
Four'·.. ,:
C0000001 to 3FFFFFFF
Yes

'

RDRV COMMAND: ReaD Real Velocity

Bit B, the B-bit output flag, is set to logic one when the
LM62B is reset, or when command PORTB is executed. Bit
'
B is cleared by command PORT12.

Command Code:
Bytes Read:
Data Range:
Executable During Motion:

Bits 0 through 7 replicate the status byte (see Table VII),
with the exception of bit o. Bit 0, the acquire next index flag,
is set to logic one when command SIP is executed; i~ then
remains set until the next index pulse occurs.
RDIP COMMAND: ReaD Index POSition
Command Code:
09 Hex
Bytes Read:
Four
Data Range:
COOOOOOO to 3FFFFFFF Hex
Executable During Motion: Yes
This'command reads the position recorded in the index register. Reading the index register can be part of a system
error checking scheme. Whenever the SIP command is executed, the new index position minus the old index position,
divided by the incremental encoder resolution (encoder
lines times four), should always be an integral number. The
RDIP command facilitates acquiring these data for hostbased calculations. The command can also be used to identify/verify home or some other special position. The bytes
are read in most-to-Ieast significant order.

OB Hex
Two
COOO to 3FFF Hex, See Text
Yes,
"

This command, reads the integer portion ,of the instantaneous actual velocity of the motor.· The internally maintained
fractional portion of velocity is not reportEld because the
reported data is derived by reading the incremental encoder, which produces only integer data. For comparison with
the result obtained by executing command RDDV (or the
user-supplied input value), the value returned by command
RDRV must be multiplied by 2 16, (shifted left 16 bit positions). Also, as with command RDDV above, data returned
by command RDRV is a Signed quantity, with negative val','
ues representing reverse-direction motion.
RDSUM COMMAND: ReaD
Value
Command Code:
Bytes Read:
Data Range:

Integration-Term SUMmation

OD Hex
Two
00000 Hex to ± the Current
Value of the Integration Limit
Executable During Motion: Yes

This command reads the value to which the integration term
has accumulated. The ability to read this yalue may be helpful in initially or adaptively tuning the system.

RDDP COMMAND: ReaD Desired Position
OB Hex
Command Code:
Bytes Read:
Four
Data Range:
COOOOOOO to 3FFFFFFF Hex
Executable During Motion: Yes
This command reads the instantaneous desired (current
temporal) position output of the profile generator. This is the
"setpoint" input to the position-loop summing junction. The
bytes are read in most-to-Ieast significant order.

Typical Applications
Programming LM628 Host Hat:1dl!haklng (Interrup,ts)
A few words regarding the, LM62B host hapdshaking will be
helpful tO,the system programmer. As indicated in variou!l
portions of the above text, the LM62B handshakes with the
host computer in two ways: 'via the host interrupt output (f>in
17), or via polling the status byte for "interrupt" conditions.
When the hardwired interrupt is used, the status byte is also
read and parsed to determine which of six possible conditions caused the interrupt.
. ..
'

RDRP COMMAND: ReaD Real Position
Command Code:
OA Hex
Bytes Read:
Four
Data Range:
COOOOOOO to 3FFFFFFF Hex
Executable During Motion: Yes

4-32

r-----------------------------------------------------------------------------,
Typical Applications (Continued)
A Monolithic Linear Drive Using LM12 Power Op Amp

When using the hardwired interrupt it is very important that
the host interrupt service routine does not interfere with a
command sequence which might have been in progress
when the interrupt occurred. If the host interrupt service routine were to issue a command to the LM62B while it is in the
middle of an ongoing command sequence, the ongoing
command will be aborted (which could be detrimental to the
application).

Figure 15 shows a motor-drive amplifier built using the LM12
Power Operational Amplifier. This circuit is very simple and
can deliver up to BA at 30V (using the LM12L/LM12CL).
Resistors R1 and R2 should be chosen to set the gain to
provide maximum output voltage consistent with maximum
input voltage. This example provides a gain of 2.2, which
allows for amplifier output saturation at ± 22V with a ± 10V
input, assuming power supply voltages of ± 30V. The amplifier gain should not be higher than necessary because the
system is non-linear when saturated, and because gain
should be controlled by the LM62B. The LM12 can also be
configured as a current driver, see 19B7 Linear Databook,
Vol. 1, p. 2-280.

Two approaches exist for avoiding this problem. If one is
using hardwired interrupts, they should be disabled at the
host prior to issuing any LM62B command sequence, and
re-enabled after each command sequence. The second approach is to avoid hardwired interrupts and poll the LM62B
status byte for "interrupt" status. The status byte always
reflects the interrupt-condition status, independent of
whether or not the interrupts have been masked.

Typical PWM Motor Drive Interfaces
Figure 16 shows an LM1B29B dual full-bridge driver interfaced to the LM629 PWM outputs to provide a switch-mode
power amplifier for driving small brush/commutator motors.
Figure 17 shows an LM621 brush less motor commutator
interfaced to the LM629 PWM outputs and a discrete device
switch-mode power amplifier for driving brush less DC motors.

Typical Host Computer/Processor Interface
The LM62B is interfaced with the host computer/processor
via an B-bit parallel bus. Figure 12 shows such an interface
and a minimum system configuration.
As shown in Figure 12, the LM62B interfaces withti1e host
data, address and control lines. The address lines are decoded to generate the LM62B
input; the host address
LSB directly drives the LM62B PS input. Figure 12 also
shows an B-bit DAC and an LM12 Power Op Amp interfaced
to the LM62B.

as

Incremental Encoder Interface
The incremental (position feedback) encoder interface consists of three lines: Phase A (Pin 2), Phase B (Pin 3), and
Index (Pin 1). The index pulse output is not available on
some encoders. The LM62B will work with both encoder
types, but commands SIP and RDIP will not be meaningful
without an index pulse (or alternative input for this input ...
be sure to tie Pin 1 high if not used).

LM628 and High Performance Controller (HPC)
Interface
Figure 13 shows the LM62B interfaced to a National HPC
High Performance Controller. The delay and logic associated with the WR line is used to effectively increase the writedata hold time of the HPC (as seen at the LM62B) by causing the WR pulse to rise early. Note that the HPC CK2 output provides the clock for the LM628. The 74LS245 is used
to decrease the read-data hold time, which is necessary
when interfacing to fast host busses.

Some consideration is merited relative to use in high Gaussian-noise environments. If noise is added to the encoder
inputs (either or both inputs) and is such that it is not sustained until the next encoder transition, the LM62B decoder
logic will reject it. Noise that mimics quadrature counts or
persists through encoder transitions must be eliminated by
appropriate EMI design.
Simple digital "filtering" schemes merely reduce susceptibility to noise (there will always be noise pulses longer than
the filter can eliminate). Further, any noise filtering scheme
reduces decoder bandwidth. In the LM628 it was decided
(since simple filtering does not eliminate the noise problem)
to not include a noise filter in favor of offering maximum
possible decoder bandwidth. Attempting to drive encoder
Signals too long a distance with simple TIL lines can also
be a source of "noise" in the form of signal degradation
(poor risetime and/or ringing). This can also cause a system
to lose positional integrity. Probably the most effective
countermeasure to noise induction can be had by using balanced-line drivers and receivers on the encoder inputs. Figure 18 shows circuitry using the DS26LS31 and DS26LS32.

Interfacing a 12-Blt DAC
Figure 14 illustrates use of a 12-bit DAC with the LM62B.
The 74LS378 hex gated-D flip-flop and an inverter demultiplex the 12-bit output. DAC offset must be adjusted to minimize DAC linearity and monotonicity errors. Two methods
exist for making this adjustment. If the DAC1210 has been
socketed, remove it and temporarily connect a 15 kO resistor between Pins 11 and 13 of the DAC socket (Pins 2 and 6
of the LF356) and adjust the 25 kO potentiometer for OV at
Pin 6 of the LF356.

If the DAC is not removable, the second method of adjustment requires that the DAC121 0 inputs be presented an allzeros code. This can be arranged by commanding the appropriate move via the LM62B, but with no feedback from
the system encoder. When the all-zeros code is present,
adjust the pot for OV at Pin 6 of the LF356.

4-33

r

3:
en
N
co
.....
r
3:
en
N

CQ

~ r-------------------------------------------------------------------------------------~

C'II

CD

.......::::iii

Typical Applications (Continued)

~

DATA BUS
8
1+-----:f-----+lDO-D7

CD

~

H

0
S
T
B
U
S

8
DACoaoO
DACO- I - - - f - - - M
DAC7
louT' ...,1""""Ir-------;~-;jooO-I

iW
t=--------+liW

Lt.i628

lOUT

ADDRESS
BUS

WR

.....--+.....--~.....--+20V

AO

RESET

t=~-------+lRST

IRQ

~;;';;"'---------1HI

iN

A B'

2.SK
Note: Av

R1 + R2
= -R-l- ::::

2:4

Rl X R2 •
Rl + R2 = 2.Sk

L..-_-f---j"-'-4"-'---20V
• SEE NOTE
ENCODER E - - - - - - - - - - - - - - - - - - - - - -

TUH/9219-14

FIGURE 12. Host Interface and Minimum System Configuration

8

AO-A71~------~-----~

A13
A14

A15
ALE

8

I+-1Y~ DO -

07

r-~::~~------~::~+=~--~Cs
ADDRESS
DECODER

G (eg: HC138)
~

HPC

RDI------------------~-~--~RD
WR~------~~~
CK21---------4---4-----~----~CLK

Bll----------------------~~
1 2 1 + - - - - - - - - - - - - - - - - - - - - - - 1 HI

-TUH/9219-15

FIGURE 13. LM628 and HPC Interface

4-34

~

"CI

0'
!!

»
o·
m

"CI

"'2.
7

11

6

10

5

9

4
OAC 3

-f>o--

l"

~

WRI

'-6

6r-- 5
5r-- 4
Q

U1

4r-- 3
3r- 2

2

2r-- 1

1

1 r-- 0

A

RFS

lourl
lour2
OAC
1210

81/82

r-

XFER

~

WR2

_....

