1982_Fairchild_High_Current_Voltage_Regulators 1982 Fairchild High Current Voltage Regulators

User Manual: 1982_Fairchild_High_Current_Voltage_Regulators

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I=AIRCHILD
A Schlumberger Company

369 Whisman Road, Mountain View, California 94043
©1982 Fairchild Camera and Instrument Corporation/369 Whisman Road, Mountain View, California 94043/(415) 962-5011/TWX 91 0-379~6435
Fairchild reserves the right to make changes in the circuitry or specifications in this book at any time without notice.
Manufactured under one of the following U.S. Patents: 2981877, 3015048, 3064167, 3108359, 3117260, other patents pending.

Fairchild reserves the right to make changes in the circuitry or specifications in this book at any time without notice.
Manufactured under one of the following U.S. Patents: 2981877, 3015048, 3064167, 3108359, 3117260, other
patents pending.
Fairchild cannot assume responsibility for use of any circuitry described other than circuitry entirely embodied in a
Fairchild product.
No other circuit patent licenses are implied.
Printed in U.S.A. 610000 100M January 1982

FAIRCHILD

Introduction

A Schlumberger Company

The Fairchild Hybrid Division was established to fulfill
the high-volume, high-quality, low-cost requirements
of a growing number of companies turning to hybrid
technology. A broad range of precision hybrid
voltage regulators is available off-the-shelf as well as
automotive ignition systems. For custom hybrid
programs we offer full design capability with rapid
prototyping and translation to volume production.
No other hybrid manufacturer in the world can match
Fairchild's total capabilities. Since Fairchild is one of
the world's leading semiconductor manufacturers,
there is no need to depend on outside suppliers for
delivery, reliability or quality of semiconductor
components. Our years of experience in developing
and qualifying sources of passive components for
the automotive hybrid market assure dependable
performance in the finished product. Facilities in
Northern California and Hong Kong can turn out
more reliable hybrid products in a day than most
hybrid suppliers can produce in a week.
Fairchild is equipped to produce hybrids for any
company in any business that uses hybrid products
in large quantities. The markets served include
automotive, consumer electronics, computer,
telecommunications, industrial controls, aerospace
and military.

FAIRCHILD

Table of Contents

A Schlumberger Company

Chapter One
Page
Capabilities Information
Design .................................... 1-3
Production ..................................1-3

Chapter Two
Reliability
What is Reliability? .......................... 2-3
Some Reliabili~v Terms ....................... 2-3
How is Reliabilicy Obtained? ................... 2-4
Design
Piece Parts
Wafer Fabrication
Assembly
Environmental Stresses
How is Reliability Tested and Maintained? ........ 2-7
Die Related Tests
Package Related Tests
Conclusion ................................ 2-8

Chapter Three
Cross Reference Guide

Ordering Information ......................... 3-3

Chapter Four
Data Sheets

ILA78H05.ILA78H05A ........................ 4-3
ILA78H12A ................................. 4-7
ILA78HGA ................................ 4-11
ILA78P05 ................................. 4-15
ILA79HG .................................. 4-19
SH323. SH223. SH123 ...................... 4-23
SH1605 .................................. 4-27

Chapter Five
Applications

High Current Voltage Regulator Applications. . . .. 5-3
Understanding the Switching Regulator ......... 5-16
Power Supply Design ....................... 5-31
Thermal Considerations ..................... 5-41

Chapter Six
Fairchild Field Sales Offices
Representatives and Distributors .............. 6-3

FAIRCHILD
A Schlumberger Company

__

l~c ap_a_b_i_lit_ie_S__ln_fo_r_m_a_t_io_n_____________1IIIII

1-2

Chapter 1
Capabilities

FAIRCHILD
A Schlumberger Company

Design
Hybrids offer all the advantages of other
semiconductor components-small size, high
reliability and low cost in high volume-while
providing fully tested functions that readily interface
with the user's overall system. In addition they offer
unique advantages such as ability to mix
technologies not achievable monolithically, ability to
operate in extremely hostile environments, and
improved ratios of reliability to. complexity, while
retaining their size advantage over the discrete
approach. A broad range of process techniques has
been developed from which to select the
manufacturing method best suited to a specific
objective. This variety of techniques provides for
wide design flexibility with minimal process
constraints. Also, since the semiconductors used in
Fairchild hybrids are almost exclusively supplied
internally, parameters can be selected and
stringently controlled for compatibility with the
overall circuit design.

New process development and materials research
takes place on a continuous basis to ensure that our
methods and materials are selected from the best
alternatives available. InternallC design compatibility
~xists for linear and other bipolar technologies,
power transistors are also designed within the
division. Design and production of custom products
follow a thorough routine. Once a user's input is
submitted, whether in the form of functional
specifications, a circuit diagram or breadboard, a
comprehensive cost analysis and circuit evaluation is
made. Only when Fairchild is satisfied with the
circuit/cost analysis is the paper design submitted.
Upon approval, a breadboard is produced for user
~valuation. A complete detailed layout is then
constructed for use in producing preliminary parts
for customer ~pproval. When the customer gives the
go-ahe~d, volume production begins. In either
instance, standard or custom, a Fairchild hybrid
subsystem, fabricated using mixed technologies, is
fully tested and delivered on time, in volume
quantities.

All materials are pre-tested and qualified before
admission to the thick film process; pastes are
subjected, on a lot basis, to stringent incoming tests
using computer controlled equipment. The flatness
and surface finish of the alumina substrates are
rigidly controlled. Printing onto these substrates is
accomplished using automatic magazine fed
machines having a high degree of stability and print
alignment. The substrates are then transferred by
automatic collation equipment to a drying and firing
furnace, in which the environment is moisture and oilfree to ensure the control required for maintenance
of tight resistor temperature coefficient of resistance
(TCR) distributions. Furnace zones are
microprocessor controlled, and interfaced to a
computer system capable of providing check profiles
on demand. Post-firing offload is accomplished using
automatic equipment eliminating handling damage.
Base conductor and dielectric layers are individually
printed and fired; subsequent resistor prints are
dried between applications and finally co-fired to the
desired pre-trim values. 'Process monitoring, again
using computer controlled equipment, constantly
verifies visual, electrical and dry-print thickness
measurements, assuring high-yield low-cost
production. Tailoring the substrate resistors to final
value is achieved using active and passive laser
trimming systems with carousel feeds and closedcircuit TV monitoring systems. Extensive computer
control atthis step provides flexibility and accuracy.

Production
Fairchild excels in high volume production of hybrid
devices. Facilities include: complete thick film
production; rubylith, photo reduction and screen
manufacturing; active and passive laser trim; wafer
sort and scribe; assembly and packaging; testing and
quality control.

1-3

Capabilities
Total thick-film production capability encompasses
gold and palladium-silver conductor systems,
resistor prints in the range 1Q to 10MQ, high quality
pinhole-free dielectric systems and multilayer
techniques. Fairchild's thick film capability is
complemented by wafer sort and scribing facilities
employing diamond and saw techniques. Wafers are
supplied to this area from the company's integrated
circuit and discrete fabrication areas. Linear devices
and power transistors can be supplied from the
division's internal capability. The proximity of all
facilities ensures rapid resolution of any technical or
scheduling problems.

bondil1g techniques is currently under development.
Because of its potential for computer controlled
assembly when combined with automatic pick and
place equipment, tape carrier appears to be the best
solution for high volume production of reliable
hybrids at minimum cost.
Many other advanced techniques in hybrid
technology have been developed over the past
decade to meet a variety of customer objectives. This
trend will continue. Fairchild is committed to
producing the highest quality hybrids possible to
endure the most stringent environmental conditions
in both commercial and military applications.

Hybrid production utilizes all the standard
manufacturing methods plus a number of proprietary
processes designed to meet exacting customer
requirements. For example, an exclusive flip-chip
solder reflow process has been developed to
eliminate bonding steps in large-volume custom
applications, while simultaneously providing an
extemely rugged micro-interconnect capable of
withstanding wide temperature excursions and the
most demanding corrosion and vibration
environments. For applications involving the use of
LSI chips with large area and I/O counts, a versatile
interconnect scheme using the latest tape automated

1-4

FAIRCHILD
A Schlumberger Company

2-2

Chapter 2
Reliability

FAIRCHILD
A Schlumberger Company

What Is Reliability

Wear-Out Failure

Reliability is defined as the behavior of a component,
a machine, or a system, as a function of time.
Statistically, it is also expressed as the probability
that the item will perform a required function under
established conditions for a given period of time.

This failure occurs as a result of degradation,
physical or chemical.

This Time is a variable covering minutes, hours,
months, or years. Some of the equipment in oil well
logging operations must have, on the average, a
useful life of only five minutes:At the other extreme,
the telephone companies want their equipment to
last a minimum of 25 years. MiSSiles are subjected to
thousands of "g" (gravity) forces and the
components must not lose their monitoring,
telemetering, or sensing capabilities during the first
critical seconds of their flight. Power supplies are
constantly being thermally cycled as they are turned
on and off. Voltage regulators undergo similar
stresses, and both must provide thousands of hours
of flawless operation.

•

Repeated thermal cycling will cause electrical
discontinuities between conductors having
different coefficients of thermal expansion.

•

Voltage incursions may cause shorting across a
dielectric.

•

Excessive current densities may introduce metal
migration, causing shorts.

•

Continuous vibrations may cause loss of contact
or create loose conducting particles and
subsequent shorting.

•

Moisture is known to degrade components
because of chemical reactions resulting in
parameter changes.

Figure 1 suggests that, to obtain the lowest failure
rate a removal of the infant mortality weaknesses is
required. Traditionally, this removal was done, as a
rule, on military products and for certain nonmilitary
users requiring the highest reliability.

Some Reliability Terms
Initial/Infant Failure

A failure occurring during the early stages of
operation, the failure rate during infancy is higher
than during long term operation.

More recently, the growing complexities of various
electronic systems, of multi-million dollar computers,
some of which contain as many as a quarter million
integrated circuits, have created demands by the
commercial users for a reliability level similar to that
of the military, the difference being only in the
temperature range of operation.

Infant failures are caused by weaknesses not
removed by the numerous inspection operations, if
detectable at all.
Random Failure

A failure which occurs sometimes between the infant
mortality and the wear-out periods; the failure rate
during this period is generally constant.
Fig. 1 A Diagrammatic Representation of Failure Patterns

_100

Eo

a:~

10

III

a:

:;)

::!

I:f

1

i-.-+l-_-----CONSTANT------*_-+l
INFANT
MORTALITY

2-3

Reliability
In Table 1 the major component parts are listed with
tests normally performed for conformance, and, for
reliability.

How Is Reliability Obtained?
Design
High Current voltage regulators are comprised of
three major parts: Active components, substrate and
package.

Table 1
Parts

A linear integrated circuit (L1C) and a power
transistor provide all the drives and controls: A start
circuit, voltage regulation, current sourcing, shortcircuit protection, thermal shutdown and .
amplification.
The high current densities typical of high power
devices and especially of power transistors,
integrated on a chip or discrete, require unif.orm
current distribution, especially along the emitter
contacts, to prevent current hogging, hot spots and
excessive heating. This joule heating can be
sufficient to reach the aluminum-silicon eutectic
temperature, melt the silicon and short the emitter
and collector. This effect is minimized by large
geometries that decrease the current densities and
by diffusion and concentration profiles tha~ insure
better current distribution. Long term aluminum
migration, a concern wherever large current
densities exist, is also eliminated by the proper
"sizing" of the conductio~ lines. -:his concept <;>f safe
margins and of conservative design rules applies
also to all components procured from outSide
vendors.

Test and Control of Major Component

Piece Part

Test/Control

Substrate

Mechanical dimensions
Mechanical strength
Thermal conduction properties
Electrical insulation
Chemical composition
Thermal cycling

Package

Mechanical dimensions and
characteristics
Solderability of leads
Electrical insulation
Lead seal check
Lead strength

Solder Preform

Mechanical dimensions
Chemical composition

Die

Visual inspection

Capacitor

Mechanical dimenSions
Electrical properties
Electrical stress on a sample

Process
Control of Wafer Fabrication Operations
Wafer fabrication is a very complex and disciplined
operation and listing all the numerous control points
and monitoring operations is beyond the scope of
this Reliability section.

Reliability, quality and yield are major concerns for
any wafer fab operation, and by exte~sion, o! any
manufacturing operation. Only a few Items Will be
mentioned here:

Materials
The substrate provides a base for the thick film
reSistors, the connections for attaching the active
components, and a means of heat dissipation.

•
•

Wafer purity
Analysis of chemicals

•
•

Dust particle concentrations
Temperature/humidity

•

Analysis of dopant sources

•

Gas flows into furnaces

•

Furnace profiles

• CN plots for checking ionic drift

The package connects to the equipment for both
testing and usage and gives an .additional path for
heat dissipation.

2-4

•

Equipment calibration

•
•

Exposure
Development

•
•

Etching
Cleaning, etc ....

Reliability
the flow referenced in MIL-STD 883 (Test Methods &
Procedures for Microelectronics), Method 5008 (Test
Procedures for Hybrids and Multichip Microcircuits).
This "hi-rei" flow performs the following:
•

Storage. Isolates product not capable, for
mechanical reasons, of storage at 150°C for 24
hours.

•

Temperature cycle. Eliminates product exhibiting
mechanical damages that would cause functional
failures.

•

Constant acceleration. Eliminates structural and
mechanical weaknesses:
-

Poor wire-to-die bonding
Poor substrate-to-package attach
Poor die-to-substrate attach

•

Seal. Prevents the components, active and
passive, from being influenced by outside factors
of the working environment, mostly humidity.

•

Burn-In. Screens or eliminates all marginal
devices, those with inherent defects resulting
from manufacturing, aberrations which cause
time and stress dependent failures. In the
absence of burn-in, these defective units would
result in infant/early mortality failures (see
paragraph on "Some Reliability Terms").

A typical assembly flow, shown in Table 2, shows
both the operation and its control equivalent.

•

Environmental Testing
An additional level of reliability can be obtained by
performing environmental and electrical tests along

Electrical testing at temperature extremes.
Removes all units not meeting functional and
parametric criteria.

Standard and hi-rei flows are compared on Table 3.

Controi of Assembly Operations
Completed wafers are electrically probed, and good
dice are identified for assembly.

Every assembly operation is critical, and every effort
is made to guarantee long term life of the product.

Table 2

A Typical Assembly Operation

Operation

Control

Scribing (or sawing)

Maintenance

Separation of good & bad die

Visual inspection, QC sample, conformance inspection

Die attach

Functional check for adherence and wetting; 100% X-Ray;
1OO%visual check
Push Test

Substrate attach

Functional check for adherence and wetting; 100% X-Ray;
100% visual check
Push Test

Wire bonding

Incoming wiretest
Pull strength
Visual check

Optical check (preseal)

QC sample conformance inspection

Package seal

Hermeticity check for fine & gross leak

100% Optical check (post-seal)

QC sample conformance inspection
2-5

Reliability
Table 3

A Comparison of Hi Rei and Standard Flows

Fairchild Unique Level B
Hi Rei

Standard

o

Package Seal

Package Seal

o

Post Seal Visual Inspection

Post Seal Visual Inspection
Post Seal Sample Inspection

Q

Post Seal Sample Inspection

o

Bake -

o

Temperature Cycling
-65°C to 150°C - 10X

o

Constant Acceleration
10KG - Y1 Axis

o

Seal- Fine
Gross

150°C/24 hrs

Seal- Fine
Gross

Q

o
o

Electrical Test

o

Electrical Test -

Q

•
25°C
• -55°C
• 125°C
Quality Conformance

Electrical Test

Burn In - TJ = 150°C Max
Time = 160 Hrs. Min.
Post Burn In

1. Electrical
•
25°C
• -55°C
• 125°C
2. Visual/Mechanical

Quality Conformance
1. Electrical
• 25°C
• O°C
·100°C
2. Visual/Mechanical

3. Group B - Re: Mil Std 883
As Applicable
4. Group C - Re: Mil Std 883
As Applicable

o

= 100% Operation
Q = Quality Conformance Inspection

2-6

Reliability
How Is Reliability Tested And Maintained?
No product will be put on the market unless it meets
the stringent reliability requirements determi.!1ed by
the procurement agency or by the factory. These
requirements can be in terms of FITs (Failures In
Time) or percent per thousand hours, quantities that
give a mathematical limit to the failure rates resulting
from a given stress. They can also be in terms of
time, e.g., time to 10%,20%, or 50% failure of a given
sample for a given test.

MIL-STD 883, previously mentioned, lists both the
tests and the frequency of these tests performed to
maintain qualification-or suitability for sale-of a
given product. New products, new processes, new
design, new materials, are all "qualified" along the
lines originally established by MIL-STD-883.
Two major series of tests designed for periodic
monitoring or for original qualification and are listed
in Table 4, together with a brief description and the
respective LTPD (Lot Tolerance Percent Defective)
that gives sample size and allowed failures.

Table 4

Qualification and Monitor Testing

A. Die Related Tests -

Group C

Test

Description

LTPD

Temperature Cycling
Constant Acceleration
Seal
Fine
Seal
Gross
Electrical Test

-65°C to 150°C
10 kg along Y1 axis
Helium or Krypton
Fluorocarbon/bubble

15

Operating Life

Static and/or dynamic

10

B. Package Related Tests - Group D
• Lead Integrity
Seal
Fine
Seal
Gross

Lead bending
See Group C above
See Group C above

15

• Thermal Shock
Temperature Cycling
Moisture Resistance
Seal
Fine
Seal
Gross
Visual Inspection

-55°Ct0125°C
15X
-65°Ct0150°C 100X
Variable temp/humidity lOx
See Group C above
See Group C above

15

• Mechanical Shock
Constant Acceleration
Seal
Fine
Seal
Gross
Visual Examination

3000g
.3 ms
1kg
Y1 axi.s
See Group C above
See Group C above

15

• Salt Atmosphere
Seal
Fine
Seal
Gross
Visual Examination

Salt Atmosphere at 35°C
See Group C above
See Group C above

15

2-7

Reliability
Conclusion

The most critical area in any electrical/electronic
system is the power supply. ,If the power supply fails,
the system goes down. Power supply failure may
result in loss of critical data or damage to other
system components.
To the equipment user, this means idle labor hours
and unexpected replacement, repair and service
costs.
To the equipment manufacturer, it can mean
customer dissatisfaction and excessive warranty and
rework costs.
The power supply is critical to any system and the
heart of the power supply is the voltage regulator.
The Fairchild Hybrid Division recognizes the
importance of quality and reliability to our
customer ... and to his customer. Quality and
reliability standards are established, before the
product is designed and are rigidly adhered to
throughout the production flow.
High Current Voltage Regulators are presently
shipped to a guaranteed AQL of 0.1%, with an actual
return rate far less. Fairchild shares its customers'
concern for quality and reliability and will continue to
improve its products to insure their equipment
achieves optimum performance.

2-8

FAIRCHIL.D
A Schlumberger Company

3-2

Chapter 3
Cross Reference Guide
and Ordering
Information

FAIRCHILD
A Schlumberger Company

Cross Reference Guide
Cross Reference
Voltage
Regulator

FixedPositive

0
AdjustablePositive

0

Output
Capability

Fairchild
Device

Lambda

National

Silicon General

5V, 3 A
5V, 5 A
5V, 5 A
5 V, 8 A
5 V, 10 A
12 V, 5 A

SH323
78H05
78H05A
78P05
78P05
78H12A

LAS1405
LAS1405, 1905
LAS1405,1905
LAS3905
Not Available
LAS1412,1912

LM323
Not Available
Not Available
Not Available
Not Available
Not Available

SG323
Not Available
Not Available
Not Available
Not Available
Not Available

5 To 24 V, 3 A
5 To 24 V, 5 A

78HGA
78HGA

LAS14U
LAS19U

LM350
LM338

SG350
Not Avaiiable

AdjustableNegative

-2 To -24 V, 5 A79HG

LAS18U

Not Available

Not Available

AdjustableSwitching

3 To 30 V, 5 A

Not Available

LH1605

Not Available

SH1605

(Step Down)

3-3

Cross Reference Guide
Ordering Information
Unique Level B Processing.
To meet the need for improved reliability in the
military market, high current voltage regulators are
available with special processing. Devices ordered to
this program are subject to 100% screening as
outlined in chapter 2. Devices may be ordered by
simply adding the letters "08" to the end of the
ordering code.

Ordering Information
Fairchild High Current Voltage Regulators may be
ordered using a simplified purchasing code.
S

C- Temperature Range Code

~ Package Code

Device Type (5 to 8 Digits)

Example
(a) 79 HG SM 08
This number code indicates a 5 amp, adjustable
negative voltage regulator, packaged in a steel,
4-lead TO -3 with an operating junction .
temperature range of -55°C TO +150°C and
screened to the Fairchild unique level 8 program as
outlined in Chapter 2.

Temperature Range Code
Operating Junction Temperature
C = Commercial
O°C to + 150°C
(unless otherwise specified)
V = Industrial (SH 223 only)
-25°C to +150°C
M = Military
-55°C to +150°C
Package Code
S = Steel TO - 3 Package
2-Lead }
4-Lead
Refer To Chapter 4
8-Lead
Device Type (5 to 8 Digits)
SH323
3 A, 5 V Fixed Regulator
78H05A
5 A, 5 V Fixed Regulator
SH1605'
5 A Switching Regulator
Examples
(a) SH 323 SC
This number code indicates a 3 amp, 5 volt fixed
regulator packaged in a steel, 2-lead TO -3 with an
operating junction temperature range of -25°C TO
+150°C
(b) 78 HG ASM
This number code indicates a 5 amp, adjustable
regulator with guaranteed maximum dropout voltage
limits, packaged in a steel, 4-lead TO -3 with an
operating junction temperature range of -55°C to
+150°C.

1

. !

3·4

FAIRCHILD
A Schlumberger Company

1IIII

~ID_a_m__S_h_e_et_s____________________

4-2

JlA78HOS • JlA78H05A

FAIRCHILD

5-Volt 5-Amp
Voltage Regulators

A Schlumberger Company

Hybrid Products
Connection Diagram
TO-3 Metal Package

Description
The jtA78H05 and jtA78H05A are hybrid regulators
with 5.0 V fixed outputs and 5.0 A output capabilities.
They have the inherent characteristics of the
monolithic 3-terminal regulators, i.e., full thermal
overload, short-circuit and safe-area protection. All
devices are packaged in hermetically sealed TO-3s
providing 50 W power dissipation. If the safe operating
area is exceeded, the device shuts down rather than
failing or damaging other system components
(Note 1). This feature eliminates costly output circuitry
and overly conservative heat sinks typical of highcurrent regulators built from discrete components.
•
•

5.0 A OUTPUT CURRENT
INTERNAL CURRENT AND THERMAL OVERLOAD
PROTECTION
• INTERNAL SHORT CIRCUIT PROTECTION
• LOW DROPOUT VOLTAGE (TYPICALLY 2.3 V @
5.0 A)
.
• 50 W POWER DISSIPATION
• STEEL TO-3 PACKAGE
• ALL PIN-FOR-PIN COMPATIBLE WITH THE SH323

(Top View)

Order Information
Type
Package
J.lA7805
Metal
jtA7805A
Metal
jtA7805
Metal
jtA7805A
Metal

Note
1. These voltage regulators offer output transistor safe·area
protection. However, to maintain full protection. the devices
must be operated within the maximum input·to-output voltage
differential ratings, as listed on this data sheet under "Absolute
Maximum Ratings." For applications violating these limits,
devices will not be fully protected.

Code
GN
GN
GN

Part No.
jtA78H05SC
jtA78H05ASC
jtA78H05SM
jtA78H05ASM

GN

Block Diagram

T

T

I
START
CIRCUIT

CURRENT SOURCE

VOLTAGE
REGULATOR

I

-::L.
7
r--

VIN

THERMAL
SHUTDOWN

1

I

SHORT
CIRCUIT
PROTECTION

R

"- "-

,.....

rK
Rsc

IJ

2
VOUT

3
COMMON

4-3

JlA78H05 • JlA78H05A
Absolute Maximum Ratings
Input Voltage
Input-to-Output Voltage
Differential, Output Short
Circuited
Internal Power Dissipation
Operating Junction
Temperature
Military Temperature Range
ILA78H05SM
ILA78H05ASM
ILA78H05 • ILA78H05A
Electrical Characteristics

Commercial Temperature
Range
ILA78H05SC
ILA78H05ASC
Storage Temperature Range
Pin Temperature
(Soldering, 60 s)

40V
35 V
50 W @ 25°C Case
150°C

O°Cto +150°C
O°C to +150°C
-55°C to +150°C
300°C

-55°C to +150°C
-55°C to +150°C
TJ

= 25°C, VIN = 10 V, lOUT = 2.0 A unless otherwise specified.
Limits

Symbol

Characteristic

Condition

Min

Typ

Max

VOUT

Output Voltage

lOUT

= 2.0 A
VIN = 8.5 to 25 V (ILA78H05)
VIN = 7.5 to 25 V (ILA78H05A)

4.85

5.0

5.25

V

10

50

mV

10

50

mV
mV

dVOUT

Line Regulation (Note 2)

dVOUT

Load Regulation (Note 2)

10 mA ::5 lOUT ::5 5.0 A

10

50

10

Quiescent Current

3.0

10

RR

Ripple Rejection

=0
lOUT = 1.0 A, f = 120 Hz, 5.0 Vpk-pk

Vn

Output Noise

10 Hz ::5 f ::5 100 kHz

lOUT

dB
40

= 5.0 A
lOUT = 3.0 A
lOUT = 5.0 A
lOUT = 3.0 A

Dropout Voltage (Note 3)

VOO

ILA78H05A
Short-Circuit Current Limit

lOS

rnA

60

lOUT

ILA78H05

Unit

ILVRMS

2.3

V

2.0

V

2.3

2.5

V

2.0

2.3

V

7.0

12.0

Apk

Notes
2. Load and line regulation are specified at constant junction
temperature. Pulse testing is required with a pulse width
~ 1 ms and a duty cycle of ~ 5"10. Full Kelvin connection
methods must be used to measure these parameters.

3. Dropout Voltage is the input-output voltage differential
that causes the output voltage to decrease by 5"10 of its
initial value.

Typical Performance Curves

Output Impedance

Output Noise Voltage

100

.

Maximum Power Dissipation
80

0,

lOUT = 1 A
YIN = lOY

YIN - 10V

CL = 0

50

0.5

1\

~

~

.
I

C,=D "\

/

i

~

'r-...

CL = 0.1

Cl

~ 0.05

10

100 .