T2

-=

~
*

5'
c:
CD
S,

~~~

::L'

1

3-

9.76K
5K

20pF

3 +

oo

364K

'--

01

~

tn

~500.o.

~

G74LS378

+5V

120K

385

cs

'-- 5
4
3 0

./>.

VREF

6

0

O·

OUTPUT
OFFSET

+5.0V

7

1

-

+15V
10K

01

8

2
LM628

Vee

5

125K

g~~SET

-

~
:!:II IV
SIGN IAL
TO PC ,WER
AMPLI FlER

+15V

~

r!L

_....
TUH/9219-16

'OAC offset must be adjusted to minimize OAC linearity and monotonicity errors. See text

FIGURE 14. Interfacing a 12-81t DAC and LM628

6~9W'/8~9W'

II

en

C'I

CD

:::E

....

r---------------------------------------------------------------------------------~

Typical Applications (Continued)

...I
CD

+30V

C'I

CD

:::E

.I.

+

...I

100}'F

MR752

1.69K

2.0K
R2

MR752

-30V

TUH/9219-17

FIGURE 15. Driving a Motor with the LM12 Power Op Amp
MOTOR
S U P P L Y - - - - - - - - - - - -.....
VOLTAGE

----"T""---,

+5V-------~~._,

(PIN 18) SIGN
FROM {
lM629

) 0 0 - -.....-15

r-"L..-_

(PIN 19) MAG

10

-1-----.

7
1O----4~-i 12

IO----IL-~

SENSE

A

SENSE

B

TL/H/9219-1B

FIGURE 16. PWM Drive for Brush/Commutator Motors

4·36

Typical Applications (Continued)
...-_ _...J.,,_ _-iRt.IUIT (X6)
18
~

+5 VOLTS

r __ !,o!E,! lW1J£!!~

___ •

MOTOR
SUPPLY
VOLTAGE

I

SINK

I

16

(5-40V)

I
I.pA

#1

lk

13 1-¥Y~i--1:--I
SOURCE

30/60 SELECT

L...-----I
lk

LM621
BRUSH LESS
MOTOR
COMMUTATOR

SINK

15 I-¥Y~r+---I
24k

#2

200 pF

12 1-¥Y~i+-1:--I
SOURCE

DIR

(PIN 18) SIGN

FROM
LM629

I-Wlr-t+---I
.pc

1
(PIN

SINK
14

#3
11

I-WIr-t+-1:--I
SOURCE

Nt;)

ROTOR POSITION
SENSORS

~o--+++---\

HSI
HS2
HS3
TL/H/9219-19

FIGURE 17. PWM Drive for Brushless Motors

FROM
ENCODER

PH~E--t(

A

PH~SE--t(

B

INDEX--t(
PULSE

iN

TO
LM628

3/4 DS26LS31
RT~LINE

IMPEDANCE
TL/H/9219-20

FIGURE 18. Typical Balanced-Line Encoder Input Circuit

4-37

:."

tflNational Semiconductor
LM 18293 Four Channel Push.. Pull Driver
General Description
The LMHi293'is designed to drive DC loads up to one amp.
Typical applications include driving such inductive loads as
solenoids, relays and stepper motors along with driving
switching power transistors and use as a buffer for low level
logic signals. The four inputs accept standard TTL and DTL
levels for ease of interfacing. Two enable pins are provided
that also accept the standard TTL and DTL levels, Each
enable controls 2 channels and when an enable pin is disabled (tied low), the corresponding outputs are forced to the
TRI-STATE® condition, If the enable pins are not connected
(i.e., floating), the circuit will function as if it has been enabled. Separate pins are provided for the main. power supply
(pin 8), and the logic supply (pin 16). This allows a lower
voltage to be used to bias up the logic resulting in reduced
power di~sipation. The chip is packaged in a specially de-

signed 16 pin powe.r DIP. The 4 center pins of this package
are tied together and form the die paddle inside the package. This provides much better heat sinking capability than
most other DIP packages available. The device is capable
of operating at voltages up to 36 volts.

Features
•
•
•
•
•
•

1A output current capability per channel
Pin for pin replacement for L293B
Special 16 pin power DIP package
36 volt operation
Internal thermal overload protection
Logical "0" input voltage up to 1.5 volts results in high
noise immunity

Typical Connection

Vs __

~

________________________________

~

__

~

TUH/8706-1

FIGURE 1. Application circuit showing bidirectional and on/off control of a single DC motor
using two outputs and unidirectional on/off function of two DC motors using a single output each.
Order Number LM18293N
NS Package Number N16A '

4-38·

r-

s:::
......

Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Output Drive Supply Voltage (Vs)
Logic Supply Voltage (Vss)

Peak Output Current (Non-Repetitive t = 5 ms)

+ 150·C

Junction Temperature (TJ)

CO
N
CD
Co)

14·C/W

Thermal Resistance Junction to Case (OJC)
80·C/W
Thermal Resistance Junction to Ambient (OJAl
Internally Limited
Internal Power Dissipation
- 40·C to + 125·C
Operating Temperature Range
- 65·C to + 150·C
Storage Temperature Range
260·C
Lead Temperature (Solder 10 seconds)

36V
36V
7V

Input Voltage (VI)
Enable Voltage (VE)

2A

7V

Electrical Characteristics
Vs = 24V. Vss = 5V. T = 25·C. L = 0.4V. H = 3.5V. each channel. unless otherwise noted
Symbol

Conditions

Parameter

Typical

Tested Limit
(Note 1)

Design Limit
(Note 2)

Units

Vs

Main Supply (Pin 8)

Maximum Supply Voltage

36

Vmax

Vss

Logic Supply (Pin 16)

Minimum Logic Supply Voltage
Maximum Logic Supply Voltage

4.5
36

Vmin
Vmax

Is

Total Quiescent
Supply Current

VI = L
VI = H

10= 0
10= 0

VE = H
VE = H
VE = L

2
16

6
24
4

mAmax
mAmax
mAmax

Iss

Total Quiescent Logic
Supply Current
(pin 16)

VI = L
VI = H

10= 0
10= 0

VE=.H
VE= H
VE = L

44
16
16

60
22
24

mAmax
mAmax
mAmax

VI

Input Voltage

Min Value of Low
Max Value of Low
Min Value of High
Max Value of High (Vss ~ 7)
Max Value of High (Vss > 7)

-0.3
1.5
2.3
Vss
7

Vmin
Vmax
Vmin
Vmax
Vmax

II

Input Current

VI = L
VI = H

-10
100

p.Amax
p.Amax

-0.3
1.5
2.3
Vss
7

Vmin
Vmax
Vmin
Vmax
Vmax

30

VE

Enable Voltage
(Pins 1. 9)

Min Value of Low
Max Value of Low
Min Value of High
Max Value of High (Vss ~7)
Max Value of High (Vss > 7)

IE

Enable Current

VE = L
VE = H

-30

-100
±10

p.Amax
p.Amax

VCEsatTop

Source Saturation
Voltage

10 = -1 amp

1.4

1.8

Vmax

VCE sat Bottom

Sink Saturation
Voltage

10= 1 amp

1.2

1.8

Vmax

t,

Rise Time

10%-90% Vo

250

ns

tf

Fall Time

90%-10% Vo

250

ns

ton

Turn·On Delay

50% VI to 50% Vo

450

ns

50% VI to 50% Vo
toll
Nole 1: Tested limits are guaranteed and 100% production tested.

200

ns

Tum-Off Delay

Note 2: Design limits are guaranteed (but not 100% production tested) over the full supply and temperature range. These limits are not used to calculate outgoing

quality levels.

4·39

II

CO)
G)

N

co
....

Connection Diagram

::::E

...J

'-/

ENABLE 1
INPUT 1

2

Input/Output Truth Table
16

Vss

15

INPUT 4

OUTPUT 1

3

14

GROUND

4

13

GROUND

5

12 . GROUND

OUTPUT 2

6

11

OUTPUT 3

INPUT 2

7

10

INPUT 3

Vs

8

9

Enable 1 activates outputs 1 & 2

OUTPUT 4
.'

GROUND

VE(")

VI (Each Channel)

Vo'

H
H

H

H'

L

L'

L
L

H

X(*)
X(*) ,

L

.,<

(') High output impedance,

(* *) Relative to the pertinent channel.

ENABLE 2
:rUH/B70~-2

Enable 2 activates outputs 3 & 4 ,

.Simplified Schematic

TL/H/B706-3

.-------------------------------------------------------~--------------------,

Typical Performance Characteristics Vs In all cases =
Output Voltage vs.
Input Voltage
VS-VCESAT H

f/l I

VSS=VI=5V

/-Tamb=25OC

I

1.0

1.5

I r....t I250C

ID

I

-

I:: .....

VCE~AT L

2.5

2.0

VCESAT.!!.-

Iii ~-40OC
I I

-40OC

VCE~TL

VI=V E=VSS=5V
2.0

V
Vi'

Tamb=25OC

....!.. 125°C

Iii I -

Saturation Voltage vs.
Output Current

VS-VCESAT H

"I I

Vss=Vr;=5V

24V

Output Voltage vs.
Enable Voltage

ID

1.5

2.0

o
o

2.5

0.5

/

VCESAT L

ID

1.5

Ia(A)

Source Saturation Voltage
vs. Ambient Temperature
3.0

3.0
VI=V E=VSS=5V

-

VI=L, Vr;=H

-'

la=I.OA

~

lo=O,5A

...,

V

. /V

/

"":J.5A

lo=O,IA

r- t-J

I

so

50

~:'5A

f!11.0A

o
-so

52

I

VI=VE=VSS=5V

loJ5A

~~

-

Quiescent Logic Supply
Current vs.
Logie Supply Voltage

Sink Saturation Voltage
vs. Ambient Temperature

lai,lA

o

-so

100

Tamb(OC)

040

so

100

o

10

20

30

Vss(V)

Tamb(OC)

TLlH/B706-4

Typical Applications
DC motor controls (witl) connections to
ground and to the supply voltages)

Bidirectional DC motor control

Vso-~----~--,

TL/H/B706-5
TLlH/B706-6

VE

Pin
10

Pin
15

M1

H

H

H

Fast Motor Stop

Run

H

H

L

Fast Motor Stop

Fast Motor Stop

H

L

H

Run

Run

H

L

L

Run

Fast Motor Stop

L
L

~

X
Low H

Free Running
Motor Stop

X
~

High X

~

Inputs

M2

Function

Pin'10 = H
Pin 15 = L
Pin 10 = L
Pin 15 = H

TurnCCW

Pin 10 = Pin 15

Fast Motor Stop

Pin 10 = X
pin15=X

Free Running
Motor Stop

VE = H

VE = L

Free Running
Motor Stop
L

Don'l care

4-41

~

Low

H

~

TurnCW

High X

~

Don't care

r

:s:::
.....
CI)
N

CD

Co)

Motor Control Block Diagram

Bipolar Stepping Motor Control

+vs

Step Sequencing Tables
Full Step •

Step

VIN 1

VIN2

L

L

1

L

H

2

H

H

3

H

L

4

L

L

1

..-+- 30V) so

+Vs

+Vs

TO GATE
DRIVE +---I--+-~!-o-...
CIRCUIT ~

TO GATE

H---. DRIVE
CIRCUIT

.....-1........

, GROUND

EXTERNAL
BOOTSTRAP
CAPACITOR'

GROUND
TL/HI10568-B

TL/H/1056B-7

FIGURE 1_ Internal Charge Pump Circuitry

FIGURE 2. Bootstrap Circuitry

4-48

Switching Time

Definition~

+5V
INPUT
0
td(ON)

3A
SOURCE
0
t(ON)
0
SINK

3A
3V
SENSE
0

TLlH/10568-9

III
4-49

Typical Applications
slightly about an externally controlled average level. The
duration of the Off-period is adjusted by the resistor and
capacitor combination of the LM555. In this circuit the Sign I
Magnitude mode of operation is implemented (see Types of
PWM Signals).

Fixed Off·Tlme Control: This circuit controls the current
through the motor by applying an average voltage equal to
zero to the motor terminals for a fixed period of time, whenever the current through the motor exceeds the commanded current. This action causes the motor current to vary
24 VOLTS

4

7

2
MAG.

8

6 LM555

>-....-+--12

3

31----,
5

1.33 AMP/VOLT

6

PWM
7
5r--+--<

~--r---'~----~6

5

1-.....""II.f'v-<) +12V

':---~2

10k.o.
LMD18200

24V
3 AMP
DC MOTOR
......- - - - 1 1 0

I

8

10k.o.

DIR
31+---<)
BRAKE

7

Torr

O•1P.F 2k.o.

= 1.1 RC
TUH/1 0568-1 0

Switching Waveforms
DIRECTION

FORWARD

REVERSE

- - - - - - -.......- - - - - - - + TIME

OUTPUT 1

_ _ _----'-IL-n.u...n...u.....n.u...n......L.I-n.......~ TIME

OUTPUT 2

[l n

nru

_W-t::J

~

TIME

~.

TIME

CONTROLLED BY RC OF LM55SN --jTorrl-TL/H/10568-11

4-50

r-----------------------------------------------------------------------------, r

iii:

Typical Applications (Continued)

C

TORQUE REGULATION

00
N

-"

Locked Anti-Phase Control of a brushed DC motor. Current sense output of the LMD18200 provides load sensing. The
LM3525A is a general purpose PWM controller.
DIRECTION CONTROL

+10V

300n

12V TO 24V

-U11~--~--------~1

LM3525A

LMD18200
+10V

0.25A TO 3.25A
24V DC MOTOR

VCURRENT
ADJUST

5
9 ~----------.

11

10k

101-..........;.;.;.---1

9
4

7

81---4j1-----,
6.19k
1% .

TL/H/l0568-12

Peak Motor Current
vs Adjustment Voltage

4

'in
D..
2

.:5-

V

3

...

I-

./

z:

'"
'"
u
'"
~

/

2

!5
2

V

""D..
is
o
o

~

V
2

/

3

456

7

8

VCURRENT ADJUST (VOLTS)
TL/H/l0568-13

4-51

o
o

C)
C)

r---------------------------------------------------------------------------------,

~
.,..

Typical Applications

C

VELOCITY REGULATION

:5

(Continued)

Utilizes tachometer output from the motor to sense motor speed for a locked anti-phase control loop.
DIRECTION CONTROL

+10V

12V TO 30V

L..r

3

11

2
LMD18200

LM3525A
+10V

o TO 7400 RPM

1

30V DC MOTOR

VSPEED
ADJUST

5
9

11

10k

10

9

+
4

7

10k

S.lk

VlACH =
1000 RPM/V

TLlH/10568-14

Motor Speed vs
Control Voltage

8000

I

/
/

6000

1/
I
I

2000

o
o

/
/
1

2

3

4

VSPEED (VOLTS)
TLlH/10568-15

4-52

ttlNational Semiconductor

LMD18201 3A, 55V H-Bridge
General Description
The LMD18201 is a 3A H-Bridge designed for motion control applications. The device is built using a multi-technology
process which combines bipolar and CMOS control circuitry
with DMOS power devices on the same monolithic structure. The H-Bridge configuration is ideal for driving DC and
stepper motors. The LMD18201 accommodates peak output currents up to GA. Current sensing can be achieved via
a small sense resistor connected in series with the power
ground lead. For current senSing without disturbing the path
of current to the load, the LMD18200 is recommended.

Features
• Delivers up to 3A continuous output
• Operates at supply voltages up to 55V
• Low ROS(ON) typically 0.330 per switch

•
•
•
•
•
•
•

TTL and CMOS compatible inputs
No "shoot-through" current
Thermal warning flag output at 145'C
Thermal shutdown (outputs off) at 170'C
Internal clamp diodes
Shorted load protection
Internal charge pump with external bootstrap capability

Applications
•
•
•
•
•

DC and stepper motor drives
Position and velocity servomechanisms
Factory automation robots
Numerically controlled machinery
Computer printers and plotters

Functional Diagram
THERMAL FLAG OUTPUT

BOOTSTRAP 1

OUTPUT 1
2

Vs

OUTPUT 2

BOOTSTRAP 2

6

10

11

THERMAL
SENSING
UNDERVOLTAGE
LOCKOUT

DIRECTION 3
BRAKE 4

PWM 5

8
Signal Ground

TLlH/l0793-1

Connection Diagram and Ordering Information
11
10

800TSTRAP 2
OUTPUT 2
THERMAL FLAG OUTPUT

o

SIGNAL GROUND

7

POWER GROUND/SENSE
Vs POWER SUPPLY
PWM INPUT

4

BRAKE INPUT
OIRECTION INPUT
OUTPUT 1

1.

BOOTSTRAP 1

MOUNTING TAB CONNECTEO TO GROUND (PIN 7)
TLlH110793-2

Top View
4-53

Order Number LMD18201T
See NS Package Number TA 11 B

Absolute Maximum Ratings

(Note 1)

If Military/Aerospace specified devices are required,

Power Dissipation (TA = 25·C, Free Air)

please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.

Junction Temperature, T J(max)

Total Supply Voltage (Vs, Pin 6)

ESD Susceptibility (Note 4)

60V

Voltage at Pins 3, 4, 5 and 9

Lead Temperature (Solderirig, 10 sec.)

2)

Power Dissipation (Note 3)

SA

Operating Ratings (Note 1)

3A

'Junction Temperature, TJ

25W

,;"

-40"C to +125·C
+ 12Vto +55V

Vs S'!pply Voltage

"

Sense Voltage (Pin 7 to Pin 8)

300"C

VOUT+ 16V

Peak Output Current (200 ms)
Continuous Output Cu~rent (~,ote

1500V
-65·Cto + 150"C

Storage Temperature, T STG

12V

Voltage at Bootstrap Pins (Pins 1 and 11)

3W
.'150"C

+P.5Vto -.1.0V

Electrical Characteristics
The following specifications apply for Vs = 42V,' unless otherwise, specified. Boldface limits apply over the entire operating
temperature range, -40·C ~ TJ ~ .,.. 125·C, all other limits are for TA = TJ = 26"C. (Note 5)
Symbol

Parameter

ROS(ON)

Switch ON R'eslstance

'

.

'CclR,dltlons
".

Typ

Limit

Units

Output Current = 3A (Note 6)

0.33

0.4/0••
0.4/0••

o (max)
o (max)

ROS(ON)

Switch ON Resistance;

: Output Current = 6A (Note 6)

0.33

VCLAMP

Clamp Diode Forward Dro~

Clamp Current = 3A (Note 6)

1.2

1.5

'V(max)

V,L

Logic Low Input Voltage

Pins3,4,5

-0.1
0.8

V (min)
V (max)

I,L

Logic Low Input Current

Y,N = -O.W, Pins = 3,4,5

-10

pA(max)

V,H

Logic High Input Voltage

Pins 3, 4, 5

2
12

V (min)
V (max)

10

pA(max)

9

V (min)
V (max)

I,L

Logic High Input Current

:V,N = 12V, Pins = 3,4,5

Undervoltage Lockout

Outputs Turn OfF

11
TJW

Warning Flag Temperature

Pin 9 ~ 0.8V, IL = 2' mA

145

VF(ON)

Flag Output Sai~ration Voltage

TJ = TJW,IL = 2mA.

0.15

IF(OFF)

Flag Output Leakage

VF = 12V

TJSO

Shutdown Temperature,

'. Outputs Turn OFF
All LogiC Inputs Low

0.2

·C
V
10

/LA (max)

25

mA(max)

·C

170

Is

Quiescent Supply Current

13

tD(ON)

Output Turn-On Delay Time

Sourcing Outputs, lOUT = 3A
Sinking Outputs, lOUT, = 3A

300
300

ns
ns

tON

Output Turn-On Switching Time

Bootstrap CapaCitor = 10 nF
Sourcing Outputs, lOUT = 3A
Sinking Outputs, lOUT = 3A

100
80

ns

".

nil

to(OFF)

Output Turn-Off Delay Times

Sourcing Outputs, lOUT = 3A
Sinking Outputs, IbuT = 3A

200
200

ns
ns

tOFF

Output Turn-Off Switching Times

Bootstrap Capacitor,= 10 nF
Sourcing Outputs, lOUT = 3A
Sinkirg Outputs, lOUT"" 3A

75
70

ns
ns

1

/Ls

20

/Ls

tpw

' ,Minimum Input Pulse Width

tCPA

Charge Pump Rise Time

Pins 3, 4 and 5
No Bootstrap Capacitor

4-54

r-

s::

Electrical Characteristics (Continued)

c......

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating
the device beyond its rated operating conditions.
Note 2: See Application Information for details regarding current limiting.
Note 3: The maximum power dissipation must be derated at elevated temperatures and I_ a function of TJ(max), 8JA, and TA. The maximum allowable power
dissipation at any temperature is po(max) = (TJ(max) - TAlI8JA, or the number given in the Absolute Ratings, whichever i_lower. The typical thermal resistance
from junction to case (8Jcl is 1.0'C/W and from junction to ambient (8JAl is 30'C/W. For guaranteed operation TJ(max) = 12S'C.
Note 4: Human·body model, 100 pF discharged through a 1.5 kn resistor. Except Bootstrap pins (pins 1 and 11) which are protected to 1000V of ESD.
Note 5: All limits are 100% production tested at 25'C. Temperature extreme limits are guaranteed via correlation using accepted SQC (Statistical Quality Control)
methods. All limits are used to calculate AOQL, (Average Outgoing Quality Level).
Note 6: Output currents are pulsed (tw < 2 ms, Duty Cycle < 5%).

Typical Performance Characteristics
VSAT vs Flag Current

ROS(ON)YS
Supply Voltage

ROS(ON) vs Temperature

3SO

1.8

0.40

300

1.6

D.J6

!

~

~

0

~

>

t50

./

1/'''

V"

/v

tA

!l!
~
-<

,/

20D

tOO

Z"
E-

,/

TJ = 1500C

2SO

1.2

0.8

0.6

s.o

i

1--'/

z

1.5 2.D 2.5 3.0 3.5 -4.D 4.5

Z"

V

1.0

iI!
0

'!.l
is

V

0035
0.34

O.JJ I~

i--'"
5 25 045 65

as

Supply Current YS
Temperature (Vs = 42V)

18

18
16

]:

16

17

§

16

14

12

15

12

OUJulS H!

~

~
6

!;'"
OUTPUlS lOW

iiil

I

!l:

iil

./

14

30

40

50

.......

.......

.......

i'.....

lD

12
20

.......

Il

I

10

I ~
I
I I
SUPPLY VOLTAGE

Supply Current YS
Frequency(VS= 42V)

]:

la-SlOE

10 15 20 25 30 35 40 045 50 55

20

i;'"

r-

O.JO
105 125

.....

I
A""""

0032

JUNCTION TEIIPERATURE (OC)

Supply Current vs
Supply Voltage

6

HI-SIDE,

\

Doll

-ss -35 -15

FLAG CURRENT (mA)

0.31
0036

I
I
I

IL = lA
TJ = 250C

0.J9

60

1

SUPPLY VOLTAGE (VallS)

10

100

6
-55 -30 -5

20 045

70 95 120 1045

JUNCTION TENPERATURE (OC)

SWITCHING FREQUENCY (kHz)

TLlH/l0793-3

Test Circuit

Switching Time Definitions
10 nF
+5V
INPUT

SINK

PWM
+5V
DlR

D"i!=~-'------;. Vs = 42V

INPUT
BRAKE
4

....ao

0.111

c

SENSE
RESISTOR

::E
....I

lA
SOURCE

0

SINK
lA

SOURCE

O.lV
SENSE

o
TLlH110793-9

TL/H/l0793-8

4·55

co

N
C

......

~

co
.....
C

:::!!
...I

Pinout Description

(See Connection Diagram)
Pin 1, BOOTSTRAP 1 Input: Bootstrap capacitor pin for
half H-Bridge number 1. The recommended capacitor
(10 nF) is connected between pins 1 and 2.
Pin 2, OUTPUT 1: Half H-Bridge number 1 output.
Pin 3, DIRECTION Input: See Table I. This input controls
the direction of current flow between OUTPUT 1 and O!JTPUT 2 (pins 2 and 1p) ~nd, therefore, the direction of rotation of a motor load.
Pin 4, BRAKE Input: See Table I. This input is used to
brake a motor by effectively shorting its terminals. When
braking is desired, this input is taken to a logic high level
and it is also necessary to apply logic high to PWM input, pin
5. The drivers that shOrt the motor are determined by the
logic level at the DIRECTION input (Pin 3): with Pin 3 iogic
high, both current sourcing output transistors are, ON; with
Pin 3 logic low, both current sinking output transistors are
ON. All output transistors can be turned OFF by applying a
logic high to Pin 4 and a logic low to PWM input Pin 5; in this
case only a small bias current (approximately -1.5 mAl exists at each output pin.
Pin 5, PWM Input: See Table i. How this input (and DIREC,TION input, Pin 3) is used is determined by the format of the
PWM Signal.
Pin 6, Vs Power Supply
Pin 7, POWER GROUND/SENSE Connection: This pin is
the ground return for'the power DMOS transistors of the HBridge. The current through the H-Bridge can be sensed by
adding a small, 0.10, sense resistor from this pin to the
power slipply ground.
Pin 8, SIGNAL GROUND: This is the ground return for the' '
internal logic circuitry used to control the PWM switching of
the H-Bridge.
"
Pin 9, THERMAL FLAG Output: This pin provides the ther- ,
mal warning flag output signal., Pin 9 becomes active-l.ow at , '
145°C ijunction temperature). However the chip will not shut"
itself down until 170"C is reached at the junction.
Pin to, OUTPUT 2: Half H-Bridge number 2 output.
Pin 11, BOOTSTRAP 2 Input: Bootstrap capacitor pin for
half M-Bridge number 2. The recommended capacitor'
(10 nF) is connected between pins 10 and 11.
TABLE I Logic Truth Table
PWM

Dir

Brake

, Active Output Drivers

H
H
L
H
H
L

H
L

L
L
L
H
H
H

Source 1, Sink :2
Sink 1, Source 2
Source 1, Source,2 ,
Source 1, Source 2
Sink 1, Sink 2
NONE

X
H
L

X

Application Information
TYPES OF PWM SIGNALS
The LMD18201 readiiy"interfaces with different forms of
PWM signals. Use, of the part with two of the more popular
forms of PWM is described in the following paragraphs.,
Simple, locked anti-phase PWM consists of a single, 'variable duty-cycle signal in which is encoded both direction
and amplitude information. A 50% duty-cycle PWM signal
represents zero drive, since the, net value of voltage (integrated over one period) delivered to the load is zero. For the
LMD18201, the PWM signal drives the direction input (pin 3)
and the PWM input (pin 5) is tied to logic high.
Sign/magnitude PWM consists of separate direction (sign)
and amplitude (magnitude) signals. The (absolute) magnitude signal is duty-cycle modulated, and the ab~ence of a
pulse signal (a continuous logic low level) represents zero
drive. Current delivered to the load is proportional to pulse
width. For the LMD18201, the DIRECTION input (pin 3) is
driven'by the sign signal and the PWM input (pin 5) is driven
by the magnitude signal.
USING THE THERMAL WARNING FLAG
The THERMAL FLAG output (pin 9) is an open collector
transistor. This permits a wired OR connection of thermal
warning flag outputs from multiple LMD18201's, and allows
the user to set the logic high level of the output signal swing
, to match system requirements. This output typically drives
the interrupt input of a system controller. The interrupt service routine would then be designed to take appropriate
steps, such as reducing load currents or initiating an orderly
system shutdown. The maximum voltage compliance on the
flag pin is 12V.
SUPPLY BYPASSING
During switching transitions the levels of fast, current changes experienced may cause troublesome voltage transients
across system stray inductances.
It is normally necessary to bypass the supply rail with a high
quality capacitor(s) connected as close as possible to the
Vs Power Supply (Pin 6) and POWER GROUND (Pin 7). A
1 p.F high-frequency ceramic capaCitor is recommended.
Care should be taken to limit the transients on the supply
pin below the Absolute Maximum Rating of the device.
When operating the chip at supply voltages above 40V a
voltage suppressor (transorb) such as P6KE62A is recommended from supply to ground. Typically the ceramic capacitor can be eliminated in the presence of the voltage
suppressor. Note that when driving high load currents a
greater amount of supply bypass capaCitance (in general at
least 100 p.F per Amp of load current) is required to absorb
the recirculating currents of the inductive loads.
Sign/Magnitude PWM Control

I

~

DlRECTlON

Locked Anti-Phase PWM Control
SOX DUTY CYCLE

m~~~
v.,-v"

5V

n

Oy..J L

ru ill,
75" DUTY CYCLE

,

AVERAGE LOAD CURRENT
FLOWS FROM OUTPUT 1
TO OUTPUT 2

L._ _ _ _ _ _ __

25" DUTY CYCLE

::::R: :Rf ill
AVERAGE LOAD
CURRENT =0

(P1N3).

AVERAGE LOAD CURRDfT
FLOWS now OUTPUT 2
TO OUTPUT 1

TLlH/l0793-4

("~:vJLf

nm

illnm

v.,-v" ..+v'lUllill
. . . . . .. ·······lJ1lTm.
-v,
MOTOR SPEED:

SLOW

.....

FAST

AVERAGE CURRENT news FROW
OUTPUT I TO OUlPUJ 2

SlOW

IIIEIlIUW

FAST

AVERAGE CURRENT FlOWS FROW
OUTPUT 2 TO OUTPUT 1

TL/H/l0793-5

r-

Application Information

(Continued)

==
.....
C

CURRENT LIMITING
Currimt limiting protection circuitry has been incorporated
into the design of the LMD18201. With any power device it
is important to consider the effects of the substantial surge
currents through the device that may occur as a result of
shorted loads. The protection circuitry monitors the current
through the upper transistors and shuts off the power device as quickly as possible in the event of an overload condition (the threshold is set to approximately lOA). In a typical motor driving application the most common overload
faults are caused by' shorted motor windings and locked
rotors. Under these conditions the inductance of the' motor
(as well as any series inductance in the Vee supply line)
serves to reduce the magnitude of a current surge to a safe
level for the LMD18201. Once the device is shut down, the
control circuitry will periodically try to turn the power device
back on. This feature allows the immediate return to normal
operation once the fault condition has been removed. While
the fault remains however, the device will cycle in and out of
thermal shutdown. This can create voltage transients on the
Vee supply line and therefore proper supply bypassing techniques are required.
The most severe condition for any power device is a direct,
hard-wired ("screwdriver") long term short from an output to
ground. This condition can generate a surge of current
through the power device on the order of 15 Amps and
require the die and package to dissipate up to 500W of
power for the short time required for the protection circuitry
to shut off the power device. This energy can be destructive, particularly at higher operating voltages (> 30V) so
some precautions are in order. Proper heat sink deSign is
essential and it is normally necessary to heat sink the Vee
supply pin (pin 6) with 1 square inch of copper on the PC
board.

INTERNAL CHARGE PUMP AND USE OF
BOOTSTRAP CAPACITORS
To turn on the high-side (sourcing) DMOS power devices,
the gate of each device must be driven approximately 8V
more positive than the supply voltage. To achieve this an
internal charge pump is used to provide the gate drive voltage. As shown in Figure 1, an internal capacitor is alternately switched to ground and charged to about 14V, then
switched to Vs thereby providing a gate drive voltage greater than Vs. This switching action is controlled by a continuously running internal 300 kHz oscillator. The rise time of
this drive voltage is typically 20 }JoS which is suitable for operating frequencies up to 1 kHz.
For higher switching frequencies, the LMD18201 provides
for the use of external bootstrap capacitors. The bootstrap
principle is in essence a second charge pump whereby Ii
large value capacitor is used which has enough energy to
quickly charge the parasitic gate input capacitance of the
power device resulting in much faster rise times. The switching action is accomplished by the power switches themselves (Figure 2). External 10 nF capacitors, connected
from the outputs to the bootstrap pins of each high-side
switch provide typically less than 100 ns rise times allowing
switching frequencies up to 500 kHz.

co

N

o
.....

INTERNAL PROTECTION DIODES
A major consideration when switching current through inductive loads is protection of the switching power dovices
from the large voltage transients that occur. Each of tho four
switches in the LMD18201 have a built-in protection diodo
to clamp transient voltages exceeding the positive supply or
ground to a safe diode voltage drop across the switch.
The reverse recovery characteristics of these diodes, once
the transient has subsided, is important. These diodes must
come out of conduction quickly and the power switches
must be able to conduct the additional reverse recovery current of the diodes. The reverse recovery time of the diodes
protecting the sourcing power devices is typically only 70 ns
with a reverse recovery current of 1A when tested with a full
. '3A of forward current through the diode. For the sinking
devices the recovery time is typically 100 ns with 4A of reverse current under the same conditions.

+Vs

+Vs

....----4,....~--+

TO GATE
DRIVE
CIRCUIT

TO GATE
DRIVE +---+-~"",""-~-o""
CIRCUIT

--1

GROUND

EXTERNAL
BOOTSTRAP
CAPACITOR

GROUND
TL/H/10793-6

TL/H/10793-7

FIGURE 1_ Internal Charge Pump Circuitry

FIGURE 2_ Bootstrap Circuitry

4-57

•

.- r------------------------------------------------------------------------------------------,
§! Typical Applications
.Q

~

BASIC MOTOR DRIVER

To sense the bridge current through the LMD18201 requires
the addition of a small sense resistor between the power
ground/ sense pin (Pin 7) and the actual circuit ground. This
resistor should have a value of 0.10 or less to stay within
the allowable voltage compliance of the sense pin, particularly at higher operating current levels. The voltage between
power ground/sense (Pin 7) and the signal ground (Pin -8)
must stay within the range of -1V to +0.5V. Internally
there is approximately 250 between pins 7 and 8 and this
resistance will slightly reduce the value of the external
sense resistor. Approximately 70% of the quieScent supply
current (10 mAl flows out of pin 7. This will cause a slight
offset to the voltage across the sense resistor when the
bridge is not conducting. During reverse recovery of t/le internal protection diodes the voltage compliance between
pins 7 and 8 may be exceeded. The duration of these spikes
however are only approximately 100 ns and do not have
enough time. or energy to disrupt the operation of the
LMD18201.

The LMD18201 can directly interface to any Sign/Magnitude PWM controller. The LM629 is a motion control processor that.outputs a Sign/Magnitude PWM signal to coordinate either positional or velocity control of DC motors. The
LMD18201 provides fully protected motor driver stage.

CURRENT SENSING
In many motor control applications it is desirable to sense
and control the current through the motor. For these types
of applications a companion produci, the LMD18200, is also
available. The LMD18200 is identical to. the LMD18201 but
has current senSing transistors that output a current directly
proportional to the current conducted by the two upper
DMOS· power devices to a separate current sense pin. This
technique does·not require a low valued, power sense resistor and does not subtract from the available voltage drive to
the motor.

BasiC Motor Driver·
+5V
Motor Vollage

10k

9

6

IRQ

Sign
Host

Olr

3
LM018201

LM629

p.C
Bus

Magnitude

Motor

PWM 5

2 or 3

TLlH/l0793-10

Current Sensing
+55V

Direction
3
PWM---+l5

Brake

+5V

9

6

"
LM018201

Motor

10k

Thermal Flag+--+---I9

7

8

0.1.0.

....--+VSEHSE
o to O.3V for up to
3A of Bridge Current
TLlHI10793-11

4-58

t!lNational Semiconductor

LMD18245
3A, 55V DMOS Full-Bridge Motor Driver
General Description

Features

The LMD18245 full-bridge power amplifier incorporates all
the circuit blocks required to drive and control current in a
brushed type DC motor or one phase of a bipolar stepper
motor. The multi-technology process used to build the device combines bipolar and CMOS control and protection circuitry with DMOS power switches on the same monolithic
structure. The LMD18245 controls the motor current via a
fixed off-time chopper technique.

.. DMOS power stage rated at 55V and 3A continuous
.. Low ROS(ON) of typically 0.3n per power switch
EI Internal clamp diodes
II Low-loss current sensing method
.. Digital or analog control of motor current
.. TIL and CMOS compatible inputs
.. Thermal shutdown (outputs off) at TJ = 155'C
• Overcurrent protection
.. No shoot-through currents
.. 15-lead TO-220 molded power package

An alrDMOS H-bridge power stage delivers continuous output currents up to 3A (6A peak) at supply voltages up to
55V. The DMOS power switches feature low ROS(ON) for
high efficiency, and a diode intrinsic to the DMOS body
structure eliminates the discrete diodes typically required to
clamp bipolar power stages.

Applications
III Full, half and microstep stepper motor drives

III Stepper motor and brushed DC motor servo drives
III Automated factory, medical and office equipment

An innovative current sensing method eliminates the power
loss associated with a sense resistor in series with the motor. A four-bit digital-to-analog converter (DAC) provides a
digital path for controlling the motor current, and, by extension, simplifies implementation of full, half and microstep
stepper motor drives. For higher resolution applications, an
external DAC can be used.

Functional Block and Connection Diagram
OUT 1

1

(15-LeadTO-220 Molded PowerPackage(T)

OUT2
15

Vee
9

THERMAL
SHUTDOWN
UNDERVOLTAGE
LOCKOUT

BRAKE 10
DIRECTION 11

5 PGND

RC3
U DAe REF

a
12

2

SGND

COMP OUT

13
CS OUT

8
Ml

Order Number LMD18245T
See NS Package Number TA 15A

4-59

7
M2

6
M3

4
M4

TL/H/11878-1

•

Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
DC Voltage at:
OUT 1, Vee, and OUT 2
COMPOUT, RC, M4, M3, M2, M1, BRAKE,
DIRECTION, CS OUT, and DAC REF
DC Voltage PGND to SGND
Continuous Load Current
Peak Load Current (Note 2)
Junction Temperature (TJ(max»
Power Dissipation (Note 3):
TO-220 (TA = 25·C, Infinite Heatsink)
TO-220 (TA = 25·C, Free Air)

ESD Susceptibility (Note 4)
Storage Temperature Range (Tsl

1500V
-65·Cto + 150"C

Lead Temperature (Soldering, 10 seconds)

+60V
+12V

300"C

Operating Conditions (Note 1)
Temperature Range (TJ) (Note 3)

-40"C to + 125·C

Supply Voltage Range (Vee)

±400mV

+12Vto +55V

CS OUT Voltage Range

3A

'OVto +5V

DAC REF Voltage Range

6A
+150·C

OVto +5V

MONOSTABLE Pulse Range

10,..st0100ms

25W
3.5W

Electrical Characteristics

The following specifications apply for Vee = + 42V, unless otherwise stated. Bold'ace limits apply over the operating temperature range, - 40·C :;:;; T .. :;:;; + 12S·C. All other limits apply for T A =
TJ = 25·C. (Note 2)
Symbol
lee

Conditions

Typical
(Note 5)

DAC REF = OV, Vee = +20V

8

Parameter
Quiescent Supply Current

Umlt
(Note 5)

Units
(Umita)

15

mA
mA(max)

POWER OUTPUT STAGE
RDS(ON)

Switch ON Resistance

ILOAD = SA
ILOAD = 6A

VDIODE

Body Diode Forward Voltage

IDIODE = SA

0.3
O.S

0.4

o (max)
o (max)
o (max)

0.6

,0 (max)

1.5

V(max)

0.4

0.6

,V

1.0

Trr

Diode Reverse Recovery Time

IDIODE = 1A

80

ns

Qrr

Diode Reverse Recovery Charge

IDIODE = 1A

40

nC

tD(ON)

Output Tum ON Delay Time
Sourcing Outputs
Sinking Outputs

ILOAD = SA
ILOAD = SA

5
900

,..s
ns

Output Tum OFF Delay Time
Sourcing Outputs
Sinking Outputs

ILOAD':= SA
ILOAD = SA

600
400

ns
ns

Output Tum ON Switching Time
Sourcing Outputs
Sinking Outputs

ILOAD = SA
ILOAD = SA

40
1

,..S
,..S

Output Tum OFF Switching Time
Sourcing Outputs
Sinking Outputs

ILOAD = SA
ILOAD = SA

200
80

ns
ns

tpw

Minimum Input Pulse Width

Pins 10 and 11

2

,..s

tDB

Minimum Dead Band

(Note 6)

40

ns

tD(OFF)

toN

toFF

4-60

Electrical Characteristics

The following specifications apply for Vee = +42V, unless otherwise stated. Bold·
face limits apply over the operating temperature range, -40·C ~ T J ~ + 125·C. All other limits apply for TA =
TJ = 25·C. (Note 2) (Continued)
Symbol

Parameter

Conditions

Typical
(NoteS)

Limit
(Note 5)

Units
(Limits)

250

200
175
300
325

p.A (min)
p.A (min)
p.A(max)
p.A (max)

±9

%
% (max)

20

p.A
p.A (max)

4

Bits (min)

CURRENT SENSE AMPLIFIER
Current Sense Output

Current Sense Linearity Error
Current Sense Offset

ILOAD

=

1A (Note 7)

0.5A ~ ILOAD :s; 3A (Note 7)

±6
5

ILOAD = OA

DIGITAL·TO·ANALOG CONVERTER (DAC)
Resolution
Monotonicity
Total Unadjusted Error

DAC REF Input Current

Bits (min)
LSB(max)
LSB(max)

50

ns

-0.5
±10

p.A
p.A (max)

0.125

Propagation Delay
IREF

4
0.25
0.5

DACREF

=

+5V

COMPARATOR AND MONOSTABLE

tDELAY

Comparator High Output Level

6.27

V

Comparator Low,Output Level

88

mV

Comparator Output Current
Source
Sink

0.2
3.2

rnA
rnA

Monostable Turn OFF Delay

(Note 8)

p.s

1.2
2.0

p.s(max)

5
8

V (min)
V (rnax)

PROTECTION AND PACKAGE THERMAL RESISTANCES
Undervoltage Lockout, Vee

TJSD

Shutdown Temperature, TJ

155

·C

9Je
9JA

Package Thermal Resistances
Junction-to-Case, TO-220
Junction-to-Ambient, TO-220

1.5
35

·C/W
·C/W

LOGIC INPUTS
VIL

Low Level Input Voltage

-0.1
0.8

V (min)
V (rnax)

VIH

High Level Input Voltage

2
12

V (rnin)
V (rnax)

liN

Input Current

±10

,...A (max)

VIN

=

OVor 12V

II
4-61

Electrical Characteristics

The following specifications apply for Vee
face Ilmlt& apply overtha operating temperature range, -40·C:s; TJ:S;
TJ
25·C. (Note 2) (Continued)

=

= + 42V, unless otherwise stated. Bold·
+ 12S·C;AII other limits applyforTA =

Note ,: Absolute MaXimum ~~tings indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when operating the device
outside the rated Operating Conditions.
N~te 2: Unless otherwise stat8d, losd currents'are pulses with widths less than 2 ms and duty cycles less than 5%.
Note 3: The maximum allowable power dissipation at any ambient temperature Is PMax = (t 25 - TA}/9JA, where 125'C is the maximum junction temperature for
operation, TA Is the ambient temperature in 'C, and 9JA is the junction·to·ambient thennal resistance in 'C/W. Exceeding Pmax voids the Electrical SpecHications by
forcing TJ above ,I 25"C. If the junction temperature exceeds 155'C, Internal circuitry disables the power bridge. When a heatsink is used, 9JA is the sum of the
jU,nctlo,n-to-case thermal resistance of the package, 9JCo and the case·to·ambient thermal resistance of the heatsink.
Note 4: ESD rating is based on the human body model of 100 pF discharged through a 1.5 kn resistor. Ml, M2, M3 and M4, pins 8,7,6 and 4 are protected to

eOOv.
Note 5: All limits are 100% production tested at 25'C. Temperature extreme limits are guaranteed via correlation using accepted SQC (Statistical Quality Control)
methods. All limits are used to calculate AOQL (Average Outgoing Quality Level). Typicals are at TJ = 25'C and represent the, most likely parametriC nann.
Note 6: AsymmetriC tum OFF and ON delay times and switching times ensure a switch turns OFF before the other switch in the same half H·bridge begins to turn
ON'(preventing.momentary short circuits between the power supply and ground}. The transitional period during which both switches are OFF is commonly referred
to as the dead band.
Note 7: (I~OAD,ISENSE) data points are taken for load currents of 0.5A, lA, 2A and 3A. The current sense gain is specified as ISENSE/I~OAD for the lA data point.
The i::urrent sense linearity is specified as the slope of the line between the 0.5A and I A data points minus the slope of the line between the 2A and 3A data points
all divided by the slope of the line between the O.SA and 1A data pOints.
Note 8: Turn OFF delay, toE~y,ls defined as the time from 'the voltage at the output of the current sense amplifier reaching the DAC output voltage to the lower
DMOS switch beginning to turn OFF. With Vee = 32V, DIRECTION high, and 200n connected between OUT1 and Vee, the voltage at RC Is Increased from OV to
5V,atl.2V1"s, and tDE~y is measured as the time from the voltage at RC reaching 2V to the time the voltage at OUT I reaches 3V.

-,

Typical Performance Cha~acteristics
,

c

0.5

0.30

0.40

Vee =.42V
~OAO

RDS(ON)vs
Supply Voltage

RDS(ON) vs Load Current

RDS(ON) vs Temperature .

~OAO

Yee = 42V
TJ = 25°C

= 3A

= 3A
TJ j25j'C

. ·0.29

0.35
0.4

"S

/

~
~. 0.3

:s

:s 0.28'

.e

~

'Z' 0.30

V

0.2~

'

0.20

-55 -35 -15 5 25 45 65 85 105125

0.5

..

800,

"< 600
.3

II(

~

~

~

200

/

~

/
1,2f.c:-

/.

1.0

2.5

0.24

3.0

'0 15 .20 ·25 30 35 40 45 50 55
SUPPLY VOLTAGE (V)

Supply Current vs