1k

-

J.LFj

'\

'\

10

'\

10 J.LF rANT.

1.0
1

"

~ 0.1

V

10 k

LOAD FREQUENCY - Hz

100 k

1M

0,0'10

o

500

.. 100

,.

FREQUENCY _ H2:

4-4

5k 10 k

_21

0

25

so

75

100

CASE TEMPEAATURE _ OC

'\

125

110

~A78H05

•

~A78H05A

Typical Performance Curves (Cont.)

Short Circuit Current
10

Quiescent Current

Dropout Voltage
Your" 5V

>
I

'"

0-,.

z>w

I--..

'"
i3'"
!::
""

"""'T 75·~'"

""""'-.TJ -2S8 C

J

~

=

"

"

0

iii
o
o

.,0

20

30

3

i

2~--f---+---+---1---~

~

.......

~

~---+--7'=-+---~-",,"-+---~

ffi

M

a

35

INPUT VOLTAGE _ V

Line Regulation
'our-

~ 100
I

>

'OUT-SA

~-10~---+-HL-+_---1-----r--~

w

~

i

1-20~---+-H--+---~-----r--~

" -~
~-100

~ -30~---+-H--+---~-----r--~

>

g

5

~-40~---+-H--+---~-----r--~

5

I"

1

25

II

~
I

~

!rl
OJ
a:

~

40

10

100

.
...
1

~

Load Transient Response

loUT

~ 14

IOUT

l

.our

lSA

10

I

3A

1-20 I------+----+-----p.;~~;____l
l'l

~-30

1~-100

\.

r_+_t----1111 /'--t--t--+-+--t-+_~

~-200

.

~-4-+~4-+-+-~-4

1M

Output Voltage
Deviation vs
Junction Temperature
V1N =10V

i!l
Ii
~

_50

.....
,

I T= 2"

= SA

.....:::

l'j

~

1-1501--+----+-+--+-+--+--+-I

5

OUTPUT CURRENT _ A

~

I! -100 r_-+--+_-1-+--+--t-+~

~-.or----t----+-----r----+----i
-~OL--~--~~--~--~--~

lOY

100
1k
10k
lOOk
INPUT FREQUENCY _ Hz

I 100 t-+-+--t-+--+-1-frCL = 0.1,.,.F

~-10~--_t~~~----r_--_+--__i

...

'"'-"""" v

~ 2OOr-;--'--r-;--;-;~~~-'N~=~'0-Y-'
>

1SO

~

..

20

80 100

PULSE WIDTH nME _

125

·c

Cl = O.1#tF

I

100

~

20

7tii

VIN

....

"
o

~

VIN = lOY

10

INPUT VOLTAGE _ V

F""'"

Ripple Rejection
120

i

Load Regulation

laJT=2A

CL = 0.1,.,.F

20

-

1",.)= 3A r---

~

JUNCTION TEMPERATURE -

h'oUT=5A

IIv

5
I

lour'" 5A

I--

INPUT VOLTAGE - Y

Line Transient Response

2A

I
Ii

I-

o

20

40

10

PULSE WIDTH TIME -

4-5

eo

It'

100
JUNCnOII T&IIPERATURE - 'C

JLA78H05 • JLA78H05A
Test Circuit
Fixed Output Voltage
1

2
"A78H05
"A78H05A

SOLID
TANTALUM

VOUT

+

+
CIN
1 p.F

3

0.1
Cl

T

1.
Design Considerations
These devices have thermal-overload protection from
excessive power and internal short-circuit protection
which limits the circuit's maximum current. Thus, the
devices are protected from overload abnormalities.
Although the internal power dissipation is limited, the
junction temperature must be kept below the maximum
specified temperature (150°C). It is recommended by
the manufacturer that the maximum junction
temperature be kept as low as possible for increased
reliability. To calculate the maximum junction
temperature or heat sink required, the following
thermal resistance values should be used:
Typ
8JC
1.8

Package
TO-3

COMMON

Caution: Permanent damage can result from forcing
the output voltage higher than the input voltage. A
protection diode from output to input should be used if
this condition exists.
Package Outline
(S Package - Steel)
.2.95 (7.49)
.265 (6.73)

r·

780 (19.81)1
.76001(A19.30)

~
SEATIN~ PlLA-NE-'---~~=*

Max
8JC

.450 (1 1.43)
.400 (10.16)

t

2.5

.057(1.45)
.037 (0.94)

.043 (1.09)
.038 (0.97)

TJ(max) - TA
8JC + 8CA

Po (max)

=

8CA

=8cs + 8SA

Solving for TJ:
TJ = TA + Po (8JC

+ 8CA)

.180 (4.57) A
.150 (3.81)
2 PLACES
.525 (13.34) A
.480 (12. 19)
PIN 1

Where:
= Junction Temperature
TJ
TA
= Ambient Temperature
Po
= Power Dissipation
8JC
= Junction-to-case thermal resistance
8CA
= Case-to-ambient thermal resistance
8CS
= Case-to-heat sink thermal resistance
8SA
Heat sink-to-ambient thermal resistance

Notes
All dimensions in inches bold and millimeters (parentheses)
Pins are solder-dipped alloy 52

=

The devices are designed to operate without external
compensation components. However, the amount of
external filtering of these voltage regulators depends
upon the Circuit layout. If in a specific application the
regulator is more than four inches from the filter
capacitor, a 1 /LF solid tantalum capacitor should be
used at the input. A 0.1 /LF capacitor should be used
at the output to reduce transients created by fast
switching loads, as seen in the basic test circuit.
These filter capacitors must be located as close to
the regulator as possible.
4-6

p;A78H12A
5-Amp Voltage
Regulator

FAIRCHILD
A Schlumberger Company

Hybrid Products

Connection Diagram
T0-3 Metal Package

Description
The IlA78H12A is a hybrid regulator with 12.0 V
fixed output and 5.0 A output capability. It has the
inherent characteristics of the monolithic 3-terminal
regulators; i.e., full thermal overload, short-circuit and
safe-area protection. All devices are packaged in
hermetically sealed TO-3s providing 50 W power
dissipation. If the safe operating area is exceeded,
the device shuts down, rather than failing or damaging
other system components (Note 1). This feature
eliminates costly output circuitry and overly
conservative heat sinks typical of high-current
regulators built from discrete components.
• 5.0 A OUTPUT CURRENT
• INTERNAL CURRENT AND THERMAL OVERLOAD
PROTECTION
• INTERNAL SHORT CIRCUIT PROTECTION
• LOW DROPOUT VOLTAGE (TYPICALLY 2.3 V@
5.0 A)
• 50 W POWER DISSIPATION
• STEEL TO-3 PACKAGE

(Top View)

Order Information
Type
Package
IlA78H12A
Metal
IlA78H12A
Metal

Note
1. This voltage regulator offers output transistor safe·area
protection. However, to maintain full protection, the device
must be operated within the maximum input-to·output voltage
differential ratings, as listed on this data sheet under "Absolute
Maximum Ratings." For applications violating these limits,
device will not be fully protected.

Part No.
IlA78H12ASC
IlA78H12ASM

Code
GN
GN

Block Diagram

T

T

I
START
CIRCUIT

CURRENT SOURCE

VOLTAGE
REGULATOR

I

~t.l
r-

V"

V IN

THERMAL
SHUTDOWN

1

1

SHORT
CIRCUIT
PROTECTION

• R

......

"-

K

......
Rsc

II

2
VOUT

3
COMMON

4-7

JLA78H12A
Absolute Maximum Ratings
Input Voltage
Input-to-Output Voltage
Differential, Output ShortCircuited
Internal Power Dissipation
Operating Junction
Temperature
Military Temperature Range
ILA78H12ASM
ILA7812A
Electrical Characteristics

40V

Commercial Temperature
Range
ILA78H12ASC
Storage Temperature Range
Pin Temperature
(Soldering, 60 s)

35 V
50 W @ 25°C Case

O°C to +150°C
-55°C to +150°C
300°C

150°C
-55°C to +150°C

TJ

= 25°C, VIN = 19 V, lOUT = 2.0 A unless otherwise specified
Limits

Symbol

Characteristic

Condition

Min

Typ

Max

Unit

VOUT

Output Voltage

lOUT

11.5

12

12.5

V

AVOUT

Line Regulation (Note 2)

= 2.0 A
VIN = 16 to 25 V

20

120

mV

AVOUT

Load Regulation (Note 2)

10 mA ::; lOUT::; 5.0 A

20

120

mV

10

Quiescent Current

10

mA

RR

Ripple Rejection

Vn

Output Noise

= 0, VIN = 17 V
lOUT = 1.0 A, f = 120 Hz, 5.0 Vpk-pk
10 Hz ::; f ::; 100 kHz, VIN = 17 V
lOUT = 5.0 A
lOUT = 3.0 A

3.7

lOUT

Voo

Dropout Voltage (Note 3)

loS

Short-Circuit Current Limit

Notes
2. Load and line regulation are specified at constant junction
temperature. Pulse testing is required with a pulse width
:$ 1 ms and a duty cycle :$ 5%. Full Kelvin connection
methods must be used to measure these parameters.

60

dB
75
2.3

2.5

VRMS
V

2.0

2.3

V

7.0

12.0

Apk

3. Dropout Voltage is the input·to-output voltage differential
that causes the output voltage to decrease by 5% of its
initial value.

Typical Performance Curves

Output Impedance

Output Noise Voltage

100

0,

Maximum Power Dissipation

1.

louT = 1A
VIN ... 11V

50

YIN""

c"

r0-

0.5

Ct.=o "\

=

0

C, =0.1"i/
10,.,

1,\
1,\

10

,ANT.

1.0
10

1\

r1"

/

1

'\
1\

I-

) t-.....

i

50

r---.

1

C,

80

'IV

,.
1k
10k
LOAD FREQUENCY _ Hz

1DOic

111

0.01

o
10

500 1 Ie

50 100

FREQUENCY - Hz

4-8

Sic 10k

-25

0

25

50

75

100

CASE TEMPERATURE - ·C

128

150

,uA78H12A
Typical Performance Curves (Cont.)

Quiescent Current

Short Circuit Current

Dropout Voltage

•

12

c" ~

TJ = -" ..

3

r---.:: t'•1.

~J=12'.C
TJ = 25°C

"" TJ = 25°C

TJ~ r:::---

2

/

,.-

.&

2.

4.

3.

INPUT VOLTAGE -

1

)

I
2.

20

"

~

IOUT!2A
IOUT=5A

100

50

...>

~-

IOUT=SA

I

Iv

"z.
'"
!;
U

,.
INPUT

.

,.

VOLT~GE

Load Regulation
~
I

-10~---t~~~--~-----r----;

~

l'l

5

>-20~---t----+---~~~~~--;

o

..

~

20

40

60

200

IOUT

.
2.

80 100

125

150

CL

""

,IY
0.1 p.F

l

3A

IQurlSA

I
1

10

100

1k

'""

~

~V

10 k

100 k

1M

INPUT FREQUENCY - Hz

Output Voltage
Deviation vs
Junction Temperature

YIN'" 19Y

'00 ~+-t--t-+--+~---r.-CL

"

=

0.1 IJ.F

~-200~+-+~t-+--+~--+--r~--1

~

1----+----+----'-1----,...__""""1

~

~

f---f---f---f---'-r-----l

-100 ~-+--+--f--t--+-~---r--;

1-'50 f-----+--+----+--+--+--+---+---l
o

OUTPUT CURRENT - A

100

~~_ 100 ~+-+----'IIIr,--+--+-+-+--f-+---l

!;

!;
~ -4.

~
~

Load Transient Response

Ie

§!

eo

PULSE WIDTH TIME - P.s

I

~
~ -30

Z

;;J
a:

o

~

75

~

I

10

- V

50

I

ill

2.

2.

3Ar--

YIN =

;!;

20

2.

100

II

w

0

•

_25

=0

0

>

-

P-

1

YIN
19 Y
CL = O.lIJ.F

II

.

-50

II

lou;
lOUT = 2A

Ripple Rejection

l'l
0

i ~

120

r'\

i!i
Ii:;-20

~-30

lOUT-SA

JUNCTION TEMPERATURE _ ·C

Line Transient Response

E
I -10

-'

INPUT VOLTAGE - V

V

Line Regulation
>

I

"

,.

00

3

>

20

40

60

80 100

PULSE WIDTH nMe - /1-.

4-9

JUNCTION TEMPERATURE _ ·C

#L A78H12A
Basic Test Circuit
1

2
)lA78Hi2A

SOLID
TANTALUM

VOUT

+

+
C1N
l/LF

i'

3

CL
0.1 /L F

COMMON

.1
Design Considerations

Caution: Permanent damage can result from forcing
the output voltage higher than the input voltage. A
protection diode from output to input should be used if
this condition exists.

This device has thermal-overload protection from
excessive power and internal short-circuit protection
which limits the circuit's maximum current. Thus, the
device is protected from overload abnormalities.
Although the internal power dissipation is limited, the
junction temperature must be .kept below the maximum
specified temperature (150°C).-lt is recommended by
the manufacturer that the maximum junction
temperature be kept as low as possible for increased
reliability. To calculate the maximum junction
temperature or heat sink required, the following
thermal resistance values should be used:

Package Outline
(S Package - Steel)
.295 (7.49)
.265 (6.73)

~
SEATlN~

r·

780 (19.81)-1
.76°ot(A19.30)

.057(1.45)
.037 (0.94)

PLJ...A-NE----'"r-t...,.,=*

Package
TO-3

PO(max) =

Typ

Max

(JJC

(JJC

1.8

2.5

.450 (11.43)
.400 (10.16)

*

TJ(max) - TA
(JJC + (JCA

.161 (4.09) otA

.151 (3.84)
2 HOLES

= (JCS + (JSA

(JCA

Solving for TJ:
TJ = TA + Po «(JJC

.043 (1.09)
.038 (0.97)

+ (JJA)

Where:
TJ
Junction Temperature
TA
Ambient Temperature
.po
Power Dissipation
(JJC
Junction-to-case thermal resistance
(JCA
Case-to-ambient thermal resistance
(JCS
Case-to-heat sink thermal resistance
(JSA = Heat sink-to-ambient thermal resistance

=
=
=

Notes
All dimensions in inches bold and millimeters (parentheses)
Pins are solder-dipped alloy 52

=
=
=

The devices are designed to operate without external
compensation components. However, the amount of
external filtering of these voltage regulators depends
upon the circuit layout. If in a specific application the
regulator is more than four inches from the filter
capacitor, a 1 IlF solid tantalum capacitor should be
used at the input. A 0.1 IlF capacitor should be used
at the output to reduce transients created by fast
switc::hing loads, as seen in the basic .test circuit.
These filter capacitors must be located as close to
the regulator as possible.

4-10

JlA78HGA
Positive Adjustable
5-Amp Voltage Regulator

FAIRCH.ILD
A Schlumberger Company

Hybrid Products
Description
The ~A78HGA is an adjustable 4-terminal positive
voltage regulator capable of supplying in excess
of 5.0 A over a 5.0 V to 24 V output range. Only
two external resistors are required to set the
output voltage.

Connection Diagram
TO-3 Metal Package

The ~A78HGA is packaged in a hermetically sealed
TO-3, providing 50 W power dissipation. The regulator
consists of a monolithic chip driving a discrete seriespass element. A beryllium-oxide substrate is used in
conjunction with an isothermal layout to optimize the
thermal characteristics of each device and still
maintain electrical isolation between the various
chips. This unique circuit design limits the maximum
junction temperature of the power output transistor to
provide full automatic thermal overload protection. If
the safe operating area is ever exceeded (Note 1),
the device simply shuts down rather than failing or
damaging other system components. This feature
eliminates the need to design costly regulators built
from discrete components.
(TOp View)

• 5_0 A OUTPUT CURRENT
• INTERNAL CURRENT AND THERMAL LIMITING
• INTERNAL SHORT CIRCUIT CURRENT LIMIT
• LOW DROPOUT VOLTAGE (TYPICALLY 2.3 V@
S.OA)
• 50 W POWER DISSIPATION
• ELECTRICALLY NEUTRAL CASE
• STEEL TO-3 PACKAGE
• ALL PIN-FOR-PIN COMPATIBLE WITH ~A78HG

Order Information
Type
Package
~A78HGA
Metal
~A78HGA
Metal

Code

Part No.

JA
JA

~A78HGASC

~A78HGASM

Block Diagram-Positive Adjustable Voltage Regulator

I

I
START
CIRCUIT

I

CURRENT SOURCE

I

VOLTAGE
REGULATOR

I

~~
,.....

;:/'

VIN

THERMAL
SHUTDOWN

R

1'- ..... .....

1

1

SHORT
CIRCUIT
PROTECTION

L

,...,.,

~
Rsc

2
VOUT

3
CONTROL

4
COMMON

Notes on following pages.

4-11

ILA78HGA
Absolute Maximum Ratings
Input Voltage
Internal Power Dissipation
Maximum Input-to-Output
Voltage
Differential Output Short
Circuit
Operating Junction
Temperature
Military Temperature Range
Il A7 8HGASM

Electrical Characteristics

40 V
50 W @ 25°C Case

Commercial Temperature
Range
Il A78HGASC
Storage Temperature Range
Pin Temperature
(Soldering, 60 s)

35 V

O°C to +150°C
-55°C to +150°C
300°C

150°C
-55°C to +t50°C

TJ = 25°C, VIN = 10 V, lOUT = 2.0 A unless otherwise specified
Limits
Typ

Symbol

Characteristic

Condition (Note 3)

Min

VOUT

Output Voltage (Note 4)

lOUT = 2.0 A, VIN = VOUT + 3.5 V

5.0

~VOUT

Line Regulation (Note 2)

VIN = 7.5 to 25 V

0.2%

~VOUT

Load Regulation (Note 2)

10 mA :5 lOUT :5 5.0 A

10

Quiescent Current

lOUT = 0

RR

Ripple Rejection

lOUT = 1.0 A, f = 210 Hz, 5.0 Vpk-pk 60

Vn

Output Noise

10 Hz :5 f :5 100 kHz,
VIN= VOUT + 5.0 V

50

VOO

Dropout Voltage (Note 5)

lOUT = 5.0 A

2.3

2.5

V

lOUT = 3.0 A

2.0

2.3

V

lOS

Short-Circuit Current Limit

Vc

Control Pin Voltage

Unit

24

V

1%

V

0.2%

1%

V

3.4

10

mA
dB

VIN = 15 V
4.85

Notes
1. This voltage regulator offers output transistor safe-area
protection. However, to maintain full protection, the device
must be operated within the maximum input-to-outpufvoltage
differential rating listed on the data sheet under •. Absolute
Maximum Ratings." For applications violating these limits,
device will not be fully protected.
2. Load and line regulation are specified at constant junction
temperature. Pulse testing is required with a pulse width
!S 1 ms and a duty cycle !S 5%. Full Kelvin connection
methods must be used to measure these parameters.

Max

Il VRMS

7.0

12.0

Apk

5.0

5.25

V

3. The performance characteristics of the adjustable series
(I'A78HGA) is specified for VOUT ,. 5.0 V, unless
otherwise noted.
Rl + R2
4. VOUT is defined as VOUT =
(VCONT) where Rl
and R2 are defined in the Basic Test Circuit diagram.
5. Dropout Voltage is the input-output voltage differential that
causes the outp.ut voltage to decrease by 5% of its
initial value.

R2

Typical Performance Curves
Output Noise Voltage

Output Impedance

Maximum Power Dissipation
so

1.0

100

lOUT - 1 A
YOUT = 5 V

so

10V

V'N

0.5

YIN'" tOY

"'r-.

YOUT = 5V
CL
0

0

z

r--.,

C L = 0 ""\
1

)

""""

r---.

./

Tl'
CL -o.1,...F/

2.0

CL
10

I~
II:

~

0
2

1\
1'\

0

1

i\

10 /L f rANT.

1.0
1

~

40

100
1k
10 k
LOAD FREQUENC'( _ Hz

100 k

1M

0.01

0
10

so

100

soo ,.

FREQUENCY - Hz

4-12

5k 10 k

-25

0

25

50

75

100

CASE TEMPERATURE _ °C

[i\

125

150

JLA78HGA
Typical Performance Curves (Cant.)

•

10

TJ=

c

E

""",TJ = 25°C

........

TJ =15"C,,"

I~ ......
.-

2

o

o

•

~

i

I

.f----

30

20

"TJ = " ..

~

II

e

TJ=25-C

1

I

I

louT = SA

I

T "T

IOUT=3A

1

20

15

10

25

i

2.

INPUT VOLTAGE - V

INPUT VOLTAGE _ V

f--

IOUT=2A ~

!!

35

75

50

100

121

150

JUNCTION TEMPERATURE - OC

Ripple Rejection

Line Transient Response

Line Regulation

VOUT =5V

>

I

2

0/
810

-lex ~

...~

I

J'...
t'--,

Dropout Voltage

Quiescent Current

Short Circuit Current

120
>

IIV

'OUT=5A

~-10~--+-H~+---1--~---1

lou! 5AI=

,louT=3A

~

L20I--+-H--I--+---iI---I

CL = 0.1 p.F

100

~J

V

~ -30~~-+-H-+---1--~---1

I
Z

0

~

80

T

t

1~3A

5 50
II:

g

~
~

5

$-~r-~-&~---+---+--~

'curlsA
~

o
20

eo

80

PULSE WIDTH TIME -

INPUT VOLTAGE - Y

Load Regulation

40

100

I
1

10

~

~ 200
VIN = 10V
I 100 1--+-t--t--+--+--j--j.frVOUT '" 5 V
I~L

100

1k

''"'"""

10 k

1M

50
VIN = 10Y

rOUT

= 0.1 p.F

5

$-200
c

7

100 k

Output Voltage
Deviation vs
Junction Temperature

i1.>-100 1-+-+-4I/-/f-+--+--+-1~+--I
o

~

INPUT FREQUENCY - Hz

Load Transient Response

III

20

YIN = lOY
YOUT = 5V
CL = O.1IJ.F _

I

Your = SV

~

f-- f!1ouT=IA

i!l

VIN = lOY

I'V

7UT 12A

p

In, T == SA

1-+-+-+-+-1--~+-4-~~

F:::::::

I

!
I.>

-500L__

~_~_-~---L---~
OUTPUT CURRENT _ A

I

o

20

40

80

80 100

PULSE WIDTH TIME - lAS

4-13

-200
-SO -25

25

50

75

100

JUNCTION TEMPERATURE _ ·C

125

150

J-LA78HGA
Test Circuit
Adjustable Output Voltage
2
VOUT
1
~A78HGA

C IN = 21-'F ::::::
+
SOLID
TANTA LUM

Rl

CONTROL

+

3

:::::: CL'" 1.0 I-' F

~

4
R2
COMMO N

Caution: Permanent damage can result from forcing
the output voltage higher than the input voltage. A
protection diode from output to input should be used if
this condition exists.

Design Considerations
This device has thermal-overload protection from
excessive power and internal short-circuit protection
which limits the circuit's maximum current. Thus, the
device is protected from overload abnormalities.
Although the internal power dissipation is limited, the
junction temperature must be kept below the maximum
specified temperature (150°C). It is recommended by
the manufacturer that the maximum junction
temperature be kept as low as possible for increased
reliability. To calculate the maximum junction
temperature or heat sink required, the following
thermal resistance values should be used:
Package
TO-3

Voltage Output
The device has an adjustable output voltage from
5.0 V to 24 V which can be programmed by the
external resistor network (potentiometer or two fixed
resistors) using the relationship
R1 + R2)
VOUT = VCONTROL (
R2
Example: If R 1 = 0 f! and R2 = 5 kf!, then
VOUT = 5 V nominal.
Or, if R1 = 10 kf! and R2 = 5 kf!, then
VOUT = 15 V.

Max
liJC
2.5

Typ
liJC
1.8

Package Outline
(S Package - Steel)

TJ(max) - TA

PO(MAX)
liCA

= li JC + liCA
= lics + liSA

Solving for TJ:
TJ
TA + Po (liJC

=

~
~I

+ liCA)

.293 (7 44)
.273 (6 93)

Where:
Junction Temperature
TJ
Ambient Temperature
TA
Po
= Power Dissipation
liJC
= Junction-to-case thermal resistance
liCA
Case-to-ambient thermal resistance
liSA
= Heat sink-to-ambient thermal resistance
liCS
Case-to-heat sink thermal resistance

=
=

.421 (10.69>!
MIN
_

r

Ii·

~:~~~g::~~.770(1956)
MAX

f--

I

1

n
n
UU
III-,

I
+

: I i 1-

t

SEATING
PLANE

.067 (170)
MAX

I __
.041 (1.04) DIA
.037 (940) .
___ 1.197 (30.40) ___
1.177 (29.90)

=
=

PIN 1

I----~~ :~~~ ~ ~~~:~
PIN 2

This device is designed to operate without external
compensation components. However, the amount of
external filtering of this voltage regulator depends
upon the circuit layout. If in a specific application the
regulator is more than four inches from the filter
capacitor, a 1 p.F solid tantalum capacitor should be
used at the input. A 0.1 p.F capacitor should be used
at the output to reduce transients created by fast
switching loads, as seen in the basic test circuit.
These filter capacitors must be located as close to
the regulator as possible.

2 HOLES
.161 (409)
.151 (3.84)
.177 (45) R
2 PLACES
.470 (11.94)
DIA PIN
CIRCLE

Notes

PIN 3

.525 (1334)
MAX

All dimensions in inches bold and millimeters (parentheses)

4-14

J,LA78P05
5-Volt 10-Amp
Voltage Regulator

FAIRCHILO
A Schlumberger Company

Hybrid Products

Connection Diagram
TO-3 Metal Package

Description
The ILA78P05 3-terminal positive 5 V regulator,
consisting of a monolithic control chip driving a seriespass transistor, is capable of delivering 10 A. This
hybrid device is virtually blow-out proof and contains
all the protection features inherent in monolithic
regulators such as internal short-circuit current
limiting, thermal overload and safe-area protection. If
the safe-operating area is exceeded, the device shuts
down rather than failing or damaging other system
components (Note 1). This feature eliminates costly
output circuitry and overly conservative heat sinks
typical of high-current regulators built with discrete
components. The ILA78P05 is packaged in a
hermetically sealed TO-3 providing 70 W
power dissipation.

•

• 10 A OUTPUT CURRENT
• INTERNAL THERMAL OVERLOAD PROTECTION
• INTERNAL SHORT CIRCUIT CURRENT LIMIT
• LOW DROPOUT VOLTAGE (TYPICALLY 2.3 V @
10 A)
• 70 W POWER DISSIPATION
• PIN-FOR-PIN COMPATIBLE WITH THE ILA78H05,
ILA78H05A AND SH323
• STEEL TO-3 PACKAGE

(Top View)

Order Information
Type
Package
ILA78P05
Metal
ILA78P05
Metal

Note
1. This voltage regulator offers output transistor safe-area
protection. However, to maintain full protection, the device
must be operated within the maximum input·to-output voltage
differential ratings as listed on this data sheet under "Absolute
Maximum Ratings." For applications violating these limits,
device will not be fully protected.

Part No.
ILA78P05SC
ILA78P05SM

Code
6N
6N

Block Diagram

I

l
START
CIRCUIT

I

CURRENT SOURCE

VOLTAGE
REGULATOR

I

~tL
~

;'/'

VIN

THERMAL
SHUTDOWN

1

R

......

......

,....

V

I

SHORT,
CIRCUIT
PROTECTION

~
Rsc

I}

2
VOUT

3
COMMON

4-15

~A78P05
Absolute Maximum Ratings
Input Voltage
Input-to-Output Voltage
Differential, Output ShortCircuited
Internal Power Dissipation
Operating Junction
Temperature

Military Temperature Range
JLA78P05SM
Commercial Temperature
Range JLA78P05SC
Storage Temperature Range
Pin Temperature
(Soldering, 60 s)

40 V
35 V
70 W @ 25°C Case
150°C

JLA78P05
Electrical Characteristics

TJ

= 25°C, VIN = 10 V, lOUT =

O°C to +150°C
-55°C to +150°C

2.0 A unless otherwise specified
Limits

Symbol

Characteristic

Condition

Min

Typ

Max

Unit

VOUT

Output Voltage

lOUT

4.85

5.0

5.25

V

~VOUT

Line Regulation (Note 2)

= 2.0 A
VIN = 8 to 25 V

10

50

mV

~VOUT

Load Regulation (Note 2)

10 mA ::S lOUT ::S 5 A

25

40

mV

~VOUT

Load Regulation (Note 2)

10 mA ::S lOUT ::S 10 A

50

75

mV

IQ

Quiescent Current

lOUT

3.4

10

mA

RR

Ripple Rejection

=0
lOUT = 1.0 A, f = 120 Hz, 5.0 Vok-pk

Vn

Output Noise

VDD

Dropout Voltage (Note 3)

loS

Short-Circuit Current Limit

60

dB

10 Hz ::S f ::S 100 kHz

40

lOUT = 5.0 A

2.0

2.3

V

= 10 A

2.5

3.0

V

lOUT

JLVRMS

14

Notes
2. Load and line regulation are specified at constant junction
temperature. Pulse testing is required with a pulse width
:oS 1 ms and a duty cycle :oS 5%. Full Kelvin connection
methods must be used to measure these parameters.

Apk

3. Dropout Voltage is the input-output voltage differential
that causes the output voltage to decrease by 5% of its
initial value.

Typical Performance Curves

Output Noise Voltage
1.0

0.5

~

v"

II

1-- -

~

e'l
---

-

r-l"-

r-l

f'.-

I
0.1

f-0.01

-

tt--

m

l-

t-

--

:

I

1-

-

+

'II

I
10

50

100

500

1k

FREQUENCY - Hz

70

5 k 10 k

r\

IOUT=1A
V1N =10V

60

50
~
I

f\.

50

z

20
CL

'!

He-

f--j

Maximum Power DisSipation

100

0

~$

I

0.05

Output Impedance
lOV

'"

i

0 .......

10

V

!II

c

)t--...

5.0

2.0

CL

110

~

it

/A.Fj

100

1k

10 k

LOAD FREQUENCY - Hz

4-16

r\

20

\

10

o
10

:\

30

\

/l-F rANT.

1.0
1

\

0:

/
C L - 0.1

40

100 k

1M

-25

0

25

50

75

100

CASE TEMPERATURE _

G

125
C

150

JLA78P05
Typical Performance Curves (Cent.)

Short Circuit Current

,.
c
.. ,.
" ,.

Quiescent Current

I

TJ=

I-

Z

~r--.,

~
U

-..

TJ - 2S"C

"0t:
"!Iiu

TJ - 75°C

4

~

3

,

I-

~

C
E

r---

~
~

10

I

...
u
0

ill

•o

.,0

20

INPUT VOLTAGE - V

"~

IOU)'- SA- l - -

I ·20

z

o

o

i:i~ -40

.

!;

-

lOUT·· 10 A

o

g

1.

10

•0

••

I'
-60

~

o"

10

20

15

It~,I,-

-~

,i

Load Regulation

_1001--+-+--"F'O,U"-'_"i'S-=A+-+_tl->+---t--t

-2001---+-+-I---+-+-f---+-+-t-l

o

I

-50

z

---

o

~
~

..

T,

20

40

60

~

_25°C

~S·C~ ....... ~
T,

1~

-100

o

~

"~

100

0.4 '--""""'-'--"""""''''''-'-V-'Nr-_-,-'0-V'
O.21--+-+-I--+-+--t-f,.-CL =- 0.1 "F

I\,

~

.O.• I---+-+--Iff--+-+--I-+-+-+-I
i -O.41---+-+---'f---+-+-t-+-+-+-l
!;
o

125

150

°C

VIN ::

..",
Z

0

.~

100

~OV

Ct. = 0.1

~F

IOUT~'A

..

~
IoUT

l

1'\

3A

60

.

loUT

ls

"7

A

'"

I

20

80 100

o

1

10

100

1k

10 k

~
1M

100 k

INPUT FREQUENCY - Hz

Output Voltage
Deviation vs
Junction Temperature
50

YIN=10Y

~

i.

-

IO~T - {o A

I

r-- -.:r-

~

IOUT=2A

-so

.........

~

"~ -150

~ -100

g
I-

!;

!;
o

S

~ -200

I!: -150

VIN

-250

75

I

PULSE WIDTH TIME-pi

Load Transient Response
T,

so

120

~

INPUT VOLT AGE - V

~

.5

;;S

••

,A

Ripple Rejection

~

o

'0 ,

JUNCTION TEMPERATURE -

~ -80
"o
-100

o
-'S

200,-...,.......,.-.--........,.-.--,......,.......,-,
~ 100 1--+-+-SJFj1'_OU_'+=_'_0I-A-+ ~~N _.~ O~~ :F

lOUT - 2 A

'OU~!f

I

~

>
E

A-

1

Line Transient Response

0

~

-F=::

TJ = 25°C

INPUT VOLTAGE - V

Line Regulation

~

)

,J, -.J

""- "'TJ = , ••·C

(

00

3.

30

1

J. c, ~
~

,

.

Dropout Voltage

o

I

10 V

10
OUTPUT CURRENT -

A

o

20

40

80

80 100

PULSE WIDTH TIME - .....

4-17

-200
-50

-25

25

50

75

100

125

JUNCTION TEMPERATURE _ °C

150

jlA78P05
Basic Test Circuit
2

1

"A78P05

SOLID
TANTALUM

+

+
CIN

CL

3

0.1 /L F

l/L F

COMMON

~

Design Considerations
This device has thermal-overload protection from
excessive power and internal short-circuit protection
which limits the circuit's maximum current. Thus, the
devices are protected from overload abnormalities.
Although the internal power dissipation is limited, the
junction temperature must be kept below the maximum
specified temperature (150°C). It is recommended by
the manufacturer that the maximum junction
temperature be kept as low as possible for increased
reliability. To calculate the maximum junction
temperature or heat sink required, the following
thermal resistance values should be used:

Caution: Permanent damage can result from forcing
the output voltage higher than the input voltage. A
protection diode from output to input should be used if
this condition exists.
Package Outline
(S Package - Steel)
.295 (7.49)
.265 (6.73)

~
SEATIN~

r·

780 (19.81)1
.760DI(A19.30)

.057(1.45)
.037 (0.94)

PL-'-A-N-E----'-r-

~

~
I

7"C

Z

..

'\
1\
I",

4.

II 2.~

-6

-4

U

L2
•o

,.

-5

-10

-15

Dropout Voltage

Quiescent Current

-20

_25

-30

-35

•

-25

0

25

50

75

INPUT VOLTAGE - V

lOUT

'" '"

100

CASE TEMPERATURE _ °C

4-20

125

150

= -2A

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

-25

0

25

50

75

100

125

JUNCnON TEMPERATURE - QC

150

f.LA79HG
Typical Performance Curves (Cont.)

Line Transient Response
~

Load Regulation

I-+-+---jf-+-+-+Vour=
-s.oy
lOUT = -3.0 A

20

i

w 10~+-+~f-+-+-1--+-~-+~

~ ol-+-+....,f--t--t-j--i?+-+--I
~-101-+-+---j~+-+~--f-~-+-4
~

~-20~+-+-1f-+-+-1__+-~-+~
>

~-101-+-+f-f--t--t-j--~+-+--I

!1
!:;

g-~I-+-+f-f--t--t-j--+-+-+--I

i

1- 10

25'C

VIN=-10Y

\

"-75"C

\. 125-C

~
Ie

> -20
i!!
w

~
"g

-30

5

1!:-40

5

-50
PULSE WIDTH TIME -

Vo!.T ='-5.~V

1\

'-

'E

Load Transient Response

o

_1

~8

-2

-3

-4

-5

•

OUTPUT CURRENT - A

Output Voltage Deviation vs
Junction Temperature

Control Current
vs Temperature

Differential Control Voltage
vs Input Voltage

0.7
0 .•

VIN = -40V

~

~
Ie

-2A

-5A
~w -50 ~-+---I----1f-+--+--t--+~

~
"g

!Ew

'"'"
'"

0.2

~

~

]'\

YIN

L-L__....L..__.L.-L__..L__' - - ' - _
-25

25
50
75
100 125
JUNCTION TEMPERATURE _ ac

150

Maximum Power Dissipation
-5

~

~ -4

1-_

25";"-

/

u

ffi

-2

,,~

-1

o

o

-5

~

~

~

~

75"C

-10 -15 -20 -25 -30 -35 -40
INPUT VOLTAGE - V

o

o

I' C'-...
TJ=25"C,",

'~UTi

'fmf

25

50

75

i'

~

<1- 8.0

"r--

= 10 v
= -5.0 Y

YOUT

I'

!iE-I.a

I"'!,
0.1

_200

t-...

> -4.0
E

I"'!,
0._

6

5 -150 f---+---I--I---I--I---r---jf---

r--- r---

0.5

"
U

-2.0

OA

5

PULSE WIDTH 11ME - Id

100

-10

"r-.

125

JUNCTION TEMPERATURE _ °C

150

lour:

-12

-5.0

_2 A
YOUT = -S.OY

-10

-15
-20
-25
INPUT VOLTAGE - V

-30

j.LA79HG
Basic Test Circuit, Adjustable Output Voltage
3
VOUT

4

2~F 1

C IN =
SOLID
TANTA LUM

~A79HG

+

R1

CONTROL

+

2

CL'" 1.0 ~ F

~

1
R2

VOUT

COMM ON

(R1 + R2)
= VCONT'--R-2-

Caution: Permanent damage can result from forCing
the output voltage higher than the input voltage. A
protection diode from output to input should be used if
this condition exists.

Design Considerations
This device has thermal overload protection from
excessive power and internal short circuit protection
which limits the circuit's maximum current. Thus, the
device is protected from overload abnormalities.
Although the internal power dissipation is limited, the
junction temperature must be kept below the maximum
specified temperature (150°C). It is recommended by
the manufacturer that the maximum junction
temperature be kept as low as possible for increased
reliability. To calculate the maximum junction
temperature or heat sink required, the following
thermal resistance values should be used.

Package

Typ

Max

TO-3

IJJC
1.8

IJJC
2.5

Voltage Output
The device has an adjustable output voltage from
-2.11 to -24 V which can be programmed by the
external resistor network (potentiometer or two fixed
resistors) using the relationship:
VOUT = VCONTROL

Package Outline
(S Package - Steel)

+ IJSA

Solving for TJ:
TJ = TA + Po (lJJC

+ R2)

R2

Example: If R 1 = 0 f! and R2 = 5 kf!, then
VOUT = -2.11 V nominal.
Or, if R1 = 12.8 kf! and R2 = 2.1 kf! then
VOUT = -15 V.

TJ(MAX) - TA
PO(MAX) =
IJJC + IJCA
IJCA = IJcs

( R1

+ IJCA)

.293(744)
.273 (6 93)

_I
J±
r
I

_ _ Ii

1

Where:
TJ = Junction Temperature
TA = Ambient Temperature
Po = Power Dissipation
IJJC = Junction-to-case thermal resistance
IJCA = Case-to-ambient thermal resistance
IJcs = Case-to-heat sink thermal resistance
IJSA = Heat sink-to-ambient thermal resistance

i

.421 (1069)
MIN
~

_
PIN 1

~;;~ g~ :~;~I
.770 (1956)
MAX

I1
I

n
n
U U
_IIt -

I

+

SEATING
PLANE

: : : 1-·-

i

.067 (170)
MAX

.041 (104) DIA
.037 ( 940)
1.197 ( 3 0 4 0 ) _
1.177 (2990)

I-------<~ .675 (17 14)
.655 (1664)
PIN 2
2 HOLES
.161 (409)
.151 (384)

The device is designed to operate without external
compensation components. However, the amount of
external filtering of these voltage regulators depends
upon the circuit layout. If in a specific application the
regulator is more than four inches from the filter
capacitor, a 2 ,uF solid tantalum capacitor should be
used at the input. A 1 ,uF capacitor should be used at
the output to reduce transients created by fast
switching loads, as seen in the basic test circuit.
These filter capacitors must be located as close to
the regulator as possible.

.177 (4 5) R

2 PLACES
.470 (1194)
DIA PIN

PIN 3

CIRCLE
.525 (1334)
MAX

Notes
All dimensions in inches bold and millimeters (parentheses)
Pins are solder-dipped alloy 52
4-22

SH323 • SH223 • SH 123
3 A, 5 V
Voltage Regulator·

FAIRCHILD
A Schlumberger Company

Hybrid Products

Connection Diagram
2-Pin Metal Package

Description
The SH323 is a hybrid regulator with 5.0 V fixed output
and 3.0 A output capability. It has the inherent
characteristics of the monolithic 3-terminal regulators,
Le., full thermal overload, short circuit and safe area
protection. All devices are packaged in hermetically
sealed TO-3s providing 50 W power dissipation. If the
safe operating area is exceeded, the device shuts
down ·rather than failing or damaging other system
components (Note 1). This feature eliminates costly
output circuitry and overly conservative heat sinks
typical of high-current regulators built from
discrete components.
• 3.0 A OUTPUT CURRENT
• INTERNAL CURRENT AND THERMAL
OVERLOAD PROTECTION
• INTERNAL SHORT CIRCUIT PROTECTION
• LOW DROPOUT VOLTAGE (TYPICALLY 2.0 V
@3.0A)
• 50 W POWER DISSIPATION
• STEEL TO-3 PACKAGE
• ALL PIN-FOR-PIN COMPATIBLE WITH THE
LM323, SG323

(Top View)

Order Information
Type
Package
SH323
Metal
SH223
Metal
SH123
Metal

Part No.
SH323SC
SH223SV
SH123SM

Code
GN
GN
GN

Block Diagram

T

T

I
START
CIRCUIT

CURRENT SOURCE

VOLTAGE
REGULATOR

I

e-~
r-

~

THERMAL
SHUTDOWN

VIN

....

1
1
SHORT
CIRCUIT
PROTECTION

,,

R

~

K

......
Rsc

IJ

2
VOUT

3
COMMON

4-23

SH323 • SH223 • SH 123
Absolute Maximum Ratings
Input Voltage
Input-to-Output Voltage
Differential
Output Short Circuited
Internal Power Dissipation
Operating Junction Temperature
Industrial Temperature Range
SH223SV
Electrical Characteristics

TJ

Military Temperature Range
SH123SM
Commercial Temperature Range
SH323SC
Storage Temperature Range
Pin Temperature
(Soldering, 60 s)

40 V

35V
50 W @ 25°C Case
150°C

-55°C to +150°C
O°C to +150°C
-55°C to +150°C
300°C

-25°C to +150°C

'.

= 25°C, VIN = 10 V, lOUT = 2.0 A unless otherwise specified.
Limits

Symbol

Characteristic

Min

Typ

Max

Unit

Condition

VOUT

Output Voltage

4.85

5.0

5.25

V

lOUT

.:lVOUT

Line Regulation (Note 2)

10

25

mV

VIN

.:lVOUT
IQ
RR

Load Regulation (Note 2)

10
3.0

50

mV

10 mA ::5 lOUT ::5 3.0 A

10

mA

lOUT

Ripple Rejection

dB

lOUT

Vn

Output Noise

40

VOO

Dropout Voltage (Note 3)

2.0

2.3

V

los

Short Circuit Current Limit

7.0

12.0

Apk

Quiescent Current
60

~VRMS

Notes
1. This voltage regulator offers output transistor safe area
protection. However, to maintain full protection, the device
must be operated within the maximum input·to·output voltage
differential ratings, as listed on this data sheet under" Absolute
Maximum Ratings." For applications violating these limits,
device will not be fully protected.
2. Load and line regulation are specified at constant junction

= 2.0 A
= 7.5 to 25V

=0
= 1.0 A, f = 120 Hz, 5.0 Vpk-pk
10 Hz ::5 f ::5 100 kHz, VIN = 10 V
lOUT = 3 A
VIN = 10 V

temperature. Pulse testing is required with a pulse width
:os 1 ms and a duty cycle :os 5%. Full Kelvin connection
methods must be used to measure these parameters.
3. Dropout Voltage is the input·output voltage differential that
causes the output voltage to decrease by 5% of its
initial value.

Typical Performance Curves

.

,.

Short Circuit Current

.

.

I

'-..

""

.,.

1\

~TJ=25"C

TJ =75-e,,",

•

>

50

.........

a

Dropout Voltage

Maximum Power Dissipation

.........

i"-.

ao

INPUT VOLTAGE _ V

'\

.......

K

30

'\

,.
35

•

-25

0

2S

5Q

75

II 1,\
1,\

100

CASE TEMPERATURE _ ·C

4-24

125

150

'oJT=31
lour=2A :::;r

~

I•

-as

25

50

75

100

JUNCTION TEMPERATURE - ·C

125

150

SH323 • SH223 • SH 123
Typical Performance Curves (Cont.)

Line Regulation

Line Transient Response

Ripple Rejection
120

~I

VIN"" 10V
CL ", 0.1 J-LF

lOUT'" 2 A

-10

f---+-+-+-"--1'---+--j

:; -20

f---+-+-+-"--1--+--j

100

~

~

!li

!;i

i!lw

I
Z

0

80

;::

~

g

l;l
OJ

f---+-+--f--"--1--+--j

-30

a:

~

5~ -40 r----+-ir-+---+---f----j
10

15

20

~

o

25

Load Regulation

...........

~ -10

t'-

.1

..1

~
/
T J "" ', 2So C

-~

10

",5

~

1/

o

"

g~ -100

~-+-i--~-+-i--~-t-,

:J:

5

o~ -150

20

40

60

1.0
lOUT = 1 A
V1N =10V

£!

">

r-

'>

<

I"--

I

V

~

)r--.

g

n-

. / CL = O.l.F /

0.1

1----

I
1

10

100

1k

10 k

LOAD FREQUENCY - Hz

I
100 k

1M

0.01

Quiescent Current
VIN

10 V

C

0

+=

lS
r-

10

I

I

C l '" 10 ~F TANT.

1.0

JUNCTION TEMPERATURE - ·C

I

~ 0.05

i

f---t---t--t---t---t--t---t--j

J- 1

I"--

0.5

CL = 0 "

r-

_ 200 I--'-_-'-_'--'-_-'-_'---'-_...J
_ 50 - 25
25
50
75
100 125 150

80 100

Output Noise Voltage

100

r:;
w

o

20

IOUT=2A

w

PULSE WIDTH TIME - /.LS

Output Impedance

~
t(

t----tr-:;;;-I--t--t-"*=::::::r---r-1

OUTPUT CURRENT - A

/

1M

-50

§

r--

lOOk

o

~

-

10k

O

"5

r---

1k

VOUT vs Junction Temperature

I--+--+-+--+-+-f--t CL "" 0 1 I-tF
I'
-50 1--+--+-1/1/'---1-+-+--+-+--+--1
~ -100 1--+--+-t-+--t-f--f-+--t---1
:>

~_40

2.0

100

INPUT FREQUENCY - Hz

I

10

~

50

w

TJ '" 2S·C ---'

5.0

"

.
20

80 100

il
5"

5

-50

60

~

VIN == 10V

YIN"" 10V

~-25·C~

~~ -30
g

40

Load Transient Response

~
!:i;;: -20

i!l

20

PULSE WIDTH TIME

INPUT VOLTAGE _ V

I

10UT = 3 A

60

50

100

1 11
500

1k

FREQUENCY - Hz

4-25

5 k 10 k
INPUT VOLTAGE - V

•

SH323 • SH223 • SH 123
Test Circuit
Fixed Output Voltage

1

2
SH323

SOLID
TANTALUM

VOUT

+

+

r

CL
0.1

3

l/'F
CIN

COMMON

~

Design Considerations
This device has thermal overload protection from
excessive power and internal short circuit protection
which limits the circuit's maximum current. Thus, the
device is protected from overload abnormalities.
Although the internal power dissipation is limited, the
junction temperature must be kept below the maximum
specified temperature (150°C). It is recommended by
the manufacturer that the maximum junction
temperature be kept as low as possible for increased
reliability. To calculate the maximum junction
temperature or heat sink required, the following
thermal resistance values should be used.

Caution: Permanent damage can result from forcing
the output voltage higher than the input voltage. A
protection diode from output to input should be used if
this condition exists.

Package Outline
(5 Package - Steel)
.295 (7 49)
.265 (6 73)

r-.

~
SEATIN~

780 (1981)1
.76001(A1930)

.057(145)
.037 (0.94)

PL"-A-N-E----yh-.

Package
TO-3

PO(MAX) =
IJCA = IIcs

Typ

Max

IIJC

IIJC

1.8

2.5

.450 (11.43)
.400 (10 16)

t

=*

.043 (1.09)
.038 (097)

TJ(MAX) - TA
IIJC + IJCA

.161 (4.09) OIA
.151 (3.84)
2 HOLES

+ liSA

Solving for T J:
TJ = TA

+ Po (OJC + IICA)

Where:
Junction Temperature
TJ
Ambient Temperature
TA
Power Dissipation
Po
Junction-to-case thermal resistance
(JJC
Case-to-ambient thermal resistance
IICA
Case-to-heat sink thermal resistance
IIcs
Heat sink-to-ambient thermal resistance
liSA

PIN 1

Notes
All dimensions in inches bold and millimeters (parentheses)
Pins are solder-dipped alloy 52

The device is designed to operated without external
compensation components. However, the amount of
external filtering of this voltage regulator depends
upon the circuit layout. If in a specific application the
regulator is more than four inches from the filter
capacitor, a 1 ~F solid tantalum capacitor should be
used at the input. A O. 1 ~F capacitor should be used
at the output to reduce transients created by fast
switching loads, as seen in the basic test circuit.
These filter capacitors must be located as close to
the regulator as possible.

4-26

SH1605
5-Amp, High-Efficiency
Switching Regulator

F=AIRCHILD
A Schlumberger Company

Hybrid Products
Description
The SH1605 is a hybrid switching regulator with high
output current capabilities. It incorporates a
temperature-compensated voltage reference, a dutycycle controllable oscillator, error amplifier, high
current-high voltage output switch, and a power
diode. The SH1605 can supply 5 A of regulated
output current over a wide range of output voltage.
•
•

•
•
•
•
•

Connection Diagram
8-Pin TO-3 Type

STEP-DOWN SWITCHING REGULATOR
OUTPUT ADJUSTABLE FROM 3 TO 30 V
5 A OUTPUT CURRENT
HIGH EFFICIENCY
FREQUENCY UP TO 100 KHz
UP TO 150 W OUTPUT POWER
STANDARD 8-PIN, TO-3 PACKAGE

•
(Bottom View)

Order Information
Output
Temperature
Voltage
Range
3 V To 30 V
O°C to +70°C
3 V To 30 V
-55°C to +150°C
Block Diagram

51----------------------18
~

1

I7
I

VOUT

STEERING DIODE
(ANODE)

1

I
1

I
1

11
GROUND

I--_........~~..L.. CASE GROUND
R1
TIMING
CAPACITOR

CT

-..J._--I

1-_ _ _ _+--_-+--'VI1v-....,1,..-3

!~~~:IER
INPUT

R2

1

I
I
1

1

12

L ______________________ -.J
4-27

g!~~~~~~~R
NC~PINS6

Part
Number
SH1605SC
SH1605SM

SH1605
Absolute Maximum Ratings
Vin - You! (Min)
Input Voltage
Output Current
Operating Temperature (TJ)
Operating Temperature (T A)
SH1605SC
SH1605SM

Storage Temperature
Internal Power Dissipation
Duty Cycle
Steering Diode Reverse
Voltage
Steering Diode Forward
Current

5V
35 V Max
6A
150°C
O°C to +70°C
-55°C to +125°C

-65°C to +150°C
20W
20% to 80%
60 V
6A

Electrical Characteristics: T c = 25°C, TIN = 15 V, VOUT = 10 V unless otherwise specified.
SH1605SC/SH1605SM
Symbol

Characteristics

Conditions

Min

VOUT

Output Voltage

VIN 2: Vo + 5 V, 10 = 2 A

3.0

Vs

Switch Saturation

lOUT = 5.0 A,
lOUT = 2.0 A

VF

Diode On Voltage

lOUT = 5.0 A,
lOUT = 2.0 A

Vcc

Supply Voltage

IRo

Diode Reverse Current

VRO = 25 V

2.0

10

Quiescent Current

lOUT = 0.2 A

30

/lA
mA

Typ

Max

Units

30.0

V

1.5
1.0

2.0
1.2

V
V

2.2
1.6

2.8
2.0

V
V

35

V

10

Reference and Oscillator Section

XYREF

Voltage on Pin 3

2.5

V

l::,.V3/T

V3 Temperature Coefficient

150

ppm/oC

Xlc

Charging Current-Pin 4

l::,.Vc

10

VIN=10V

20

VIN = 35 V

20

VIN = 10 V

150

VIN = 35 V

150

Voltage Swing-Pin 4

25

50

V

0.5

Discharging Current - Pin 4

/lA

70

225

250

/lA

350

Switching Characteristics (See Test Circuit)
Symbol

Characteristics

Conditions

tr

Voltage Rise Time

lOUT = 2.0 A
lOUT = 5.0 A

700
1.8

ns

tf

Voltage Fall Time

lOUT = 2.0 A
lOUT = 5.0 A

700
900

ns
ns

ts

Storage Time

lOUT = 5.0 A

2.6

/lS

td

Delay Time

lOUT = 2.0 A

2.5

/lS

Min

Typ

Max

Units
/lS

Thermal Characteristics

Po

Power Dissipation

lOUT = 5.0 A
VOUT = 10 V

16

W

1)

Efficiency

lOUT = 10 V
VOUT = 5 A

75

%

8J-c

Thermal Resistance

4.5

°C/W

Notes
1. Typical is 30°C/W for natural convection cooling.
2. For heatsinking requirements see power derating curve.
3. VOUT refers to the output voltage range of a switching supply
the output LC filter as shown in the typical application circuit.