Temperature

7

8,

"<

..s
0-

25°C

~.

r--

~

r-

0
, 0.5

2.0

Supply Current vs
Supply Voltage

;

-55lc~ ~

Vee = 42V

B

'.5

L/I

0.25

"

;

Current Sense Output
vs Load Current

400

1.0

ISID~/

'

LOAD CURRENT (~) ,

JUNCTION T.EMPERATURE (·c)

j

HIIGH

0.25

./

','

0.27

~ 0.26

~

/

"

LOW SIDE

:::

6

5

...... f-"" r-

f-'"

,/

i/

ill

1.5

2.0 , 2.5

LOAD CURRENT (A)

3.0

4
10 15 20 25 30 35 40 <15 50 55
~UPPLY, V~LTAGE (V)

4-62

"<

..s

7

'0-

~
~

6

Vee

'"

"-

i'
r-....

5

=.42V

.....

,

4
-55 -35-'5 5 25456585 '05125
JUNCTION TEMPERATURE t·C}
TUHIt 1878-27

,------------------------------------------------------------------------------,
Pin 13, CS OUT: Output of the current sense amplifier. The
current sense amplifier sources 250 ".A (typical) per ampere
of total forward current conducted by the upper two
switches of the power bridge.
Pin 14, DAC REF: Voltage reference input of the DAC. The
DAC provides an analog voltage equal to VDAC REF X
D/16, where D is the decimal equivalent (0-15) of the binary number applied at M4 through M1.

Connection Diagram
PGND

0

o

15
14
13
12
11
10
9
8
7
6
5
4
3
2
01

OUT 2
DAC REF
CSOUT
SGND
DIRECTION
BRAKE

Vee

Pin 15, OUT 2: Output node of the second half H-bridge.

Ml
M2
M3
PGND
M4
RC
COMPOUT
OUT 1

TABLE I. Switch Control Logic Truth Table
BRAKE

DIRECTION

MONO

Active Switches

H

X

X

Source 1, Source 2

L

H

L

Source 2

L

H

H

Source 2, Sink 1

L

L

L

Source 1

L

L

H

Source 1, Sink 2

TUH/11878-2

Top View
15-Lead TO-220 Molded Power Package
Order Number LMD18245T
See NS Package Number TA 15A

x=

don't care

MONO Is the oulput of the monostable.

Pinout Descriptions (See Functional Block

Functional Descriptions

and Connection Diagrams)
Pin 1, OUT 1: Output node of the first half H-bridge.
Pin 2, COMP OUT: Output of the comparator. If the voltage
at CS OUT exceeds that provided by the DAC, the comparator triggers the monostable.

TYPICAL OPERATION OF A CHOPPER AMPLIFIER
Chopper amplifiers employ feedback driven switching of a
power bridge to control and limit current in the winding of a
motor (Figure 1). The bridge consists of four solid state
power switches and four diodes connected in an H configuration. Control circuitry (not shown) monitors the winding
current and compares it to a threshold. While the winding
current remains less than the threshold, a source switch
and a sink switch in opposite halves of the bridge force the
supply voltage across the winding, and the winding current
increases rapidly towards Vcc/R (Figures 1a and 1d). As
the winding current surpasses the threshold, the control circuitry turns OFF the sink switch for a fixed period or off-time.
During the off-time, the source switch and the opposite upper diode short the winding, and the winding current recirculates and decays slowly towards zero (Figures 1b and 1e).
At the end of the off-time, the control circuitry turns back ON
the sink switch, and the winding current again increases
rapidly towards Vcc/R (Figures 1a and 1d again). The
above sequence repeats to provide a current chopping action that limits the winding current to the threshold (Figure
19). Chopping only occurs if the winding current reaches the
threshold. During a change in the direction of the winding
current, the diodes provide a decay path for the initial winding current (Figures 1c and 1t). Since the bridge shorts the
winding for a fixed period, this type of chopper amplifier is
commonly referred to as a fixed off-time chopper.

Pin 3, RC: Monostable timing node. A parallel resistorcapacitor network connected between this node and ground
sets the monostable timing pulse at about 1.1 RC seconds.
Pin 5, PGND: Ground return node of the power bridge. Bond
wires (internal) connect PGND to the tab of the TO-220
package.
Pins 4 and 6 through 8, M4 through M1: Digital inputs of
the DAC. These inputs make up a four-bit binary number
with M4 as the most significant bit or MSB. The DAC provides an analog voltage directly proportional to the binary
number applied at M4 through M1.
Pin 9, Vee: Power supply node.
Pin 10, BRAKE: Brake logic input. Pulling the BRAKE input
logic-high activates both sourcing switches of the power
bridge-effectively shorting the load. See Table I. Shorting
the load in this manner forces the load current to recirculate
and decay to zero.
Pin 11, DIRECTION: Direction logic input. The logic level at
this input dictates the direction of current flow in the load.
See Table I.
Pin 12, SGND: Ground return node of all Signal level circuits.

4-63

~

!!!:

o
....

CD
N

""

(II

~
....
Q
:::E

.....

Functional DescTiptions(ContinU~d)
(b)
vee

(a)

Vee

TL/H111878-3

(c)

vee

TL/H/11878-4

TL/H/11878-5

(d)

(f)

vee

Vee

TUH/11878-6

TL/H/11878-7

TL/H111878-8

(g)

a

TUH/11878-9

FIGURE 1. Chopper Amplifier Chopping States: Full Vee Applied Across the Winding (a) and (d), Shorted
Winding (b) and (e), Winding Current Decays During a Change In the Direction of the Winding Current (c)
and (f), and the Chopped Winding Current (g)

4-64

ri:
C

Functional Descriptions (Continued)
switch in opposite halves of the bridge forces the full supply
voltage less the switch drops across the motor winding.
While the bridge remains in this state, the winding current
increases exponentially towards a limit dictated by the supply voltage,_ the switch drops, and the winding resistance.
Subsequently turning OFF the sink switch causes a voltage
transient that forward biases the body diode of the other
source switch. The diode clamps the transient at one diode
drop above the supply voltage and provides an alternative
current path. While the bridge remains in this state, it essen,
tially shorts the winding and the winding current recirculates
and decays exponentially towards zero. During a change in
the direction of the-winding current, both the switches and
the body diodes provide a decay path for the initial winding
current (Figure 3).

THE LMD18245 CHOPPER AMPLIFIER

The LMD18245 incorporates all the circuit blocks needed to
implement a fixed off-time chopper amplifier. These blocks
include: an all DMOS, full H-bridge with clamp diodes, an
amplifier for sensing the Imid current, a comparator, a
monostable, and a DAC for digital control of the chopping
ihreshold. Also incorporated are logiC, level shifting and
drive blocks for digital control of the direction of the load
current and braking.
THE H-BRIDGE

The power stage consists of four DMOS power switches
and associated body diodes connected in an H-bridge configuration (Figure.2). Turning ON a source s,,":itch and a sink

....
c»
N
A
U1

Vee

-IIF-

L...;.-.....

------I.~51

-- - - - - - -

~

and 54 ON

------I.~52

51 ON

-- - - - - - -

~

TUH/11878-10

and 53 ON

52 ON
TLlH/11878-11

FIGURE 2. The DMOS H-Bridge

Vee _

Vee

II
TLlH/11878-12

TLlH/11878-13

FIGURE 3. Decay Paths for Initial Winding Current During a Change in the Direction of the Winding Current

4-65

U) ~------------------------------------------------------------------------------------,

•

N
CD

Functional Descriptions (Continued)

Q

THE CURRENT SENSE AMPLIFIER
Many transistor cells in parallel make up the DMOS power
switches. The current sense amplifier (Figure 4) uses a
small fraction of the cells of both upper switches to provide
a unique, low-loss means for sensing the load current. In
practice, each upper switch functions as a 1x sense device
in parallel with a 4000x power device. The current sense
amplifier forces the voltage at the source of the sense device to equal that at the source of the power device; thus,
the devices share the total drain current in proportion to the
1:4000 'cell ratio; Only the current flowing from drain to
source, the forward current,' registers at the output of the
current sense amplifier. The current sense amplifier, therefore, sources 250 p.A per ampere of total forward current
conducted by the upper two switches of the power bridge.

....

~

While the specified maximum DC voltage compliance at CS
OUT is 12V, the specified operating voltage range at CS
OUT is OV to 5V.
THE DIGITAL·TO·ANALOG CONVERTER (DAC)
The DAC sets the threshold voltage for chopping .ilt
VOAC REF X D/16, where D is the decimal equivalent (015) of the binary number applied at M4 through M1, the
digital inputs of the DAC. M4 is the MSB or most significant
bit. For applications that require higher resolution, an external DAC can drive the DAC REF input. While the specified
maximum DC voltage compliance at DAC REF is 12V, the
specified operating voltage range at DAC REF is OV to 5V.
THE COMPARATOR, MONOSTABLE AND WINDING
CURRENT THRESHOLD FOR CHOPPING
As the voltage at CS OUT sUrpasses that at the output of
the DAC, the comparator triggers the monostable, and the
monostable, once triggered, provides a timing pulse to the
control logic. During the timing pulse, the power bridge
shorts the motor winding, causing current in the winding to
recirculate and decay slowly towards zero (Figures 1b and
1e again). A parallel resistor-capacitor network connected
between RC (pin #3) and ground sets the timing pulse or
off-time at about 1.1 RC seconds.
Chopping of the winding current occurs as the voltage at CS
OUT exceeds that at the output of the DAC; so chopping
occurs at a winding current threshold of about

The sense current develops a potential across Rs that is
proportional to the load current; for example, per ampere of
load current, the sense current develops one volt across a
4 kO resistor (the product of 250 p.A per ampere and 4 kO).
Since chopping of the load current occurs as the voltage at
CS OUT surpasses the threshold (the DAC output voltage),
Rs sets the gain of the chopper amplifier; for example, a
2 kO resistor sets the gain at two amperes of load current
per volt of the threshold (the reciprocal of the product of
250 p.A per ampere and 2 kO). A quarter watt resistor suffices. A low value capacitor connected in parallel with Rs filters the effects of switching noise from the current sense
signal.

(VOAC REF X D/16) + «250

x 10- 6) x Rs)) amperes.

~C-----1~---1~-----------------------------------1~---1~---

Current Sense
Amplifier

TL/H/11878-14

FIGURE 4. The Source Switches of the Power Bridge and the Current Sense Amplifier

4-66

Applications Information
supply line must be properly bypassed at )Icc for the motor
driver to survive an extended overcurrent fault.

POWER SUPPLY BYPASSING
Step changes in current drawn from the power supply occur
repeatedly during normal operation and may cause large
voltage spikes across inductance in the power supply line:
Care must be taken to limit voltage spikes at Vee to less
than the 60V Absolute Maximum Rating. At a change in the
direction of the load current, the initial load current tends to
raise the voltage at the power supply rail (Figure 3 again).
Current transients caused by the reverse recovery of the
clamp diodes tend to pull down the voltage at the power
supply rail.

In the case of a locked rotor, the ind!lctance of the winding
tends to limit the. rate of change of. tne fault current to Ii
value easily handled by the protection circuitry. In the case
of a low inductance short from either output to ground or
between outputs, the fault current could surge past the 12A
shutdown threshold, forcing the device to dissipate a substantial amount of power for the brief period required to disable the source switches. Because the fault power must be
dissipated by only one source switch, a short from output to
ground represents the worst case fault. Any overcurrent
fault is potentially destructive, especially while operating
with high supply voltages (;,,30V), so 'precautions are in order. Sinking Vee for heat with 1 square inch of 1 ounce
copper on the printed circuit board is highly recommended.
The sink switches are not internally protected against shorts
to Vee.

Bypassing the power supply line at Vee is required to protect the device and minimize the adverse effects of normal
operation on the power supply rail. Using both a 1 ,..F high
frequency ceramic capacitor and a large-value aluminum
electrolytic capacitor is highly recommended. A value of
100 ,..F per ampere of load current usually suffices for the
aluminum electrolytic capacitor. Both capacitors should
have short leads and be located within one half inch of Vee.

THERMAL SHUTDOWN

OVERCURRENT PROTECTION

Internal circuitry senses the junction temperature near the
power bridge and disables the bridge if the junction temperature exceeds about 155°C. When the junction temperature
cools past the shutdown threshold (lowered by a slight hysteresis), the device automatically restarts.

If the forward current in either source switch exceeds a 12A
threshold, internal circuitry disables both source switches,
forcing a rapid decay of the fault current (Figure 5). Approxiafter the fault current reaches zero, the device
mately 3
restarts. Automatic restart allows an immediate return to
normal operation once the fault condition has heen removed. If the fault persists, the device will begin cycling into
and out of thermal shutdown. Switching large fault currents
may cause potentially destructive voltage spikes across inductance in the power supply line; therefore, the power

,..S

UNDERVOLTAGELOCKOUT
Internal circuitry disables the power bridge if the power supply voltage drops below a rough threshold between BV and
5V. Should the power supply voltage then exceed the
threshold, the device automatically restarts.

OA

TUH/llB7B-15
Trace: Fault Current at 5A1div
Horizontal: 20 f's/div

FIGURE 5. Fault Current with Vee = 30V, OUT 1 Shorted to OUT 2, and CS OUT Grounded

II
4-67

The Typical Application
Figure 6 shows the typical application, the power stage of a

200 mA per volt of the threshold for chopping. Digital signals control the thresholds for chopping, the directions of
the winding currents, and, by extension, the drive type (full
step, half step, etc.). A I.I.processor or I.I.controlier usually
provides the digital control signals.

chopper drive for bipolar stepper motors. The 20 kO resistor
and 2.2 nF capacitor connected between RC and ground
set the off-time at about 48 I.I.s, and the 20 kO resistor conI)ected between CS OUT and ground sets the gain at about
40V

SV

DAC REF

DIRECTION A - - - - I
FRON
!,CONTROLLER

1!'F

Vcc

p

100!'F

OUT 11-------(>-...... 200 STEP/REVOLUTION HYBRID
12V, 0.9SA, 12 mH, 12fl

BRAKE A - - - - I
N4·A-.;....--I

PHASE A

LMD18245

M3A----I
M2 A - - - - I
loll A - - - - I
CS OUT

OUT 21-----(>-....1
PGND SGND

RC

8
PHASE B

20kfl

40V

5V

DAC REF

DIRECTION 9 - - - I
9RAKE 9 - - - - 1
FROM
!,CONTROLLER

1!'F

N4 9 - - - - 1
N39----I

Vee

p
OUT

l00!'F

1t-------~

LMD18245

N29----I
M19----I

OUT21------------~

CS OUT

RC

PGND SGND

20kfl

TL/H/11878-16

FIGURE 6. Typical Application Circuit for Driving Bipolar Stepper Motors

4-68

The Typical Application

(Continued)

ONE·PHASE-oN FULL STEP DRIVE (WAVE DRIVE)

TWO·PHASE·ON FULL STEP DRIVE

To make the motor take full steps, windings A and B can be
energized in the sequence

To make the motor take full steps, windings A and B can
also be energized in the sequence

A-B-Ao-Bo-A- ... ,

AB-A"B-AoB* -ABo -AB- ... ,

where A represents winding A energized with current in one
direction and A' represents winding A energized with current in the opposite direction. The motor takes one full step
each time one winding is de-energized and the other is energized. To make the motor step in the opposite direction,
the order of the above sequence must be reversed. Figure 7
shows the winding currents and digital control signals for a
wave drive application of the typical application circuit.

and because both windings are energized at all times, this
sequence produces more torque than that produced with
wave drive. The motor takes one full step at each change of
direction of either winding current. Figure 8 shows the winding currents and digital control signals for this application of
the typical application circuit, and Agure 9 shows, for a single phase, the winding current and voltage at the output of
the associated current sense amplifier.

OA
OA

TUH/11878-17

Top Trace: Phase A Winding Current at 1A1div
Bottom Trace: Phase B Winding Current at 1A1div
Horizontal: 1 ms/div
'500 steps/second

DIRECTION A

l

I I I
2

3

I

I

4

I

I I I
3

I

'"

4 I

DIRECTION B

4

4

"

M4 A, M3 A, M2 A,
and MI A

M4 B. M3 B, M2 B,
and !AI B

FORWARD

REVERSE
TUH/11878-18

BRAKE A = BRAKE B = 0

FIGURE 7. Winding Currents and Digital Control Signals for One·Phase·On Drive (Wave Drive)

4-69

II

U) r-------------------------------------------~------------------~----~~--~----~

~

CD

..-

The Typical Application

(Continued)

Q

....:::&
OA
OA

TLIH/11878-19

Top Trace: Phase A Winding Currenl allAidiv
Bottom Trace: 'Phase B Winding Currenl allAidiv
Horizontal: 1 ms/div
'500 sleps/second

I I II
2

DIRECTION A

I

3

I~:__. . 1
.

1

-.I~
. __-V

DIRECTION B

FORWARD

REVERSE
TLIH/11878-20

=

M4 A Ihrough Ml A
M4 B through Ml B
BRAKE A = BRAKE B = 0

=1

FIGURE 8. Winding Currents and Digital Control Signals for Two-Phase-on Drive

OA

OV

TLlH/11878-21

Top Trace: Phase A Winding Current atlAidiv
Bottom Trace: Phase A Sense Voltage al5V/div
Horizontal: 1 ms/div
'500 steps/second

FIGURE 9. Winding Current and Voltage at the Output of the Associated Current Sense Amplifier

4·70-

The Typical Application

(Continued)

HALF STEP DRIVE WITHOUT TORQUE
COMPENSATION
To make the motor take half steps, windings A and B can be
energized in the sequence

The motor takes one half step each time the number of
energized windings changes. It is important to note that although half stepping doubles the step resolution, changing
the number of energized windings from two to one decreases (one to two increases) torque by about 40%, resulting in
significant torque ripple and possibly noisy operation. Figure
10 shows the winding currents and digital control signals for
this half step application of the typical application circuit.

A-AB-B-A'B-A'A'Bo-Bo-ABo-A- ...

OA
OA

TLIH/11878-22

Top Trace: Phase A Winding Current at lA1div
Bottom Trace: Phase B Winding Current at 1A/div
Horizontal: 1 ms/div
'SOD steps/second

: 11213141 s ls171 al

:11213H s ls171 al

DIRECTION A

1

LI___~

I

I

I

I

I

DIRECTION 8
I

I

M4A, M3A, M2A, --; r----1 r----1 ~

U

and Ml A

U

U

M48. M38. M28, r----1 r----1 r----1 ~
and Ml 8

J

U

U

U

FORWARD

REVERSE
TLIH/11878-23

BRAKE A

= BRAKE B = 0

FIGURE 10. Winding Currents and Digital Control Signals for Half Step Drive without Torque Compensation

II
4-71

~
co

....

c

::E
...I

The Typical Application

(Continued)
of these advantages are obtained by replacing full stEiPS
with bursts of microsteps. When compared to full.step drive,
the motor runs smoother and quieter.
. . .' .
Figure 12 shows the lookup table for thisapplicati~n'of the
typical application circuit. Dividing eO"electrical per full step
by two microsteps per full ~tep yields 4?" electrical per microstep. a, therefore, increases from 0 to 315" in increments of 45". Each full 360" cycle comprises eight half
steps. Rounding Icosal to four bits gives D A, the decimal
equivalent qf the binary number applied at M4 A through
M1 A. DIRECTION A controls the polarity of the current in
winding A. Rgure 11 shows the sinusoidal winding currents.

HALF STEP DRIVE WITH TORQUE COMPENSATION
To make the motor take half steps; the windings can also be
energized with sinusoidal currents (Figure 11). Controlling
the winding currents In· the·fashion shown doubles the step
resolution without the significant torque ripple of the prior
drive technique: The 'motor· takes one half step each time
the level of either winding current changes. Half step drive
with torque compensation is microstepping drive. Along with
the obvious advantage of increased step resolution, microstepping reduces both full step oscillations and resonances
that occur as the motor and load combination is driveriat its
natural resonant frequency or subharmonics thereof. Both

OA

OA

TL/H/11878-24

Top Trace: Phase A Winding Current at lA1div
Bottom Trace: Phase B Winding Current at lA1div
Horizontal: 2 ms/div
.
'500 steps/second

: 1121314151 s171 al

:11213H sls171 al

DIRE~~~ON
.

A

l'

I

I

1L __. . .'"

I

I

I

I

DIRECTION. B

1_'"
...

I

I

M4 A, t.i2'A,

M~ ---i, 'r--! I I ~

and t.t3B

t.i4 B, M2 B,

t.i~

and t.t3A

.

U

U

U

r--, I I I I r-'\t
J '. U
U
U
FORWARD

BRAKE A

REVERSE

= BRAKE B = a

TL/H/11878-25

FIGURE 11. Winding Currents and Digital Control Signals for Half Step Drive with Torque Compensation

4-72

r---------------------------------------------------------------------~------,

The Typical Application

90' ELECTRICAL/FULL STEP

a
FORWARD

,J,

t
REVERSE
i

0
45
90
135
180
225
270
315
REPEAT

-0-

r

3:

(Continued)

C
.....

co

2 MICROSTEPS/FULL STEP = 45' ELECTRICAL/MICROSTEP

icos(a)i
1
0.707
0
0.707

DA
15
11
0
11 .

0.707
0
0.707

15
11
0
11

DIRECTION A
1
0
0
0.,
0

isln(a)i
0
0.707
1
0.707
0
0.707
1
0.707

DB
0
11
15
11
0
11
15
11

N

~

en

DIRECTIONB

0
0
0
0

FIGURE 12. Lookup Table for Half Step Drive with Torque Compensation
QUARTER STEP DRIVE WITH TORQUE
COMPENSATION

Figure 13 shows the winding currents and lookup table for a
quarter step drive (four microsteps per full step) with torque
compensation.

.'

OA

OA

TLIH111878-26
Top Trace: Phase A Winding Current at lA1div
BoHom Trace: Phase B Winding CUrrent at lA1div
Horizontal: 2ms/div
'250 steps/second

90' ELECTRICAL/FULL STEP

a

FORWARD

,J,

t
REVERSE
i

BRAKE A

o

22.5
45
67.5
90
112.5
135
157.5
180
202.5
225
247.5
270
292.5
315
337.5
REPEAT

-0-

4 MICROSTEPS/FULL STEP = 22.5' ELECTRICAL/MICROSTEP

icps(a)i
1
0.924
0.707
.0.383
' 0
0.383.
0.707
0.924
1
0.924
0.707
0.383
0
0.383
0.707
0.924

DA
15
14
11
6
0

6
11
14
15
14
11

6

DIRECTION A
-1

1
0
0,
0
0
0
0
0
0

iSin(a)i
0
0.383
0.707
0.924
0.924
0.707
0.383
0
0.383
0.707
0.924

0

6
11
14

0.924
0.707
0.383

DB
0
6
11
14
15
14
11

DIRECTION B

6
0

1
0

6

0

11
14
15
14
11

6

0
0
0

0
0

0

= BRAKE B = 0
FIGURE 13. Winding Currents and Lookup Table for Quarter Step Drive with Torque Compensation

II

U) r-------------------------------------------------------------------------------------~
~

~
....
Q

Test Circuit and Switching T,me Deflnltl()ns

:=5
1--___,

SINK

lOkI!

DIRECTION

....==~-.....------+ Vee =42V

11

...-.:;;BR;;;;AK.;::E.... 10

'""It

:,;:
Q

:::I

'-'

lOkI!

1 5 1 - - -...... SOURCE

+5V
DIRECTION

'o(ON)

Vee
SOURCE

~OH)
Vee
SINK

TLlH/11878-28

4-74

Section 5
Surface Mount

Section 5 Contents
Packing Considerations (Methods, Materials and Recycling) ..••....•••.......•..•...•...
Board Mount of Surface Mount Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . • • • .
Recommended Soldering Profiles--Surface Mount •...•... . . . . . . . . . . . . . . . . • • . . . . . . • • . . .
AN-450 Small Outline (SO) Package Surface Mounting Methods-Parameters and Their
Effect on Product Reliability. . . . • • . . . . . . . . . . . . • . . . . • . . . . . . . . . . • . . . . . . • . . . . . . . . . . . . . .
Land Pattern Recommendations ••...•..•..•..••.•..•.....•.......•.............•....

5-2

5-3
5-19
5-23
5-24
5-35

t!lNational Semiconductor

Packing Considerations (Methods, Materials and Recycling)
Transport Media
INTERMEDIATE CONTAINER

All NSC devices are prepared, inspected and packed to insure proper physical support and to protect during transport
and shipment. All assembled devices are packed in one or
more of the following container forms-immediate containers, intermediate containers and outer/shipping containers.
An example of each container form is illustrated below.

Tape l< Reel
Box

IMMEDIATE CONTAINER
Reel

TLlP/11809-4

~_\ -----'~~--\
\
~

TL/P/llB09-1

-

Ie Device

Label

"l:~~
Rail/Tube

\ Rail/Tube

TL/P/11809-5

.
TLlP/llB09-2

Trays
TL/P/11809-6

OUTER/SHIPPING CONTAINER
TLlP/llB09-3

TLlP/11809-7

5-3

Methods of immediate carrier packing include insertion of
components into molded trays and rails/tubes, mounting of
components onto tape and reel or placement in corrugated
cartons. The immediate containers are then packed into intermediate containers (bags or boxes) which specify quantities of trays, rails/tubes or tape and reels. Outer/shipping
containers are then filled or partially filled with intermediate
containers to meet order quantity re'quirements and to further insure protection from transportation hazards. Additional dunnage filler material is required to fill voids within the
intermediate and outer/shipping containers.

-

Ease of handling-it should be easy to assemble, load
and unload products in and from it; and
....:. Impacts to the environment':""it shall be reusable and
recyclable.

Levels of Product Packing
IMMEDIATE CONTAINER
The first level of product packing is the immediate container.
The immediate container type varies with the product or
package being packed. In addition, the materials used in the
immediate container depend on ~he fragility, size,and profile
of the product. The four types of immediate containers used
by NSC are rails/tubes;trays, tape and reel, and corrugated
and chipboard containers.
Rails/tubes Ilre generally made of acrylic or polyvinyl chloride (PVC) plastics. The electrical characteristics of the material are altered by either intrinSically adding carbon fillers,
and/or topically coating it with antistatic solution., Refer to
Table I for rail/tube material and recyclabillty information.

General Packing Requirements
NSC packing methods and materials are designed based on
the following considerations:
- Optimum protection to the producls-it must provide adequate protection from handling (electrostatic discharge) and transportation hazards;

TABLE I. Plastic Rail/Tube and Stopp~r Requirements
Rail

Package
Type

Material

Code/Symbol
(Note 1)

DIP's
Plastic
Ceramic
Sidebraze

Polyvinylchloride
Polyvinylchloride
Polyvinylchloride

03/PVC
03/PVC
03/PVC

Pin
Pin
Pin

Polyamide
Polyamide
Polyamide

07/PA
07/PA
07lPA

Yes
Yes
Yes

Type

Stopper
Material

Code/Symbol
(Note 1)

Recyclablllty

.'

PLCC

Polyvinylchloride

03/PVC

Plug

Rubber

07/SBR

Yes

TapePak

Polyvinylchloride

03/PVC

Plug

Rubber

07/SBR

Yes

Flatpack

Polyvinylchloride

03/PVC

Pin

Polymide

07/PA

Yes

Cerpack

Polyvinylchloride

03/PVC

Pin

Polymide

07/PA

Yes

TO-220/202

Polyvinylchloride

03/PVC

Pin

Polymide

07/PA

Yes

TO-5/B
(in Carrier)

Polyvinylchloride

03/PVC

Pin

Polymide

,,07/PA

Yes

SOP

Polyvinylchloride

03/PVC

Plug

Rubber

07/SBR

Yes

LeC
1BL-44L

Polyvinylchloride

03/PVC

Plug

Rubber

07/SBR

Yes

Note 1: ISO 1043-1 International Standards-f'lastic Symbols.
SAE JI344 Marking of Plastic Parts.
ASTM D 1972-91 Standard Practice for Generic Marking of Plastic Products.
DIN 6120, German Recycling Systems, RESY for paperbased and VGK for plastic packing materials.

,.

5-4

"'U

depending on the material type. Vacuum formed trays are
only used in ambient room temperature conditions. Refer to
Table II for tray material and recyclability information.

Molded injection and vacuum formed trays can be either
conductive or static dissipative. Molded injection trays are
classified as either low-temperature or high-temperature

TABLE II. Tray Requirements
Tray

Package
Type

Material

Class

PQFP(AII)

Code/Symbol
(Note 1)

Recyclability
(Note 1)

High Temperature

Polyethersulfone

Yes

Low Temperature

Acrylonitrilebutadiene
Styrene

Yes

PGA,LDCC
CERQUADs
andLCC
(48Ieads-125 leads)

Low Temperature
Only

ASS/PVC

Yes

07/ASS-PVC

Wire Tie

PPGA

Low Temperature
Only

Polyarylsulfone

Yes

07/PAS

Wire Tie

Tape and reel is a multi-part immediate container system.
The reel is made of either polystyrene (PS) material coated
with antistatic solution or chipboard. The embossed or cavity tape is made of either PVC or PS material. The cover tape

07lPES

Binding Type

07lASS

Reel

..

Material

Cover Type
Code/
Symbol
(Note 1)

Wire Tie or
Nylon Strap

is made of polyester (PEn and polyethylene (PE) materials.
Refer to Table III for tape and reel material and recyclability
Information.

. TABLE III. Tape and Reel Requirements

Package
Type

Wire Tie or
Nylon Strap

Code/
Symbol
(Note 1)

Material

Carrier Tape
Material

Code/
Symbol
(Note 1)

Recyclability
(Note 1)

TO-92

Chipboard

Resy

N/A

SOP-23

Polystyrene
Chipboard

06/PS
Resy

Polystyrene

06/PS

Paper Tape
PVC

03/PVC

Yes

SOP,SSOP
and PLCC

Polystyrene
Polyethylene

06/PS

Polyester

07/PET-PE

PVC

03/PVC

Yes

Nole I: 150 1043-1 International Standards-Plastic Symbols.
SAE J1344 Marking of Plastic Parts.
ASTM D 1972-91 Siandand Practice for Generic Marking of Plastic Products.
DIN 6120. German Recycling Systems, RESY for paperbased and VGK for plastic packing materials.

5-5

Yes

~
ii!5:
::s

ca
oo
::s
en

a:
CD

i.o
::s
en

o
C

o

~CD

r---------------------------------------------------------------------------------~

fibreboard facing. Facings and corrugated medium are,kraft
(brown) fibreboard, and, generally single wall construction.
Refer to Table IV for material and recyclability information.

Corrugated containers are generally constructed with fibreboard'facingsand,a fluted corrugated medium in between
the facings. Chipboard containers are comprised of just one

'a

·iii

c

TABLE IV. Fibreboard Container Requirements

8
Q

C
~

i

,Pack Method
Package
Type

Container Type

, Codel
Material

Immediate (lMM)
Intermediate (INn
Outer or Shipping ,(SHP)

Symbol
(Note 1)
Resy

Recyclability

,TO-92/18,
TO-46/5,
TO-39,22,O,
TO-202/126,
TO-237

Corrugated
(E070BOX)

All Products

Corrguated

Resy

INT and SHIP

Yes

All Products

3-PlyPaper
(Padpak)

Resy

Dunnage

Yes

All Products
,.
PLCC

Plastic
Bubble Sheet

04/PE

Dunnage

Yes

IMM

Yes

'.

Note 1: ISO 1043-1 International Standards-Plastic Symbols,
SAE J1344 Marking 01 Plastic Paris.
ASTM 01972-91 Standard Practlc

TP40A

.Coinstack
Tube

100

Flat Rail

25

Plastic Pin
Grid Array
(PPGA)

UP124A

Tray

30

UP159A

Tray

20

UP175A

Tray

20

Plastic
Leaded Chip
Carrier
(PLCC)

V20A

Rail/Tube

40

Tape and Reel

1000

V28A

Rail/Tube

35

Tape and Reel

750

500

V32A

Rail/Tube

30

V44A

Rail/Tube

25

Tape and Reel

V52A

Rail/Tube

22

Tape and Reel

500

V68A

Rail/Tube

18

Tape and Reel

250

V84A

Rail/Tube

15

Tape and Reel

250

5-16

Immediate Packing Method for Plastic Packages (Continued)
Package
Type
(Code)

Primary
Immediate
Container

Package
Marketing
Drawing

Quantity

Method
Plastic Quad
Flatpack
(PQFP)

TO-92

Secondary
Immediate,
Container

VEF44A

Tray

96
60

VBG48A

Tray

VHGBOA

Tray

60

VJE80A

Tray

84

VCC80A

Tray

50/66

VCE100A

Tray

84

VLJ100A

Tray

50

VJG100A

Tray

60
60

Method

Quantity

VNG144A

Tray

VUL160A

Tray

24

VQL160A

Tray

,24

VUW208A

Tray

24

VF132A

Tray

36

VF196A

Tray

21

l03A

Box

1800

Tape and Reel

2000

l03B

Box

1800

Tape and Reel

2000

l03C

Box

1800

Tape andReel

2000

l03D

Box

1800

Tape and Reel

2000

l03E

Box

1800

Tape and Reel

2000 '

l03G

Box

1800

Tape and Reel

2000

l03H

Box

1800

Tape and Reel

2000

l03J

Box

1800

Tape and Reel

2000

Labeling
National Semiconductor offers 3 standard bar code labels;
reel and intermediate container labels for Tape and Reel;
intermediate container labei other than for Tape and Reel;,

and outer/shipping container labels. The tape and reel, and
intermediate container labels 'are National's own format
while the outer/shipping container label is based on the
EIA-556-A label standard.

NSC Standard Tape and Reel Label

CP) CPN: CPN 123456789B12

IIIIIII~ I~IIIII~ 1 1 1
ca) aTY: 1000

I

IIIIII~III~IIIII

XYZ COMPANY
111111111111111111

PO H: PO 123456789012
CD) D/C: P9236
1111111111111111111111111111111111111111

NSID:

DM74ALS253WM

Co~C ~ ~6~C ~~;:5678912
TL/P/11609-6

This label is placed on the reel (immediate container) as
well as on the intermediate box.

5-17

•

(I) . - - - - - - - - - - - - - - - - - - - - ,

c

o
:;:::
I!

I

~

NSC Standard Intermediate Container Label

XYZ COI"'Pff'.N

( P) CPN 'CPN 1234567898

1

at
C

J

([;I)

IIIII '

[;lTV 1888

(D)D.C. P9236

1 1111111111

' IIIUIIIII

(A) P.O. PO 123456789812

IIIIIIII~II

NSID
: DM74fLS253I.I1
FIN OPT : SPECl234

LOT

P. L.
: PLl234
REQR: RV1234

: LOT 123456789

BOX 1211 Of' 03

tflTIOI'R SEMIcotDl..H:TOR
TLIP/11809-9

NSC Standard Outer/Shipping Container Label

ID:

EIA14+EP123456

iii

FROM:

IIIIIIIIIIII~IIIIIII~IIIIIII

00_

N 5 C

SNn"A CLARA ~ CA 95051

TO:

xvz

I--(=:-Z)SPE='=C=-:-:--"IAl.:_ _ _ _--L..--.,

SMZ" TO _ 5 5 1
SHIP TO ADDRESS

a

SHIP TO ADDRESS

a

SHIP TO ADDRESS ...
SHIP TO NXJRESS 5

PACKAGE COUNT
02 OF 05

10000 EA

PACKAGE IJEIGHT

1~
(P)

~~ CPN12345678901234567890

'

KG 2540 L8

'

111111111111111111111111
TL/P/11809-10

5-18

m

2
tflNational Semiconductor

a..

iii:
c

o

a

Board Mount of Surface Mount Components
Due to the limited number of devices that are surface mount
components, it is necessary to mix both lead inserted components and surface mount components on the same
board.

Abstract
In facing the challenges of "Surface Mount Technology",
many manufacturers of printed circuit boards have taken
steps to convert some portions of their boards to this process. However, as the availability of all products as surface
mount components is still limited, many have had to mix
lead-inserted components with surface mount devices
(SMD's). Furthermore, to take advantage of using both
sides of the board, some surface mounted components are
adhered to the bottom side of the board while the top side is
reserved for the conventional lead-insert packages and fine
pitch surface mount packages.

Some components such as relays and swRches are made of
materials which would not be able to survive the temperature exposure in a vapor phase or IR furnace.

PW Board Assembly Procedures
There are two considerations in which through-hole ICs may
be combined with surface mount components on the PW
Board:
a) Whether to mount ICs on one or both sides of the board.

There are three surface mount processes in hi-volume use
today:
1. WAVE SOLDER; the surface mounted components are
adhered to the bottom side of the board while the top
side is reserved for the lead-inserted packages. The surface mount components are subjected to severe thermal
stress when they are immersed into the molten solder.

b) The sequence of soldering using Vapor Phase, IR or
Wave Soldering singly or a combination of two or more
methods.
The various processes that may be employed are:
A) WAVE SOLDER BEFORE VAPOR/IR REFLOW
SOLDER

2. INFRA-RED mass reflow; the surface mount components are placed on the solder paste which has been
applied to the board, the solder jOints are formed when
the board is passed thru the reflow media. The surface
mount devices are subjected to a controlled thermal environment.

1. Components on the same side of PW Board. Lead insert
standard DIPS onto PW Board Wave solder (conventional). Wash and lead trim. Dispense solder paste on SEM
pads. Pick and place SMDs onto PW Board. Bake Vapor
phase/IR reflow. Clean.

3. VAPOR PHASE mass reflow; the surface mount components are placed on the solder paste which has been
applied to the board, tbe solder jOints are formed when
the board is passed thru the reflow media. The surface
mount devices are subjected to a controlled thermal environment, more severe than Infra-red but much less
than wavesolder.

2. Components on opposite side of PW Board. Lead insert
standard DIPs onto PW Board Wave Solder (conventional). Clean and lead trim. Invert PW Board. Dispense drop
of adhesive on SMD sites (optional for smaller components). Pick and place SMDs onto board. Bake/Cure.
Invert board to rest on raised fixture. Vapor/IR reflow
soldering. Clean.

A discussion of the effect of these processes on the reliability of plastic semiconductor packages follows.

B) VAPOR/IR REFLOW SOLDER THEN WAVE SOLDER
1. Components on the same side of PW Board. Solder
paste screened on SMD side of Printed Wire Board. Pick
and place SMDs. Bake Vapor/IR reflow. Lead insert on
same side as SMD's. Wave solder. Clean and trim underside of PCB.

Role of Wave Soldering in
Application of SMDs
The generally acceptable methods of soldering SMDs are
vapor phase reflow soldering and IR reflow soldering, both
requiring application of solder paste on PW boards prior to
placement of the components. However, sentiment still exists for retaining the use of the old wave soldering machine.
The reasons being:

C) VAPOR/IR REFLOW ONLY
1. Components on the same side of PW Board Trim and
form standard DIPs in "gull wing" configuration. Solder
paste screened on PW Board. Pick and place SMDs and
DIPs. Bake Vapor/IR reflow. Clean.

Most PC Board Assembly houses already possess wave
soldering equipment. Switching to another technology such
as vapor phase soldering requires substantial investment in
equipment and people.

2. Components on oPPosite sides of PW Board. Solder
paste screened on SMD-side of Printed Wire Board. Adhesive dispensed at central location of each component
Pick and place SMDs. Bake. Solder paste screened on
all pads on DIP-side or alternatively apply solder rings
(performs) on leads. Lead insert DIPs. Vapor/IR reflow.
Clean and lead trim.

5-19

2rn
c

~

iii:
oc

a

f1:I

g

!

0''-~------------~----------------------------------~---r

c'
~
8.
E

o

(.)

C
::I
o

:::&

!

::I

CI)

'0

§
o

:::&

'E

!

Transition Temperature

PW Board Assembly Procedures
(Continued)
Z

D) WAVE SOLDERING ONLY
1. Components on opposite sides of PW board. Adhesive
dispense on SMD side of PW Board. Pick and place
SMDs. Cure adhesive. Lead insert top side with DIPs.
Wave solder with SMDs down arid 'into solder bath.
Clean and lead trim.
All of the above assembly procedures can be divided into
three categories for IC. Reliability considerations:
1'), Components' are 'subjected to both a vapor phaseliR
heat cycle then followed by wave-solder heat'cycle or
'vice v e r s a . '
,
2) Components are subjected to only a vapor phase/lR
'"
heal cycle.
"
'
3) Corriponents.. are subjected' to wave-soldering only arid
SMDs are subjected to heat by immersion into a solder
pot.
ot the~e three categories, the last is the rnost severe regarding heat trelltment to a semiconductor device. However, note that semicOnductor molded packages generally
possess a coating of solder on their leads as a final finish
for'solderability and protection of base leadframe material.
Most semiconductor manufacturers solder-plate the component.ieads, while others perform hot solder dip. In the latter
case the packages may be subjected to total immersion into
a hot solder bath under controlled conditions (manual operation) or be partially immersed while in a "pallet" where
automatic wave or DIP 'soldering processes are used. It is,
therefore, possible to subject SMDs to solder heat under
certain conditions and not cause catastrophiC failures.

0",

Vi!::
<::>

zz
D-

...~g'"
x>-

ffi~

::c<

....

A-42=4.6