4-28

SH1605
Switching Waveforms

V3--------------.r---------------i
CLOCK SIGNAL
(PIN 4)

V2-----r
OV -

-

--

-+----...- - - - - I O F F - - - + i

-------t~

v,

-----------r

(PIN a)

WHERE V2-S0.2 V
4.0V" V3" 2.0V

Switching Characteristics Test Circuit

a

5

+

+

3

1000

-

SH1605

+

~F

15 V
4

.......---

----

1

7J:

T'"

~

CLOCK SIGNAL

Power Derating Curve
25
I/Jc=4.5"C/W CASE

\.
\

I'\.
"JA~35·C/W

o

.0

30

FREE AIR

eo

r- I90

-

120

~
'50

AMBIENT TEMPERATURE - DC

4-29

VL

RL ~15"±10%

SH1605
Design Equations

Inductance = Ll = ( Vin(nom) - VOUT) X tON
611

. .
POUT X 100
Efficiency (I)) = --"'---PIN
tON
Transistor DC Losses (PT) = louT X Vs -----'--tON + tOFF

Where:

.
tOFF
Diode DC Losses (Po) = louT X VF - - - tON + tOFF
Drive Circuit Losses (DL) = V30lN02 X

tON
tON

Switching Losses Transistor
(Ps) = VIN X louT

t,
2 (tON

Transistor Duty Cycle =

+ tf
+ tOFF)

~::r: tON X (~_
1\
VOUT
')

tON
tON

Diode Duty Cycle =

+ tOFF

+ tOFF

Delay Time = td = 2.5 /lS Typical
Storage Time = ts = 2.6/ls Typical
Nominal Input Voltage = VIN(NOM)
Output Voltage = VOUT

tOFF
= 1
tON + tOFF

Power Inductor
(PL) = louT2 X RL (Winding Resistance)
Efficiency (I)) =
VOUT louT
VOUT louT + PT + Po + DL
Where:

POUT =
PIN
lOUT
Vs

X 100

Output Power Dissipation
Input Power Dissipation
Output Current
Darlington Switching Saturation
Voltage
Regulator "On" Time
Regulator "Off" Time
Steering Diode Forward
Voltage Drop
Input Voltage
Regulator Switching Rise Time
Regulator Switching Fall Time
Output Voltage
Inductor Winding Resistance

[VOUT~::: R2)] -

.
Timing Capacitance (CT)
Where:

+ Ps + PL

VOUT SET RESISTANCE = Rs
=

Change in Inductor Current = 61 1
= 2 X louT(Min)
Minimum Continuous Output Current
= IOuT(Min)
On Time = tON> (td + ts)
tON is determined by the design and
depends upon the desired
frequency of operation under
constant load conditions where
frequency = 1/(ton + tOil). Off Time,
toll, is determined by the ratio of
input voltage and output voltage

tON X Ie
6V e

= ---

Charging Current on Pin 4 = Ie
= 25/lA Typical
Voltage Swing on Pin 4 = 6 Ve
= 0.5 V Typical

Frequency = F = - - - - - - - CT 6Vc + 611 Ll
Ie
VOUT + VF
Where:

Steering Diode Forward Voltage Drop
= VF
= 2.2 V @ 5 A Typical
(From Elect. Char.)
= 1.6V @ 2 A Typical
(From Elect. Char.)

Minimum Output Capacitance
6it

=

COUT(MIN)

(8 X F(MIN) X VRIPPLE(MAX))

[Rl

+ R2J

= [2 X 103 VoUT - 2 X 103J
VREF

Where:

Minimum Expected Frequency = F(MIN)
F(MIN) =
CT 6Vc
Ie

= 8 X 102 VOUT - 2 X 103 Typical

+

6it (MAX) L

VOUT

+ VF

Maximum Change in Inductor Current
Where:

Internal Resistors = Rl = R2
=1X103 f!
Reference Voltage On Pin 3 = VREF
= 2.5 V Typical

=

AI I(MAX) = (VIN(MAX) - VOUT) X t ON
Ll

L>

SH1605
Maximum Expected Input Voltage
=

VIN(MAX)

Maximum Expected Ripple Voltage
=

VRIPPLE(MAX)

Effective Series Resistance of
=

CONT

= ESR

VRIPPLE(MAX)

L:. 11(MAX)

Typical Application
300 ~H

8

5

3

C,
1000

SH1605

;

Rs

~F

VII';

+ 50V
;;;,

--

1

2

CT

.O~~~

Rs

=

1~F

.-----~

- . - - -

,

1-

1/=70%

.875 (22.225) DlA MAX

I

I

Load Reg. = 50 mV
Line Reg. = 50 mV
Ripple = 100 mV

I

.100~~
.085 (2.16)

~-IIf-r--'-----------'---'--+--'---'1

---1

-'-...,.i-'-----,.,-"'TT-TT'"'TT"---'-f--'.......... t

L....

VOUT

VIN = 12-18V
VOUT = 5V
lOUT = 5 A (Max)
lOUT = 1 A (Min)

'I

.280-,----(7.,,)
_ '_
.220
(5.59)

t

+

+

"'

-I--

2.5

Package Outline
(S Package - Steel)

Co
2000 ~F
50 V

7

;;;,

_
03...:(c..
V",OU",Tc..-_
2--.:...
5)
2_X_1_

.450 (11.43)
.250 (6.35)

--

CASE
4

Rs = VOUT Set Resistor

L,

~

~ ~ ~ ~
-II-

SEATING
PLANE

.042 (1.07) CIA 8 PLACES
.039 (0.99) TYP

1-_ _ _ '.197 (30.40) _ _ _.1
1.177 (29.90)

.,--+--- ~~OCIRCLE
.159 (4.04) CIA
.154 (3.91)

.188 (4.78) R MAX.
2 PLACES

Notes
All dimensions in inches bold and millimeters (parentheses)
Pins are solder-dipped alloy 52
4-31

SH1605
Following is a partial list of sockets and heat
dissipators for use with the SH1605. Fairchild
assumes no responsibility for their quality or
availability.
a-Lead TO-3 Hardware
Sockets

Heat Sinks

Mica Washers

Robinson Nugent
0002011

Thermalloy 2266B Keystone 4858
(35°C/W)

Azimuth 6028 (test IERC LAIC 3B4CB
socket)
IERC HP1-T03Augat 8112 - AG6 33CB (7°C/W)
AAVID 5791B
AAVID
ENGINEERING
30 Cook Court
Laconia, New Hampshire 03246
Azimuth Electronics
2377 S. EI Camino Real
San Clemente, CA 92672
Augat
P.O. Box 779
Attleboro, MA 02703
IERC
135 W. Magnolia Blvd.
Burbank, CA 91502
Keystone Electronics Corp
49 Bleecker St.
New York, N.Y. 10012
ROBINSON
NUGENT INC.
800 E. 8th St.
New Albany, IN 47150
Thermalloy
P.O. Box 34829
Dallas, Texas 75234

4·32

F=AIRCHIL.O
A Schlumberger Company

5-2

High Current Voltage
Regulator Applications

I=AIRCHILO
A Schlumberger Company

This application note is to assist the user in
designing power supplies and on card regulation
systems using Fairchild's family of series pass High
Current Voltage Regulators.

VOUT(Max)

Selecting the Correct High Current Voltage
Regulator
The regulator selection guide (Table 1) provides a
concise table of key regulator specifications by
device number. Select the device that provides the
desired output voltage and current, then proceed as
follows.

Maximum output voltage of regulator

VOO(max)

=

6. VL

Maximum line voltage change

VR(pk)

=

Maximum dropout voltage

Peak ripple voltage

=

Also determine T A(max) = Maximum ambient
temperature and select TJ < TJ(max) from the data
sheet and see the application note titled "Thermal
Considerations" for heat sink requirements.

Determine the required input voltage (VIN).
VIN(maX)

=

Design Precautions
When designing and laying out a regulator circuit,
follow these guidelines to save time, money and
simplify design.

> VIN > VOUT(max) + VOO(max) + 6. VL + VR(pk)

where
•
VIN(max) = Maximum allowable input voltage
VIN

=

Regulator input voltage under load

Keep all ground leads as short as possible. Use
ground conductors sufficiently large enough to
handle rated currents to reduce unwanted voltage
drops across leads, and to minimize heating
effects and lead inductance.

High Current Voltage Regulator Selection Guide

·S

..

0

:::J
LL

I:

41
U
41

SH323

0

U

I:

-.. . .
- »
41
01

eu
0.-

-:::J>e
Q.eu

..5:!:

Fixed
Positive

40

78H05A

Fixed
Positive

78H12A

41
01

eu
0'-

>2:."S~

.e-I:

:::Jeu

oa:

I:

I:

I:

0

0

:::J

eu
:;

:;

41

0.-

-<
:::J_

Q.>e
"Seu

O:!:

I:

;(
-:!:
1:_

01
41

01
41

-

~~

0... >
o_

eu.-

.-

ii';

...I~

00

""C

41..5~

4I""C

a:'ID

..

11141
41 ..
:::J:::J

o::.!!

eu
0

U

41
'Qj'

UI:

41_

a:

...1_

41
01

0

eu

a:

. >

:::J

Thermal
Resistance
Max (OC/W)

0

41
01

eu

.¥

Q.

IJJC

IJJA

2.5

38

U

III

n.

2-Pin

4.85
5.25

3

40

4.85
5.25

5

0.2

0.2

3

60

2.3

2.5

38

2-Pin
TO-3

Fixed
Positive

40

11.5
12.5

5

0.2

0.2

3.7

60

2.3

2.5

38

2-Pin
TO-3

78HGA

Adjustable
Positive

40

5
24

5

0.2

0.2

3.4

60

2.3

2.5

38

4-Pin
TO-3

79HG

Adjustable
Negative

-40

-2.11 -5
24

0.4

0.7

-5

60

-2.2

2.5

38

4-Pin
TO-3

78P05

Fixed
Positive

40

4.85
5.25

0.2

1.0

3.4

60

2.5

1.8

38

2-Pin
TO-3

0.2

0.2

3

60

2

TO-~

10

5-3

High Current Voltage Regulator
Applications
•

Use single-point grounding at the regulator
common terminal whenever possible to prevent
circulating currents or ground loops.

•

When using the adjustable multi-terminal
regulators, especially at high output current
levels, derive the feedback sense voltage from
across the load rather than from across the
regulator to improve circuit performance.

•

abuse and fault conditions that may be
encountered occasionally. Continuous operation
of the device under fault conditions such as a
short or in a thermal shutdown mode is not a
recommended procedure.
Proper attention must be paid to the safe-area
protection network when these regulators are
operating with excessive input voltage or
excessive input-output differential-voltage
conditions. In addition to reducing the available
output current with high input-output differential
conditions, the safe-area protection network may,
under certain conditions, cause the device to
latch-up if the output is shorted to ground. This
situation is aggravated as the input voltage, load
current or the operating junction temperature is
increased. This mode of operation does not
damage the device but power (input voltage or
load current) must be interrupted momentarily for
the device to recover from the latched condition.

High Current Voltage Regulators are particularly
attractive because of the small number of external
components required. It is good practice,
however to use bypass capacitors at all times.
Input bypass capacitors (1 ~F for positive positive
regulators and 2~F for negative regulators) are
especially critical if the regulator is located any
appreciable distance from the power supply filter.
Output bypass capacitors (0.1 ~F for positive
regulators and 1.0 ~F for negative regulators) are
also required to improve transient response.
These bypass capacitors should be mylar,
ceramic or tantalum with good high frequency
characteristics. If more than one bypass capacitor
source or more than one type is used, stability
should be checked on each source or type. Stable
operation with one capacitor from one vendor
may not necessarily result in stable operation with
a capacitor of the same type from a second
vendor, since the characteristics of the capacitors
may vary.

Precautions must also be taken to avoid regulator
operation beyond its absolute maximum ratings.
Switching transients exceeding the maximum
input voltage rating of a regulator, for instance,
can destroy a regulator. These transients, which
. occur especially if the regulator input voltage is
switched instantaneously rather than ramped by
the natural smoothing provided by the ac line and
the filter capacitors, are usually hard to track and
normally caused by lead inductance and fast
switching currents. Good quality bypass
capacitors that have low series resistance cause
the inrush current to increase further, thereby
causing a higher magnitude transient at the input
of the regulator. In such cases, a lower quality and
cheaper bypass capacitor may be the answer.

Regulator output impedance is in the order of
100 ml1 or less and increases as a function of
frequency above 10kHz due to the gain rolloff of
the error amplifier. A tantalum electrolytic bypass
capacitor connected to the regulator output will
maintain low impedance for frequencies up to 1
MHz. A ceramic capacitor should be placed in
parallel with the tantalum capacitor for driving fast
switching loads to compensate for the rising
impedance of the electrolytic capacitor above 1
MHz. If switching loads are distributed over a
large area, additional ceramic bypass capacitors
should be located at the loads. Very large-value
output bypass capacitors should not be used
unless adequate measures are taken to prevent
the output from rising above the input, or to avoid
discharging the bypass capacitor through the
series-pass transistor of the regulator if the input
is accidentally grounded. A reverse-biased diode
connected from input to output is normally
sufficient to achieve this protection.
•

Because of their output stage configurations,
positive regulators source current and negative
regulators sink current. These restrictions should
be kept in mind and, under no circumstance,
should a regulator output terminal be allowed to
go more than a few volts higher than the regulated
output of the regulator. The power should be
turned off before removing or inserting a regulator
into a test socket. However, if it is necessary to
insert a regulator intoa "live" socket, care must
be taken to ensure that the common terminal
connection is made prior to, or simultaneously
with, the input terminal connection. In the absence
of the common terminal. connection, the output
voltage of the regulator is 1 or 2 V below the input
voltage. This type of fault condition can cause an
excessive output voltage which may adversely
affect the circuits supplied by the regulator. If the
common terminal is quickly connected, the
regulator can be dest~~yed. Also, damage to the
regulator may result from the discharging of the
bypass capacitor through the output and common
terminals.

Internal protection circuits are provided in all High
Current Voltage Regulators to improve reliability
and make these regulators immune to certain
types of overloads. These on-chip components
protect the regulators against short-circuit
conditions (current limit), excessive input-output
voltage differential conditions (safe-area limit) and
excessive junction temperatures (thermal limit).
The protection circuits protect the device against

5-4

High Current VOltage Hegulalor
Applications
•

The thermal properties and limitations of voltage
regulators are extremely important in circuit
design. Whether or not a heat sink is required
should be determined before the circuit is laid out.
See the application note entitled "Thermal
Considerations.' '

Adjustable regulators are ideal for applications that
require non-standard output voltages. Output
voltages are determined by the following equation:

Applications
A few of the most popular High Current Voltage
Regulator Applications are illustrated in this section.
These illustrations include both basic applications
and some applications more exotic to extend the
capabilities of the regulator.

Where: R1 and R2 are set resistors as shown in
Figures 2 and 3.
VCONTROL

=
=

5 V(NOMINAL) for the /-lA78HGA
-2.23 V(NOMINAL) for the /-lA79HG

Output voltage can be set anywhere between + 5 V
to +24 V for the /-lA78HGA and -2.11 V to -24 V for
the /-lA79HG. A trimpot may also be substituted for R1
and R2 to allow for either full range adjustments or
output voltage trimming.

Basic High Current Voltage Regulator
Configurations
Figure 1 shows the basic connection diagram for
fixed positive high current voltage regulators
including the SH323, SH223, SH123, /-lA78H05,
/-lA78H05A, /-lA78H12A and the /-lA78P05. The user
may refer to Table 1 or the individual data sheets to
determine which regulator satisfies his system
needs.

Fig. 1 Basic Fixed Positive High Current Voltage Regulator with Bypass Capacitors
OUTt--,,-+VOUT

+VIN-_~IN

POSITIVE
REGULATOR'
COM
CASE
COMMON

COMMON

SINGLE POINT GROUND

* Device Type SH323, SH223, SH123, /-lA78H05,

/-lA78H05A, /-lA78H12A, or /-lA78P05 depending
upon desired system parameters. See Table 1.

Fig. 2 A Basic Positive Adjustable High Current Voltage Regulator

r---------------~2
OUT 1--.._-_- +VOUT
IN

R,

"A78HGA
COM CONTROL
4

3

+

COUT
0.1 "F

R2

SOLID
TANTALUM
COMMON-----~~~~~==~-----COMMON

SINGLE POINT GROUND

Notes
V OUT

R1 + R2
= --R2

V CONTROL

Nominal = 5 V
Recommended R2 current

VCONTROL

~

1mA
5-5

High Current Voltage Regulator
Applications
Fig. 3 A Basic Negative Adjustable High Current Voltage Regulator
OUT

4

IN

t-......-....----....-+ •
0.001

~A79HG

-VOUT

~F
COUT

1

COM CONTROL

~F

+
SOLID
TANTALUM

COMMON----~~~~====~---------COMMON
SINGLE POINT GROUND

'May be necessary with long leads

VOUT =

( R1+R2)

R2

V CONTROL

VCONTROL

Nominal = -2.23 V

Fig. 4 Parallel Operation of Regulators For Very High Current

+VIN

IN

2
OUT I - - - - _ - + V O U T

~A78H05

COM
CASE

IN

~A78H05

OUT

2

COM
CASE

IN

~A78H05

OUT

2

CIN l~F
SOLID TANTALUM
COMMON

SINGLE POINT GROUND

Parallel Regulators
To obtain even higher output current, several
regulators in parallel may be used. Regulation of the
overall system can be improved if the individual
devices are matched for output voltages as shown in
Figure 4. If the outputs are not matched, it is likely
that the output current will not be shared between the
regulators and, as a result, some of the regulators
will operate at or near the current limit while others
are at their quiescent no-load levels.

Excessive Input/Output Differential
When a regulator is operating with a large inputoutput differential, the addition of a series resistor
with the input extends the operating range of the
device by sharing the power dissipation, see Figure
5. The value of the series resistor R1 must be low
enough so that, under worst-case conditions, (lowest
supply voltage, highest output voltage, and highest
load) the device remains in regulation. R1 can be
calculated as follows.

5-6

High Current Voltage Regulator
Applications
R1

=

Fig. 5 Reducing Power Dissipation in a Regulator
with Dropping Resistor R1

VS(min) - VOUT(Max) - VDD(maX)
louT(max)

+ IO(max)

where
RI

Vs(min) is the minimum supply voltage
VDD(max) is the maximum dropout voltage
IO(max) is the maximum quiescent current
VOUT(maX) is the maximum output voltage

=

=

Line Regulation (Max)

------'~--~~--

+ lo(max)] R1

120 mV
X 6.6 V
25 V - 16 V

88 mV

From PD(max) = (35 - 11.5) X 3
70.5 W (without R1).

=

To PD(max) = (35 - 3.3 X 3 - 11.5) X 3 =
40.8 W (with R1)
Note that the power dissipation is shared between
the regulator and R1.

Load regulation at constant Vs = load regulation
at constant VIN + line regulation

Although bypass capacitors are not shown in Figure
5, it is recommended that they be incorporated in the
design as illustrated in Figure 1.

Example: Assume a supply range of 25 to 35 V used
with a J.LA78HG12A regulator delivering an output
current of 1 to 3 Amps.

Input Voltage> VIN(maX)
When a regulator is used with supply voltages
greater than the rated regulator maximum input
voltage, the circuit shown in Figure 6 can be used.
This circuit essentially provides a constant voltage to
the regulator with supply voltage variations. The
choice of Zener diode voltage is dictated by VIN(min) of
the regulator and VSE(max) of Q1.

From the data sheet: VOUT(min) = 11.5 V
VOUT(max) = 12.5 V

=

=

The inclusion of the 33 Q reduces the maximum
power dissipation of the regulator as shown below.

The load regulation can therefore be calculated as
follows.

IO(max)

X 6 VIN =

The effect is 88 mV additional change at the output
terminal.

For load regulation, assuming constant supply
voltage, the combined effects of the change at the
input due to the voltage change across R1 must be
taken into consideration. In this configuration, as the
load is increased, the regulator input voltage
decreases and the net result, in most cases, is a
slight degradation in the performance of the
regulator since these two effects are additive.

=

lOUT

6 VIN (For Line Regulation Test)

For a constant load, the regulator input voltage
varies by the same amount as the supply voltage and
consequently the line regulation of the device
remains essentially the same.

VDD(maX)

COM

The effect of the 6.6 V change at the regulator input
under worst case conditions can be determined from
a ratio of data sheet parameters:

[VIN(max) - VOUT(min)]loUT(max)
VS(max) - [louT(max)

2.

OUT ~

CASE1 • IQ

where
VIN(maX)

REGULATOR
IN

Vs

Maximum regulator dissipation, however, occurs
with highest supply voltage and highest load
current.
PD(max)

VIN

2.5 V
10 mA

R1 = 25 - 12.5 - 2.5 = 3.3Q
3 + .01
With this value of R1 and a load varying from 1 to 3A,
the input voltage to the regulator varies,
6 VIN = 610uT R1 = 6.6V

5-7

•

High Current Voltage Regulator
Applications
Fig 6 Regulator Input Circuit for Input Voltage Source Greater than

VIN(max)

REGULATOR

+vs

OUT

IN

+VOUT

i----r---'" +

COUT
0.1

~F

COMMON------~==::::==~~~----------COMMON

Fig. 7 High Output Voltage Regulator, No Short-Circuit Protection

IN

+VIN

POSITIVE
REGULATOR

C,N

CASE

OUT

2

+VOUT
+COUT
0.1

R,0PTIONAL
SEE TEXT

~F

COMMON--~----------~--------------COMMON

Fig 8 High Output Voltage Regulator with Short-Circuit Protection
Q2

2

OUTt-_---.._-+VOUT

COMMON

COMMON

voltage exceeds the maximum input voltage rating of
the regulator.
Figure 8 can be used to take advantage of the
protective features of the regulator. Here too, the
regulator common terminal operates on the pedestal
established by Zener diode D1. Zener diode D2 and
the Darlington configuration of 01, 02 reduces the
regulator input voltage to a safe value. The
Darlington configuration prevents loading of Zener
diode D2, and thus maintains a high level of
regulation. Diode D3 protects the regulator against
accidental shorts by clamping the common terminal
of the regulator to a diode drop above the shorted
output.

High Output Voltages
Figure 7 shows a simple circuit that can be used to
obtain an output voltage greater than the standard
fixed voltages available. The quiescent current
biases Zener diode D1 and the regulator common
terminal rides on the pedestal established by D1. If
the Zener must be operated at currents greater than
the quiescent current level of the regulator, then R1
can be used to increase the Zener current. If, on the
other hand, lower Zener current is satisfactory, R1
can be placed in parallel with D1 to shunt some of the
current. Caution: this circuit configuration cannot
utilize the thermal shutdown or short-circuit
protection features of the regulator if the input
5-8

High Current Voltage Regulator
Applications
The input voltage VIN must be high enough to
accommodate the dropout voltage at the low end, but
must not exceed the maximum input voltage rating at
the high end.

Remote Shutdown
Electronic shutdown is used in some applications
where, under certain conditions, the removal of
power from the load is desired. The 3-terminal
regulator circuit of Figure 9 has a remote shutdown
feature. Under normal conditions, 02 is on and
provides the base current of 01 .

Positive and Negative Adjustable Regulators
The concepts used above for positive fixed
regulators can easily be extended to the JlA78HGA,
positive adjustable regulator, by simply including the
R1, R2 resistor network shown in Figure 2.

01 acts as a switch and is either in saturation, when
the signal to the base of 02 is high, or is off when the
signal to the base of 02 is low. It must have a current
rating equal to the load current. Turn-off time is
dependent on C2 and the load current; the higher the
load current, the faster the turn-off time.

Also, since negative voltage regulators are
complements of the positive voltage regulators,
almost all the positive regulator applications can be
converted into negative versions by appropriate
changes in the polarity of the input voltages. If
external active components such as series-pass
transistors are used, they should be the
complements of those used in the positive-regulator
application, i.e., npn transistors replaced by pnp and
vice versa. Finally, these concepts can be extended
to the JlA79HG, negative adjustable regulator, by
simply including the R1, R2 Resistor Network shown
in Figure 3.

Constant Current Regulator
Any regulator can be used as a constant-current
regulator as shown in Figure 10. The current lOUT
which dictates the regulator type to be used is
determined by this equation.

lOUT

=

VOUT

--

R1

+ 10

where VOUT is the regulator output voltage and 10 is
the quiescent current.
Fig. 9 Remote Shutdown

+VIN _ _ _--"' 0,

POSITIVE
2
REGULATOR OUT

IN

+VOUT

COM
CASE
CIN

+COUT

+1"F

O.1"F

SOLID
TANTALUM

COMMON-----~-~-~-~----~COMMON

Fig. 10 Constant Current Regulator (Positive Output)

~J...

IN

POSITIVE OUT
REGULATOR
COM

::; CIN
SOLID
TANTAL U'; 1"F

CASEl

L

2

t

VOUT
Q, _

~

;;;

COUT

::;O.1"F

R,

,.:
COMMON

5-9

lOUT

~

High Current Voltage Regulator
Applications
Dual Regulators
Dual regulators, or dual power supplies, are normally
used for applications requiring two output voltages
of opposite polarities that do not necessarily have
equal magnitudes, for example, +12 V, -5 V.
However, the word dual can also imply two supplies
of the same polarity but of different magnitudes, such
as +5 V, + 12 V. With dual tracking, not only are the
output voltages of different polarities, but one output
voltage always follows the other one, i.e., an increase
in the positive voltage results in a decrease in the
negative output voltage.
Dual Supplies
The simplest dual-polarity high current supply can be
obtained by using a positive and a negative
adjustable regulator with a center-tapped

transformer as shown in Figure 11. The same type of
dual supply can be achieved with two positive (or two
negative) adjustable regulators if a transformer with
two isolated windings is used as shown in Figure 12.
The reverse-biased diodes connected across the
outputs of the dual regulator circuits are not
necessary if the loads are referenced to ground. If
the loads are tied between the two outputs, however,
a latch-up may occur at the instant power is turned
on, especially if one regulator input voltage rises
faster than the second one. The diodes, that ensure
proper start-up of the regulators by preventing a
parasitic action from taking place when power is
turned on, should have a current rating equal to half
the load current.

Fig. 11 Dual Supply using a Center Tapped Transformer with a
Positive and a Negative Adjustable High Current Voltage Regulator
r------.J.-

CASE GROUND

R1
TIMING
CAPACITOR

C,

--''-----I

I
I
I
,

1 - - - - - + -_ _""""'V\tv--r'-3 !~~~~'ER
INPUT

R2

, ______________________
L
4-27

'2 g!~~~~~~~R

~

~-~6

Part
Number
SH1605SC
SH1605SM

High Current Voltage Regulator
Applications
Fig. 13 A Dual Positive Supply with a +5 Vand +10 V Output
2

+VIN-.....- - - - - - - - 1 I N

"A78HOS
A

OUTt-<~........--VOUT

10 V

COM

0,

CASE

IN

"A78HOS
B

...-----'-----VOUT
SV

OUT t-_-~

COMMON-~----~----.....~--4--------------COMMON

Fig. 14 A Dual Polarity Supply from a Single Transformer Winding

SECONDARY
WINDING

IN

POSITIVE
REGULATOR OUT
A

lOUT + A
+VOUT

COM

RL+

CASE

IN

POSITIVE
IOUTB
REGULATOR OUT
B
2

COMMON

RL -CASE

Figure 13 shows a single positive-polarity dual
supply with + 5 and + 10 V output. It uses two 5 V
!LA?8H05 regulators operating from a single positive
voltage source. The + 10 V output is achieved by
connecting the common terminal of the top regulator
A to the output of the bottom regulator B. Diode 01
ensures proper start-up of the top regulator and
prevents a latch-up that may occur under a heavy
load condition on regulator A. Resistor R1 provides a
path for the quiescent current of regulator A and can
be eliminated if regulator B has a minimum load
current greater than the quiescent current of
regulator A.

-VOUT

adjustable regulators. Because of the internal
feedback of the 4-terminal regulators, a constant
voltage is developed across the resistor string R1,
R2 and R3. Variations at one of the output nodes are
reflected at the control nodes causing corresponding
variations at the opposite output node. Note that
tracking between the two outputs is not one to one
but rather depends on the absolute value of the two
references and the feedback resistors R1, R2, and
R3. The output voltages are determined by
VOUT+ =

VREF+

R1
+(VREF+

-

VREF-)

R2

The concept of Figure 13 can be used to achieve a
dual-polarity output from a floating single supply as
shown in Figure 14. This circuit is restricted in that
RL + > RL -, since all of the current provided by the
positive regulator A must flow through RL -.

VOUT- =

R4

VREF - - (VREF+ -

VREF-)

R3
Tracking between the outputs can be improved by
adding a !LA? 41 and modifying the circuit as shown in
Figure 16. This circuit yields an adjustable true dualtracking regulator with internal short-circuit
protection, safe-area limiting, thermal overload
protection, and is capable of a 5 A maximum output
current. The outputs of the regulators are
independently adjustable by potentiometers R1 and

Adjustble Dual Tracking Regulators
For applications requiring adjustble tracking outputs,
the circuit of Figure 15 can be used. Tracking is
accomplished by connecting a common resistor
between the control terminals of the two 4-terminal
5-11

High Current Voltage Regulator
Applications
R2. With the component values shown, the output
voltage of the positive JlA78HGA can be varied from
5 to 24 V, and the negative JlA79H6 can be varied
from -2.11 to -24 V.

follows: any change in the positive regulator output
causes an opposite change on the common
terminals and also on the negative regulator output.
For example, a decrease in the positive regulator
output voltage causes a like change in the amplitude
of the negative regulator output. Since each regulator
has a reference, no slaving exists between the
outputs and, as a result, tracking is true and
independent of polarity.

This circuit has a positive and a negative regulator
and an operational amplifier used as a comparator.
Tracking is accomplished by connecting the two
regulator common terminals to the output of the
JlA 741 that provides a potential on which the
common terminals of the regulators float. The
summed regulator outputs, Vo+ and Vo-, are then
compared to the power supply common.

Proper care must be taken to insure that the
maximum supply voltage rating of the JlA741 is not
exceeded when the regulators are operating with
high input voltage sources.

The positive and negative regulator outputs track as
Fig. 15 Adjustble Dual Tracking Regulator
OUT

L~

IN "A78HGAI "A79HG
+
"F

+VOUT
+
r"0.1 "F

Fl1

caNT

COM

1

COMMON

COMMON

+~hF

+

R2

COM

CONT

1 "FJ,.

~

IN "A78HGA/"A79HG
OUT

'f~~

R3

Fig. 16 Independently Adjustable True Dual Tracking Power Supply
OUT
1

IN

COM
;;;

L~

"A78HGA

+
O.33"F

+VOUT
R1

25k

CONT
3

4

+",
O.l"F'"r-

R3

5k

COMMON

~'7
"A741

3V

6
R4

4

2.2k
*+
l"F
1

+
2"F
4

-v IN

IN

CONT~

"A79HG

++

OUT

.1

3

r:

R2

i> 25k
VOUT

COMMON
-'-

5-12

High Current Voltage Regulator
Applications
Miscellaneous Applications
This section consists of a set of illustrations showing
a variety of additional high current voltage regulator
applications.
Fig. 17 Negative Output Voltage Circuit

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

r-----<~-----

~II

~OUTPUT

+

POSITIVE
REGULATOR

':"

Fig. 18 Programmable Supply
+10V

+35 V
TIMER COUNTER

I

20 k

16

1

3~

15

2

;6 k

20 k 14

3

8k

4

4k

5

2k

13

1

"F

2240
0.1"F

+ 10 V

F

1

10 k

11

OUT
0----

10 k
10
....-+---4>--W\r-.......-t

"A78HGA

---

Output Waveform

30V------/

/

~/64STEPS

5vI

OV----------_______

5-13

VOUT

IN
2.5
k

COMMON
CONTROL

I---'

" 0.1

"F

•

High Current Voltage Regulator
Applications
Fig. 19 Motor Speed Control

OUT
~A78HGA

25k

IN

+V'N

12 TO 20 V
DC MOTOR

R,

0.1 ~F

I

........

VOUT =

V RI

(

1

+

:~ )

+ IQR2

5-14

R2

OUTPUT

High Current Voltage Regulator
Applications
Fig. 22 Signal Driver/Modulator

1

2

~A78H05

0.1
3

OUTPUT

1 "F
47

SIGNAL
INPUT

n

1

l.
Fig. 23 High-Current ECl Regulator Using ILA79HG

Out

5.2

"A79HG

Rl 2.7 K 1%

In

Unr
Inpu

r

33 on

Control

2.0

'~"r'

~F

Common

V VOUT

~
1 ~F

R2 2 K 1%

_

....

'Solid Tantalum Close to Device

Fig. 24 Operational Amplifier Supply (± 15 V @ 5 A)
+15 V OUTPUT
10 kn
+20V
INPUT

+
1 ~F

IN4001
OR EQUIVALENT

0.1 "F

3
7.5 kll

GND

GND

2.0~F

2
-20V
INPUT

4

+
1 ~F

~A79HG

IN4001
OR EQUIVALENT

12 k!l

3

-15 V OUTPUT

5·15

Understanding the
Switching Regulator

FAIRCHILO
A Schlumberger Company

keep components small and switching inaudible.
Filter F serves as an averaging filter, converting the
pulse from S into a dc voltage. Assuming no losses,
the power in equals the power out:

A basic switching regulator is composed of four
major components: a voltage source Ein, a switch S1,
a pulse generator Ep, and a filter F1. The block
diagram in Figure 1 shows the interconnection
between these elements. The voltage source may be
any dc supply needing conversion and/or regulation
- a battery, an unregulated rectified and filtered
supply, or even a regulated voltage to be converted
into some other required voltage. The requirements
for a voltage source are:
•

It must be capable of supplying the required
output power plus the losses associated with the
switching regulator.
Pin

=

Pout

•

The input voltage must be sufficiently high to
overcome any IR drops and meet the minimum
requirements of the system.

•

The input voltage must be large enough to supply
sufficient dynamic range for line and load
variations.

•

This switching mechanism allows a conversion
similar to transformers, thus the switching regulator
has often been referred to as a dc transformer. The
relationship of input and output voltage is a function
of duty cycle. The duty cycle is the ratio of the ontime (ton) to the period (tp = ton + toft = 1/f). Thus, the
duty cycle
(J

=

ton
ton

+ toft

, Eout =

(J

Ein = ( t o n ) Ein
ton + toft

With (ton + tott = tp) constant, the output voltage Eout
is directly proportional to the on-time ton. Thus,
varying ton varies the output voltage (i.e., pulse width
modulation).
With ton held constant, the output VOltage, Eout, is
inversely proportional to the period, tp = ton + toft, or
directly proportional to the frequency, f = 1/(ton +
toft).

In a modern computer power supply, the input
voltage may be required to store energy for a
specified amount of time during brownouts or
power failures.

These techniques allow efficient generation of low
voltages from high voltages in a stepdown regulator.
Operating from voltages much too high for linear
conversion affords a wide dynamic range and high
energy input storage for brownouts and missing
cycles.

Fig. 1 Basic Switching Regulator

The Filter
The filter or integrating network is of major
importance in the proper design for the switching
regulator. The filter basically has three forms:

RC filter

RL filter

RLC filter

While all these filters are used in switching
regulators, the RLC filter is most often used in series
switching regulators. A brief analysis of the RC and
RL filters gives the foresight needed for
understanding the RLC filter design.

SwitchS is typically a transistor or thyristor
connected as a power switch. The switch is
inherently efficient because it is operated in the
saturated mode. The pulse generator alternately
turns S on and off. The pulse is generally an
asymmetrical square wave varying in either
frequency (frequency modulation) or pulse width
(pulse with modulation). Theoretical analysis and
formulas generally apply to both frequency or pulse
width modulated systems. The frequency f1 of the
pulse generator is usually in the tens of kilohertz to
5-16

Understanding the Switching
Regulator
The RC Filter
A simple switching regulator employing an RC filter is
shown in Figure 2. When a switch 01 closes, the
instantaneous current in capacitor C1 is very large
and limited only by the series resistance Rs and the
ESR* of the capacitor. This instantaneous current
can be found from Kirchhoff's Voltage Law, using
Laplace transforms.

The resultant formula is the familiar equation for
finding the current in an RC circuit. It can easily be
seen that at t = 0 +, the current is limited by R only.
When switch 01 is open, the voltage across C1
starts to decay in accordance with the formula:

(See Figure 2)
E

S -

~

-

IsR

+

_15_;
CS

Is ( R +

R

=

Rs

+ ESR*
In order to maintain the voltage on C1 (Le., Eout)
relatively constant, it is necessary to make the
charge time constant much shorter than the load time
constant

ds )

*ESR = Effective Series Resistance =

Is

E

=

~
Q

As R becomes smaller, the averaged square wave
approaches a dc source. However, as R becomes
smaller, the peak current Ie becomes larger. These
peak currents are very high and impractical to switch
reliably. As R is increased to limit the current, it
becomes noticeably lossey and dissipates excessive
power.

-1

a=

RC

- - - eat

The Rl Filter
A simple switching regulator employing an RL filter is
shown in Figure 3. As switch 01 closes, the voltage
across the inductor is the full power supply voltage
E. The current supplied to the load at t = 0+ is
approximately equal to zero and exponentially

s-a

-t

Is

=

E
R

-e

RC

Fig. 3 Simple Switching Regulator with Rl Filter
RS

Rs

+

Ee

EL ~ E (INDUCTOR)

TIME

5-17

Understanding the Switching
Regulator
The RLC Filter
Combining the RC and RL filters gives all of the
advantages of both, with few of the disadvantages.
Figure 4 depicts the RLC filter in the simple switching
regulator. The inductor L 1 is used to limit the peak
currents associated with the charging of capacitor
C1. This current will be highest during the initial turnon of the power supply with all initial conditions set to
zero. This circuit is shown in Figure 5. The peak
current then is again derived by Laplace transforms
from Kirchhoff's Voltage Law.

increases as shown in the curve in Figure 3. In a
similar fashion, the instantaneous current can be
found using Laplace transforms and Kirchhoff's
Voltage Law:

E

S

= IsR + IsLS;

. . . RE[1

Yielding: IL =

R = Rs + Rinductor
~

e

~RtJ

-L~

The resultant formula is the familiar equation for
finding the current in an RL circuit. It can easily be
seen that at t = 0+, the current is zero. Thus the
time constant L/R must be smaller than the load time
constant to average the square wave into a dc
source.
L1

L1

R

RL

-

E

S

1
= IsRs + IsLS + IsRL l i CS

E

S

-«Is

While the inductor does overcome the large peak
current phenomenon of the RC filter, there are three
important disadvantages associated with the RL
filter.
•

Since the current cannot change instantaneously
in an inductor, a sudden change in the load (RL)
will cause an abrupt change in the output voltage.
This phenomenon is the limiting factor that
determines the transient response of a switching
regulator.

•

The energy stored in an inductor is determined
from the equation

e=

1

2

[

R~S+1
RLLCS2 + (Rs R L C + L) S + Rs + RL

U2.
Is

Since the energy changes with the square of the
current, the inductor must be very large to provide
constant current flow when the load current is small.
•

[~Jx

The disruption of current in 01 (shutting 01 off)
causes the magnetic field associated with L 1 to
collapse and induce a potential in accordance
with Lenz' law:

Resulting in the form:
This negative voltage places a very large voltage
across transistor switch 01 and will probably
result in its destruction.
VCE(Off)

= Ein

f(s) =

+ IeL I

5-18

S (S

S+d
a) (S

~

~

b)

]

Understanding the Switching
Regulator
Yielding the general equation: I = Ae at + Be bt + K
A=

a+d
a(a - b)

B=

b+d
b(b - a)

K=

d
ab

diode D1 steers the current developed by the
collapsing magnetic field and charges capacitor C1
during the off-time; D1 also acts as a clamp and limits
the negative potential to one diode drop. Diode D1 is
called a steering diode, com mutating diode or free
wheeling diode. This circuit not only protects switch
01, but also uses the energy stored in the magnetic
field to charge capacitor C1 ; thus, Ll2 = CE2.
Optimization of the RLC filter requires examination of
the current loop equation for the RLC filter. Figure 5
depicts the RLC circuit used for the analysis.

This formula is used in the section analyzing a typical
switching regulator. A typical curve for Is is shown in
Figure 6.
Under light load conditions, the capacitor C1
supplies the necessary current to the load in
accordance with the equation e =

~ CE2.
2

-R

Under

8, =--a-+

heavy load conditions, the energy stored in L1
supplies the current in accordance with the equation
e=

-R

82 = - - +
2L

~ Ll2. The energy stored in the magnetic field

2
that resulted in the negative induced voltage can now
be applied as an advantage. As shown in Figure 4,
Fig. 4 Basic Switching Regulator with RLC Filter

0,

V
A =_0
2L

1= Aes,t - Aes2t;

V
V

R2
1
4L2 - LC

R2
4L2

1
LC

Fig. 6 Turn-On Peak Current

c,

Fig. 5 Equivalent Circuit (Turn-On)

Fig. 7 Frequency Response Curve of an RLC Filter
RL

A: CRITICALLY DAMPED
B: OVERDAMPED
C

C: UNDERDAMPED

TIME

5-19

Understanding the Switching
Regulator
The waveforms for the dual circuit are the same as
those in Figure 7. Thus, to insure that for both on and
off conditions of switch 01, both circuits are slightly
overdamped.

Examining the roots of the equation shows that three
special conditions exist:

*

Underdamped case:
R2
1
4L2 < LC ;

W<0.5R

V-f<

The solution is complex and is exhibited as an
oscillatory condition. This condition is undesirable
due to the associated losses, i.e., energy in the
ringing, and the RFI produced. See Figure 7.

W>0.5R

In the off-condition, RL is variable, with the worst
case occurring during light loads. This can be
alleviated with a minimum RL or a snubber network
as used in the on-condition. As aforementioned,
meeting these inequalities enhances both the RFI
characteristics and the possibility of parasitic
oscillations.

The solution for these roots is real. This condition is
also undesirable in the extreme case due to its
associated losses. See Figure 7.
Critically damped case:

4L2

LC

0.5 RL (off-condition)

In the on-condition, Rs is a fixed quantity and should
be made small to minimize IR losses. Thus, a
snubber network may be required to dampen any
oscillations associated with a small Rs.

Overdamped case:

~ __1_

0.5 Rs (on-condition)

~CL

"\

V i-

Overshoot and Undershoot
When the load is abruptly changed (i.e., load current),
the output voltage changes accordingly. This is
called overshoot for decreasing loads and
undershoot for increasing loads. Expressions for
overshoot and undershoot can be derived from the
two equations:

0.5 R

=

The equation has a real solution and is the most
desirable case since losses are at a minimum.
However, since this is not a practical case state, the
circuit is operated in a slightly overdamped condition.
See Figure 7.

di
-eL = L dt

During the off-condition of switch 01, the circuit
becomes the dual of Figure 5. This too has three
similar conditions:
Underd ampe d case

V-f
-

L

where
eL = Ein - Eout for increasing loads
eL = Eout for decreasing loads
di = ic = change in load current = 61
t = transient time
dv = overshoot/undershoot voltage

0.5

>R

VIc
-t <0.5R

Overdamped case "\

·· II y d amped case
C ntlca

V-f
-

L

.

IC=

0.5
=
-

C - dv
.
d'
IC= I
dt '

dt=C

R

Ldi
eL

=

~
di

C ~
di

Ldi 2
dv=-C eL
6 Eout =

L 61 2
f
. Ioa d s
or'increasing
C (Ein - Eout)

L 61 2
6Eout=-C Eout
5-20

for decreasing loads

Understanding the Switching
Regulator
Transient Response

is directly proportional to the inductance. Item 5, the
circuit overshoot

The transient response, as mentioned earlier, is
limited by the size of inductor L1. This transient
response time tR is the time necessary before the
system can compensate for an abrupt change in the
load, assuming zero loop response. Transient
response time can be found from the equation:

[ .6Eout

=

L .61 2
C (Ein - Eout)

J

is directly proportional to the inductance. Item 6, the
size and cost are directly effected by the inductance
as well as a host of other factors.

di
-eL= L dt
2L .61

Item 7, the effect of the inductor on radiated electrical
and magnetic noise is a function of geometry,
frequency, size and cost. It becomes apparent that
selecting the inductor requires careful consideration
of the aforementioned tradeoffs. Applications of
these tradeoffs are considered in the analysis of a
typical switching regulator.

for increasing loads

Ein - Eout

for decreasing loads
The Inductor

The inductor is perhaps the least understood of the
switching regulator components and yet one of the
most important. There are seven major areas with
tradeoffs to be considered.

2. Peak current limiting in 01

Inductor design has many philosophies associated
with it. Size constraints are radiated electrical and
magnetic fields may dictate a powder toroid or pot
core; however, in most applications (computer and
peripherals), the decision is left to the design
philosophy. The three most common techniques
employed in the industry are:

3. Output ripple

•

Powdered permalloy toroids

4. Transient response

•

Ferrite EI, U and toroid cores

5. Overshoot

•

Silicon steel EI butt stacks

6. Size and cost limits

The first technique, the powdered permalloy toroid,
yields perhaps the most stable and predictable
inductor. Powdered permalloy toroids have low
leakage inductance, high permeability and low core
losses. The major disadvantage is the cost of
manufacturing and mounting toroid inductors.

1. Energy storage for the regulator

7. Radiated electric and magnetic fields
As inductance is increased, items 1 through 3 are
enhanced. Item 1, the energy (e = ~ L 12) is

2

The ferrite EI, U and toroid cores exhibit low losses.
The ferrite toroid has low leakage inductance but is
as expensive to manufacture as its powdered
permalloy counterpart. All ferrite cores have low
permeability, poor high temperature performance
and the expense in mounting. The silicon steel EI butt
stack offers one of the best tradeoffs in low voltage
switching regulators. The silicon steel laminations
exhibit high permeability, high flux densities, ease of
construction and mounting. Core losses, while higher
than the powdered permalloy and ferrite cores, are
usually insignificant at low voltage levels. The silicon
steel lamination is a common material in most
magnetic houses and often can be found on the
shelf.

directly proportional to the inductance. Item 2, the
peak current,

is inversely proportional to the inductance. Item 3,
the ripple voltage
[ ERIPPLE --

Ein - Eoutl
41!'2f2LC

J

is also inversely proportional to the inductance.
However, as the increase in inductance enhances
operation of items 1 through 3, it is detrimental to
items 4 through 6. In item 4, the transient response
[ tR

=

2.61
Ein - Eout

J
5-21

Understanding the Switching
Regulator
The magnetizing from Ampere's Law is found from
the equation:

Inductor Design
Combining Faraday's Law and Lenz' Law yields:

E

N

=

~

X 10-8

~

L

=

dt

Hdc

dt

=

0.4 Nldc

The inductance is found from the equation:
L

N d4>x 10- 8

=

3.19N2Ac X 10- 8

dt

=

.f

L

Ig

6J.L

d'

_I

=

LI

BAeN X 10- 8

=

Incremental permeability can be found from
manufacturers' data sheets as shown in Figure 8.
Linearity of the inductor can be enhanced by making
Ig large.

dt

Multiplying both sides by
~ L 12 =

~ yields:
2

Units:
Ac = cross sectional area (in.2)
Bac = ac flux (Gauss)
Bdc = dc flux (Gauss)
f = frequency (Hz)
Hdc = magnetizing force (Oersteds)
Ie = mean length of core (in.)
Ig = gap (in.)
N = number of turns
6J.L = incremental permeability

B Ae NI x 10- 8

2

2

which is the energy stored in the inductor. Integrating
Faraday's Law E
flux in the core.

=

N de/> yields the formula for ac
dt

3.49 E x 106 G
auss
f Ac N

Bac

There are several off-the-shelf inductors
manufactured by Sprague called Soft Inductors. The
Soft Inductor is designed specifically for switching
regulators, with a special variable reluctance gap.

The dc flux is found from the equation:
Bdc

=

+..!£

0.6 Nldc Gauss
Ig

Figure 8
10,000

130

sooo

o.~

,/

100

.

r----

H, 0

>>10

20

50 100 200

..........

1"\

0

"-["'\

I)"
2

r\

0

5

\

¥'

.

500 1000 2000 5000 10,000

o

~

~

~

~

~

m

[\
\
_

~

PERCENT OF RATED DIRECT CURRENT

BMAX(GAUSSJ

a. Incremental permeability curve for AISI grade M-

b. Effect of dcin a typical filter choke. Inductance
drops linearly until rated dc is flowing through coil,
then drops rapidly as core saturates. The linear
portion of the curve has less slope for inductors that
have larger air gaps.

22 laminations where Ho is the dc magnetizing force
in core.

5-22

Understanding the Switching
Regulator
The Output Capacitor
Selection of the output capacitor also requires care.
Consideration must be given to both the ESL and the
ESR. Very often the ESR contributes more to ripple
and noise than its reactance does. Desirable
characteristics can be achieved by carefully
paralleling three or four different types of capacitors
such as tantalum, electrolytic and ceramic
capacitors. Capacitors especially developed for
switching regulators are now available in a multitude
of ranges, sizes and types, with low ESR and low
ESL at the switching frequencies. A curve of the 4terminal UFT capacitor (manufactured by Cornell
Dubilier) compared to a conventional electrolytic is
shown in Figure 9. The curve plots impedance versus
frequency. The UFT capacitor remains quite flat
beyond 1 MHz. The UPT capacitor, also
manufactured by Cornell Dubilier, is designed for
switching regulators and gives one of the best
performance/cost tradeoffs available. A simplified
equivalent circuit is shown in Figure 10.

=

Z3

=

Rdo

Z2//Z3

,=

+ Ij(XESL - Xc)
(Rs + rs + ESR) + j(X2 + XESL ESR

------~---~---

ERIPPLE

E [
(Rs

In

ERIPPLE

Xc)

=

=

ESR + j(XESL - Xc)
+ rs + ESR) + j(Xc + XESL -

]
Xc)

'Y Ein

The formula:

C1 =

Ein - Eou!
4 7r 2f2LERIPPLE

is a good approximation for finding the minimum
capacitance; however, the preceding formula must
be used to accurately determine the ripple voltage.

~

is
w

~

jXc

,= ------Z1 + Z2//Z3

Figure 9

Closed Loop
In order for the switching regulator to maintain an
output voltage relatively constant, some feedback
mechanism must be employed. Figure 11 shows a
typical feedback system.

0.1

i

•

K3 represents the power switch, filter and all the
associated losses.

•

K2 represents the transfer function for the pulse
generator.

FREQUENCY - HERTZ

Fig. 10 Simplified Equivalent Circuit of RLC Filter

,------,

Rs

Z2

+ rs + jXL
ESR + jXESL -

Z1 = Rs

•

K1 is the open loop gain of the error amplifier.

I

•

{3 is the attenuation factor usually determined by a
simple voltage divider.

I
L _ _ _ _ _ _ .-.l

•

~ is a summing network that produces an error
voltage 6e from the difference between the
reference voltage EREF and the feedback voltage

I

Rs

Efb.

,- - - l
I
I

n

EIN

I
I ESL
I
I
I
I

L_

Xc

II
ESR

The total loop gain will determine the percentage
regulation of the switching regulator.

I
I
I
I
I
I

A=

RL

6 Eou! = % regulation

6E
The error amplifier gain then is defined by:

I

K1

__ J

=

A-1
{3K2, K3

While this model is an approximation, it yields
relatively close results.

5-23

Understanding the Switching
Regulator
Fig. 11 Typical Switching Regulator Feedback Loop

EREF

,-----,

r-----l

I

I

I

I

I

I
---If---I

I
I
I

I

L __
SUMMING

I

L _____ ---1

NETWORK

PULSE WIDTH
MODULATOR

ERROR AMPLIFIER

I

I

I

I
I

I

I
I

I

I

I

L _____ J

I

SWITCH, FILTER &
CIRCUIT LOSSES

r-------,
I
I

I
I

~Efb
tJ = -_._-~Eo

~Eo

I
I

I

L _______ J
FEEDBACK NETWORK

Therefore, a switching regulator maintains a
constant output voltage against variations in input by
appropriately modifying the system duty cycle. The
basic switching regulator operates as follows.
Control transistor S1 switches on when first
energized, thereby applying a voltage approximately
equal to the input across L 1 and Co. This causes
current h to increase linearly with time, supplying
current to the load while storing energy in L 1. Diode
D1 insures that, when S1 switches off, current
continues to flow to the load thereby achieving a
continuous load-current flow.