~~~~::::;:::::;=;+:
;::::~:::=: T (Oc)
100 110 120 130 140 150 160,170 180
Tg

a

,

TL/P/11828-1

'FIGURE 1. Thermal Expansiol1 and Glass

Conventional Wave Soldering
Most wave soldering'operations occur at temperatures between 240·C-260·C. Conventional epoxies for encapsulation have glass-transition temperatures between 140·C170·0. An I'.C. directly exposed to these temperatures risks
its long term functionality due to epoxy/metal separation.
Fortunately, there are factors that can reduce that elem~rit
of risk:
',
1. The PW board has a certain' amount of heat-sink effort
and tends to shield the components from the temperature of the solder (if they were placed orr the top side of
the board). In actual measurements, DIPs achieve a temperature between 120·C-150·C in a 5-second pass' over
the solder. This' accounts for the fact that DIPs mounted
in the conventional manner are reliable:
2)' In conventional soldering, only the tip of each lead in DIP
'would experience the solder temperature because the
epoxy and die are standing above the PW board 'and out
of the solder bath.
"

Thermal Characteristics of Molded
Integrated Circuits

Effect on Package Performance by
Epoxy;'Metal Separation

Since Plastic DIPs and SMDs are encapsulated with a ther-,
moset epoXy, the, thenmal characteristics of. the material
gimerally corresPC?nd to a T~A (Tnermo-Mechanical Analysis) graph. The critical parameters are (a) ,its Linellr thermal
expansion, characteristics and (b) its glass tram~ition temperature after the epoxy has been fully cured. A typiqal TMA
graph is iIIustnited in Figure 1. Note tliat the ,epoxy changes
to a higher thermal expansion once it is subjected to temperatures exceeding its glass transition temperatu're. Metals
(as used on leadframes, for example) do not have this characteristic and generally will have a consiste!!t Linear thermal
expansion over the same temperature range.
In any good reliable plastic package, the choice of leadframe material should be such to match its thermal expansion properties to that of the encapsulating epoxy. In the
event that there is a mismatch betWeen the two, stresses
can build up at the interface of the epoxy antl'inetal. There
now' exists tendency for ,the 'epoxy to separate from the
metal leadframe in a manner similar to that observed' on
bimetallic thermal range.
'
." '

In wave soldering, it is necessary to use fluxes to assist the
solderability of, the cOmponents and PW boards. SOf!le facilities may even process the boards and components through
some form of acid cleaning prior to the spldering temperature. If separation occurs, the flux residues and acid residues (which may be present owing to inad,equate clealling)
will be forced into the package mainly I;>y capillary action as
the residues move away from the solder heat source. Once
the package is cooled, these contaminants are now trapped
within the package and are available to diffuse with moisture
from the epoxy over time. It should be noted that electrical
tests performed immediately after soldering generally will
ghie no in~ication of. this pptential problem., In any case, the
end result will, be corrosion of the chip metalizatiol'] over
time and p'rem~t~re failure of the device in the field.

a

In most cases when the packages are kept at temperatures
below their glass' transition, there' is ,a small possibility of
separation at the epoxy-metal' interface. However, I,f the
pacl
Mixed Surface-Mount and Axial-Leaded Insertion
Components Production Flow

Thermal stress of the packages during surface-mounting
processing is more severe than during standard DIP PC
board mounting processes. Figure B illustrates package
temperature versus wave soldering dwell time for surface
mounted packages (components are immersed into the
molten 'solder) and the standard DIP wave soldering process. (Only leads of the package are immersed into the mol·
ten solder).
'

z

~

(II

o

SOLDER TEMPERATURE 260"C

DWELL TIME
TLlF/8766-6

FIGUREB
For an ideal package, the thermal expansion rate of the
encapsulant should match that of the leadframe material in
order for the package to maintain mechanical integrity during the soldering process. Unfortunately, a perfect matchup
of thermal expansion rates with most presently used packaging materials is scarce. The problem lies primarily with the
epoxy compound.
Normally, thermal expansion rates for epoxy encapsulant
and metal lead frame materials are linear and remain fairly
close at temperatures approac!1ing 160·C, Figure C. At low.
er temperatures the difference in expansion rate of the two
materials is not great enough to cause interface separation.
However, when the package reaches the glass-transition
temperature (Tg) of epoxy (typically 160-165·C), the ther·
mal expansion rate of the encapsulant increases sharply,
and the material undergoes a transition into a plastiC state.
The epoxy begins to expand at a rate three times or more
greater than the metal leadframe, causing a separation at
the interface.

TLlF/8766-5

al

I

100 110 120 130 140 150 160,170 180

Tg

T(OC)
TLlF/8766-26

FIGUREC

5-25

II

The basic component-placement systems available are
classified as:
(a) In-line placement

When this .happens during a conventional wave soldering
process using flux and acid cleaners, process residues and
even solder can. enter the cavity created by the separation
and become entrapped when the material cools. These
contaminants can eventually diffuse into the interior of the
package, especially in the presence of moisture. The result
is die contamination, excessive leakage, and even catastrophiC failure. Unfortunately, electrical tests performed immediately following soldering may not detect potential flaws.

-

Fixed placement stations
Boards indexed under head and respective components placed
(b) Sequential placement
-

Most soldering processes involve temperatures ranging up
to 260'C, which far exceeds the glass-transition temperature of epoxy. Clearly, circuit boards containing SMD packages require tighter process controls than those used for
boards populated solely by DIPs.

Either a X-V moving table system or a 8, X-V moving
pickup system used

-Individual components picked and placed onto boards
(c) Simultaneous placement
- Multiple pickup heads
- Whole array of components placed onto the PCB at
the same time

Figure D is a summary of accelerated bias moisture test
performance on the 30V bipolar process.
Group 1 - Standard DIP package
Group 2 - SO packages vapor-phase reflow soldered on
PC boards
Group 3-6 SO packages wave soldered on PC boards
Group 3 - dwell time 2 seconds
4 - dwell time 4 seconds
5 - dwell time 6 seconds
6 - dwell time 10 seconds

(d) Sequential/simultaneous placement
- X-V moving table, multiple pickup heads system
- Components placed on PCB by successive or simUltaneous actuation of pickup heads
The SO package is treated almost the same as surfacemount, passive components requiring correct orientation in
placement on the board.
Pick and Place Action

66(10 SEC)

'5(6 SEC)
#4(4 SEC)

o

2000

..aoo

6000

TEST nME (HRS)
TUF/B766-7

FIGURED
It is clear based on the data presented that SO packages
soldered onto PC boards with the vapor phase reflow process have the best long term bias moisture performance
and this is comparable to the performance of standard DIP
packages. The key advantage of reflow soldering methods
is the clean environment that minimized the potential for
contamination of surface mounted packages, and is preferred for the surface-mount process.