A Switching Regulator Using the SH1605
The SH 1605 is a hybrid integrated circuit, designed
specifically to be used as a major building block in
high-current, step-down switching regulator
systems. It contains a temperature-compensated
voltage reference, comparator, oscillator, highcurrent Darlington and high-power steering diode.
This device is capable of supplying up to 5 A
continuous current; its package dissipation capability
is 20 W maximum. This circuit provides excellent
performance, with efficiencies up to 85%, for
applications requiring high power densities and large
operating currents.

At equilibrium, the average current through L1 is
equal to the load current. The rate of current change

Switching Regulator Theory
Figure 12 shows the basic switching regulator
configuration. This circuit provides an output voltage
VOUT, related to the input voltage V IN by the duty cycle
of switch S1. Thus:
VOtJT

=

VIN

(

ton
ton

)

+ toll

Fig. 12 Basic Switching Regulator
L

l'

VOUT

'----+__

TO CONTROL CIRCUITRY
COUT

5-24

I

Understanding the Switching
Regulator
SH1605 Theory of Operation
The SH1605 simplified block diagram is shown in
Figure 14. Circuit operation is as follows. When
power is first applied, the output voltage VOUT is low,
thus forcing the comparator output into a HIGH state.
As a result, the oscillator freely toggles the output
switch on and off at a rate determined by the charge
and discharge rate of the timing capacitor CT. This is
a temporary condition that continues until VOUT has
exceeded the reference voltage level times the factor
set by Rs, R2 and LRs. The output voltage can be
expressed as follows.

through the inductor, 61" during the on and off
period is defined by Equations 1 and 2 below.
6h

(VIN

=

~ 1VOUT )

ton

(1 )

(2)

Since, in a conventional switching regulator the
excursions 1' (on) and 1,(011) are equal, Equations 1 and
2 can be written as follows:

~-1 =

toft

VOUT

ton

V
- V
(Rs + R2 + Rs)
OUT - REF
(R1 + R2)

(3)

Since the value of R1 and R2 (1 krl each) inside the
SH1605 is established, Rs can be determined as
follows.

Equation 3 shows the natural tendency for the on-tooff time ratios to remain proportional to the inputoutput voltage differential. Voltage regulation can be
achieved when this information is properly fed back
to the switch.

Rs = (2 X 103 ) (VOUT - 2.5) for Rs in ohms
2.5

13 Typical Switching Regulator Waveforms

VOUT + V01
L1

OA

I
I
I
I
I
I

I
I
I
I
I

I
I
I

I

I

I
I

- t r-.' t-~----IOUT
rI-

ton

=

toll

=

OA

61,L1
VOUT

+ VF

(8)

where:

I

L 1 = Filter Inductance
61, = Change in Inductor Current
VOUT = Output Voltage
CT = Timing capacitor
Ic = Oscillator charging current
6 v = 0.5 V Typical
VF = Steering Diode Forward Voltage Drop

==~---VOUT
t

CT6v
Ic

101

VOUT

(6)

Whenever VOUT falls to the level specified in Equation
4, the comparator changes state and the output
switches on. It remains in this state until the voltage
across CT reaches a positive threshold level. The rate
of CT charge is determined by the size of the timing
capacitor and the magnitude of the constant current
source inside the oscillator. Charging current is
typically 25 /lA and discharging current is 225 /lA.
From the equation describing on and off time
duration, the frequency of oscillation can be
deduced:

I
I I
I
~--IOUT
1L1

(5)

Equilibrium is reached at the completion of the on
cycle when the comparator input has exceeded the
reference level. When the comparator output goes
LOW, the oscillator output is disabled and Q1
switches off. VOUT then begins to fall at a rate
determined by the ratio of the output voltage to the
inductor value.

Since the duty cycle is dependent only upon the
magnitude of the input-to-output voltage differential,
it follows that variations of output voltage with load
should be minimal. Basic switching regulator
waveforms are shown in Figure 13.
Fig~.

(4)

RIPPLE
I

ovl

5-25

Understanding the Switching
Regulator
Fig. 14 SH1605 Block Diagram

,----------Ql(2)------i 8

-

L1

I,

I

I
I
I
I

lOUT

7

I

+

I
I

Rs

I

Co
VOUT

I
I

I
I

R2

Rl

I
.::.v

3

I
IL ____________________

~

CEXT

SWITCH ON COMMAND ~ TLCOMPARATOR
SWITCH OFF COMMAND

~ .tr.::.V

Nominal Frequency = - - - - - - CT6v + 6 I, (nom)L 1
Ie

Notes:
1. Use a 47 /-LF input capacitor to minimize switching transients.
2. Maximum T c for 5 A operation is 60°C.
3. All measurements taken relate to ground unless otherwise
shown.

VOUT

(9)

Since the required louT(min) is 1 A to maintain
continuous operation, the peak-to-peak current
excursion must be equal to 2 A or less, i.e.,

+ VF

61, = 2 IOuT(min)
For improved system efficiency, the operating period
should always be many times longer than the device
transition times. A trade off must be sought between
inductor size and efficiency when selecting the
frequency of operation.

To calculate the value of the inductor keeping the
efficiency/component-size tradeoff in mind use
Equation 1. For this example ton = 60 f.LS is selected.
ton is determined by the designer and depends upon
the desired frequency of operation under expected
constant load conditions where frequency = 1/(ton +
toll). ton must always be greater than ts + td = 5.1 f.LS,
typically, from the SH 1605 data sheet. Off time, tofl, is
determined by the ratio of input voltage to output
voltage where

Design Example
Figure 15 is a typical design of a step-down switching
regulator using the SH1605.
Nominal Design Objectives
VOUT = + 5 V
Line Regulation = 2%
IOuT(max) = 5.0 A
Load Regulation = 2%
IOUT(min) = 1.0 A
Ripple (max) = 0.1 Vpk-pk
VIN = 12 to 18 V
Efficiency = 70%

~

tofl=tonX ( -VIN
--1
VOUT

First, Rs is calculated from Equation 5:
Rs = (2 X 103 ) (VOUT - 2.5) = 2 kf!
2.5

5-26

Understanding the Switching
Regulator
Fig. 15 Design Example

r

SHI605

+

25~F

V'N

1

.OO33~F

4

50V

Load Reg. ~ 50 mV (1 A :s lOUT :s 5 A)
Line Reg. ~ 50 mV (12 V:s V'N:S 18 V)

Circuit Performance
V'N ~ 12-18 V
VOUT ~ 5.06 V
Note
In this example the SH1605 must be mounted on a heat sink with
a maximum thermal resistance of  4° C/W.

(Equation 3). Thus with a known ratio of VINNoUT the
designer is offered a trade-off between frequency of
operation. efficiency and component size.

Minimum Frequency

From Equation 1:
---- =

L1 =

1.7X10-4

(VIN(nOm) - VOUT) ton
L':.11
10

2" (6 X

( VIN(max)L-1 VOUT) X ton

Wh ere: L':. I1(max)
10- 5 )

=

5.9 kHz

300 /-LH

where VIN(nOm) = 15 V, ton = 60 /-LS

= 2.6A

One very important element in achieving the optimum
performance in a switching regulator is to insure the
inductor is kept below the specified saturation limits.

From Equation 1

Since the timing capacitor controls the 60 /-LS on time,
CT can be determied using Equation 7:

The output capacitor can now be determined as
follows:

CT = (ton) (Ic) = (6 X 10- 5) (2.5 X 10- 5L 3000 pF
L':.v
5 X 10- 1

CO(min)

=

(8 f(min) Vripple(maX))

where Ie = 25 /-LA nominal per data sheet.

2
(8 X 5.9 X 103 ) X (1 X 10- 1)

The final step is to determine the requirements for
the output capacitor Co to obtain the desired value of
ripple voltage. Consideration must be given to the
absolute value of Co as well as the internal effective
series resistance (ESR). Since the capacitor size is
inversely proportional to the operating frequency, the
lowest frequency of operation must be calculated.
Minimum operating frequency can be determined by
uSingL':.1 1(max) vs L':.h(nom) in Equation 9.

The maximum acceptable ESR is therefore
ESR(max)

=

Vripple(maX)
L':.11(maX)
1 X 10- 1
2.6
= 0.038\1

5-27

Understanding the Switching
Regulator
Short Circuit Current Limit
Space limitations and the already high packing
density attained in the SH1605 prevent the inclusion
of a short circuit current limit in the product. For
those occasions where short circuit protection is
required (i.e., prototype designs and lab testing), a
schematic for an external protection network is
shown in Figure 16.

Normally, the minimum capacitance value should be
increased considerably if a low ESR capacitor is not
used.
As a final step for minimizing switching transients at
the device input, a low ESR capacitor must be used
for decoupling purposes between the input terminal
and ground.
Conclusion
The SH1605 is a highly versatile building block for
high current, step-down switching regulator systems.
However, to attain optimum performance and
reliability the following guidelines should be followed:
•

Keep operating period long, relative to the device
switching times, for optimum efficiency

•

Insure that the inductor stays out of saturation
and minimize the series resistance.

•

Use high quality capacitors for input and output to
minimize ripple and noise.

Heatsink Designs
While heatsinking is generally not a problem with the
SH1605 due to its high efficiency, mounting of the
package can have a dramatic effect on OJA. Cutting a
large hole or curved slot around all eight leads leaves
only the package fringes for heat transfer. A Ocs
thermal resistance of 4.0 to 4.5°C/W will result from
this type of mounting. A Ocs thermal resistance of 0.3
to O.4°C/W can be obtained using a hole
configuration similar to Thermalloy pattern 15 or
IERC pattern LAIC, UP or HP and a good thermal
conducting compound.
8 Pin TO-3 Sockets
Sockets are a .definite convenience when
prototyping, testing and even sometimes for small
volume production runs. Standard sockets are
commercially available from a number of
manufacturers. For a partial list of suppliers refer to
the SH 1605 data sheet.

Designer's Note
As an aid in designing with the SH1605, 5 Amp
Switching Regulator, the following is a review of
several characteristics of the device which should be
recognized and understood by the designer.

Figure 16. Switching Regulator with Short Circuit Protection

.1

~!

I-....".f\r--.......- - - - - - - - - - - VOUT

1k
FDH600

6

10k
2N2222

1k
5k

5-28

Understanding the Switching
Regulator
grounding pOints in the system. "Input ground" is
defined as the connection point between the negative
side of the input filter capacitor and the incoming
ground line. "Output ground" is a ground point as
close to the load as possible. The input and output
ground pOints are connected but distinctly separate
thus minimizing system ground loops and their effect
on output voltage regulation.

Grounding
Switching power supplies are by nature more
susceptible to grounding problems than linear power
supplies because of larger ripple currents. It is
generally recommended that a ground plane be used.
An ideal connection diagram to minimize grounding
problems is shown in Figure 17.

A common problem encountered with the SH1605 is
excessive noise, or ripple, which is almost always
generated by improper grounding. Care must be
taken in the design and layout of the breadboard to
eliminate any possible ground loops. This is
accomplished by observing very standard layout
procedures. The following diagram explicitly
illustrates where the ground connections must be
made to avoid potential problems.

Frequency of Operation
The SH1605 is a frequency modulated switcher.
Thus, frequency will vary somewhat during operation
depending upon power demand. When frequency is
designed to fall mostly within audio ranges, users
may find the continuously varying tone an
annoyance. It is, therefore, recommended that users
either provide for sound insulation or design for
frequencies outside the normal human audio range.

Pin 7, which is the anode of the steering diode and
which carries up to 5 A of ripple, must be tied to
"input ground" ... not the case and not "output
ground". An incorrect connection here accounts for
at least 80% of the field problems. To further improve
system performance, the negative sides of both the
timing capacitor and the decoupling capacitor should
be tied together at the case with a single lead going
to "output ground" and the negative side of the
output filter capacitor should be connected directly to
"input ground." Note that there are two distinct

Although the SH 1605 is capable of operating across
a broad range of frequencies, it is recommended that
the user design his system to operate between
20KHz and 30KHz for optimum efficiencies and
performance.
For convenience, a circuit for frequency locking is
shown in Figure 18.

Figure 17. An Ideal Connection Diagram
-+

r

-

RIPPLE

SA RIPPLE
_S

8

+C'N
1000 "F
SOV

3

SH160S

+

300 "H

Rs'

~c
~(I\
COUT

t

r

+

V,N

2000 "F
SOV

VOUT

+

7

COECOUPLING
SA!
DC

RIPPLE

LOAD

t
SINGLE POINT
INPUT
GROUND

_SADC
_SmADC
_
2S MA RIPPLE

'Metal Film Resistor or Temp. Coel. < 100ppmfOC

5-29

SINGLE POINT
OUTPUT
GROUND

Understanding the Switching
Regulator
Figure 18. SH1605 Frequency Locking Network
L

8

5

VOUT

SH160S

3

Rs

CASE

4

2
FDH600

33 k!l

Notes
1. Diode FDH600 in series with 33KO resistor are the frequency
locking network which facilitates measurement and
minimizes noise.
2. As input to output voltage ratio is increased, the operating
frequency (fo), will decrease according to the expression
shown below:

Vo
1
F(o) = ( - ) ( - ) where Ton
Vin Ton

C T 6V
Ie

5-30

r

Power Supply Design

FAIRCHIL.D
A Schlumberger Company

A power supply normally operates from an ac line.
This ac input voltage must be converted to
unregulated dc by some form of rectifier/filter
combination and then to regulated dc using a voltage
regulator. This chapter discusses the performance
characteristics of the most common forms of
rectifier/filter combinations and provides appropriate
design equations for any output voltage and current.

Definition of Terms

Single Phase, Half Wave Rectifier
Figure 1 is a half wave rectifier and capaCitor filter.
Without the capacitor, peak current is

VM
1M = - - Rs + RL

Parameter

Definition

VM

peak input voltage

Vo

dc output voltage

Vpk

transformer peak voltage

Vs

ac input voltage

F

form factor of the load current:
Irms/lo

lac

effective value of all alternating
components of load current, i.e.,
the current reading on an ac meter

on the positive half cycle (or forward conduction
cycle) of the input voltage. Some additional electrical
characteristics follow.
Irms

10

=

=

1M

peak current through each rectifier
average value of the load current,
the reading on a dc meter

1'=1.21
Irms

Po

7JR

effective value of the total load
current

=

40.6

~;~

ac input power
%

dc output power
load resistance
total series resistance, or the
source resistance plus any added
resistance plus the diode series
resistance

Note that for a resistive load, the maximum ripple
factor is 121 % which, under most circumstances,
requires filtering. When the capacitor is added
across the load resistor, the ripple is reduced
proportionate to the RLC product (Figure 2).

ripple factor in all charts
normalized
as 100% equal to 1,

One possible problem with any capacitive filter is the
high peak current drawn due to the diode back-bias
present throughout most of the input cycle. This is a
result of the voltage stored across the filter
capacitor. The rectifier conducts only during that
short period of time when the input voltage exceeds
the capacitor voltage by one diode drop. During
conduction, the rectifier must supply the capaCitor
with sufficient energy to hold the ripple within
specification until the next conduction cycle. Figure 3
is a plot of the IM/lo ratio versus the RLC product with
the Rs/RL ratio as a variable. Notice thatthe surge-todc ratio of current increases as a function of both
increasing capacitor value and of a reduced sourceto-load impedance ratio.

l' =

I

)

2

(F2-1) = [ ( ;:s_1

]

rectification efficiency,
Po X 100%
Pin

w

5-31

2 71'f where f

=

line frequency

1/2

Power Supply Design
Fig. 1 Half-Wave Rectifier Circuit with Capacitive Filtering
RS

c

rv Vs = VM sin wt

Fig. 2 Ripple Factor vs WRlC
100

10

1,0

a:
0

..
...

i

l-

t>
u.. 0.1
~

I

910

/

V
l-

~

ii:

0,01

0,02
0,06
0,1
0,2

0.5
1

;j'.
I
~

2
6

a:

10
50
100

a:

;;;

1
10

100

1000 10,000

0,1

100

1000

wRle

Fig. 4 DC-to-Peak Ratio
0,05
0,5
1
2
4
6
10

1,0
0,9
0,8
0,7

12.5 rfl
15
I
~
20
25 a:
30
C/l
40 a:
60
80
100

::i! 0,6
': 0,5

0

>

0,4
0,3
0,2
0,1
10

100

1000

wRLe

Fig. 5 Half-Wave Rectifier
RS

rv Vs = VM sin wt

de output-to-peak input voltage ratio approaches
unity as the filter factor goes up and also as the
source-to-Ioad impedance ratio decreases. Because
of the relatively large value of the filter capacitor
required for a given ripple factor, the use of the halfwave capacitor filter is usually limited to low current
applications.

When the ripple factor, load impedance, and ware
known, the required capacitance can be determined
from Figure 2, Because of the high turn-on surge, an
external series limiting resistor is normally needed.
Figure 4 is a plot of the dc-to-peak voltage ratio with
the filter product as the X axis and the source/load
impedance ratio as the third parameter, Note that the
5-32

Power Supply Design
Half Wave Rectifier With Series Inductive Filter
Figure 5 is a half-wave rectifier with series inductive
filtering. The inductor, in series with the load,
prevents any rapid changes in the current flow and
thus reduces the ripple factor by acting as an energy
storage device. When the current flow is above the
average current required, energy is stored in the
inductor, and when the current is below the average,
the stored energy is released. Figure 6 is the plot of
ripple factor versus filter product for the inductor
input filter. Because of the energy storage available
with an inductor, the peak current through the
rectifier is little more than the average current.
However, the peak inverse voltage PIV seen by the
rectifier is simply VM, the peak input voltage. Figure 7
is a plot of VOIVM ratio as a function of the inductor
filter product.

Single-Phase Full-Wave Rectifier
Figure 8, a basic full wave rectifier, has the following
electrical characteristics.
Irms =

Po

l1R

1M

21M

10

V2

1'=0.48

1r

r

(!

VM 2RL
(Rs+RL)2

81.2
( 1+

:~)

0/0

Fig. 8 Basic Full-Wave Rectifier
Fig. 6 Ripple Factor vs Filter Product
2.0

1.76
1.50

~ 1.25

t;
~

1.0

w

to.

76

\

"'0.50
0.25

r--

o
0.1

There are two interesting features. Efficiency has
doubled, as can be expected when doubling the
number of rectifiers. In addition, the ripple factor has
decreased from 121 % to 48% in comparison with the
half-wave circuit. Even with ripple reduction, a 48%
factor is normally too high to be useful and must be
filtered. Figure 9 is the filter product plot for both
capacitive and inductive filters, assuming Rs < < RL.
High peak currrents are always associated with
capacitive filters and Figure 10 plots the ratio of
peak-to-dc current as a function of the filter product.
The relationship between the filter product, the Rs/RL
ratio and the dc output-to-peak input voltage is given
in Figure 11 for the capacitive input filter. Load
regulation may also be determined from Figure 11 by
using the high and low limits for RL.

1.0

10

100

1000

wL/RL

Fig. 7 VOIVM Ratio
0.5

0.4

:IE 0.3
>

o

> 0.2

1\

0.1

o
0.1

"

10

Fig. 9 Filter Product
100

0.5

1000

~.

wL/AL

0.4

0.3

0.2

(>

~

\Cl~

0.1

:i

o

I

0.1

5-33

\:
\

~
'2.~

~

10

100

1000

Power Supply Design
Fig. 10 Peak-to-DC Ratio
1000

rl~

-

:J

-

ii'

100

RL

-

c-1
i

20

-

-"

=

Step 5 Find the transformer peak input voltage from
the following.

Vpk = diode forward voltage. One diode
forward-voltage drop for a center-tapped fullwave input, two diode forward-voltage drops
for a full-wave bridge

i

1

10

0.1

100

+~

Fig. 11 Load Regulation

i 1:1 !

I

0.9

::;
:: 0.6

o
>

0.5

• Ie'

0.4
0.3
0.1

"

using the filter values from Figure 11.

1
5

6
8
10
12.5
15
20
25

i
i

~

VONM

0.05
0.1
0.5

0.8
0.7

Vpk

10

100

Vpk = 0.7

wRlC

1Q

proceed with the following steps.
Step 1

{=

Find the filter product from Figure 9

Calculate RL

26 V peak or
52 V pk-pk or
18.6 Vrms

0.47

0.47
{= ------------------------------

(4w 2 L 1C1 -1) (4w2 L2C2 -1 )-(4w 2 Ln Cn -1)

Calculate C

C

from Figure 11.)

or, if n L-section filters are cascaded, then the ripple
factor is:

20
RL = = 20[1
1
Step 3

+ 25.3 =

10

4w 2 LC-1

for
Step 2

=

LC Section Filter
The LC section filter is one method of reducing ripple
levels without the need for single, large value filter
omponents. The basic circuit is shown in Figure 12.
As a general rule, the capacitive reactance should
always be less than 10% of the load resistance at the
second harmonic of the incoming frequency. All the
succeeding information is based upon this ratio. The
ripple factor for an L-section filter has the form:

{ < 0.1
=

0.82

Step 6 Check peak diode current from Figure 10. For
this example at a filter product of 10, the peak
current is seven times the dc current, or 7 A.

1A

with Rs

O.7 + -.20.
- (Intersect'Ion 0 f

1000

Vo = 20V
=

=

5 0//0 -Rs and WRLC
RL

35
40
50
60
80
100

Design Example
For a full-wave circuit with the following
requirements,

10

5%

.;-

10

1.0

~

Step 4 Calculate

=

=~
WRL

24011"

10
120 X 2011"
= 1300ILF

5-34

Power Supply Design
Fig. 12 LC Filter

c

Figure 13 is a plot of the filter factor versus the w2 LC
product. The one additional requirement is
continuous current flow through the inductance. This
says, in effect, that there is a critical inductor size. To
assure this continuous current flow, a bleeder
resistor RK must be used at the filter output. The
critical value of inductance is
Lc

=

Rs

Fig. 13 Filter Factor vs w2 LC

eua:

0.1

:tw

+ Ref!

.

~ 0.01

----

3w

iO

0.001

where

and
10

Bleeder current IK may be assumed to be 10% of
minimum load current or, if this is not a practical
value, then some reasonable minimum bleeder
current is selected. Once the critical inductance is
found, then the capacitor value may be determined
by the following steps: Set L = 2 Lc. Determine w2 LC
from Figure 13for the required ripple factor. Solve
for C from w2 LC = X, where X is the product from
Figure 13.

1000 10.000

For minimum power dissipation, RK should be as
large as possible. In some cases, since the value of
critical inductance is proportional to the value of the
bleeder resistor, the selection of a high value results
in an inductance too large to be practical. In this
case, a swinging choke or a choke whose inductance
decreases with increasing current flow is needed.

The peak rectifier currents depend upon the size of
the inductor selected such that if L = Lc then 1M
= 2 IL and if L = 2 Lc then 1M = 1.5 IL. The
transformer secondary voltage is given by
Vrrns = 1.11 [ Vo

100

wile

+ Rs (lL(rnax) IK) ]

and the minimum PIV for the rectifier is 1.57 VO(rnax)
for a full-wave bridge rectifier.

5-35

Power Supply Design
Design Example
Full wave, single-section, choke input filter design,

Vo = 50 V

IK = 100 mA

10

Rs

=

1A

=

'Y =

Step 6 Calculate voltage drop both at no load and full
load
Va no load = IK (Rs) = 0.1 X 10 = 1 V

1%

10 Q

Va full load = (10

Step 1 Calculate RK

+ Rs (IO(rnax) + IK)]
(50 + 10 X 1.1)

Vrrns = 1.11 [Vo
Vrrns

=

1.11

Vrrns = 1.11 (61)

Step 2 Calculate Rell
RKRL(rnax)
RK

= 1.1 X 10 = 11 V

Step 7 Calculate transformer minimum rms voltages

RK = Vo = ~ = 500 Q
IK
100 mA

Reff =

+ IK) Rs

+ RL(rnax)

Vrrns = 67.5 Vrrns

500 Q (RL(rnax) = (0)

Step 8 Calculate maximum output voltage
Step 3 Calculate Lc
Vrrns
VO(rnax) = - - IKRs
1.11

Reff + Rs _ 500 + 10
Lc = -=.c'------'-_
3w
1130

VO(rnax)= 67.5 -0.1 X 10 = 61-1 = 60Vdc
1.11

510 :;;,,;0.5H
1130

Step 9 Calculate PIV rating required
Step 4 Calculate C
(See Table 4-1)

PIV = (1.57) VO(rnax)
'Y

= 0.01
PIV = 1.57 X 60

then,

=

94 V

w2LcC = 12 from Figure 13

C=~=
w2LC

Transformer ratios are determined from Table 1.
12
(12071')20.5

2
142 X 103 X 0.5

= 0.169 X 10- 3 = 169 ~F
Step 5 Calculate 1M
Since L = Lc
then 1M = 2 (10

+ IK)

1M = 2 X 1.1 = 2.2 A

5-36

Power Supply Design
Table 1. Electrical Reference Table and Rectifier Circuit Wave Shapes

Characteristic

Load

Average
Current
Through
Through
Rectifier IF

Current
Through
Rectifier 1M

Three Phase
Star
(Half-Wave)
(See 1-0)

1.11 Vo

1.11 Vo

0.855 Vo

0.428 Vo

0.741 Vo

0.855 Vo

0.707 Vo

0.707 Vo

0.707 Vo

0.408 Vo

0.707 Vo

0.707 Vo

Single Phase
Single Phase Full Wave
Center-Tap
Half Wave
(See 1-B)
(See 1-A)

RMS
Resistive & 2.22 Vo
Input Voltage
Inductive
Per Transformer
Leg
(V1)
Capacitive 0.707 Vo
Peak
Inverse
Voltage
Per Rectifier
(P & V)

Single Phase
Full Wave
Bridge
(See 1-C)

Three Phase
Six-Phase
Double Wave
Three Phase Star
With
Full Wave
(Three Phase Interphase
Diametric)
Transformer
Bridge
(See 1-E)
(See 1-F)
(See 1-G)

R&L

3.14 Vo

3.14 Vo

1.57 Vo

2.09 Vo

1.05 Vo

2.09 Vo

2.09 Vo

C

2.00 Vo

2.00 Vo

1.00 Vo

2.00 Vo

1.00 Vo

2.00 Vo

2.00 Vo

R.L.
&C

1.00 10

0.5010

0.5010

0.333 10

0.333 10

0.16710

0.16710

R

3.1410

1.5710

1.5710

1.21 10

1.05 10

1.0510

0.525 10

1.0010

1.0010

1.00 10

1.0010

1.0010

0.50010

L
C

Depends on Size of Capacitor
Transformer
Total
Secondary
PA

Sine Wave 3.49 Po

1.75 Po

1.23 Po

1.50 Po

1.05 Po

1.81 Po

1.49 Po

Sq. Wave

3.14 Po

1.57 Po

1.11 Po

1.48 Po

1.05 Po

1.81 Po

1.48 Po

Transformer
Total
Primary
PA

Sine Wave 3.49 Po

1.23 Po

1.23 Po

1.23 Po

1.05 Po

1.28 Po

1.06 Po

Sq. Wave

1.11 Po

1.11 Po

1.21 Po

1.05 Po

1.28 Po

1.05 Po

47%

47%

17%

4%

4%

4%

1 FI

2 FI

2 FI

3 FI

6 FI

6 FI

6 FI

40.6%

81.2%

81.2%

97%

99.5%

99.5%

99.5%

% Ripple
Lowest
Ripple Frequenc~
Conversion
Efficiency

3.14 Po

Sine Wave
Resistive
121%
Load

-

5-37

Power Supply Design
Table 1. Electrical Reference Table and Rectifier Circuit Wave Shapes (Cont.)
SINGLE PHASE
HALF WAVE
(1-A)

SINGLE PHASE
FULL WAVE
CENTER TAP
(1-B)

SINGLE PHASE
FULL WAVE
BRIDGE
(1-C)

THREE PHASE
STAR
(HALF WAVE)
(1-0)

Vo
Vo

0-----

THREE PHASE
FULL WAVE
BRIDGE
(1-E)

SIX PHASE
STAR
(THREE PHASE
DIAMETRIC)
(1-F)

THREE PHASE
DOUBLE WAVE
WITH
INTERPHASE
TRANSFORMER
(1-G)

Vo

0-------

0-------5-38

0--------

Power Supply Design
Swinging Choke LC Section Filter
When designing a swinging choke section filter, the
inductance required at the minimum and maximum
output currents can be determined as follows.

When the voltage and current levels are known,
Table 2 can be used to select the optimum
configuration and determine transformer and rectifier
characteristics.

1. Find Lc (critical inductance)

Voltage Doublers
Increased dc output voltage from a transformer
winding can be obtained using a voltage multiplier
circuit. However, this method requires additional
components, i.e., two filter capacitors, and reduces
the output current. A full-wave doubler and a halfwave doubler are shown in Figure 14. The half-wave
doubler is generally preferred since it has a common
input and output terminal. In operation, C2 is charged
on one half cycle; on the second half cycle, Cl is
charged thereby summing the voltages across each
capacitor. This provides a doubling effect since the
output voltage is approximately twice the input
voltage.

+ Reft

Rs

Lc

3w

where, as before:
RKRL(max)

Reft

RK

+ RL(max)

2. Find L2 (inductance at maximum load current)
L2

=

Rs

+ Reft2

3w

Fig. 14. Voltage Doublers

where:
Reft2

HALF WAVE

FULL WAVE

RL(min) RK
RL(min) + RK
C2

Vo

When Lc has been determined, then the capacitor
value may be calculated as before. The condition
w2Lc:S 1/4 should be avoided due to possible filter
instabilities.
Capacitive Input Filter Characteristics
Rs/RL(min)

=

0.02

WCRL(min)

=

12

Table 2. Capacitive Input Filter Characteristics and Rectifier Circuit Wave Shapes

Characteristic

Single Phase
Half Wave
(See 2-A)

Single Phase
Full Wave
Center-Tap
(See 2-B)

Single Phase
Full Wave
Bridge
(See 2-C)

Single Phase
Full Wave
Voltage Doubler
(See 2-D)

V1
PIV
Ripple
IM/Rect.
IRMS/Rect.
SEC VA
PRIVA

0.910 Vo
2.56 Vo
0.12 Vo
7.8010
2.50 10
2.35 Po
2.35 Po

0.825 Vo
2.34 Vo
.06Vo
4.7510
1.33 10
2.16 Po
3.05 Po

0.805 Vo
1.14Vo
.06Vo
4.75 10
1.3310
2.16 Po
2.16 Po

0.552 Vo
1.56 Vo
.09 Vo
3.0010
1.1010
1.22 Po
1.72 Po

5-39

Vo

Power Supply Design
Table 2. Capacitive Input Filter Characteristics and Rectifier Circuit Wave Shapes (Cont.)
SINGLE PHASE
FULL WAVE
CENTER TAP
(2-B)

SINGLE PHASE
HALF WAVE

(2-A)

c

c

o

o

SINGLE PHASE
FULL WAVE
VOLTAGE DOUBLER
(2-D)

SINGLE PHASE
FULL WAVE
BRIDGE
(2-C)

RS

c

c

c

References

1. Schade, O.H., "Analysis of Rectifier Operation,"
Proc IRE, July 1943, Vol. 31 #7, pp. 341-361.

4. Seeley, Samuel, "EJectron Tube Circuits,"
McGraw-Hili, 1958, pp. 194-230.

2. Ryder, John D., "Electronic Engineering
Principles," Prentice Hall, Inc. 1947, pp. 94-125.

5. Gray, Truman, S., "Applied Electronics," John
Wiley and Sons, Inc., 1954 pp. 250-277.

3. Martin, Thomas L., Jr., "Electronic Circuits,"
Prentice Hall, Inc., 1955, pp. 506-541.
5-40

Thermal Considerations

FAIRCHILD
A Schlumberger Company

To realize the full capabilities of the High Current
Voltage Regulator, sufficient attention must be paid
to proper heat removal. For efficient thermal
management, the user must rely on important
parameters supplied by the manufacturer, such as
junction-to-case and junction-to-ambient thermal
resistance and maximum operating junction
temperature. The device temperature depends on
the power dissipation level, the means for removing
the heat generated by this power dissipatioh and the
temperature of the body (heat sink) to which this heat
is removed.

Thermal Evaluation of Regulators
To measure thermal resistance, the difference
between the junction temperature and the chosen
reference temperature, case, sink or ambient, must
be determined. Ambient or sink temperature
measurement is straightforward. For casetemperature measurement, the device should have a
sufficiently large heat sink and the power level should
be close to the specified rating of the package-die
combination. The case temperature can be
measured by an infrared microradiometer or by using
a thermocouple soldered to a point in the center of
the case heat-sink interface as close to the die as
practical.

Figure 1 shows a simplified equivalent circuit for a
typical semiconductor device in equilibrium. The
power dissipation, which is analogous to current flow
in electrical terms, is caused by a heat source similar
to a voltage source. Temperature is analogous to
voltage potential and thermal resistance to ohmic
resistance. Extending the analogy of Ohm's law to

Measurement of the junction temperature,
unfortunately, is not as simple and involves some
calibrations. There are several methods available for
junction-temperature measurement; the one most
commonly used is described here.
Thermal Shutdown Method
With this method, the thermal shutdown temperature
of each device is used as the thermometer in
determining the thermal resistance. The device is
first heated externally, with as little internal power
dissipation as practical, until it reaches thermal
shutdown. Then, with the device mounted on a heat
sink, the regulator is powered externally until it
reaches thermal shutdown again. In some cases, the
ambient of the device and its heat sink may have to
be elevated sufficiently to force the regulator into
shutdown. The thermal resistance of the device can
then be calculated by using

Thermal resistance, then, is the rise in the
temperature of a package above some reference
level per unit of power dissipation in that package,
usually expressed in degrees in centigrade per watt.
The reference temperature may be ambient or it may
be the temperature of a heat sink to which the
package is connected. There are several factors that
affect thermal resistance including die size, the size
of the heat source on the die (or substrate), dieattach material and thickness, substrate material and
thickness, and package material, construction and
thickness.
.

_ TJ-Tc
()JC---

Po

where (}JC is the junction-to-case thermal resistance
TJ is the measured. thermal shutdown
temperature
Tc is the measured case temperature
Po is the power dissipated to force the device
into shutdown and is equal to

Fig. 1 Simplified Thermal Circuit

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

..
POWER(P)

TJ JUNCTION TEMPERATURE
"JC JUNCTION-TO-CASE
THERMAL RESISTANCE
TC CASE TEMPERATURE

(VIN - VOUT) lOUT
HEAT
SOURCE

"cs CASE-TO-SINK
THERMAL RESISTANCE
T5 SINK TEMPERATURE
"SA SINK-TO-AMBIENT
THERMAL RESISTANCE

L--_ _ _ _ _ _ _---6

+ VIN 10

10 is the quiescent current of the device and
can be neglected for low thermal resistance
packages such as the TO-3

Heat Sink Requirements
When is a heat sink necessary, and what type of a
heat sink should one use? The answers to these
questions depend on reliability and cost

TA AMBIENT TEMPERATURE

5-41

Thermal Considerations
requirements. Heat sinking is necessary to keep the
operating junction temperature TJ of the regulator
below the specified maximum value. Since
semiconductor reliability improves as operating
junction temperature is lowered, a reliability/cost
compromise is usually made in the device design.

lies - Case-to-heat-sink thermal resistance
which for large packages, can range from about
O.2°C/W to about 1°C/Wdepending on the
quality of the contact between the package
and the heat sink.
eSA - Heat-sink-to-ambient thermal resistance,
specified by heat-sink manufacturer.

Thermal characteristics of voltage-regulator chips
and packages determine that some form of heat
sinking is mandatory whenever the power dissipation
exceeds 3.2 W for the high current voltage regulator
TO-3 package at 25°C ambient or lower power
levels at ambients above 25°C.

Maximum permissible dissipation without a heat sink
is determined by

P

If the device dissipation Po exceeds this figure, a
heat sink is necessary. The total required thermal
resistance may then be calculated.

To choose or design a heat sink, the designer must
determine the following regulator parameters.
PO(max) (VIN -

Maximum power dissipation:
VOUT) lOUT

_ T J(max) - T A(max)
O(max) IIJA

+ Ocs

IiJA(tot) = IiJC

+ VIN 10

TA(max) - Maximum ambient temperature the
regulator will encounter during operation.
TJ(max) - Maximum operating junction
temperature, specified by the manufacturer.
IIJC, IIJA - Junction-to-case and junction-toambient thermal resistance values, also
specified by the regulator manufacturer.
(IIJA = 38°C/W max. IIJC = 2.50°C/W max).

= liSA =

TJ(max) - T A(max)

Fig. 2 Heat Sink Material Selection Guide
SURFACE AREA
(BOTH SIDES OF THE HEAT SINK)
SQUARE INCHES

[111111111111111111111111[111111111[111111111[111111111[111111111[1111[I 11I[lliiliill[lilllllIi[1 11I[lIliliiil[
3 4 5 6 8 10 15 20 25 30 40 50 60 80

THICKNESS

3/16" III 11111111 11111 1IIIIIIdll!IIIIIIIIII!l11I1I11I11I1I1I1 i11i 1111 I I I 1I 1I
:
7 7 6
65 5 44 3 3 2 2.;·5 2 1
3/32,,1111111111111111111[111111111[111 11 111111111111111 11111 11111 1
3/16"

II III Illilliilllllllililillililililllllillilil i1iill II II III 1
7

THICKNESS

6

5

4

3

2

1.5

6
5
4 . 3 2.5
IlIlilllllllllllllllllllllllllllllllllllllllllll

1

7

3/32"

I I

2
I

3/16" 1"I'11T'T1I"11"1I"I TTII I1Im'l irml lnTlIl1T1'l lm'1I1"'l m
lil"rI"III"1'I"rI"'1"'1"r1"'1'I'II""II""II""II'T'MII1

COPPER;
HORIZONTALLY·
MOUNTED

COPPER.
VERTICALLY·
MOUNTED

n1

7

THICKNESS

3/32"
THICKNESS

PD

Case-to-sink and sink-to-ambient thermal resistance
information on commercially available heat sinks is
normally provided by the heat sink manufacturer. A
summary of some commercially available heat sinks
is shown in Table 1. However, if a chassis or other
conventional surface is used as a heat sink, Figure 2
can be used as a guide to estimate the required
surface area.

6 5 4
3
2.5 2
8
7
6 5
4 3.5
3 2.5 2
111111111I11I1Il!11I11I1I11111I11I11111111 I I I I I 1I11 111I111Ii!

3/16" 11"11111111111111111"111""111111111111 I I I I 11111
7
6 5
4
3
2.5
2
7
6
5
4 3.5
3 2.5 2
3/32,,111111111111111111111111111111111111111111111111111
THERMAL RESISTANCE IN

To determine either area required or thermal resistance of a
given area, draw a vertical line between the top (or area) line
down to the material of interest.

5-42

°c/w

ALUMINUM.
HORIZONTALLY·
MOUNTED

ALUMINUM.
VERTICALLY·
MOUNTED

Thermal Considerations
Table 1
Heat Sink Selection Guide
This list is only representative. No attempt has been
made to provide a complete list of all heat sink
manufacturers. All values are typical as given by
manufacturer or as determined from characteristic
curves supplied by manufacturer.

How to Choose a Heat Sink - Example
Determine the heat sink required for a regulator
which has the following system requirements:

Operating
Maximum
Maximum
Maximum

ambient temperature range: 0°C-40°C
junction temperature: 125°C
output current: 3 A
input to output differential: 5 V

(JSA

(JJC =

2.5°C/W maximum (from data sheet)

(JJA(tot)

=

(JCS

(JJC

+ (JSA =

Assuming

PD

(Jcs

=

.16°C/W

=

then

3.16°C/W

(JSA

=

Manufacturer and Type

0.4 (9" length)
Thermalloy (Extruded) 6590 Series
Thermalloy (Extruded) 6660,
0.4 - 0.5
(6" length)
6560 Series
Wakefield 400 Series
0.56 - 3.0
0.6 (7.5" length) Thermalloy (Extruded) 6470 Series
Thermalloy (Extruded) 6423, 6443,
0.7 - 1.2
(5 - 5.5" length) 6441, 6450 Series
Thermalloy (Extruded) 6427, 6500,
1.0 - 5.4
6123, 6401, 6403, 6421, 6463,
(3" length)
6176,6129,6141,6169,6135,
6442 Series
1.9
IERC E2 Series (Extruded)
2.1
IERC E1, E3 Series (Extruded)
2.3 - 4.7
Wakefield 600 Series
4.2
IERC HP3 Series
4.5
Staver V3-5-2
Thermalloy 6001 Sries
4.8 - 7.5
5-6
IERG HP3 Series
Thermalloy 6013 Series
5 - 10
Staver V3-3-2
5.6
Wakefield 680 Series
5.9 - 10
Wakefield 390 Series
6
6.4
Staver V3-7-224
6.5 - 7.5
IERG Up SEries
8
Staver V1-5
8.1
Staver V3-5
8.8
Staver V3-7-96
9.5
Staver V3-3
9.5 - 10.5
IERG LA Series
9.8 - 13.9
Wakefield 630 Series
10
Staver V1-3
11
Thermalloy 6103, 6117 Series

TJ - TA
+ (Jcs + (JSA = -125 - 40 - 2.5
3X5

Approx.

(OC/W)

For this example assume the IlA78HGA, 5 Amp
Positive Adjustable High Current Voltage Regulator
has been selected.

3°C/W

This thermal resistance value can be achieved by
using either 22 square inches of 3/16 inch thick
vertically mounted aluminum (Figure 2) or a
commercial heat sink (Table 1).
Tips for Better Regulator Heat Sinking
Avoid placing heat-dissipating components such as
power resistors next to regulators.

Keep lead lengths to a minimum and use the largest
possible area of the printed board traces or mounting
hardware to provide a heat dissipation path for the
regulator.
Be sure the heat sink surface is flat and free from
.ridges or high spots. Check the regulator package
for burrs or peened-over corners. Regardless of the
smoothness and flatness of the package and heatsink contact, air pockets between them are
unavoidable unless a lubricant is used. Therefore, for
good thermal conduction, use a thin layer of thermal
lubricant such as Dow Corning DC-340, General
Electric 662 or Thermacote by Thermalloy.
If the regulator is mounted on a heat sink with fins,
the most efficient heat transfer takes place when the
fin is in a vertical plane, as this type of mounting
forces the heat transfer from fin to air in a
combination of radiation and convection.
If it is necessary to bend any of the regulator leads,
handle them carefully to avoid straining the package.
Furthermore, lead bending should be restricted since
repeated bending will fatigue and eventually break
the leads.

5-43

FAIRCHILD
A Schlumberger Company

Fairchild Field Sales Offices,
Representatives and Distributors

6-2

FAIRCHILD
A Schlumberger Company

Alabama

Hall Mark Electronics
4900 Bradford Drive
Huntsville, Alabama 35807
Tel: 205-837-8700 TWX: 810-726-2187
Hamilton/Avnet Electronics
4692 Commercial Drive
Huntsville, Alabama 35805
Tel: 205-837-7210 TWX: 810-726-2162

Arizona
Hamilton/Avnet Electronics
505 South Madison Drive
Tempe, Arizona 85281
Tel: 602-231-5100 TWX: 910-950-0077
Kierulff Electronics
4134 East Wood Street
Phoenix, Arizona 85040
Tel: 602-243-4101
Wyle Distribution Group
8155 North 24th Avenue
Phoenix, Arizona 85021
Tel: 602-249-2232 TWX: 910-951-4282
California

Anthem Electronics, Inc.
21730 Nordhoff Street
Chatsworth, California 91311
Tel: 213-700-1000 TWX: 910-493-2083
Anthem Electronics, Inc.
4125 Sorrento Valley Blvd.
San Diego, California 92121
Tel: 714-279-5200
Anthem ElectroniCs, Inc.
174 Component Drive
San Jose, California 95131
Tel: 408-946-8000
Anthem Electronics, Inc.
2661 Dow Avenue
Tustin, California 92680
Tel: 714-730-8000
Arrow Electronics

9511 Ridge Haven Court
San Diego, California 92123
Tel: 714-565-4800 TWX: 910-335-1195
Arrow Electronics
521 Weddell Avenue
Sunnyvale, California 94086
Tel: 408-745-6600 TWX: 910-339-9371
Avnet Electronics
340 McCormick Avenue
Costa Mesa, California 92626
Tel: 714-754-6111 (Orange County)
213-558-2345 (Los Angeles)
TWX: 910-595-1928
Bell Industries

Electronic Distributor Division
1161 N. Fair Oaks Avenue
Sunnyvale, California 94086
Tel: 408-734-8570 TWX: 910-339-9378

Franchised
Distributors

United States and
Canada

Hamilton/Avnet Electronics
3170 Pullman Avenue
Costa Mesa, California 92626
Tel: 714-641-1850 TWX: 910-595-2638

Connecticut

Hamilton Electro Sales
10912 West Washington Blvd.
Culver City, California 90230
Tel: 213-558-2121 TWX: 910-340-6364
Hamilton/Avnet Electronics
4545 Viewridge Avenue
San Diego, California 92123
Tel: 714-571-7527 TWX: 910-335-1216
Hamilton/Avnet Electronics
1175 Bordeaux Drive
Sunnyvale, California 94086
Tel: 408-743-3355 TWX: 910-339-9332
"Sertech Laboratories
2120 Main Street, Suite 190
Huntington Beach, California 92647
Tel: 714-960-1403
Wyle Electronics
124 Maryland Street
EI Segundo, California 90245
Tel: 213-322-8100 TWX: 910-348-7111
Wyle Distributor Group
17872 Cowan Avenue
Irvine, California 92714
Tel: 714-641-1600
Telex: 910-595-1572
Wyle Distributor Group
18910 Teller Avenue
Irvine, California 92715
Tel: 714-851-9955
Wyle Distribution Group
9525 Chesapeake
San Diego, California 92123
Tel: 714-565-9171 TWX: 910-335-1590
Wyle Distribution Group
3000 Bowers Avenue
Santa Clara, California 95051
Tel: 408-727-2500 TWX: 910-338-0541
Colorado

Arrow Electronics
2121 South Hudson
Denver, Colorado 80222
Tel: 303-758-2100 TWX: 910-331-0552
Bell Industries
8155 West 48th Avenue
Wheatridge, Colorado 80033
Tel: 303-424-1985 TWX: 910-938-0393
Hamilton/Avnet Electronics
8765 E. Orchard Rd., Suite 708
Englewood, Colorado 80111
Tel: 303-740-1000 TWX: 910-935-0787
Wyle Distribution Group
451 East 124th Avenue
Thornton, Colorado 80241
Tel: 303-457-9953 TWX: 910-936-0770

Arrow Electronics
12 Beaumont Road
Wallingford, Connecticut 06492
Tel: 203-265-7741 TWX: 710-476-0162
Hamilton/Avnet Electronics
Commerce Drive, Commerce Park
Danbury, Connecticut 06810
Tel: 203-797-2800 TWX: 710-546-9974
Harvey Electronics
112 Main Street
Norwalk, Connecticut 06851
Tel: 203-853-1515 TWX: 710-468-3373
Schweber Electronics
Finance Drive
Commerce Industrial Park
Danbury, Connecticut 06810
Tel: 203-792-3500 TWX: 710-456-9405
Florida

Arrow Electronics
1001 Northwest 62nd Street
Suite 108
FI. Lauderdale, Florida 33309
Tel: 305-776-7790 TWX: 510-955-9456
Arrow Electronics
50 Woodlake Drive West
Building B
Palm Bay, Florida 32905
Tel: 305-725-1480
Hall Mark Electronics
1671 West McNab Road
FI. Lauderdale, Florida 33309
Tel: 305-971-9280 TWX: 510-956-3092
Hall Mark Electronics
7233 Lake Ellenor Drive
Orlando, Florida 32809
Tel: 305-855-4020 TWX: 810-850-0183
Hamilton/Avnet Electronics
6801 NW15thWay
FI. Lauderdale, Florida 33309
Tel: 305-971-2900 TWX: 510-955-3097
Hamilton/Avnet Electronics
3197 Tech Drive, North
51. Petersburg, Florida 33702
Tel: 813-576-3930 TWX: 810-863-0374
Schweber Electronics
2830 North 28th Terrace
Hollywood, Florida 33020
Tel: 305-927-0511 TWX: 510-954-0304
Georgia

Arrow Electronics
2979 Pacific Drive
Norcross, Georgia 30071
Tel: 404-449-8252 TWX: 810-766-0439
Hall Mark Electronics
6410 Atlantic Blvd., Suite 115
Norcross, Georgia 30071
Tel: 404-447-8000 TWX: 810-766-4510
Hamilton/Avnet Electronics
5825-0 Peachtree Corners East
Norcross, Georgia 30092
Tel: 404-447-7500 TWX: 810-766-0432

•• This distributor carries Fairchild die products only.

6-3

•

FAIRCHIL.D
A Schlumberger Company

Illinois
Arrow Electronics

492 Lunt Avenue
Schaumburg, illinois 60193
Tel: 312-893-9420 TWX: 910-291-3544
Hall Mark Electronics
1177 Industrial Drive
Bensenville, Illinois 60106
Tel: 312-860-3800

Franchised
Distributors

United States and
Canada

Pioneer Electronics
9100 Gaither Road
Gaithersburg, Maryland 20760
Tel: 301-948-0710 TWX: 710-828-9784

Minnesota
Arrow Electronics
5230 West 73rd Street
Edina, Minnesota 55435
Tel: 612-830-1800 TWX: 910-576-3125

Schweber Electronics
9218 Gaither Road
Gaithersburg, Maryland 20760
Tel: 301-840-5900 TWX: 710-828-9749

Hamilton/Avnet Electronics
1130 Thorndale Avenue
Bensenville, Illinois 60106
Tel: 312-860-7780 TWX: 910-227-0060

Massachusetts
Arrow Electronics
Arrow Drive
Woburn, Massachusetts 01801
Tel: 617-933-8130 TWX: 710-392-6770

Kierulff Electronics
1536 Landmeier Road
Elk Grove Village, Illinois 60007
Tel: 312-640-0200 TWX: 910-227-3166

Cadence Electronics
15 Strathmore Road
Natick, Massachusetts 01760
Tel: 617-879-3000 TWX: 710-346-0397

Schweber Electronics
1275 Brummel Avenue
Elk Grove Village, Illinois 60007
Tel: 312-364-3750 TWX: 910-222-3453

Gerber Electronics
128 Carnegie Row
Norwood, Massachusetts 02062
Tel: 617-329-2400

Indiana
Arrow Electronics
2718 Rand Road
Indianapolis, Indiana 46241
Tel: 317-243-9353 TWX: 810-341-3119

Hamilton/Avnet Electronics
50 Tower Office Park
Woburn, Massachusetts 01801
Tel: 617-273-7500 TWX: 710-393-0382

Graham Electronics Supply, Inc.
133 S. Pennsylvania Street
Indianapolis, Indiana 46204
Tel: 317-634-8486 TWX: 810-341-3481
Hamilton/Avnet Electronics
485 Gradle Drive
Carmel, Indiana 46032
Tel: 317-844-9333 TWX: 810-260-3966
Pioneer Electronics
6408 Castle Place Drive
Indianapolis, Indiana 46250
Tel: 317-849-7300 TWX: 810-260-1794

Kansas
Hall Mark Electronics
10815 Lakeview Drive
Lenexa, Kansas 66215
Tel: 913-888-4747
Hamilton/Avnet Electronics
9219 Quivira Road
Overland Park, Kansas 66215
Tel: 913-888-8900 TWX: 910-743-0005

Maryland
Hall Mark Electronics
6655 Amberton Drive
Baltimore, Maryland 21227
Tel: 301-796-9300
Hamilton/Avnet Electronics
6822 Oak Hall Lane
Columbia, Maryland 21045
Tel: 301-995-3500 TWX: 710-862-1861

Harvey Electronics
44 Hartwell Avenue
Lexington, Massachusetts 02173
Tel: 617-861-9200 TWX: 710-326-6617
Schweber Electronics
25 Wiggins Avenue
Bedford, Massachusetts 01730
Tel: 617-275-5100 TWX: 710-326-0268
"Sertech Laboratories
1 Peabody Street
Salem, Massachusetts 01970
Tel: 617-745-2450

Michigan
Arrow Electronics
3810 Varsity Drive
Ann Arbor, Michigan 48104
Tel: 313-971-8220 TWX: 810-223-6020
Hamilton/Avnet Electronics
2215 29th Street S.E.
Space A5
Grand Rapids, Michigan 49508
Tel: 616-243-8805 TWX: 810-273-6921
Hamilton/Avnet Electronics
32487 Schoolcraft
Livonia, Michigan 48150
Tel: 313-522-4700 TWX: 810-242-8775
Pioneer Electronics
13485 Stamford
Livonia, Michigan 48150
Tel: 313-525-1800
Schweber Electronics
33540 Schoolcraft
Livonia, Michigan 48150
Tel: 313-525-8100 TWX: 810-242-2983

* Minority Distributor

•• This distributor carries Fairchild die products only.