TUF/8786-B

BAKE
This is recommended, despite claims made by some solder
paste suppliers that this step be omitted.
The functions of this step are:

When wave soldering is used to surface mount components
on the board, the dwell time of the component under molten
solder should be no more than 4 seconds, preferrably under
2 seconds in order to prevent damage to the component.
Non-Halide, or (organic acid) fluxes are highly recommended.

• Holds down the solder globules during subsequent reflow
soldering process and prevents expulsion of small solder
balls.
• Acts as an adhesive to hold the components in place during handling between placement to reflow soldering.
• Holdscomponents in position when a double-sided surface-mounted board is held upside down going into a vapor-phase reflow soldering operation.

PICK AND PLACE
The choice of automatic (all generally programmable) pickand-place machines to handle surface mounting has grown
considerably, and their selection is based on individual
needs and degree of sophistication.

• Removes solvents which might otherwise contaminate
other equipment.
• Initiates activator cleaning of surfaces to be soldered.
• Prevents moisture absorption.

5-26

.

~-------------------------------------------------------------------.~

The process is moreover very simple. The usual schedule is
about 20 minutes in a 65·C-95·C (dependent on solvent
system of solder paste) oven with adequate venting. Longer
bake time is not recommended due to the following reasons:

z

VAPOR-PHASE REFLOW SOLDERING
Currently the most popular and consistent method, vaporphase soldering utilizes a fluoroinert fluid with excellent
heat-transfer properties to heat up components until the solder paste rellows. The maximum temperature is limited by
the vapor temperature of the fluid.

• The flux will degrade and affect the characteristics of the
paste.

The commonly used fluids (supplied by 3M Corp) are:

• Solder globules will begin to oxidize and cause solderability problems.

• FC-70, 215·C vapor (most applications) or FX-38

• The paste will creep and after reflow, may leave behind
residues between traces which are difficult to remove and
vulnerable to electro-migration problems.

HTC, Concord, CA, manufactures equipment that utilizes
this technique, with two options:

REFLOW SOLDERING

• Batch systems, where boards are lowered in a basket and
subjected to the vapor from a tank of boiling fluid.

• FC-71 , 253·C vapor (low-lead or tin-plate)

There are various methods for reflowing the solder paste,
namely:

• In-line conveyorized systems, where boards are placed
onto a continuous belt which transports them into a concealed tank where they are subjected to an environment
of hot vapor.

• Hot air rellow
• Infrared heating (furnaces)

Dwell time in the vapor is generally on the order of 15-30
seconds (depending on the mass of the boards and the
loading density of boards on the belt).

• Convectional oven heating
• Vapor-phase reflow soldering
• Laser soldering

Vapor-Phase Profile

For SO applications, hot air reflow/infrared furnace may be
used for low-volume production or prototype work, but vapor-phase soldering rellow is more efficient for consistency
and speed. Oven heating is not recommended because of
"hot spots" in the oven and uneven melting may result. Laser soldering is more for specialized applications and requires a great amount of investment.

RECOMMENDED

R (1!I20 DEG C/sec )

HOT GAS REFLOW/INFRARED HEATING
A hand-held or table-mount air blower (with appropriate orifice mask) can be used.
The boards are preheated to about 1OO·C and then subjected to an air jet at about 260·C. This is a slow process and
results may be inconsistent due to various heat-sink properties of passive components.

o

20 40 60

eo 100 120 140 160 160
TIME
TL/F/87611-28

INFRARED REFLOW SOLDERING

In-Line Conveyorlzed Vapor-Phase Soldering

Use of an infrared furnace is currently the most popular
method to automate mass reflow, the heating is promoted
by use of IR lamps or panels. Early objections to this method were that certain materials may heat up at different rates
under IR radiation and could result in damage to those components (usually sockets and connectors). This has been
minimized by using far-infrared (non-focused) systems and
convected air.
Infrared Profile

CONDENSATION

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TL/F/8766-9

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The question of thermal shock is asked frequently because
of the relatively sharp increase in component temperature
from room temperature to 215·C. SO packages mounted on
representative boards have been tested and have shown
little effect on the integrity of the packages. Various packages, such as cerdips, metal cans and TO-5 cans with glass
seals, have also been tested.

TIME
TLlF/876l1-27

5-27

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Vapor-Phase Furnace

Batch-Fed Production Vapor-Pllase Soldering Unit

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SECONOARY

PRIMARY

TLlF/B766-11

TLlF/B766-10

Solder Joints on a SO-14 Package on PCB

Solder Joints on a SO-14 Package on PCB·

TL/F/B766-12

5-28

common and well-tried method. The paste is forced through
the screen by a V-shaped plastic squeegee in a sweeping
manner onto the board placed beneath the screen.

PRINTED CIRCUIT BOARD
The SO package is molded out of clean, thermoset plastic
compound and has no particular compatibility problems with
most printed circuit board substrates.

The setup for SO packages has no special requirement
from that required by other surface-mounted, passive components. Recommended working specifications are:
• Use stainless-steel, wire-mesh screens, # 80 or # 120,
wire diameter 2.6 mils. Rule of thumb: mesh opening
should be approximately 2.5-5 times larger than the average particle size of paste material.

The package can be reliably mounted onto substrates such
as:
o G 10 or FR4 glass/resin
o FRS glass/resin systems for high-temperature

applications
o Polymide boards, also high-temperature
o

• Use squeegee of Durometer 70.
• Experimentation with squeegee travel speed is recommended, if available on machine used.

applications
Ceramic substrates

General requirements for printed circuit boards are:

• Use solder paste of mesh 200-325.

o Mounting pads should be solder-plated whenever

• Emulsion thickness of 0.005" usually used to achieve a
solder paste thickness (wet) of about 0.008" typical.

applicable.
o Solder masks are commonly used to prevent solder bridg-

• Mesh pattern should be 90 degrees, square grid.

ing of fine lines during soldering.
The mask also protects circuits from processing chemical
contamination and corrosion.

• Snap-off height of screen should not exceed
damage to screens and minimize distortion.

SOLDER PASTE
Selection of solder paste tends to be confusing, due to numerous formulations available from various manufacturers.
In general, the following guidelines are sufficient to qualify a
particular paste for production:
• Particle sizes (see following photographs). Mesh 325 (approximately 45 microns) should be used for general purposes, while larger (solder globules) particles are preferred for leadless components (LCC). The larger particles
can easily be used for SO packages.

If coated over pre-tinned traces, residues may accumulate
at the mask/trace interface during subsequent reflow,
leading to possible reliability failures.
Recommended application of solder resist on bare, clean
traces prior to coating exposed areas with solder.
General requirements for solder mask:
-

Good pattern resolution.

-

Complete coverage of circuit lines and resistance to
flaking during soldering.

- Adhesior: should be excellent on substrate material to
keep off moisture and chemicals.
-

Va" , to avoid

• Uniform particle distribution. Solder globules should be
spherical in shape with uniform diameters and minimum
amount of elongation (visual under 100/200 x magnification). Uneven distribution causes uneven melting and subsequent expulsion of smaller solder balls away from their
proper sites.

Compatible with soldering and cleaning requirements.

SOLDER PASTE SCREEN PRINTING

With the initial choice of printed circuit lithographic deSign
and substrate material, the first step in surface mounting is
the application of solder paste.

• Composition, generally 60/40 or 63/37 Sn/Pb. Use 62/36
Sn/Pb with 2% Ag in the presence of Au on the soldering
area. This formulation reduces problems of metal leaching
from soldering pads.

The typical lithographic "footprints" for SO packages are
illustrated below. Note that the 0.050" lead center-center
spacing is not easily managed by commercially-available air
pressure, hand-held dispensers.
Using a stainless-steel, wire-mesh screen stencilled with an
emulsion image of the substrate pads is by far the most

• RMA flux system usually used.
• Use paste with aproximately 88-90% solids.

II
5-29

o ,-----------------------------------------------------------------------------,

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zIII(

RECOMMENDED SOLDER PADS FOR SO PACKAGES

•••• _\
L•••• !~

SO-8, SO-14, SO-16

.

So-16L, SO-20

0.045"·:t 0.005"

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0.245"

0.160"

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0.030" :to ..005"

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TL/F/8766-14

SOT-23
0.030" :to.005"1

0.030"

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TL/F/8766-15

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0.060"
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TL/F/8766-16

Comparison of Particle Size/Shape of Various Solder Pastes
200 X Alpha (62/36/2)

200 X Kester (63/37)

TL/F/8766-18

TL/F/8766-17

5-30

»
z

.

Comparison of Particle Size/Shape of 'Varlou~ SOlder Pastes (Continued)

~

Solder Paste Screen on Pads

U1

,200 x Fry Metal (63/37)

o

TL/F/B766-20

TL/F/B766-19

200 ESL (83/37)

TL/F/B766-21

Hot-Air Rework Machine

CLEANING
The most critical process in surface mounting SO packages
is in the cleaning cycle. The package is mounted very close
to the surface of the substrate and has a tendency to collect
residue left behind after reflow soldering.
Important considerations in cleaning are:
• Time between soldering and cleaning to be as short as
possible. Residue should not be allowed to solidify on the
substrate for long periods of time, making it difficult to
dislodge.
• A low surface tension solvent (high penetration) ~hould be
employed. CFC solvents are being phased out as they are
hazardous to the environment. Other approaches to
cleaning are commercially available and should be investigated on an individual basis considering local and government environmental rules.

TLlF/8766-23

lead tips or, if necessary, solder paste can be dispensed
onto the pads using a varimeter. After being placed into
pOSition, the solder is reflowed by a hot-air jet or even a
standard soldering iron.

Prelete or 1,1,1-Trichloroethane
Kester 5120/5121

WAVE SOLDERING

• A defluxer system which allows the workpiece to be subjected to a solvent vapor, followed by a rinse in pure solvent and a high-pressure spray lance are the basic requirments for low-volume production.

In a case where lead insertions are made on the same
board as surface-mounted components, there is a need to
include a wave-soldering operation in the process flow.
Two options are used:

• For volume production, a conveyorized, multiple hot solvent spray/jet system is recommended.

• Surface mounted components are placed and vapor
phase reflowed before auto-insertion of remaining components. The board is carried over a standard wave-solder
system and the underside of the board (only lead-inserted
leads) soldered.

• Rosin, being a natural occurring material, is not readily
soluble in solvents, and has long been a stumbling block
to the cleaning process. In recent developments, synthetic flux (SA flux), which is readily soluble in Freon TMS '
solvent, has been developed. This should be explored
where permissible.

• Surface-mounted components are placed in position, but
no solder paste is used. Instead, a drop of adhesive about
5 mils maximum in height with diameter not exceeding
25% width of the package is used to hold down the package. The adhesive is cured and then proceeded to autoinsertion on the reverse side of the board (surface-mounted side faCing down). The assembly is then passed over a
"dual wave" soldering system. Note that the surfacemounted components are immersed into the molten solder.
Lead trimming will pose a problem after soldering in the
latter case, unless the leads of the insertion components
are pre-trimmed or the board specially designed to localize
certain areas for easy access to the trim blade.
The controls required for wave soldering ·are:

The dangers of an inadequate cleaning cycle are:
• Ion contamination, where ionic residue left on boards
would cause corrosion to metallic compol)ents, affecting
the performance of the board.
• Electro-migration, where ionic residue and moisture present on electrically-biased boards would cause dentritic
growth between close spacing traces on t~e substrate,
resulting in failures (shorts).

REWORK
Should there be a need to replace a component or re-align
a previously disturbed component, a hot air system with appropriate orifice masking to protect surrounding components may be used.
When rework is necessary In the field, specially-designed
tweezers that thermally heat the component may be used to
remove it from its site. The replacement can be fluxed at the

• Solder temperature to be 240-260·C. The dwell time of
components under molten solder to be short (preferably
kept under 2 seconds), to prevent damage to most components and semiconductor devices.
• RMA (Rosin Mildly Activated) flux or more aggressive OA
(Organic Acid) flux are applied by either dipping or foam
fluxing on boards prior to preheat and soldering. Cleaning
procedures are also more difficult (aqueous, when OA flux
is used), as the entire board has been treated by flux (unlike solder paste, which is more or less localized). Nonhalide OA fluxes are highly recommended.

Hot-Air Solder Rework Station
MASeK

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RETRACT POSITION

- - --c:------.
...
,

./

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--

• Preheating of boards is essential to reduce thermal shock
on components. Board should reach a temperature of
about 100·C just before entering the solder wave.

HEAT SHIELD

• Due to the closer lead spacings (0.050· vs 0.100" for
dual-in-llne packages), bridging of traces by solder could
occur. The reduced clearance between packages also
causes "shadowing" of some areas, resulting in poor solder coverage. This Is minimized by dual-wave solder systems.

HOT AIRTLlF/8788-22

5-32

.

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Mixed Surface Mount and Lead Insertion

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(b) Opposite Sides

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PREHEAT

SOLDER FLOW
TL/F/B766-24

A typical dual-wave system is illustrated below, showing the
various stages employed. The first wave typically is in turbulence and given a transverse motion (across the motion of
the board). This covers areas where "shadowing" occurs. A
second wave (usually a broad wave) then proceeds to perform the standard soldering. The departing edge from the
solder is such to reduce "icicles," and is still further reduced
by an air knife placed close to the final soldering step. This
air knife will blow off excess solder (still in the fluid stage)
which would otherwise cause shorts (bridging) and solder
bumps.

Dual Wave

AQUEOUS CLEANING
• For volume production, a conveyorized system is often
used with a heated reCirculating spray wash (water temperature t30·C), a final spray rinse (water temperature
45-55·C), and a hot (t20·C) air/air-knife drying section.
• For low-volume production, the above cleaning can be
done manually, using several water rinses/tanks. Fastdrying solvents, like alcohols that are miscible with water,
are sometimes used to help the drying process.
• Neutralizing agents which will react with the corrosive materials in the flux and produce material readily soluble in
water may be used; the choice depends on the type of flux
used.

TUF/B766-25

CONFORMAL COATING
Conformal coating is recommended for high-reliability PCBs
to provide insulation resistance, as well as protection
against contamination and degradation by moisture.
Requirements:

• Final rinse water should be free from chemicals which are
Introduced to maintain the biological purity of the water.
These materials, mostly chlorides, are detrimental to the
assemblies cleaned because they introduce a fresh
amount of ionizable material.

• Complete coating over components and solder joints.
• Thixotropic material which will not flow under the packages or fill voids, otherwise will introduce stress on solder
jOints on expansion.
• Compatibility and possess excellent adhesion with PCB
material/components.
• Silicones are recommended where permissible in
application.

5-33

II

~r-----------------------------------------------------------------~

'T

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cc

SMD Lab Support
Techniques-Develop techniques for handling different
materials and processes in surface mounting.
Equipment-In conjunction with equipment manufacturers,
develop customized equipments to handle high density,
new technology packages developed by National.
In-House Expertise-Availability of' in-house expertise on
semiconductor research/development to assist users on
packaging queries.

FUNCTIONS

Demonstration-Introduce first-time users to surfacemounting processes.
Service-Investigate problems experienced by users on
surface mounting.
Reliability Builds-Assemble surface-mounted units for reliability data acquisition.

5-34

r-----------------------------------------------------------------------------, r

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Land Pattern Recommendations

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The following land pattern recommendations are provided as guidelines for board layout and assembly purposes.
These recommendations cover the following National Semiconductor packages: PLCC, PQFP, SOP, SSOP and TSOP.
For SOT·23 (5·Lead) and TO·263 (3· or 5·Lead) packages, refer to land patterns shown in the Physical Dimensions for MA05A
and TS3B or TS5B packages, respectively.

Plastic Leaded Chip Carriers (PLCC)

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(mm)
(mm)
(mm)
(mm)
(mm)
(mm)
(mm)
(mm)
(mm)
8.89

8.89

20

10.03

10.03

0.53

1.27

6.73

6.73

10.80

10.80

0.63

11.43 11.43

28

12.57

12.57

0.53

1.27

9.27

9.27

13.34

13.34

0.63

11.43 14.05

32

12.57

15.11

0.53

1.27

9.27

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13.34

16.00

0.63

16.51 16.51

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17.65

17.65

0.53

1.27

14.35

14.35

18.42

18.42

0.63

19.05 19.05

52

20.19

20.19

0.53

1.27

16.89

16.89

20.96

20.96

0.63

24.13 24.13

68

25.27

25.27

0.53

1.27

21.97

21.97

26.04

26.04

0.63

29.21 29.21

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30.35

30.35

0.53

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27.05

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10.53

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0.38

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9.08

9.08

15.17

15.17

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14.00

14.00

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11.48

11.48

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18.50

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16

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20

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24

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0.025

0.145

0.281

0.014

0.300

48

0.340

0.420

0.012

0.025

0.300

0.460

0.Q16

0.300

56

0.340

0.420

0.012

0.025

0.300

0.460

0.Q16

II
5·37

!o
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EIAJ Small Outline, Shrink Small Outline, and Thin Small Outline Packages (SOP, SSOP and TSOP)

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Lead/Pad
Pitch
(mm)

Inner Pad
to Pad Edge

Outer Pad
to Pad Edge

(mm)

(mm)

X
Pad
Width
(mm)

to Shoulder

L
Lead Tip
to Tip

(mm)

(mm)

W
Lead
Width
(mm)

14

6.280

8.000

0,400

1.270

5.010

9.270

0.600

5.300

16

6.280

8.000

0.400

1.270

5.010

9.270

0.600

5.300

20

6.280

8.000

0,400

1.270

5.010

9.270

0.600

D

C
Shoulder.

Lead
Count
No.

Body
Size
(mm)

SOP TYPE II

5.300

SSOPTYPEII .

5.300

20

6.600.

8.100

. 0,400

0.650

5.584

9.116

0.451

5.300

24·

6.600

8.100

0.400

0.650

5.584

9.116

0.451

SSOPTYPEIII

7.500

1

40

1

8.900

1

10.500

1

0.350

1

0.650

1

19.000

1

20.200

1

'0.250

1

0.500

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7.884

1

11.516

1

0.452

17.984

1

21.216

1

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TSOPTYPEI

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5-38

1

Section 6
Appendicesl
Physical Dimensions

Section 6 Contents
Appendix A General Product Marking and Code Explanation .............................
Appendix B Device/Application Literature Cross-Reference. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix C Summary of Commercial Reliability Programs ...............................
Appendix D Military Aerospace Programs from National Semiconductor ...................
Appendix E Understanding Integrated Circuit Package Power Capabilities. . . . . . . . . . . . . . . . . .
Appendix F How to Get the Right Information from a Datasheet. . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix H Safe Operating Areas for Peripheral Drivers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Physical Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bookshelf
Distributors

6-2

6-3
6-4
6-10
6-11
6-21
6-26
6-30
6-38

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Appendix A
General Product Marking & Code Explanation

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GlasslMetal DIP
Ceramic Leadless Chip Carrier (LCG)
GlasslMetal Flat Pak (%" x %")
12 Lead TO-8 Metal Can (M/C)
Multi-Lead Metal Can (M/C)
4 Lead MIC (T0-5) } Shipped with
4 Lead MIC (T0-46)
Thermal Shield
Lo-Temp Ceramic DIP
8 Lead Ceramic DIP ("MiniDIP")
14 Lead Ceramic DIP (-14 used onlywheri
product is also available in -8 pkg),
K
TO-3 MIC in Steel, except LM309K
which is shipped in Aluminum
TO-3 MIC (Aluminum)
KC
KSteel TO-3 MIC (Steel)
M
Small Outline Package
M3
3-Lead Small Outline Package
M5
5-Lead Small Outline Package
N
Molded DIP (EPOXY B)
N-Ol
Molded DIP (Epoxy B) with Staggered Leads
8 Lead Molded DIP (Epoxy B) ("Mini-DIP")
N-8
14 Lead Molded DIP (Epoxy B)
N-14
(-14 used only when product is also
available in -8 pkg),
P
3 Lead TO-202 Power Pkg
Q
Cerdip with UV Window
3,5,11, & 15 Lead TO-263 Surf. Mt. Power Pkg
S
T
3,5,11,15 & 23 Lead TO-220 PWR Pkg (Epoxy B)
Multi-lead Plastic Chip Carrier (PCG)
V
W
Lo-Temp Ceramic Flat Pak
WM
Wide Body Small Outline Package
D
E
F
G
H
H-05
H-46
J
J-8
J-14

Package Type (See Right)
'

Del(ice Number (Generic Type)
and Suffix Letter (Optional)
A or B: Improved
Electrical
Specification
C, I, E or M: Temperature
Range
Device Family (See Below)

Device Family
ADC
AF
AH
DAC
DM
HS
LF
LH
LM
'LMC
LMD
LP
LPC
MF
LMF

it

Package Type

R""bm, (Refer
Prog~to Appendix
(Opt",.,G)

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CD
::::II
CD

Data Conversion
Active Filter
Analog Switch (Hybrid)
Data Conversion
Digital (Monolithic)
Hybrid
Linear (BI-FETTM)
Linear (Hybrid)
Linear (Monolithic)
Linear CMOS '
LinearDMOS
Linear (Low Power)
Linear CMOS (Low Power)
Linear (Monolithic Filter)
Linear Monolithic Filter

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DATE CODE
1ST DIGIT - CALENDAR YEAR
2ND DIGIT - 6-WEEK PER10D
IN CALENDAR YEAR
3RD &: 4TH D1GITS - WAFER LOT CODE

DATE CODE
NON-MILITARY
2ND DIGIT - CALENDAR YEAR
JRD UTH DIGITS - CALENDAR WORK WEEN
MILITARY - 883& MJ8510
1ST & 2ND 'DIGITS - CALENDAR YEAR
JRD& ~TH DIGITS - CALENDAR WORK WEEN
(EKAMPLE: 9201'; 1ST WEEK'OF 1992)

INDICATES PLANT
OF MANUFACTURE

MILITARY ONLY

ESD
INDICATES PLANT
OF MANUFACTURE

(ELECTROSTATIC DISCHARGE)
SENSITIVITY INDICATOR

LOGO
PART NUMBER
PIN 1 ORIENTATION

WAFER LOT
CODE
--......::...,:::,...
PART NUMBER

TUXX/0027 -3
TL/XX/0027 -2

PIN 1 ORIENTATION

6-3

•

~National

Semiconductor

Appendix B
Devicel Application Literature Cross-Reference
Application Literature

Device Number

ADCXXXX ....•.•..........••••..••.......••.••••.••.....••••..•....• ,.•..•••.... , ........•.•............... AN-156
ADC80 ........................................•..........•..........•............•............••.•..••...AN-360
ADC0801 ......................•....•.••............••.••.•.. AN-233, AN-271, AN-274, AN-280, AN-281, AN-294, LB-53
ADC0802 ••... : ...........••.•.•.........•••.•..........•..•..........•..... AN-233, AN-274, AN-280, AN-281, LB-53
ADC0803 •..............................•..................................,.AN-233, AN-274, AN-280, AN-281, LB-53
ADC08031 ...........•.............••.•••.......•..•.•.•.....•••...•••........••.••...........•••........• AN-460
ADC0804 ................•••..............•.•........ AN-233, AN-274, AN-276, AN-280, AN-281, AN-301, AN-460, LB-53
ADC0805 .................•.. '..............•......•..••...........•••.••.... AN-233, AN-274, AN-280, AN-281, LB-53
ADC0808 ......•....•....•..•...•.........•.••.•.•.........•••.•••...•...••••••..........•.AN-247, AN-280, AN-28,1
ADC0809 •........................,.........•. , ........................................ : •...•...... AN-247, AN-280
ADC0816 •........................................... : ......•.........••.•......•.. AN-193, AN-247, AN-258, AN-280
ADC0817 ..............••......•...••..........•...••.••......•••.•••••.....•••••••.•••.... AN-247, AN-258, AN-280
ADC0820 .................•...•.........••..............••..•.......•..••.......•.......•.•.....••.....•.•AN-237
ADC0831 ...........................•.•.............••••........•••••.••........•••..•••........,.. AN-280,AN-281
ADC0832 ....•..•..•..••.•....• ,. •••.....•..••••.•.......•..•••...••..•..•.•.•••.•..•.•. : .••..••.•. AN-280,AN-281
ADC0833 ....•...........•.•.. : •......•....•••••••......•..••....•.......••••••....•....•••••..•.. AN-280,AN-281
ADC0834 .... , .............•...........•...................•......•..•......•.•...•...............AN-280,AN-281
ADC0838 .............•.•...........•.••........•..•.••.......•.•.•.••••........••••..••.......... AN-280, AN-281
ADC1001 ...••...........•..••...........••........•.....••.•.........•..••..........•...••AN-276, AN-280, AN-281
ADC1005 ...........................•......•........•.•.........•....•••...•.....•..•.••...•.....•.•••••..AN-280
ADC10461 ............................•••..•......•••........•..•....•••.........•.•.•••...•......••.•.•..AN-769
ADC10462 ........••.••...•....••••..•.....••...•.••......•••.••.••.......••••••.••.•....•....•.••••....•.AN-769
ADC10464 .•.............•.•.........................•..•.........•.......•.......•......•.•.•..........•.AN-769
ADC10662 .............••.•......•••.••••....•.•...•.•••...•.•...••.•••••.•.•.....•..•••...........•..••..AN-769
ADC10664 ......••.••.•.....•.•.••••.....••.•.••••.........••.••.....•..••.•..••.••........••.••••.•......AN-769
ADC12030 .•.•...................................... '..............•....................................... AN-929
ADC12032 .................•................•....................................•........•...............AN-929
ADC12034 ........•.••.....•.......••••............•.•.•........•.••..••..........•.•...............••.•..AN-929
ADC12038 .......•••..•....•.•..•••.•...•.•.•••.•..•..•..••.•••.•.......•.•••••..••........•..•.•••.....•.AN-929
ADC12H030 •.......... .' .......•...........•................................•............•..•.•..........•.AN-929
ADC12H032 ................•.........•••........••...•••.......•..•••..•.•....•........•..................AN-929
ADC12H034 ...........................•....................•................•.•...•..................•....AN-929
ADC12H038 .......•••.........•..••.....•....•..•••.•..........•••••.....•.••..•..••••••.......••.•••••.•. AN-929
ADC12L030 ..••..........•••••.........•••.................•............•••.•.............••••...•..•...•• AN-929
ADC12L032 ..................................•........•...........•...••..•...........•........•..........AN-929
ADC12L034 .........•.•.•..•........•••••........•••••••.......•..•••...••...•....••.•.•............••.•.. AN-929
ADC12L038 ...........................•............................•......................................AN-929
ADC1210 .......•......•..•. '..•......•...•.•.•.•.••.....•.•.•••.•.......••...•••.•..•........••••.•.•.•... AN-245
ADC12441 .••...........................•....•...............•....•.........••.......•..••..•...........•. AN-769
ADC12451 ...........................••..............•.••..........•••.•..•........ : .•...•.....•.......... AN-769
DACXXXX ...........•..•...........•.•••.....••••••....•.•...•..•••.••..•.•••..••.••...•........•..•••.•.. AN-156
DAC0800 ..................•••••.............••.•........••.•••......•...•..•..............•..•.•.........AN-693
DAC0830 ....••..•..•.......•••.•••.......•.•••..•..•....•.•.•••...•....•.•••••••.........•.....•.•.••.... AN-284
6-4

r-------------------------~--------------------------------------------.c

~

DevicelApplication Literature Cross-Reference (Continued)
Device Number

C:;"
Application Literature

DAC0831 ......•..•.....•.•........••••..•.•..•.•..•••.•••.•.••••.••.•..........•..••....••.•..•.•AN-271, AN-284
DAC0832 .................•................•.....•.•••..............•.•.........•.•.•..•..•..•...•AN-271, AN-284
DAC1006 •...•.....................................•.........•.•..........•........ AN-271, AN-275, AN-277, AN-284
DAC1007 .................................•.•...•••..•.•••...•......••.•••.••..•... AN-271, AN-275, AN-277, AN-284
DAC1008 .....................•.....•...•.......••.•..•..•...•.........•..•.••.••.. AN-271, AN-275, AN-277, AN-284
DAC1020 .........•...........•...•.•...•.........•••..•••.•....•..•.•..•. AN-263, AN-269, AN-2293, AN-294, AN-299
DAC1021 ..................••••.••....•............•..•..•..•............••...............................AN-269
DAC1022 •...............•..•.•.••.•..•............•..•..•..••.•.•.•.....•................................AN-269
DAC1208 ........•....•.•..............•....•..•.••.•.•••..•.••.•.••.•.•.....•..•...•.••.....•..•. AN-271, AN-284
DAC1209 ..•.....•....•.....................•........•.••...•.•..••.•..•.••.•.••.••............... AN-271, AN-284
DAC1210 •.••..•.••..•................. ; •..••......••.•••...••.•..••.•..•.••.••.......•..••.••.•.. AN-271, AN-284
DAC1218 .•..............•....•........•...•.........••.•..•..•..•..•.••.•.•..•.•.••.••.•..............•.. AN-293
DAC1219 ...........................•...............•...•........•..••.••..••.•••.••.•........•.....•.....AN-693
DAC1220 .....••.....•..••.•...•.....................•.......•.•..•.........•.....................AN-253, AN-269
DAC1221 ...•.............................•....•..•..•.••.••..•.••.••.••.•.•..•..•.••.••••.•..•........... AN-269
DAC1222 .. ." ..........•..........•...•............•.....•.....•....•...•.••..•..•..•......................AN-269
DAC1230 •..•.....•........•..•..•............•...•.•..•..•..•.••.••.••......•.....•..•.....•..•.......... AN-284
DAC1231 ..................•.......................•.............•.••..•.••••..•..•.••..•.........AN-271, AN-284
DAC1232 ....•..........•.....•.............. ; ...........•..•.•..•..•..•.••.•.....•.............•. AN-271, AN-284
DAC1280 ......•....•..••.•..•.••....•..•.••.•..•..•..••.•••••.••.•.•.....•........•.....•........AN-261, AN-263
DH0034 ... ~ .....•..........•............•............••.•..•..•.••.•..•.••••••••.•.•••..•.•..••.•.•.•..... AN-253
DH0035 ............•..•..•..•..........•..•..•..........••..•........•.•.....•.•...........................AN-49
INS8070 .•..•..............•.....•....•.....•.•...•....••.•..••••.••....•.••.••..••...•..••.••.......•.... AN-260
LF111 •...•..•......•............•....•..•..••.••.••.•••...••••••.•••.••••.••.•..•.••..••.••.•........•..•.. LB-39
LF155 ...... '..............•......................•...............••.•..••••...••........•..•..•..•AN-263, AN-447
LF198 .....•.••.....•...•...••....•..•..•..•.•...•.••.••.••.•..•.••.••.••••••.•.•..•..•.....•.....AN-245, AN-294
LF311 ...•...........................•......•.•...•.........•••.••..•..•.••.•..••.•••••...••.••...•...•.•. AN-301
LF347 .•......•........•.......•....••.••..•. AN-256, AN-262, AN-263, AN-265, AN-266, AN-301, AN-344. AN-447, LB-44
LF351 ..••..............•....••................. AN-242, AN-263, AN-266, AN-271, AN-275, AN-293, AN-447, Appendix C
LF351A ....•.......•........•.•...•.•...•..•.••.•..•..•..••..•••...•••..•..........•..•...................AN-240
LF351 B ..•..•...... : ......................•.•..•.....•..••.•.•..........••..•.••..•.•..•.............. Appendix D
LF353 ....•.....•........• AN-256, AN-258, AN-262, AN-263, AN-266, AN-271, AN-285, AN-293, AN-447, LB-44, Appendix D
LF356 •••••..•...............•..••.•..........••.•..••.•••• AN-253, AN-258, AN-260, AN-263, AN-266, AN-271, AN-272,
AN-275, AN-293, AN-294, AN-295, AN-301, AN-447, AN-693
LF357 ........•....................................•......•.....•......•..•..•..•..•....••..AN-263.AN-447, LB-42
LF398 •..•............••..•..........••....••.•.....•••••••.•••.•..•. AN-247, AN-258, AN-266, AN.294, AN-298, LB-45
LF411 •..••.•..•..•..•..•..••..........•••........••.•••••..•....••.•.••.••••.••.•• AN-294, AN-301, AN-344, AN-447
LF412 ............................................•.•...••..•......•......• AN-272, AN-299, AN-301, AN-344, AN-447
LF441 .•..... '•..•.....•..•.••....••........•....•..•..••.••.••••..••..•..•••.•..•..•.•............ AN-301,AN-447
LF13006 •.....•.....•..•...•....•••••.•..•.••.•.....•..•..••.••.•..•.••.•••••.•..•.•..•..••.••.••......... AN-344
LF13007 ....•........•.•...•........•......................•...•.••.•.•••.•..•..•..•.••....•..............AN-344
LF13331 .......•...................•.................•......•..•...•...•.........•.•.............•AN-294,AN-447
LH0002 ... , •..•..•..•.. " ... , .. , •.••..•..•.•••..•.•.•••••.••.•.•.•••.••.•••• AN-13, AN-227, AN-263, AN-272, AN-301
LH0024 .•..•......•••...•....•..••.••.•..•.....•.••.••..•..•..••••••••••.•.••...•.••..••••••••.••....•.... AN-253
LH0032 ..•..•..............•....•..............•.....•.•....•......•.•.•...•...........•.•.•••.••. AN-242, AN-253
LH0033 .....•..•.......•.................................•.....•...•....•.•...•.•.•..•..•.. AN.48, AN-227, AN-253
LH0063 •....................•..........•.....•..•..•...•.••.••.••.•.......•••.•...........•.........•..... AN-227
LH0070 .•..•..•..•.•..•......•.•....••.•••.......•..•.••..•.••••.•.•••.••••••.•..•.••.••.•..•..••..••...•. AN-301
LH0071 ....•...•.••.......•...•....••.•••...•.....••...••.••••••.••••..•..•.••.••.••.••.•..•.••....•...... AN-245
LH0094 ............•......•................•.•...•.....••..••....•...•..................•.................AN-301
LH0101 ..............•...............••••..•.•.....•.••••..•.•...•.....•.••..•..•.........................AN-261
6-5

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Device!Application

Lite~ature Cross~Reference (Continued)

DevIce Number.

Application LIterature

LH1605 ............................. ,' .... . ,',' ........................... ,' ................... ,' ............. . AN-343
LH2424 ...................................................................................................
AN-867
.
.
.
.
LM10 ............. , ....................... . AN-211, AN-247, AN-258, AN-271, AN-288, AN-299, AN-300, AN-460, AN-693
LM11 ....................... '............................................... AN~241, AN-242, AN-260, AN-266, AN-271
LM12 .......... : ........ ; ' .." ...... .', .............. , ....... .' ......... , ........ .' ............ . AN-446,AN-693, AN-706,
LM 101 ..' ................................. .' ............. .' ................ AN-4, AN-13, AN-20, AN-24, LB-42, Appendix A
LM101A .................. AN-29, AN-30, AN-31, AN-79, AN-241 AN-711, LB-1, LB-2, LB-4, LB-8, LB-14, LB-16, LB-19, LB-28
LM102 ............ , ................... , .......................... .' ..... . AN-4, AN-13, AN-30, LB-1, LB-5, LB-6, LB-11
LM103 ................................... , .. .' ..... .'.' ....... .' .............. .' ....... , ................ . AN-110, LB-41
LM105 ..... ................................. .'.' ....... .' ..................... ,' ..... ,' ............. . AN-23,AN-110, LB-3
LM106 ............................. , .................... , ....... ,' ............... , .............. . AN-41, LB-6,LB-12
LM107 ........................ .' ...................................... .' .AN-20,AN~31, LB-1, LB-12, LB-19,AppendixA
LM108 ............................' ................. . AN-29, AN-30, AN-31 , AN-79, AN~211, AN-241, LB-14, LB-15, LB-21
LM1 08A ...................... '........................ '.................... '.................... AN-260, LB-15, LB-19
LM109 ................... , ....... , ....... , .... .' .................................................... . AN-42, LB-15
LM109A ................................... '.' ..................................................................... . LB-15
LM110 .................. ....... ,' ........... ,' .. ,' ............................................... ,',' ..... . LB-11, LB-42
LM111 ......... ,' . .' ................... . ,',' .. ,' ............................. .. AN:41,AN-103, LB-12, LB-16, LB-32, LB-39
LM112 ....................... ,' .. , ............................................. ,' ............................... LB-19.
LM113 .................................... ,' ............................... AN-56,AN-110, LB-21, LB-24, LB-28, LB-37
LM117 ........................................................................ . AN-178, AN-181, AN-182, LB·~6, LB-47
LM117HV .................. ,' ........ ,',' .. ,' .................. .'.,' ....................... ,' .. .' ........... . LB-46, LB-47
LM118 ................... .' .................. ,' ..... .' .......................... LB-17, LB-19, LB-21 , LB-23,AppendixA
LM119 .......................... , ....... , ..... , ......... ,' .................................... , .............. LB-23
LM120 ..... ..............................................................................,' ... ,' ....... ,' ..... AN~182.
LM121 .......................................................................... . AN-79, AN-1 04, AN-184, AN-260, LB-22
LM121A ................................. ...................................................................... . LB-32
LM122 .................................................. ,...... '.'." ..................... ,' .................. . AN-97, LB"38
LM125 ........................ .' .. :................. .' ............... .' ... , . .' ......................................... . AN-82
LM126, ................... ,' ................................................................................AN-82
LM129 ................................... .' ........................................ AN-173, AN-178, AN-262, AN-266
LM131 ............................... I • • • . • • • • • • • • • • . , • • • • • . • • • • • • • • • • • • • • • • . • • • • • • • • • • • • '.' .'.AN-210,AN-460, Appendix 0
LM131A .. .' ......... ,.......................... .' ..•• ,'., ....................................................... . AN-210
LM134 ............................. , ... , ................ ,' ............................................... LB-41,AN-460
LM135 ....................................................................... AN-225, AN-262, AN-292, AN-298, AN-460
LM137 .............. , ... ,. ................................................................................... . LB-46
LM137HV .............. I • • . • • • . • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • ,' • • • • • • • • • • • • • • • • • • • • • • • • • • • • LB-46
LM138 ............. ; .............. : .. "., ... ,'.',' .. ,' .............................................. ,' ............ . LB-46
LM139 ... ..... ,' .....................................................................' .. ,' .................... . AN-74
LM143 ....... " ........................... ,' ....... .' ... ,' ......... ,' ................................ . AN-127, AN-271
LM148 .......................................... .' ... ,' ......... , ...................... .' ............... .' .... AN-260
LM150 ........................................................................................................ LB-46
LM158 .....................................................................................................
AN· 116
.
. ' "
.
,
LM160 .....................................................................................................
AN-87
.
.
LM161 .................................................,' ............................................. . AN-87,AN-266
LM163 ..... ,' ....................................... ,' ...... ... ,' ............................................. . AN-295
LM194 ................................................................................................ . AN-222, LB-21
LM195 .......... : ........... , .......... ,.' ....... , .. .' .................................................... , .AN-110.
LM199 ............... .' ............ .' ........ .' ............................................. .' ........ AN-161,AN-260
LM199A ................................................................................................. . AN-161
LM211 ...........................................,' ....................... ,' ................................... . LB-39
6-6

cCD

<

Device!Application Literature Cross-Reference (Continued)

n"

Application Literature

Device Number

LM231 ........................................................•..••......•.......•........................AN-2l0
LM231A ..•................................•......•..........•............................................AN-2l0
LM235 ..................................•.................................................................AN-225
LM239 ..................•.................•.......................•........................................AN-74
LM258 ....................................................................................................AN-116
LM260 ............................................•...•.............•.........•............................AN-87
LM261 .................................... , ................................................................ AN-87
LM34 .....................................................................................................AN-460

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LM35 ...........................................................•....•..•.......•..............•..........AN-460

(")

LM301 A ........................................•..•.......................................AN-178, AN-18l , AN-222

o

LM308 ......................................•.......•..•.••....•...AN-88, AN-184, AN-272, LB-22, LB-28, Appendix D
LM308A ............................................................•...............................AN-225, LB-24
LM309 .............•.............•.....•.....•.•...•..•..•....•...............•................... AN-178, AN-182

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LM3ll ..................•.. AN-4l , AN-l 03, AN-260, AN-263, AN-288, AN-294, AN-295, AN-307, LB-12, LB-16, LB-18, LB-39

Cil

LM3l3 .............................•......................................................................AN-263

n

LM3l6 ................•.............•.. " ., .........•.•..•......... , .•.•.•..•....•........................ AN-258
LM3l7 ...............................................••...•................•................. AN-178, LB-35, LB-46
LM3l7H ....................................................................•............................... LB-47
LM3l8 .....................•......•......•...•......•.••.•...........•......•......................AN-299, LB-2l
LM3l9 ...•................................................................................ AN-828, AN-27l, AN-293
LM320 .................................................. , ...•.•....•...................................... AN-288
LM321 ..........................................•.......................•..........•....................... LB-24
LM324 .........................................••.. AN-88, AN-258, AN-274, AN-284, AN-30l, LB-44, AB-25, Appendix C
LM329 ................................•................................... AN-256, AN-263, AN-284, AN-295, AN-30l
LM329B .........................•..........•................•..•....•...........•........................ AN-225
LM330 ....................................................................................................AN-30l
LM331 ..•.............•.........•...•. AN-2l 0, AN-240, AN-265, AN-278, AN-285, AN-3ll, LB-45, Appendix C, Appendix D
LM331 A ...........................................................................••..........AN-2l 0, Appendix C
LM334 .......................................................•............................AN-242, AN-256, AN-284
LM335 .........................................•.....•..•...........•................•.••.AN-225, AN-263, AN-295
LM336 .....................................•. , .•...•...•...•.....•.•.. " .•.•.............. AN-202, AN-247, AN-258
LM337 .................................................•••..•...........•...........•....•........•........ LB-46
LM338 ............................•....•...•..................................•......•...•........... LB-49, LB-5l
LM339 ............. , .•........... " ..........•. " .•.. " . " •..•............................. AN-74, AN-245, AN-274
LM340 .............................••.............•...•.•.....•.•........................•........AN-l03, AN-182
LM340L. ..........................................•..........................•...•........................AN-256
LM342 ...............................................•.....................•. " ..• " ... , .................. AN-288
LM346 .........................................•.....•....•..•........................•...........•AN-202, LB-54
LM348 ......................................•.....•..••••..•..........•.•..........................AN-202, LB-42
LM349 ..................•...........................................••.•................................... LB-42
LM358 ...................................•.............AN-ll6, AN-247, AN-27l, AN-274, AN-284, AN-298, Appendix C
LM358A ...............................................................................................AppendixD
LM359 ............................•..........................•..•..•............................... AN-278, AB-24
LM360 ................•...........•.•...........•..•.....•.•..••••.........................................AN-87
LM361 ...........................•.......•.•...........................••..........................AN-87, AN-294
LM363 ..................................••....•.....••.•..•..••..................•........................AN-27l
LM380 .........................................•........................•..•...... " ........•...... AN-69, AN-146
LM385 ....................•.•.............................. AN-242, AN-256, AN-30l, AN-344, AN-460, AN-693, AN-777
LM386 ..............................•................•................................•..•................. LB-54
LM391 .................................•..•.....•....••.••.........•......................................AN-272
LM392 .................................•..•..•..•.•••••.••..•...•..•..............................AN-274,AN-286

6-7

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DevicelApplication Literaturi;; Cr.p$S~,Reference
.

. ~~;

Device Number

.

(Continued)

'

Application Literature

LM393 , ...............................................,............................ AN-271, AN-274, AN-293, AN-694
LM394 ..................................... ; ................ AN-262, AN-263, AN-271, AN-293, AN-299, AN-311, LB-52

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LM395 .............................................. AN-178, AN-181, AN-262, AN-263, AN-266, AN-301, AN-460, LB-28
LM399 ............................................. : .. : ................................................... AN-184
LM555 ................................ ;. ~: .•.. ; .. : .... ,' ......... " .................................... AN-694,AB-7
LM556 ., .............................•.. , . , ...... ',' ; ..............•..................•.•..............•....•AB-7
LM565 .............................................................................................AN-46,AN-146

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LM566 ....................................................................................................AN-146

~
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LM628 .............................................................................................AN-693, AN-706

o

LM604 .....................................................................................................AN-460
LM629 .............. '................................................... ; ............... ; .. AN-693, AN-694, AN·706
LM709 .. '................•........ '....•.......•...................................................•.•AN-24, AN-30

c.
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~

LM710, ..............................................................................................AN-41, LB-12

.~

LM741 ....................................' ....................... .' ............................ AN-79, LB-19, LB-22

o

LM833 ....................................................................................................AN-346

u

LM725 ................................................................................ : .................... LB-22

LM1036 ............................•............................•............•...............•............AN-390
LM1202 .....................................................................................................AN-867
LM1203 ...................................................................................................AN-861
LM1204 ...................................................................................................AN-934
LM1458 .............. '............................ : ........................................................ AN-116
LM1524 ................... '........................ : ............................... AN-272, AN-288, AN-292, AN-293
LM1558 ..........................................,......................................................... AN-116
LM1578A ....................................... '... :' ....... : '......................................•..•..... AB-30
LM1823 ............................................... , ................................................... AN-391
LM1830 ...........................................................•....................•...................AB-10
LM1865 ..................................... : .............................................................. AN-390
LM1886 ................................................ " .. : ...... , , . : ...................................... AN-402
LM1889 ............................................... , .................................................... AN-402
LM1894 ............................................... ,' ................................... AN-384, AN-386, AN-390
LM2419 ............................•................ ~ ..................................................... AN-861
LM2577 ................................................................... : ...................... AN-776, AN-777
LM2876 .•.............................•.•.............................................•....••.............AN-898
LM2889 ........................................ '... : . : ............................................. AN-391, AN-402
LM2907 ............................................................ : ...................................... AN-162
LM2917 .....................................................................................•.............AN-162
LM2931 ........................................................................................•...........AB-12
LM2931CT ................................................................. : ............................... AB-11
I

LM3045 ........................................... '................................•....................... AN-286
LM3046 ......................................... '.................................................. AN-146, AN-299
LM3089 ....•.................... , . " ..........• : •... :., ................................................... AN-147
LM3524 ....... '.................... " ............. , .' .. ',' ........................... AN-272, AN-288, AN-292, AN-293
LM3525A .......................... : ...... " ...... : ........ : ............................................... AN-694
LM3578A .................................... : .............................................................'AB-30
LM3875 ............•.................................. ; ................................................... AN-898
LM3676 ................................•....•... : .........•......................•........................ AN-696
LM3666 ...................................... ; .............................................................. AN-896
LM3900 ............................ ~ .................................. AN· 72, AN-263, AN-274, AN-276, LB-20, AB-24
LM3909 .................................................' .....•.. :.......................................... AN-154
LM3914 ...................................................................................... AN-460, LB-46, AB-25
LM3915 .................................. ;~.,' .............................................................. AN-366
LM3999 ................................. .-.';.; ........ '.; ...... : ............................................ AN-161

DevicelApplication Literature Cross-Reference (Continued)
Device Number

Application Literature

LM4250 ............................................................................................ . AN-88, LB-34
LMB181 .......................................................................................... . AN-813,AN-840
LM7800 . ..................................................................................................AN-178
LM12454 ................................................................................. . AN-90B, AN-947, AN-949
LM12458 " ...................... " ........................' ................................ AN-90S, AN-947, AN-949
LM12H454 ................................................................................AN-90S, AN-947, AN-949
LM12H458 ............................................................................... . AN-90B, AN-947, AN-949
LM12L458 . ................................................................................AN-90S, AN-947, AN-949
LM18293 ................................................................................................ . AN-70B
LM78L12 ................................................................................................ . AN-14S
LM78S40 ................................................................................................ . AN-711
LMC555 ......................................................................................... . AN-4BO,AN-828
LMCBBO ................................................................................................. . AN-85B
LMC835 ................................................................................................. . AN-435
LMCB044 ................................................................................................ . AN-85S
LMCS062 ................................................................................................ . AN-856
LMC6082 ................................................................................................ . AN-856
LMC6484 .................................................................................................AN-856
LMD18200 ........................................................................................AN-694, AN-828
LMF40 .................................................. : ................................. ................. . AN-779
LMF60 ....................................................................................................AN-779
LMF90 ....................................................................................................AN-779
LMF100 ................................................................................................. . AN-779
LMF380 ................................................................................................. . AN-779
LMF390 .......... ; ...................................................................................... . AN-779
LP324 ..............................................' ...................................................... AN-284
LP395 ..............................................'..................................................... . AN-460
LPC660 ...................................................................................................AN-856
MF4 ........................................ .............................................................. . AN-779
MF5 ..................... ................................................................................ . AN-779
MF6 ......................................................................................................AN-779
MF8 ......................................................................................................AN-779
MF10 .............................................................................................AN-307,AN-779
MM2716 .................................................................................................. . LB-54

MM54104 ..................•...........•..•....•....................•........•............. . AN-252, AN-287, LB-54
MM57110 .................................................................................................AN-382
MM74COO ..................................................................................................AN-88
MM74C02 ................................................... ............................................... . AN-88
MM74C04 ..................................................................................................AN-88
MM74C948 ................................................................................................AN-193
MM74HC86 ...................................................................................... . AN-861,AN-867
MM74LS138 ................................................................................................ LB-54
MM53200 ................................................................................................ . AN-290
2N4339 ................................................................................................... . AN-32

6-9

I!fINational Semiconductor

Appendix C
Summary of Commercial.Reliability Programs
P + Product Enhancement
The P+ product enhancement program involves ·dynamic·
tests that screen out assembly related and silicon defects
that can lead to infant mortality and/or reduce the surviva-

bility of the device under high stress conditions. This program includes but is not limited to the following power
devices:

Package Types
Device
LM12
LM109/~09

LM117/317
LM117HV/317HV
LM120/320
LM123/323
LM133/333
LM1371337
LM137HVl337HV
LM138/338
LM140/340
LM145/345
LM150/350
LM195/395

TO·3
KSTEEL

X
X
X
X
X
X
X
X
X
X
X
X
X
X

TO·39
(H)

X
X
X
X

X
X

TO·220
(T)

DIP
(N)

SO
(M)

X

TO·263
(S)

X

X
X
X
X
X

X

LM2930/2935/2984
LM2937
LM2940/2941
. LM2990/2991
LM2575/2575HV
LM2576
LM2577
LMD18200/18201

6·10

X
X
X
X
X
X
X
X
X
X

X

X

X

X

X
X
X
X
X
X
X

»

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Appendix D
Military Aerospace Programs
from National Semiconductor

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This appendix Is Intended to provide a brief overview of
military products available from National Semiconductor, The process flows and catagorles shown below are
for general reference only, For further information and
availability, please contact the Customer Response
Center at 1-800-272-9959, MllltarylAerospace Marketing
group or your local sales office,

Process Flows
(Integrated Circuits)

CCI

JANB

OML products processed to
MIL-I-38S3S Level B or 0 for
Military applications.

o
3
z

SMD

OML products processed to a
Standard Microcircuit Drawing with
Table I Electricals controlled by
DESC.

883

MLP

6-11

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o

OML products processed to
MIL-I-38S3S Level S or V for Space
level applications.

JANS

National Semiconductor's Military/Aerospace Program is
founded on dedication to excellence. National offers complete support across the broadest range of products with
the widest selection of qualification levels and screening
flows. These flows include:

CD

Description

OML products processed to
MIL-STD-883 Level B for Military
applications.
Products processed on the
Monitored Line (Program)
developed by the Air Force for
Space level applications.

-MIL

Similar to MIL-STD-883 with
exceptions noted on the Certificate
of Conformance.

MSP

Military Screening Products for
initial release of advanced
products.

MCP

Commercial products processed in
a military assembly. Electrical
testing performed at 2SD C, plus
minimum and maximum operating
temperature to commercial limits.

MCR

Commercial products processed in
a military assembly. Electrical
testing performed at 2SD C to
commercial limits

MRP

Military Ruggedized Plastic
products processed to avionics
requirements.

MRR

Commercial Ruggedized plastic
product processed in a commercial
assembly with electrical testing at
2SD C.

MPC

Commercial plastic products
processed in a commercial
assembly with electrical testing at
2SD C.

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TABLE I. JAN S or B Part Marking
~~~O/X~X_XXYYY

[

TABLE I·A. JAN Package Codes
JAN
Package
Designation

Lead Finish
A = Solder Dipped
B Tin Plato
C Gold Plato
X Any lead finish above
is accoptablo

=
=
=

A
B
C
D
E
F
G
H
I

Oovic. Packago
(soo Tablo II)
L--

-

Screening Levol
S or B
Device Number on
Slash She.t

Slash Shoet Numbor

' - - - - - - For radiation hard devices
this slash is roplaced by the

J
K
L

Radiation Hardness Assurance
Oosignator (M, 0, R, or H of

MIL-I-38535)
' - - - - - - NIL-M-3851 0

M
N

' - - - - - - - - J A N Profix
TL/XX/0030-1

P
Q

R
S
T

U
V
W
X

y
Z
2
3

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Microcircuit Industry Description

a.
§(.
C

14-pin %" x %" (Metal) Flatpak
14-pin 0/.." x %" (Metal) Flatpak
14-pin %" x %n Dual-ln.Line
14-pin %" x %" (Ceramic) Flatpak
16-pin %" x %'" Dual-In-Line
16-pin %" x %" (Metal or Ceramic) Flatpak
B-pin TO-99 Can or Header
10-pin %" x %" (Metal) Flatpak
1O-pin TO-1 00 Can or Header
24-pin Yz" x 1%" Dual-ln·Line
24-pin %" x %n Flatpak
24-pin %" x 1%" Dual-In-Line
12-pin TO-1 01 Can or Header
(Note 1)
8-pin %" x %" Dual-In-Line
40-pin 0/.6" x 21j,6" Dual-In-Line
20-pin %" x 11j,." Dual-In-Line
20-pin %" x Yz" Flatpak
(Note 1)
(Note 1)
18-pin %" x 10/.." Dual-In-Line
22-pin %" x 1 Ys" Dual-In-Line
(Note 1)
(Note 1)
(Note 1)
20-terminal 0.350" x 0.350" Chip Carrier
28-terminal 0.450" x 0.450" Chip Carrier

Note 1: These lellers are assigned to packages by individual detail specifi·
cations and may be assigned to different packages in different specifica·
tions.

6-13

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TABLE II. Standard Military Drawing
(SMD) Marking

t"'

TABLE II-A. SMD Package Codes
SMD
Package
Designation

5962-~02MXA

Package Code.
, (see Table IIA)

De~igna'tor

G

= hlIL-STD-883
B or Q = Class B
S or V = Class C
hi

i...----!-

14-pin Flatpak
14-pinCDIP
16-pinCDIP
16-pin Flatpak
B-pin TO-99 Can
10-pin (Metal) Flatpak
1O-pin to-100 Can
(Note 2)
(Note 2)
B-pinCDIP
20-pinLCC
20-Pin DIP,

C
D
E
F

no".

(Solder)

Class

Mlcroplrcult Industry Description

H
I

X

Device Number

y

Drawing' Number -

P
2

Vear of Issue

The "/" and "-" can,

R

be, replaced by RHA

designations
D =; 10 krad

Note 2: These leHers are assigned to packages by individual detail specifi.

R

tions.

cations and may be assigned to different packages in different specifics·

= 100 krad

rederal Sloc,k, Class
TLlXX/OO30-2

TABLE 111.100% Screening Requirements
ClassS

Screen

Method

ClassB
Reqmt

Method

Reqmt

1.

Wafer Lot Acceptance

5007

All Lots

2.

Nondestructive Bond Pull (Note 14)

2023

100%

3.

Internal Visual (Note 1)

2020, Condition A

100%

2010, Condition B

100%

4.

Stabilization Bake (Note 16)

100B, Condition C, Min
24 Hrs. Min

100%

1OOB, Condition C, Min
24 Hrs. Min

100%

5.

Temperature CyCling (Note 2)

1010, Condition C

100%

1010, Condition C

100%

6.

Constant Acceleration

2001, Condition E Min
y 1 Orientation Only

100%

2001, Condition E Min
Y 1 Orientation Only

100%

7.

Visual Inspection (Note 3)

B.

Particle Impact Noise Detection (PIND)

2010, Condition A (Note 4)

100%

9.

100%

100%

Serialization

(Note 5)

100%

10.

Interim (Pre-Burn-In) Electrical Parameters

Per Applicable Device
Specification (Note 13)

100%

Per Applicable Device
Specification (Note 6)

11.

Burn-In Test

1015
240 Hrs. @ 125°C Min
(Cond. F Not Allowed)

100%

1015
160 Hrs.

Per Applicable Device
Specification (Note 3)

100%

12.

Interim (Post Burn-In)
Electrical Parameters

6-14

100%
@

125°C Min

~
"'CI

TABLE 111.100% Screening Requirements (Continued)
ClassS

Screen
13.

Reverse Bias Burn-In (Note 7)

Method

Reqmt

1015; Test Condition A, C,
72 Hrs. @ 150·C Min
(Cond. F Not Allowed)

100%

100%

14.

Interim (Post-Bum-In) Electrical
Parameters

Per Applicable Device
Specification (Note 13)

15.

PDA Calculation

5% Parametric (Note 14),
3% Functional

16.

CD
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Co

ClassB
Method

Reqmt

)c.

?
~

AU Lots

Per Applicable Device
Specification
5% Parametric (Note 14)

1000/0
AU Lots

iir

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1:

a

til
"'C

Final Electrical Test (Note 15)
a) Static Tests
1) 25·C (Subgroup 1, Table I, 5005)
2) Max & Min Rated Operating Temp.
(Subgroups 2, 3, Table I, 5005)
b) Dynamic Tests or Functional Tests
1) 25·C (Subgroup 4 or 7)
2) Max and Min Rated Operating Temp.
(Subgroups 5 and 6 or 8, Table I,
5005)
c) SWitching Tests 25·C
(Subgroup 9, Table I, 5005)

Per Applicable Device
Specification

17.

Seal Fine, Gross

1014

1B.

Radiographic (Note 10)

2012 Two Views

100%

19.

Qualification or Quality Conformance
Inspection Test Sample Selection

(Note 11)

Samp.

20.

External Visual (Note 12)

2009

100%

~

Per Applicable Device
Specification
100%
100%

100%
100%

100%
100%

100%
100%

CD
"'D

a

c.a
Dl
3
til

-a
3

z

100%
100% .
(Note 8)

1014

100%

a
o·
::lI

100%
(Note 9)

en
CD

Samp.

o::lI

100%

Nota 2: For Class B devices, this test may be replaced with ther.mal shock Method lOt I, Test Condition A, minimum.
Nole 3: At the manufacturer's option, visual Inspeellon for catastrophic failures may be conducted after each of the thermal/mechanical screens, after the
sequence or after seal test. Calastrophlc failures are defined as missing leads, broken packages, or lids off.
Note 4: The PI NO test may be performed in any sequence after step 6 and prior to step 16. See MIL-I·38585 paragraph 40.8.3.
Note 5: Class S devices shall be serialized prior to interim electrical parameter measurements.
Note 6: When speCified, all devices shall be tested for those parameters requiring della calculations.
Note 7: Reverse bias bum-In is a requirement only when specified In the applicable device specification. The order of performing bum.in and reverse bias bum·in
may be inverted.
Nota 8: For Class S devices, the seal test may be performed In any sequence between step 16 and step 19, but Hshall be performed after all shearing and forming
operations on the terminals.
Note 9: For Class B devices, the fine and gross seal tests shall be performed separately or together in any sequence and order between step 6 and step 20 except
that they shall be performed after all shearing and forming operations on the terminals. When 100% seal screen cannot be performed after shearing and forming
(e.g., flatpaks and chip cerners) the seal screen shall be done 100% prior to these operations and a sample test (LTPO = 5) shall be performed on each inspection
lot following these operations. If the sample fails, 100% rescreening shall be required.
Note 10: The radiographic screen may be performed In any sequence after step 9.
Note 11: Samples shall be selected for testing in accordance with the specific device class and lot requirements of Method 5005.
Nota 12: External Visual shall be performed on the lot any time after step 19 and prior to shipment.
Note 13: Read and record is required at steps 10 and 12 only for those parameters for which post·bum·in della measurements
be read and recorded at step 14.

Note 16: May be performed at any time prior to step 10.

6-15

3

c:i"

(Note 11)

Note 1: Unless otherwise specified, at the manufacture~s option, test samples for Group B, bond strength (Method 5005) may be randomly selected prior to or
following internal visual (Method 5004), prior to sealing provided all other specification requirements are satisfied (e.g., bond strength requirements shall apply to
each inspection lo~ bond failures shall be counted even if the bond would have failed internal visual).

Nota 14: The POA shall apply to all subgroup 1 parameters at 25'C and all della parameters.
Nata 15: Only one view Is required for flat packages and leadless chip carriers with leads on all four sides.

!!!..

are specifi~d. All p~rameters shall

Co
C

S
....

Military Analog Products Available from National Semiconductor

D~lVlce

Package
Styles
(Note 1)

Description

,.

Process
Flows
(Note 2)

SMD/JAN
(Note 3)

HIGH PERFORMANCE AMPLIFIERS AND BUFFERS
LF147
LF155A
LF156
LF156A
LF157
LF157A
LF411M
LF412M
LF441M
LF442M
LF444M
LHOO02
LH0021
LH0024
LH0032
LH0041
LH0101

D,J
H
H

I:i
H
,H
H
H,J
H
H
0
H

K
H
G
G

K

LM10
LM101A
LM108A
LM118
LM124
LM124A
LM146
LM146
LM156A
LM156
LM611AM
LM613AM
LM614AM
LM709A
LM741
LM747

H
J,H,W
J,H,W
J,H
J,E,W
J,E,W
J
J, E
J,H
J,H
J
J, E
J
H,J,W
J,H,W
J,H

LM6116
LM6121
LM6125
LM6161
LM6162
LM6164
LM6165
LM6161AM
LM6182AM

J,E
H,J
H
J,E,W
J,E,W

Wide BW Quad JFET Op Amp
JFET Input Op Amp
JFET Input Op Amp
'JFET Input Op Amp
JFET Input Op Amp
JFET Input Op Amp
Low Offset, Low Drift JFET Input
Low Offset, Low Drift JFET Input-Dual
Low Power JFET Input
Low Power JFET Input-Dual
Low Power JFET Input-Quad

SMD/JAN
883
883
883
883
883
883/JAN
883/JAN
883
883
883

Buffer Amp
1.0 Amp Power Op Amp
High Slew Rate Op Amp
Ultra Fast FET-Input Op Amp
0.2 Amp Power Op Amp
PowerOpAmp

"-MIL"
"-MIL"

Super-Block™ Micropower Op Amp/Ref
General Purpose Op Amp
Precision Op Amp
.. ,
FastOpAmp
Low Power Quad Op Amp
Low Power Quad
Quad Programmable Op Amp
Quad 741 Op amp
Low Power Dual Op Amp
Low Power Dual Op Amp
Super-Block Op Amp/Reference
' Super-Block Dual Op Amp/Dual Comp/Ref
Super-Block Quad Op Amp/Ref
General Purpose Op Amp
General Purpose Op Amp
General Purpose Dual Op Amp

"_MIL"
"-MIL"

"_MIL"
"-MIL"
883/SMD
883/JAN
88~/JAN

883/JAN
883/JAN
883/JAN
683
663/JAN,
863/SMD
663/SMD
663/SMD
663/SMD
683/SMD
883/SMD
663/JAN
683/JAN

/11906

-

/11904
/11905

-

5962-87604
/10103
/10104
/10107
/11005
/11006

' /11001
5962-6771002
5962-6771001

7600701

110101
110102

J"E,W
J,E,W
J
J

VIP Dual Op Amp
VIP Buffer
VIP Buffer with Error Flag
VIP Op Amp (Unity Gain)
VIP Op Amp (Av > 2, - 1)
VIP Op Amp (Av > 5)
VIP Op Amp (Av > 25)
VIP Current Feedback Op Amp
VIP Current Feedback Dual Op Amp

663/SMD
683/SMD
683/SMD
663/SMD
863/SMD
663/SMD
663/SMD
683/SMD
883/sMD

5962-91565
5962-90612
5962-90815
5962-69621
5962-92165
5962-69624
5962-69625
5962-9061602
5962-9460301

LMC660AM
LMC662AM
LPC660AM
LPC662AM
LMC6462AM
LMC6464AM

J
J
J
J
J
J

Low Power CMOS Quad Op Amp
Low Power CMOS Duai' Op Amp
Micropower CMOS Quad Op Amp
Micropower CMOS Dual Op Amp
Rail to Rail CMOS Dual Op Amp
Rail to Rail CMOS Quad Op Amp

663/SMD
663/SMD
663/SMD
683/SMD
683/SMD
683/SMD

5962-9209301
5962-9209401
5962-9209302
5962-9209402
5962-9453401
5962-9453402

OP07

H

Precision Op Amp

663

-

6-16

»

'a
'a

Military Analog Products Available from National Semiconductor (Continued)

(1)

Device

Package
Styles
(Note 1)

Description

Process
Flows
(Note 2)

SMD/JAN
(Note 3)

COMPARATORS
LF111
LH2111
LM106
LM111
LM119
LM1S9
LM1S9A
LM160
LM161
LM19S
LM19SA
LM612AM
LM61 SAM

H
J,W
H,W
J,H,E,W
J,H,E,W
J,E,W
J,E,W
J,H
J,H,W
J,H
J,H
J
J, E

LM615AM
LM710A*
LM711A'
LM760

J
J,H,W
J,H,W
J,H

Voltage Comparator
Dual Voltage Comparator
Voltage Comparator
Voltage Comparator
High Speed Dual Comparator
Quad Comparator
Precision Quad Comparator
High Speed Differential Comparator
High Speed Differential Comparator
Dual Comparator
Dual Comparator
Dual-Channel Comparator/Reference
Super-Block Dual Comparator/
Dual Op Amp/ Adj Reference
Quad Comparator/Adjustable Reference
Voltage Comparator
Dual LM710
High Speed Differential Comparator

"-MIL"
88S/JAN
BBS/SMD
BBS/JAN
BBS/JAN
BBS/JAN
BBS/SMD
BBS/SMD
BBS/SMD
BBS
8BS/JAN
BBS/SMD
BBS/SMD

-

BBS
BBS/JAN
BBS/JAN
BBS/SMD

-

/10S05
BOOS701
/10S04
/10S06
/11201
5962-B77S9
B767401
5962-B7572

-/11202

5962-9S002
5962-9S00S

/10S01
110S02
5962-B7545

'Formerly manufactured by Fairchild Semiconductor as part numbers pA710 and pA711.

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if

~

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3

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3
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II)

0'
!!.
::I

LINEAR REGULATORS

(J)

Positive VOltage Regulators
LM105
LM109
LM109
LM117
LM117HV
LM117HV
LM12S
LM1SB
LM140-5.0
LM140-6.0
LM140-B.0
LM140-12
LM140-15
LM140-24
LM140A-5.0
LM140A-12
LM140A-15
LM140K-5.0
LM140K-12
LM140K-15
LM140LAH-5.0
LM140LAH-12
LM140LAH-15
LM150
LM2940-5.0
LM2940-8.0
LM2940-12
LM2940-15
LM2941
LM4S1
LM72S
LP2951
LP295SAM

::I

a..

H
H
K
H,E,K
H
K
K
K
H
H
H
H
H
H
K
K
K
K
K
K
H
H
H
K
K
K
K
K
K
H,K
H,J,E
H, E,J
J

(1)

Adjustable Voltage Regulator
5V Regulator, 10 = 20 mA
5V Regulator, 10 = 1A
Adjustable Regulator
Adjustable Regulator, 10 = 0.5A
Adjustable Regulator, 10 = 1.5A
SA Voltage Regulator
5A Adjustable Regulator
0.5A Fixed 5V Regulator
0.5A Fixed 6V Regulator
0.5A Fixed BV Regulator
0.5A Fixed 12V Regulator
0.5A Fixed 15V Regulator
0.5A Fixed 24V Regulator
1.0A Fixed 5V Regulator
1.0A Fixed 12V Regulator
1.0A Fixed 15V Regulator
1.0A Fixed 5V Regulator
1.0A Fixed 12V Regulator
1.0A Fixed 15V Regulator
100 mA Fixed 5V Regulator
100 mA Fixed 12V Regulator
100 mA Fixed 15V Regulator
SA Adjustable Power Regulator
5V Low Dropout Regulator
8V Low Dropout Regulator
12V Low Dropout Regulator
15V Low Dropout Regulator
Adjustable Low Dropout Regulator
Adjustable Shunt Regulator
Precision Adjustable Regulator
Adjustable Micropower LOO
250 mA Adj. Micropower LDO

6-17

BBS/SMD
BBS/JAN
BBS/JAN
BBS/JAN
BBS/SMD
BBS/SMD
BBS

....MIL"
BBS/JAN
BBS
BBS
BBS/JAN
BBS/JAN
BBS
BBS
BBS
BBS
BBS/JAN
BBS/JAN
B8S/JAN
BBS
8BS
BBS
BBS
BBS/SMD
BBS/SMD
B8S/SMD
B8S/SMD
BBS/SMD
BBS
BBS/JAN
BBS/SMD
BBS/SMD

5962-B95BB
/10701BXA
/10701BYA
/1170S,/11704
770S402XA
770S402YA

-

-/10702
-/1070S
/10704

---

/10706
/10707
/1070B

-

-

5962-B9587
5962-90BBS
5962-90BB4
5962-90B85
TBD

-

/10201
5962-SB705
5962-92SS601

3
o
::I
a..

(i'

c

...g

Military Analog Products Available from National Semiconductor (Continued)
Device

Package
Styles
(Note 1)

Description

Process
Flows
(Note 2)

SMD/JAN
(Note 3)

LINEAR REGULATORS (Continued)
Negative Voltllge Regulators
883/JAN
883
883/JAN
883/JAN

K
K
K

= -5V
= -8V
= -12V
= -15V
Fixed 1.0A Regulator, VOUT = - 5V
Fixed 1.0A Regulator, VOUT = -12V
Fixed 1.0A Regulator, VOUT = -15V

883/JAN
883/JAN
883/JAN

/11505
/11506
/11507

LM137A
LM137A
LM137
LM137HV
LM137HV

H
K
H,K
H
K

Precision Adjustable Regulator
Precision Adjustable Regulator
Adjustable Regulator
Adjustable (High Volta.ge) Regulator
Adjustable (High Voltage) Regulator

883/SMD
883/SMD
883/JAN
883/SMD
883/SMD

7703406XA
7703406YA

LM145-5.0
LM145-5.2

K
K

Negative 3 Amp Regulator
Negative 3 Amp Regulator

883/SMD
883

J,K
J,K
J,K
J,K
K
K
K
K
K
K
K

Simple Switcher™ Step-Down, VOUT = 5V
Simple Switcher Step-Down, VOUT = 12V
Simple Switcher Step-Down, VOUT = 15V
Simple Switcher Step-Down, Adj VOUT
Simple Switcher Step-Down, VOUT = 5V
Simple Switcher Step-Down, VOUT = 12V
Simple Switcher Step-Down, VOUT = 15V
Simple Switcher Step-Down, Adj VOUT
Simple Switcher Step-Up, VOUT = 12V
Simple Switcher Step-Up, VOUT = 15V
Simple Switcher Step-Up, Adj VOUT

883/SMD
883/SMD
883/SMD
883/SMD
883
883
883
883
883/SMD
883/SMD
883/SMD

LM1578

H

750 mA Switching Regulator

883/SMD

5962-89586

LM78S40·

J

Universal Switching Regulator Subsystem

883/SMD

5962-88761

883/SMD
883/SMD
883/SMD
883/SMD

7702806
7702807
7702808
7702809

LM120-5.0
LM120-8.0
LM120-12
LM120-15

H
H.

H

LM120-5.0
LM120-12
LM120-15

H

Fixed 0.5A Regulator, VOUT
Fixed 0.5A Regulator, VOUT
Fixed 0.5A Regulator, VOUT
Fixed 0.5A Regulator, VOUT

/11501

-

/11502
/11503

/11803,111804
7703404XA
7703404YA
5962-90645

-

SWITCHING REGULATORS
LM1575-5
LM1575-12
LM1575-15
LM1575-ADJ
LM1575HV:5
LM1575HV-12
LM1575HV-15
LM1575HV-ADJ
LM1577-12
LM1577-15
LM1577-ADJ

5962-9167201
5962-9167301
5962-9167401
5962-9167101

-

-'5962-9216701
5962-9216801
5962-9216601

'Formerly manufactured by Fairchild Semiconductor as the p.A78S40DMQB.

VOLTAGE REFERENCES
H
H
H

Reference Diode,
Reference Diode,
Reference Diode,
Reference Diode,

LMl13
LMl13-1
LMl13-2

H
H
H

Reference Diode with 5% Tolerance
Reference Diode with 1 % Tolerance
Reference Diode with 2% Tolerance

883/SMD
883/SMD
883/SMD

5962-8671101
5962-8671102
5962-8671103

LM129A
LM129B

H
H
H

Precision Reference, 10 ppml"C Drift
Precision Reference, 20 ppml"C Drift
2.5V Reference Diode, 1 % VOUT Tolerance
5V Reference Diode, 1 % VOUT Tolerance
2.5V Reference Diode, 2% VOUT Tolerance
5V Reference Diode, 2% VOUT Tolerance

883/SMD
883/SMD
883
883/SMD
883
883

5962-8992101 XA
5962-8992102XA

LM1~6A-2.5

LM136A,5.0
LM136-2.5
LM136-5.0

H

.H
.H
H

BV
BV
BV
BV

= 3.0V
=. 3.3V
= 3.6V
= 3.9V

LM103-3.0
LM103-3.3
LM103-3.6
LM103-3.9

6-18

-

8418001

-

Military Analog Products Available from NatIonal SemIconductor (Continued)

Device

Package
Styles
(Note 1)

DescrIption

Process
Flows
(Note 2)

SMD/JAN
(Note 3)

VOLTAGE REFERENCES (Continued)
LMt69
LM1B5B
LM1B5BX2.5
LM1B5BY
LM1 B5BY1.2 .
LM1B5BY2.5
LM1B5-1.2
LM1B5-2.5

H
H,E
H
H
H
H
H,E
H,E

10V Precision Reference, Low Tempco 0.05% Tolerance
Adjustable Micropower Voltage Reference
2.5V Micropower Reference Diode, Ultralow Drift
Adjustable Micropower Voltage Reference
1.2V Micropower Reference Diode, Low Drift
2.5V Micropower Reference Diode, Low Drift
1.2V Micropower Reference Diode, Low Drift
2.5V Micropower Reference Diode, Low Drift

BB3
BB3/SMD
BB3/SMD
BB3
BB3/SMD
BB3/SMD
BB3/SMD
BB3/SMD

-

LM199
LM199A
LM199A-20

H
H
H

Precision Reference, Low Tempco
Precision Reference, Ultralow Tempco
Precision Reference, Ultralow Tempco

BB3/SMD
BB3/SMD
BB3

5962-BB56102
5962-BB56101

LM611AM
LM612AM
LM613AM
LM614AM
LM615AM

J
J
J,E
J
J

Super-Block Op Amp/Reference
Super-Block Dual-Channel Comparator/Reference
Super-Block Dual Op Amp/DuaIComp/Dual Ref
Super-Block Quad Op Amp/Reference
Super-Block Quad Comparator/Reference

BB3
BB3/SMD
BB3/SMD
BB3/SMD
BB3/SMD

LH0070-0
LH0070-1
LH0070-2

H
H
H

Precision BCD Buffered Reference
Precision BCD Buffered Reference
Precision BCD Buffered Reference

"_MIL"
"-MIL"
"-MIL"

-

ADCOB020L
ADCOB51

J
J

BB3/SMD
BB3/SMD

5962-90966
TBD

ADCOB5B

J

BB3/SMD

TBD

ADCOB061CM
ADC10061CM
ADC10062CM

J
J
J

BB3/SMD
8B3/SMD
BB3/SMD

TBD
TBD
TBD

ADC10064CM

J

BB3/SMD

TBD

ADC1241CM

J

BB3/SMD

5962-9157B01

ADC12441CM
ADC1251CM

J

BB3/SMD
8B3/SMD

5962-9157B02
5962-9157B01

ADC12451CM
DACOB54CM

J
J

BB3/SMD
BB3/SMD

TBD
TBD

DAC1054CM

J

BB3/SMD

TBD

LM1245BM
LM12H45BM

EL,W
EL,W

B-Bit j.tP-Compatible
B-Bit Analog Data Acquisition
& Monitoring System
B-Bit Analog Data Acquisition
& Monitoring System
B-Bit Multistep ADC
1O-Bit Multistep ADC
1O-Bit Multistep ADC w/Dual
Input Mutiplexer
1O-Bit Multistep ADC w/Quad
Input Multiplexer
12-Bit Plus Sign Self-Calibrating
with Sample/Hold Function
Dynamically-Tested ADC1241
12-Bit Plus Sign Self-Calibrating
with Sample/Hold Function
Dynamically-Tested ADC1251
Quad B-Bit D/ A Converter
with Read Back
Quad 1O-Bit D/ A Converter
with Read Back
12-Bit Data Acquisition System
12-Bit Data Acquisition System

BB3/SMD
BB3/SMD

5962-9319501
5962-9319502

5962-9041401
5962-B759404

5962-B759405
5962-B759406
5962-B759401
5962-B759402

5962-9300201
5962-9300301
5962-9300401
TBD

DATA ACQUISITION

J

6-19

~ r-------------------------~--------------------------------------------------------------_,

~
g

Military Analog Products Available from National Semiconductor (Continued)

~

"a

.2
E

Package
Styles
(Note 1)

Devrce

~

DATA ACQUISITION SUPPORT

'ii

Switched Capacitor Flit rs
LMF60CMJ50
LMF6OCMJ100

c

o

zi

E

-2
U)

!en

G.

g
a.
U)

2

.:l

~

~
:i

LMF90CM
LMF100A
Sample and Hold
LF198
Motion Control
LMD18200-2

I
I

J
J
J
J,E
H

0

Process
Flows
(Note 2)

SMD/JAN
(Note 3)

6th Order Butterworth Lowpass
6th Order Butterworth Lowpass

883/SMD
883/SMD

5962·90967
5962-90967

4th Order Elliptic Notch
Dual 2nd Order General Purpose

883/SMD
883/SMD

5962-90968
5962-9153301

Description

I
I

Monolithic Sample and Hold

Dual3A, 55V H-Bridge

I
I

SMD/JA

883/JAN

I
I

5962-87608
/12501
5962-9232501

Note 1: D: Side-Brazed DIP
Note 2: Process Flows
E: Leadless Ceramic Chip Canier
JAN = JM38510, Level B
G: Metal Cen (T0-8)
SMD = Standard Military Drawing
H: Metal Cen (TO-39, TO-5, TO-99, To-l00)
883 = MIL-STD-883 Rev C
J: Ceramic DIP
-MIL = Exceptions to 883C noted on
K: Metal, Cen (T0-3)
Certificate of, Conlonnance
W: F1atpek
Note 3: Please call your local sales office 10 detennine price and availability of space-level products. All "LM" prefix products in this guide are avallble with specelevel processing.

c!
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6-20

»

"0
"0
CD

tJ1National Semiconductor

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Appendix E·
Understanding Integrated Circuit
Package Power Capabilities

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CO

INTRODUCTION

The short and long term reliability of National Semiconductor's interface circuits, like any integrated circuit, is very dependent on its environmental condition. Beyond the mechanical/ environmental factors, nothing has a greater influence on this reliability than the electrical and thermal stress
seen by the integrated circuit. Both of these stress issues
are specifically addressed on every interface circuit data
sheet, under the headings· of Absolute Maximum Ratings
and Recommended Operating Conditions.
However, through application calls, it has become clear that
electrical stress conditions are generally more understood
than the thermal stress conditions. Understanding the importance of electrical stress should never be reduced, but
clearly, a higher focus and understanding must be placed on
thermal stress. Thermal stress and its application to interface circuits from National Semiconductor is the subject of
this application note.

Failure rate is the number of devices that will be expected to
fail in a given period of time (such as, per million hours). The
mean time between failure (MTBF) is the average time (in
hours) that will be expected to elapse after a unit has failed
before the next unit failure will occur. These two primary
"units of measure" for device reliability are inversely related:
MTBF =
. 1
•
Failure Rate
Although the "bathtub" curve plots the overall failure rate
versus time, the useful failure rate can be defined as the
percentage of devices that fail per-un it-time during the flat
portion of the curve. This area, called the useful life, extends
between t1 and t2 or from the end of infant mortality to the
onset of wearout. The useful life may be as short as several
years but usually extends for decades if adequate design
margins are· used in the development of a system.
Many factors influence useful life including: pressure, mechanical stress, thermal cycling, and electrical stress. However, die temperature during the device's useful life plays an
equally important role in triggering the onset of wearout.

FACTORS AFFECTING DEVICE RELIABILITY

Figure 1 shows the well known "bathtub" curve plotting failure rate versus time. Similar to all system hardware (mechanical or electrical) the reliability of interface integrated
circuits conform to this curve. The key issues associated
with this curve are infant mortality, failure rate, and useful
life.

FAILURE RATES vs TIME AND TEMPERATURE
The relationship between integrated circuit failure rates and
time and temperature is a well established fact. The occurrence of these failures is a function which can be represented by the Arrhenius Model. Well validated and predominantly used for accelerated life testing of integrated circuits, the
Arrhenius Model assumes the degradation of a performance
parameter is linear with time and that MTBF is a function of
temperature stress. The temperature dependence is an exponential function that defines the probability of occurrence.
This results in a formula for· expressing the lifetime or MTBF
at a given temperature stress in relation to another MTBF at
a different temperature. The ratio of these two MTBFs is
called the acceleration factor F and is defined by the following equation:

~~ .,

...

3A), thermal resistance may be
lower. Consult product datashset for more information.
10k

CD

a.
o

'"D

DIE SIZE (kMIL'1

~g:18.:~

~

II)

CQ

'Packages from 8- to 20.pin 0.3 mil width

SO-16-N

S"

c;-

CQ

n

2

No.
so- 8-N

S·

II)

20

N.W1

ia.

120

~~~

..

180

CD

c;:;:

140

Ii'S
O!j::!.

.........

a.

~.

Cavity (J Package) DIP'
Poly Die Attach Board
Mount-Still Air

iii 52'

'Packages from 8· to 20.pin 0.3 mil width

I'!!

c:
::J

CQ

at 11.8 mWI"C above 2S'C.

130 "'--""'-"--'-"'r-T"rn

1

a.

;C'

::J

mwrc above 25°C; derate molded package

If the molded package is used at a maximum ambient temperature of 70'C, the package power capability is 945 mW.
Po @ 70'C= 1476 mW-(11.B mWI'C)X (70'C-25'C)
= 945mW

Molded (N Package) DIP'
Copper Leadframe-HTP
Die Attach Board MountStili Air

3D

~

"0
CD
::J

lOOk

FIGURE 13. Thermal Resistance (typ.·) for 3-,5-,
and 7-L TO-263 packages mounted on 1 oz.
(O.036mm) PC board foil

TL/H/9312-'12

FIGURE 12. Thermal Resistance for "SO" Packages
,
. (Board Mount)

6-25

~r------------------------------------------------------------------

=ac><

lc..

tfI.N.a t ion a I Se m i con due tor

JA on the specific devices data sheet). The difference between the thermal resistance of Copper and Kovar in a molded package is shown in

1.8

z

125

TL/F/5860-12

2.0

co

100

FIGURE 12. Maximum Package Rating Copper vs
Kovar Lead Frame Packages

National Semiconductor specifies the thermal resistance
from device junction through the device leads soldered in a
small PC board, measured in one cubic foot of still air. Figure 11 shows the maximum package power rating for an 8
pin Molded, an 8 pin Ceramic, 14 pin Molded and a 14 pin
Ceramic package. The slope of the line corresponds to thermal resistance (JA = APIIlT).

~

75

AMBIENT TEMPERATURE ('C)

FIGURE 10. Components of Thermal Reactance
for a TypicallC Package

I
O.B

Figure 12.

0.6

Another variance in thermal resistance is the size of the IC
die. If the contact area to the lead frame is greater, then the
thermal resistance from the Die to the Lead Frame is reduced. This is shown in Figure 13. The thermal resistance
shown in Figure 11 corresponds to die that are 6000 mil2 in
area.

0.4
0.2
0
25

50

75

100

IZ5

150

175

AMBIENT TEMPERATURE rC)
TL/F/5860-11

140

FIGURE 11. Maximum Package Power Rating
The maximum allowable junction temperature for ceramic
packages is 175'C; operation above this temperature will
reduce the reliability and life of the device below an acceptable level. At a temperature of 500'C the aluminum metallization paths on the die start to melt. The maximum allowable junction temperature for a molded device is 150'C, operations above this may cause the difference in thermal expansion between the molding compound and package lead
frame to sheer off the wire bonds from the die to the package lead. The industry standard for a molded device is
150'C, but National further recommends operation below
135'C if the device in its application will encounter a lot of
thermal cycling (such as powered on and off over its life).

~ 120

~

100

~

80

iii0:

60

~

40

i=

20

r-- r-

-r-

o
Ik

2k

5k

10k

DIE SIZE (MIL2)
TL/F/5860-13

FIGURE 13. Thermal Resistance vs Ole Size
In most applications the prime medium for heat conduction
is through the device leads to the PC board, but the thermal
resistance can be significantly improved by cooling air driven across the surface of the package. The conduction to air
is limited by a stagnant film of air at the surface of the package. The film acts as an additional thermal resistance. The
thickness of the film is proportional to its resistance. The
thickness of the film is reduced by the velocity of the air

The way to determine the maximum allowable power dissipation from Figure 11, is to project a line from the maximum
ambient temperature (TAl of the application vertically
(shown dotted in Figure 12), until the line intercepts the diagonal line of the package type, and then project a line
(shown dotted) horizontally until the line intercepts the Power Dissipation Axis (PMAX).

6-33

....

~r-----------------------------------------------------------------~

~

~

across the package as shown in Figure 14. In most cases,
the thermal resistance is reduced 25% to 250 linear feet/
min, and 30% at 500 linear feet!min, above 500 linear feet!
min the improvement flattens out.

j\.

"""'"

f..., I- ~

This capacity is shown as a capacitor in Figure 9. In the lab
(under a microscope) a device may be observed to glow
orange around the parameter of the junction under excessive peak power without damage to the device. Figure 15
shows a plot of maximum peak power vs applied time for
the 053654, and the same information plotted as energy vs
applied time. To obtain these curves, the device leakage
current when it switches off was used to monitor device
limitation. Note in Figure 15 there is a transition in the curve
about 10 ",s. At this pOint, the thermal capacity of the die
has been exceeded. The thermal delay to the next thermal
capacity (the package) was too long, and limited the peak
power. These levels are not suggested operating levels, but
an exemple of a Peripheral Driver to handle peak transient
power.

r-

....

:ii

f5

OA

"'
i!:
!c
....

02

j!:

::!

o

o

&00
AIR FLOW (LINEAR FEET/MINI

100

lk

PEAK POWER (WATTSI

TUF/5B60-14

FIGURE 14. Thermal Resistance vs Air Velocity

,

The thermal resistance can also be improved by connecting
the package to the PC board copper or by attaching metal
wings to the package. The improvement by these means is
outside the control of the IC manufacturer, but is available
from the manufacturer of the heat sink device. If the IC is
mounted in a socket rather than soldered to a PC board, the
thermal resistance through the device leads will worsen. In
most cases, the thermal, resistance is increased by 20%;
again this is a variable subject to the specific socket type.

EINEIR~I~ (J~UmIX

P

10-3II

III
III

0.01

I

10

100

lk

10k

(APPLIED TIME (PSI
TL/F/5B60-15

The maximum package rating shown in this note corresponds to a 90% confidence level that the package will
have thermal resistance equal to or less than the value
shown. The thermal resistance varies ± 5% about the mean
due to variables in assembly and package material.

FIGURE 15. Peak Power and Energy vs the
Period of Time the Power was Applied
To calculate power dissipation, the only information available to the design engineer is the parametric limits in the
device data sheet, and the same information about the load
reactance. If tlie calculations indicate the device is within its
limits of power diSSipation, then using those parametric limits is satisfactory. If the calculation of power dissipation is
marginal, the parametric limits used in the calculations
might be worst case at'low temperature instead of high temperature due to a positive temperature coefficient (Tcl of
resistance. IC resistors and resistors associated with the
load generally have a positive Tc. On the other hand, diodes
and transistor emitter base voltages have a negative T c;
which'may in some circuits negate the effect of the resistors
Tc. Peripheral output transistors have a positive Tc associated with VoG while output Darlington transistors have ,8
negative Teat low currents and may be flat at high currents.
Figure 16 shows an example of power dissipation vs temperature; note that the power dissipation at the application's
maximum temperature (TA) was less than the power dissipation at lower temperatures. Since maximum junction temperature is the concern of the calculation, then maximum
ambient temperature power should be used. The junction
temperature may be determined by projecting a line (shown
dotted in Figure 16), with a slope proportional to JA back to
the horizontal axis (shown as TJ). If the point is below the
curve then TJ will be less than 150°C. TJ must not exceed
the maximum junction temperature for that package type. In
this example, TJ is less than 150°C as,required by a molded
package. To calculate the power vs temperature, it is necessary to characterize the device parameters vs temperature.
Unfortunately, this information is not always provided by IC
manufacturers in the device data sheets. A method to calcu-

CALCULATIONS OF POWER DISSIPATION
Most IC devices (such as T2L) operate at power levels well
below the device package rating, but peripheral drivers can
easily be used at power levels that exceed the package
rating unknowingly, if the power dissipation isn't calculated.
As an example, the 053654 Ten Bit Printer Driver could
dissipate 3 watts (DC and, even more AC), and it is only in a
0.8 watt package. In this example, the device would be destroyed in moments, and may even burn a hole in the PC
board it is mounted on. The 053654 data sheet indicated
that the 10 outputs could sink 300 mA with a VOL of 1 volt,
but it wasn't intended that all the outputs would be sinking
this current at the same time, and if so, not for a long period.
The use of the 053654 requires that the power be calculated vs the duty cycle Of the outputs.
The DC power dissipation is pretty obvious, but in another
example, a customer used the 053686 relay driver to drive
6.5h'inductive load. The 053687 has an internal clamp network to quench the inductive back swing at 60V. At 5 Hz the
device dissipates 2 watts, with transient peaks up to 11
watts. After 15 minutes of operation, the driver succumbs to
thermal overload and becom'es non-functional. The 053687
was intended for telephone relay, which in most applications
switches 20 times a day.
Peripheral driver will dissipate peak power levels that greatly
e)(ceed the average DC power. This is due to the capacity of
the die and package to consume the transient energy while
still maintaining the junction temperature at a safe level.

6-34

late Icc vs temperature is to measure a device, then normalize the measurements vs the typical value for Icc in the data
sheet, then worst case the measurements by adding 30%.
Thirty percent is normally the worst-case resistor tolerance
that IC devices are manufactured to.
1.4

~

.

1.2 NEVICE
RATING

'z

i

ilic;
IC

~

O.B

JACKAG~

T=

~

'", ,-

PA

L

25

50

75

120.0.

_VB - VOL _ 30 - 1.5 - 375 A
IL-----2 . m
RL
120
Ip = Id1 - e -TONlT)
Ip = 237.5mA(1 - e-IOO ms/41.7 ms)

~

~~
TJ

TA

LL=~=41.7ms

RL

I

0.2

o

PON = Average power dissipation in device output
when device is ON during total period (T)

' " CIRCUIT POWER

0.6

OA

Refer to Figure 18 voltage and current waveforms corre·
sponding to the power dissipation calculated for this example of an inductive load.

100

125

TEMPERATURE eCI

Ip = 215.9mA

'"

TON [
fToNe-tlTdt]
PaN = VOL X IL X 1--T
•
TON

150

TON [
T
-TONIT ]
PaN = VOL X IL X 1- (1 - e
)
TON
T

TL/F/5860-16

FIGURE 16.IC Power Dissipation vs Temperature

100 [ 1--(1-e-l00/41.7)
41.7
]
PaN = 1.5x237.5mAx200
100

CALCULATION OF OUTPUT POWER WITH
AN INDUCTIVE LOAD

PaN = 110.6 mW
POFF = Average power dissipation in device output when
device is OFF during total period (T)

For this example, the device output circuit is similar to the
DS3654 (10-Bit Printer Solenoid Driver) and the DS3686
and DS3687 (Telephone Relay Driver) as shown in Figure
17. Special features of the circuit type are the Darlington
output transistors 01 and 02 and the zener diode from the
collector of 01 to the base of 02. The Darlington output
requires very little drive from the logic gate driving it and in
turn dissipates less power when the output is turned ON and
OFF, than a single saturating transistor output would. The
zener diode (Dz) quenches the inductive backswing when
the output is turned OFF.
Device and Load Characteristics Used for
Power Calculation
Output Voltage ON
1.5V
VOL
Output Clamp Voltage
65V
Vc
Load Voltage
30V
VB
Load Resistance
1200.
RL
Load Inductance
5h
LL
Period ON
100 ms
TON
Period OFF
100ms
TOFF
Total Period
T
200ms

Vc - VB
65 - 30
IA = - - - = - - - = 291.7 mA
RL
120.0.
Ip + IA)
tx = Tin ( -I-A215.9 + 291.7)
tx = 41.7 ms In (
291.7
= 23.1 ms

tlT

tx [
POFF = Vc X - (lp

e-- dt
+ IA) fIx -

tx [
POFF = Vc X - (Ip
T

+ IA)' x

T

•

tx

T

s - (1 - e
tx

23.1 [
POFF = 65 X 200 (215.9 mA

]

IA

-tXIT

) - IA

]

41.7

+ 291.7 mAl 23.1

(1 - e-23.1/41.7) - 291.7 mA]
POFF = 736mW
Po = Average power dissipation in device output
Po ~ PON + POFF = 11 0.6 + 736 = 846.6 mW
In the above example, driving a 1200. inductive load at 5 Hz,
the power dissipation exceeded a more simple calculation
of power dissipation, which would have been:

VB

Po = VOL (VB - Vou X TON
RL
T
P = 1.5 (30 - 1.5) X 100 ms = 182.5 mW
120
200ms
o
An error 460% would have occurred by not including the
reactive load. The total power dissipation must also include
other outputs (if the device has more than one output), and
the power dissipation due to the device power supply currents. This is an example where the load will most likely
exceed the device package rating. If the load is fixed, the
power can be reduced by changing the period (T) and duty
rate (TON ITOFF)·

-=-

-=-

TL/F/5860-17

FIGURE 17. Peripheral Driver with Inductive Load
6-35

»
z

•

N

C o)

~ r---------------------------------------------------------------------------------~
....
N

~

~5V-------------r~

50

,L



0.2

7:18ms

0-

o

10

20

30

40

50

TIME (ms)
TL/F/S860-21

in

3D

...

g"

w

z

20

I;;
in
w

Ie

10

.....

~

:&

t:'

38

FIGURE 21. Transient Incandescent Lamp Current
Calculation of the energy dissipated by a peripheral driver
for the transient lamp current shown in Figure 21 is shown
above, and the plot of energy vs time is shown in Figure 22.
Figure 22 also includes as a reference the maximum peak
energy from Figure 15. It can be seen from Figure 22 that in
this example there is a good safety margin between the
lamp load and the reference max peak energy. If there were
more drivers than one per package under the same load,
the margin would have been reduced. Also, if the peripheral
driver couldn't saturate because it couldn't sink the peak
transient lamp current, then the energy would also reduce
the margin of safe operation.

~ r""'"

,1141:.18

2100.F T

T

1122.F

f-I-

OL-JL......----~~_-I

o

10 20 30 40 50 60 70 80 90 100

TIME (ms)
TUF/S860-19

FIGURE 19. Transient Response of
an Incandescent Lamp

6·36

100

VB=6.3V

III

I=::lpEkkl~N~R.lY

f-' REFERENCE

INCANDESCENT
LAMP LOAD

>
'"
a:
w

ffi

RB RS

100

0.1

6.3 -1)
= (1

180

= 95.4:::

1000

0.01
100

10

11,

101,

lOOk

TL/F/5B60-23

FIGURE 23. Circuit Used to Reduce Peale
Transient Lamp Current

TIME (ps)
TL/F/SBSO-22

FIGURE 22. Energy vs Time for a Peripheral
Driver with an Incandescent. Lamp Load

PERIPHERAL DRIVER SECTION
National Semiconductor has a wide selection' of peripheral
drivers as shown in this section's guide. The DS75451,
DS75461, DS3631 and the DS3611 series have the same
selection of logic function in an 8-pin package. The
DS75461 is a high voltage selection of the DS75451 and
may switch slower. The DS3611 and DS3631 are very high
voltage circuits and were intended for slow relay applications. The DS3680, DS3686, and DS3687 were intended for
56V telephone relay applications. The DS3654 contains a
10-bit shift register followed by ten 250 mA clamped drivers.
The DS3654 was intended for printer solenoid applications.

CALCULATION OF ENERGY IN AN
INCANDESCENT LAMP
Energy =
.
IRI

=

f:

VOL (lRl

VB - VOL
R1

+ IR2) dt

= IRI

iR2 = (VB ;2VOL ) e-tlT
= IR2 e- tlT

Energy =
Given:

f:

T = R2C2

VOL (lRl

= VOL [JRlt
VOL = 0.6V

High current and high voltage peripheral drivers find many
applications associated with digital systems, and it is the
.intention of the application note to insure that reliability and
service life of peripheral drivers equal or exceed the performance of the other logic gates made by National.

+ IR2 e- tlT ) dt

+ IR2T (i -

e- tlT )]

IRI = 0.2 Amps
IRI + IR2 = 1 Amp
A common technique used to reduce the 10 to 1 peak to DC
transient lamp current is to bias the lamp partially ON, so
the lamp filament is warm. This can be accomplished as
shown in Figure 23. From Figure 20 it can be seen that the'
lamp resistance at OV is 5.70, but at 1V the resistance is
180. At 1V the lamp dosen't start to'emit light Using a lamp
resistance of 1000 and lamp voltage of 1V, RB was calculated to be approximately 1000. This circuit will reduce the
peak lamp current from 1 amp to 316 mAo

For additional information, please contact the Interface Marketing Department at National or one of the many field application engineers world-wide.

6-37

I

t!lNational Semiconductor

6

20 Lead Ceramic Leadless Chip Carrier, Type C
NS Package Number E20A
All dimensions are in inches (millimeters)
D.200±0.0D5

l5.Oiffiii7i
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3 Lead (0.200" Diameter P.C.) TO-39 Metal Can Package, Low Profile
NS Package Number H03A
All dimensions are in inches (millimeters)

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6-38

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8 Lead (0.200" Diameter P.C.) TO-5 Metal Can Package
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NS Package Number H1OC
All dimensions are in inches (millimeters)

0.165 -0.185
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6-39.

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All dimensions are in inches

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RO.0.l0 TYP

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0.310 MAX

0.220
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14 Lead Ceramic Dual-in-Line Package
NS Package Number J 14A
All dimensions are in inches (millimeters)
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6-40

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All dimensions are in inches [millimeters]

~ [19.94)MAX - 0.785

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0.290-0.320_-t-_ _ _~
[7.37-8.13)
GLASS SEALANT

0.0 10:1: 0.002 TYP
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0.125-0.200 TYP
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0.080 MAX
[2.03)
BOTH ENDS

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0.310-0.410
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2 Lead TO-3 Metal Can Package
NS Package Number K02A
All dimensions are in inches [millimeters]
0.420-0.500 -+----;----:0'1- 0 325-0 352
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,

4X f/J 0.038-0.043
[0.97-1.09]

2X R 0.168-0.178
[4.27-4.52)

UNCONTROLLED
LEAD,DIA
0.025 MAX ......

[0.64)

SEATING PLANE

6-42

K04A (REV F)

.-----------------------------------------------------------------------------~ ~

:7

8 Lead TO-3 Metal Can Package
NS Package Number K08A

':i
All dimensions are in inches (millimeters)

::J
UJ

0.760-0.175
(19.304-11.6851 ~

0'

~~

(0.63&1
0.345-0.395
MAX
UNCONTROLLED (8.76310.033
LEAD

-0.280 0.085-0.100
~
(5.&18-7.1121 (2.151-2.&41

,
:

t

L

t

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.!:!!!!:!!:!!!i ~

t o.t22

iffiil

(0.914-1.11B1

MAX

TVP

OA90-D.&10
(12.440-12.9&41 ~
LEAD CIRCLE

80'

(14.159-1&.241
1.177-1.197
(29.198-3D.4041

40' (7xl

2 Lead TO-3 Metal Can Package, Aluminum
NS Package Number KC02A
All dimensions are in inches (millimeters)
-+

0.107-D.I23

0.800-0.815
(20.32-20.70)
DIA

0.940 -0.980
(23.98-24.89) I .
DIA
0.250 -D.350
(6.350 r.8SO)

(2.718-3:124)~

L....

0.025
(0.635)

Jf f

UNCONTROLLED LEAD OIA

..!!:ill.
(3.429)
MAX

c

3'
ft)

0.880-lI.92&
(22.3&-23.&01 ~

SEATING PLANE

~

U kIND PLANE f

II

t

0.445-0.522
(11.30-13. 26)

-

0.038 0.043

~ i'+-(D.965-1.092)

OIA TTP
0.42O-D.44O
(10.67-11.18)

0.151 -0.161

(3.835-4.089)
OIA TTP
0.165 -D.I79

(4.191-4.547)
RTTP
0.210-0.220
(5.334-5.5981

1.177-1.197

(29.90 -30.40)
KCOIA(IIEVCI

6-43

::J

UJ

8 Lead (0.150" Wide) Molded Small Outline Package, JEDEC
NS Package Number M08A
All dimensions are in inches (millimeters)
0.189-0.197
(4.810-5.004)
8

~X4501 (r::!~:=:::)

l

(D.254-0.508)

__ ~~r~
~

0.004

iDToii

0.008-0.010
(0.203-0.254)

All LEAD TIPS _

TYPALlLEADS

&

5

0.053 -0.069
(1.348-1.753)

8° MAX TYP

t=
T

r

7

0.004 -0.010
(8.102-0.254)

.1.

:.'

~

~

. J

.0.014

0.01&-0.050

(8.35&)

~~~J

,

~

..!!:!!!!!!..

(1.270)
. . TYP

.!!!!!.TYP

SEA11N4I

tPlAN£

_

0.014 -0.020 TYP
(1.35&-0.508)

(0.203)

""
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