6-4

Hamilton/Avnet Electronics
10300 Bren Road East
Minnetonka, Minnesota 55343
Tel: 612-932-0600 TWX: 910-576-2720
Schweber Electronics
7422 Washington Avenue S.
Eden Prairie, Minnesota 55344
Tel: 612-941-5280 TWX: 910-576-3167

Missouri
Hall Mark Electronics
13789 Rider Trail
Earth City, Missouri 63045
Tel: 314-291-5350
Hamilton/Avnet Electronics
13743 Shoreline Court, East
Earth City, Missouri 63045
Tel: 314-344-1200 TWX: 910-762-0606

New Hampshire
Arrow Electronics
1 Perimeter Road
Manchester, New Hampshire 03103
Tel: 603-668-6968 TWX: 710-220-1684
New Jersey
Arrow Electronics
Pleasant Valley Avenue
Moorestown, New Jersey 08057
Tel: 609-235-1900 TWX: 710-897-0829
Arrow Electronics
285 Midland Avenue
Saddle Brook, New Jersey 07662
Tel: 201-797-5800 TWX: 710-988-2206
Hall Mark Electronics
Springdale Business Center
2091 Springdale Road
Cherry Hill, New Jersey 08003
Tel: 609-424-0880
Hamilton/Avnet Electronics
10 Industrial Road
Fairfield, New Jersey 07006
Tel: 201-575-3390 TWX: 710-734-4388
Hamilton/Avnet Electronics
#1 Keystone Avenue
Cherry Hill, New Jersey 08003
Tel: 609-424-0100 TWX: 710-940-0262
Harvey Electronics
45 Route 46
Pinebrook, New Jersey 07058
Tel: 201-575-3510 TWX: 710-734-4382
Schweber Electronics
18 Madison Road
Fairfield, New Jersey 07006
Tel: 201-227-7880 TWX: 710-734-4305
Sterling Electronics
774 Pfeiffer Blvd.
Perth Amboy, New Jersey 08861
Tel: 201-442-8000 Telex: 138-679

FAIRCHILD
A Schlumberger Company

New Mexico
Arrow Electronics
2460 Alamo Avenue S.E.
Albuquerque, New Mexico 87106
Tel: 505·243·4566 TWX: 910·889·1679

Franchised
Distributors

United States and
Canada

Summit Distributors, Inc.
916 Main Street
Buffalo, New York 14202
Tel: 716·884·3450 TWX: 710·522·1692

Pennsylvania
Arrow Electronics
650 Seco Road
Monroeville, Pennsylvania 15146
Tel: 412·856·7000

Bell Industries
11728 Linn Avenue N.E.
Albuquerque, New Mexico 87123
Tel: 505·292·2700 TWX: 910·989·0625

North carolina
Arrow Electronics
938 Burke Street
Winston·Salem, North Carolina 27102
Tel: 919·725·8711 TWX: 510·931-3169

Pioneer Electronics
261 Gibraltar Road
Horsham, Pennsylvania 19044
Tel: 215·674·4000 TWX: 510·665·6778

Hamilton/Avnet Electronics
2524 Baylor Drive, S.E.
Albuquerque, New Mexico 871 06
Tel: 505·765·1500 TWX: 910·989·0614

Hall Mark Electronics
1208 Front Street, Bldg. K
Raleigh, North Carolina 27609
Tel: 919·823·4465 TWX: 510·928·1831

Pioneer Electronics
259 Kappa Drive
Pittsburgh, Pennsylvania 15238
Tel: 412·782·2300 TWX: 710·795·3122

New York
Arrow Electronics
900 Broadhollow Road
Farmingdale, New York 11735
Tel: 516·694·6800
TWX: 510·224·6155 & 510·224·6126

Hamilton/Avnet Electronics
2803 Industrial Drive
Raleigh, North Carolina 27609
Tel: 919·829·8030 TWX: 510·928·1836

Schweber Electronics
101 Rock Road
Horsham, Pennsylvania 19044
Tel: 215·441·0600 TWX: 510·665·6540

Pioneer Electronics
103 Industrial Drive
Greensboro, North Carolina 27406
Tel: 919·273·4441

Texas
Arrow Electronics
13715 Gamma Road
Dallas, Texas 75234
Tel: 214·386·7500 TWX: 910·860·5377

Arrow Electronics
20 Oser Avenue
Hauppauge, New York 11787
Tel: 516·231-1000
Arrow Electronics
P.O. Box 370
7705 Maltlage Drive
Liverpool, New York 13088
Tel: 315·652·1000 TWX: 710·545·0230
Components Plus, Inc.
40 Oser Avenue
Hauppauge, New York 11787
Tel: 516·231·9200 TWX: 510·227·9869
Hamilton/Avnet Electronics
'5 Hub Drive
Melville, New York 11746
Tel: 516·454·6000 TWX: 510·224·6166
Hamilton/Avnet Electronics
333 Metro Park
Rochester, New York 14623
Tel: 716-475·9130 TWX: 510·253·5470
Hamilton/Avnet Electronics
16 Corporate Circle
E. Syracuse, New York 13057
Tel: 315·437·2642 TWX: 710·541-1560
Harvey Electronics
(mailing address)
P.O. Box 1208
Binghamton, New York 13902
(shipping address)
1911 Vestal Parkway East
Vestal, New York 13850
Tel: 607·748·8211
Harvey Electronics
60 Crossways Park West
Woodbury, New York 11797
Tel: 516·921·8920 TWX: 510·221·2184
Schweber Electronics
Jericho Turnpike
Westbury, LI., New York 11590
Tel: 516·334·7474 TWX: 910·222·3660

Ohio
Arrow Electronics
7620 McEwen Road
Centerville, Ohio 45459
Tel: 513·435·5563 TWX: 810·459·1611

Arrow Electronics
10700 Corporate Drive, Suite 100
Stafford, Texas 77477
Tel: 713·491·4100 TWX: 910·880·4439

Arrow Eiectronics
6238 Cochran Road
Solon, Ohio 44139
Tel: 216·248·3990 TWX: 810·427·9409

Hall Mark Electronics
12211 Technology Blvd.
Austin, Texas 78759
Tel: 512·258·8848

Hamilton/Avnet Electronics
954 Senate Drive
Dayton, Ohio 45459
Tel: 513-433·0610 TWX: 810·450·2531

Hall Mark Electronics
11333 Page Mill Drive
Dallas, Texas 75243
Tel: 214·343·5000 TWX: 910·867·4721

Hami~on/Avnet Electronics
4588 Emery Industrial Parkway
Warrensville Heights, Ohio 44128
Tel: 216·831·3500 TWX: 810·427·9452

Hall Mark Electronics
8000 Westglen
Houston, Texas 77063
Tel: 713·781·6100

Pioneer Electronics
4800 E. 131st Street
Cleveland, Ohio 44105
Tel: 216·587·3600

Hamilton/Avnet Electronics
2401 Rutland Drive
Austin, Texas 78758
Tel: 512·837·8911 TWX: 910·874·1319

Pioneer Electronics
4433 Interpoint Blvd.
Dayton, Ohio 45424
Tel: 513·236·9900 TWX: 810·459·1622

Hamilton/Avnet Electronics
8750 Westpark
Houston, Texas 77063
Tel: 713·780·1771 TWX: 910·881·5523

Schweber Electronics
23880 Commerce Park Road
Beachwood, Ohio 44122
Tel: 216-464·2970 TWX: 810·427·9441

Hamilton/Avnet Electronics
2111 W. Walnut Hill Lane
Irving, Texas 75062
Tel: 214·659·4111 TWX: 910·860·5929

Oklahoma
Hall Mark Electronics
5460 S. 103rd East Avenue
Tulsa, Oklahoma 74145
Tel: 918·665·3200 TWX: 910·845·2290

Schweber Electronics, Inc.
4202 Beltway Drive
Dallas, Texas 75234
Tel: 214·661·5010 TWX: 910·860·5493

Oregon
Hamilton/Avnet Electronics
6024 S.W. Jean Road
Building C, Suite 10
Lake Oswego, Oregon 97034
Tel: 503·635·8157 TWX: 910·455·8179

6·5

Schweber Electronics, Inc.
10625 Richmond, Suite 100
Houston, Texas 77042
Tel: 713·784·3600 TWX: 910·881·4836

FAIRCHILD
A Schlumberger Company

Sterling Electronics
4201 Southwest Freeway
Houston, Texas 77027
Tel: 713-627-9800 TWX: 910-881-5042
Telex: STELECO HOUA 77-5299
Utah
Bell Industries
3639 West 2150 South
Salt Lake City, Utah 84120
Tel: 801-972-6969 TWX: 910-925-5686

Franchised
Distributors

United States and
Canada

Wisconsin

Hamilton/Avnet Canada Ltd.
2670 Sabourin Street
SI. Laurent, Quebec, H4S 1M2, Canada
Tel: 514-331-6443 TWX: 610-421-3731

Hall Mark Electronics
9657 South 20th Street
Oakcreek, Wisconsin 53154
Tel: 414-761-3000
Hamilton/Avnet Electronics
2975 South Moorland Road
New Berlin, Wisconsin 53151
Tel: 414-784-4510 TWX: 910-262-1182

Hamilton/Avnet Electronics
1585 West 2100 South
Salt Lake City, Utah 04119
Tel: 801-972-2800 TWX: 910-925-4018

Canada
Future Electronics Inc.
4800 Dufferin Street
Downsview, Ontario M3H 5S8, Canada
Tel: 416-663-5563

Washington
Arrow Electronics
14230 N.E. 21st Street
Bellevue, Washington 98005
Tel: 206-643-4800 TWX: 910-443-3033

Future Electronics Inc.
Baxter Center
1050 Baxter Road
Ottawa, Ontario, K2C 3P2, Canada
Tel: 613-820-8313

Hamilton/Avnet Electronics
14212 N.E. 21st Street
Bellevue, Washington 98005
Tel: 206-453-5844 TWX: 910-443-2469

Future Electronics Inc.
237 Hymus Blvd.
Pointe Clare (Montreal), Quebec, H9R 5C7, Canada
Tel: 514-694-7710 TWX: 610-421-3251

Radar Electronic Co., Inc.
168 Western Avenue W.
Seattle, Washington 98119
Tel: 206-282-2511 TWX: 910-444-2052

Hamilton/Avnet Canada Ltd.
6845 Rexwood Road, Units 3-4-5
Mississauga, Ontario, L4V 1R2, Canada
Tel: 416-677-7432 TWX: 610-492-8867

Wyle Distribution Group
1750 132nd Avenue N.E.
Bellevue, Washington 98005
Tel: 206-453-8300 TWX: 910-444-1379

Hamilton/Avnet Canada Ltd.
210 Colonnade Road
Nepean, Ontario K2E 7L5, Canada
Tel: 613-226-1700 Tlx: 0534-971

6-6

Semad Electronics Ltd.
620 Meloche Avenue
Dorval, Quebec, H9P 2P4, Canada
Tel: 604-299-8866 TWX: 610-422-3048
Semad Electronics Ltd.
105 Brisbane Avenue
Downsview, Ontario, M3J 2K6, Canada
Tel: 416-663-5670 TWX: 610-492-2510
Semad Electronics Ltd.
864 Lady Ellen Place
Ottawa, Ontario Kl Z 5M2, Canada
Tel: 613-722-6571 TWX: 610·562-1923

A Schlumberger Company

Sales
Representatives

United States and
Canada

California

Nevada

Utah

Magna Sales, Inc,
3333 Bowers Avenue, Suite 295
Santa Clara, California 95051
Tel: 408-727-8753 TWX: 910-338-0241

Magna Sales, Inc,
4560 Wagon Wheel Road
Carson City, Nevada 89701
Tel: 702-883-1471

Simpson Associates, Inc.
7324 South 1300 East, Suite 350
M idyale, Utah 84047
Tel: 801-566-3691 TWX: 910-925-4031

New York

WaShington

Tri-Tech Electronics, Inc.
3215 E. Main Street
Endwell, New York 13760
Tel: 607-754-1094 TWX: 510-252-0891

Magna Sales, Inc.

FAIRCHIL.D

Colorado
Simpson Associates, Inc.

2552 Ridge Road
Littleton, Colorado 80120
Tel: 303-794-8381 TWX: 910-935-0719
Illinois

Micro Sales, Inc,
54 W, Seegers Road
Arlington Heights, Illinois 60005
Tel: 312-956-1000 TWX: 910-222-1833
Maryland

Delta III Associates
1000 Century Plaza, Suite 224
Columbia, Maryland 21044
Tel: 301-730-4700 TWX: 710-826-9654
Massachusetts
Spectrum Associates, Inc.
109 Highland Avenue
Needham, Massachusetts 02192
Tel: 617-444-8600 TWX: 710-325-6665
Missouri

Micro Sales, Inc,
514 Earth City Plaza, Suite 314
Earth City, Missouri 63045
Tel: 314-739-7446

Tri-Tech Electronics, Inc.
590 Perinton Hills Office Park
Fairport, New York 14450
Tel: 716-223-5720 TWX: 510-253-6356
Tri-Tech Electronics, Inc.
6836 E. Genesee Street
Fayetteville, New York 13066
Tel: 315-446-2881 TWX: 710-541-0604
Tri-Tech Electronics, Inc,
19 Davis Avenue
Poughkeepsie, New York 12603
Tel: 914-473-3880 TWX: 510-253-6356
Oregon

Magna Sales, Inc.
8285 S.W. Nimbus Avenue, Suite 138
Beaverton, Oregon 97005
Tel: 503-641-7045 TWX: 910-467-8742

6-7

Benaroya Business Park

Building 3, Suite 115
300 120th Avenue, N.E,
Bellevue, Washington 98004
Tel: 206-455-3190

Wisconsin
Larsen Associates
10855 West Potter Road
Wauwatosa, Wisconsin 53226
Tel: 414-258-0529 TWX: 910-262-3160

A Schlumberger Company

Sales
Offices

United States and
Canada

Alabama
Huntsville Office
500 Wynn Orive, Suite 511
Huntsville, Alabama 35805
Tel: 205-837-8960

Indiana
Ft. Wayne Office
2118 Inwood Drive, Suite 111
Ft. Wayne, Indiana 46815
Tel: 219-483-6453 TWX: 810-332-1507

North Carolina
Raleigh Office
1100 Navaho Drive, Suite 112
Raleigh, North Carolina 27609
Tel: 919-876-9643

Arizona

Indianapolis Office
7202 N, Shadeland, Room 205
Castle Point
Indianapolis, Indiana 46250
Tel: 317-849-5412 TWX: 810-260-1793

Ohio
Dayton Office
5045 North Main Street, Suite 105
Day1on, Ohio 45414
Tel: 513-278-8278 TWX: 810-459-1803

Kansas
Kansas City Office
8600 West 11 Oth Street, Suite 209
Overland Park, Kansas 66210
Tel: 913-649-3974

Oklahoma
Tulsa Office
9810 East 42nd Street, Suite 127
Tulsa, Oklahoma 74145
Tel: 918-627-1591

Maryland
Columbia Office
1000 Century Plaza, Suite 225
Columbia, Maryland 21044
Tel: 301-730-1510 TWX: 710-826-9654

Oregon
Portland Office
8285 S.W. Nimbus Avenue, Suite 138
Beaverton, Oregon 97005
Tel: 503-641-7871 TWX: 910-467-7842

Massachusetts
Framingham Office
5 Speen Street
Framingham, Massachusetts 01701
Tel: 617-872-4900 TWX: 710-380-0599

Pennsylvania
Philadelphia Office'
2500 Office Center
2500 Maryland Road
Willow Grove, Pennsylvania 19090
Tel: 215-657-2711

FAIRCHIL.C

Phoenix Office
2255 West Northern Road, Suite B112
Phoenix, Arizona 85021
Tel: 602-864-1000 TWX: 910-951-1544
California
Los Angeles Office'
Crocker Bank Bldg,
15760 Ventura Blvd" Suite 1027
Encino, California 91436
Tel: 213-990-9800 TWX: 910-495-1776
San Diego Office'
4355 Ruffin Road, Suite 100
San Diego, California 92123
Tel: 714-560-1332
Santa Ana Office'
1570 BroOkholiow Drive, 'Suite 206
Santa Ana, California 92705
Tel: 714-557-7350 TWX: 910-595-1109
Santa Clara Office'
3333 Bowers Avenue, Suite 299
Santa Clara, California 95051
Tel: 408-987-9530 TWX: 910-338-0241
Colorado
Denver Office
7200 East Hampden Avenue, Suite 206
Denver, Colorado 80224
Tel: 303-758-7924
Connecticut
Danbury Office
57 North Street, #206
Danbury, Connecticut 06810
Tel: 203-744-4010
Florida
Ft. Lauderdale Office
Executive Plaza, Suite 112
1001 Northwest 62nd Street
Ft. Lauderdale, Florida 33309
Tel: 305-771-0320 TWX: 510-955-4098
Orlando Office'
Crane's Roost Office Park
399 Whooping Loop
Altamonte Springs, Florida 32701
Tel: 305-834-7000 TWX: 810-850-0152
Georgia
Atlanta Sales Office
Interchange Park, Bldg, 2
4183 N,E, Expressway
Atlanta, Georgia 30340
Tel: 404-939-7683
Illinois
Itasca Office
500 Park Blvd" Suite 575
Itasca, Illinois 60143
Tel: 312-773-3300

Michigan
Detroit Office'
21999 Farmington Road
Farmington Hills, Michigan 48024
Tel: 313-478-7400 TWX: 810-242-2973
Minnesota
Minneapolis Office'
4570 West 77th Street, Room 356
Minneapolis, Minnesota 55435
Tel: 612-835-3322 TWX: 910-576-2944
New Jersey
New Jersey Office
Vreeland Plaza
41 Vreeland Avenue
Totowa, New Jersey 07511
Tel: 201-256-9006
New Mexico
Albuquerque Office
North BUilding
2900 Louisiana N,E. South G2
Albuquerque, New Mexico 87110
Tel: 505-884-5601 TWX: 910-379-6435
New York
Fairport Office
815 Ayrault Road
Fairport, New York 14450
Tel: 716-223-7700
Melville Office
275 Broadhollow Road, Suite 219
Melville, New York 11747
Tel: 516-293-2900 TWX: 510-224-6480
Poughkeepsie Office
19 Davis Avenue
Poughkeepsie, New York 12603
Tel: 914-473-5730 TWX: 510-248-0030

, Field Application Engineer

6-8

Tennessee
Knoxville Office
Executive Square 1/
9051 Executive Park Drive, Suite 502
Knoxville, Tennessee 37923
Tel: 615-691-4011
Texas
Austin Office
8240 Mopac Expressway, Suite 270
Austin, Texas 78759
Tel: 512-837-8931
Dal/as Office
1702 North Col/ins Street, Suite 101
Richardson, Texas 75081
Tel: 214-234-3391 TWX: 910-867-4757
Houston Office
9896 Bissonnet-2, Suite 470
Houston, Texas 77036
Tel: 713-771-3547 TWX: 910-881-8278
Canada
Toronto Regional Office
2375 Steeles Avenue West, Suite 203
Downsview, Ontario M3J 3A8, Canada
Tel: 416-665-5903 TWX: 610-491-1283

Franchised
Distributors

I=AIRCHILD
A Schlumberger Company

Austria
BVG elektrot. bauelemente
vertriebsges.mbH
Rottstr. 8-1 0
1140Wien
Tel: (0043) 0222/949373 TWX: 135123
Brazil
Alfatronic Imp Exp Repres Llda.
Av. Repousas, 1498 - Sao Paulo, Brazil
Tel: (011) 852-8277
Comercial Radio Car Llda.
Av. Alberto Bins, 615 - Porto Alegre, Brazil
Tel: (0512) 25-8879
Datatronix Eletr Ltda.
Av. Pacaembu, 746 - Sao Paulo, Brazil
Tel: (011) 826-0111
Eletropan Imp Repres Llda.
R. Barra Bonita, 18 - Sao Paulo, Brazil
Tel: (011) 295-0293
Intertek Comp Eletr Llda.
R. Tagipuru, 235 - 80A Tel: (011) 67-0582
Karimex Imp Exp Llda.
Rua Guararapes, 1826 Tel: (011) 241-2814

Sao Paulo, Brazil

Sao Paulo, Brazil

Semicon Sem E Comp Eletr Llda.
R. Coronel Oscar Porto, 841 - Sao Paulo, Brazil
Denmark
E Friis Mikkelsen AS
51 Krogshojvej
DK2880 Bagsvaerd, Denmark
Tel: (02) 986333 TWX: 37350
Multikomponent (Standard Electric) AS
Fabriksparken 31
DK 2600 Glostrup, Denmark
Tel: (02) 456645 TWX: 33355
Finland
Multikomponent
Kuortaneenkatu 1
SF-00520 Helsinki 52, Finland
Tel: 009358/073 91 00 TWX: 12 1450
France
Almex
48, Rue De L' Aubepine
B.P.102
Tel: 666-21-12 TWX: 250.067
Aufray
Centre De Gros
Zone Industrielle
76800 St Etienne Du Rouvray
Tel: (35) 65-22-22 TWX: 180.503
Bellion Electronique
Z.I. Kerscao Brest
B.P.16
29219 Le Relecq Kerhuon
Tel: (98) 28-03-03 TWX: 940.930
Dimex (Stockiste)
12, Rue Du Seminaire
94516 Rungis Cedex
Tel: 686.52.10 TWX: 200.420

Feutrier

Avenue Trois Clorieuses
42270 St Priest En Jarez
Tel: (77) 74-67-33
Feutrier lie De France
8, Rue Benoit Malon
92150 Suresnes
Tel: 772-46-46 TWX: 610.237
Gros Electronique
13, Avenue Victor Hugo
B.P.63
59350 St Andre Lez Lille
Tel: (20) 51.21.33 TWX: 120.257
Paris Sud
1 Route De Champlan
91300 Massy
Tel: 920-66-99
R.E.A.
9, Rue Ernest Cognacq
B.P.5
92300 Levallois
Tel: 758-11-11 TWX: 620.630
S.C.T. (Toutelectric)
15, Boulevard Bon Repos
B.P.406
31008 Toulouse
Tel: (61) 62.11.33 TWX: 531.501
Scientech
11, Avenue Ferdinand Buisson
75016 Paris
Tel: 609-91-36 TWX: 260.042
S.R.D.
Chemin Des Pennes Au Pin
Plan De Campagne
13170 Les Pennes Mirabeau
Tel: (42) 02.91.08 TWX: 440.076
Germany
Astek GmbH
Carl-Zeiss-Str.3
2085 Quickborn
Tel: (0049) 04106171 084 TWX: 0214082
Dr. G. Dohrenberg
Bayreuther Str. 3
1000 Berlin 30
Tel: (0049) 030/2138043 TWX: 0184860
E2000 Vertriebs GmbH
Neumarkter Str. 75
8000 Manchen 80
Tel: (0049) 089/434061 TWX: 0522561
ElcowaGmbH
Str. der Republik 17-19
6200 Wiesbaden
Tel: (0049) 06121/65005 TWX: 04186202
IBH
Gutenbergring 35
2000 Norderstedt
Tel: (0049) 040/5231933 TWX: 02174188
ProtecGmbH
Franz-Liszt-Str. 4
Tel: (0049) 089/603006 TWX: 0529298

6-9

International
Positron Bauelem.
Vertriebs GmbH
Benzstr.1
7016 Gerlingen
Tel: (0049) 07156/23051 TWX: 07245266
Spezial Electronic KG
Kreuzbreite 15
3062 Backeburg
Tel: (0049) 05722/2030 TWX: 0971624
T echnoprojekt
Heinrich-Baumann-Str.30
7000 Stuttgart
Tel: (0049) 0711/280281 TWX: 0721437
Italy
Region Of Campania:
A.E.P.
Via Terracina. 311 - 80125 Napoli
Tel: 081-630006 TWX: 721129
Region Of Emilia Romagna:
Adelsy S.A.S.
Via Lombardia. 17/2 - 40139 Bologna
Tel: 051-540150 TWX: 510226 Adelsy
Hellis
P. ZZA Amendola. 1 - 41049 Sassuolo (MO)
Tel: 059/8041 04-864990
Region Of Lazio:
Pantronic S.R.L.
Via Flaminia Nuova. 219
00191 Roma
Tel: 06/3284866-3288048 TWX: 612405 Pantron
Region Of Lombardia:
Claitron S.P.A.
Viale Certosa 269 - 20151 Milano
Tel: 3088063/5/7/-3087330-3088506
3088030-306539-305580
TWX: 313843 Claimi
Comprel S.R.L.
Viale Romagna. 1
20092 Cinisello Balsamo (MI)
Tel: 6120641 TWX: 332484
Kontron S.P.A.
Via Fantoli. 16/15 - 20138 Milano
Tel: 50721 TWX: 315430 Kontmi I
Region Of Marche:
Comprel S.R.L.
Traversa Carlo Moderno. 24
Casella Postale 9
60025 Loreto (AN)
Tel: (071) 977693
Region Of Piemonte:
Claitron S.P.A.
Via Tazzoli. 158
10137 Torino
Tel: 011/3097173/306540
Pantronic S.R.L.
Via Crevacuore. 65
10146 Torino
Tel: 011-790079-795981 TWX: 221420

A Schlumberger Company

Franchised
Distributors

Region Of 3 Venezie:
Comprel S.R.L.
Via V. Veneto. 33
36100 Vicenza
Tet: 0444-26912

Hakou Corp.
Daishin Bldg.
Gokisho-Dohri. Showa-Ku
Nagoya-Shi. Aichi 466. Japan
Tel: (052) 853-5621

Kontron S.P.A.
Via Forcellini. 4
35100 Padova
Tel: 049/754717/850377

Hamilton Avnet Electronics Corp.
Nishi-Honmachi Zennikku Bldg.
10-10. Nishi-Honmachi 1-Chome. Nishi-Ku
Osaka 550. Japan
Tel: (06) 533-5855

FAIRCHIL.D

Japan
Alpha Denshi Corp.
Yamajin Bldg.
1-11. Esaka-Cho 2-Chome. Suita-Shi
Osaka 564. Japan
Tel: (06) 384-2281
Asahi Glass Corp.
Hankyu Terminal Bldg.
1-4. Shibata 1-Chome. Kita-Ku
Osaka 530. Japan
Tel: (06) 373-5895
Asahl Glass Corp.
Kishimoto Bldg.
2-1. Marunouchi 2-Chome. Chiyoda-Ku
Tokyo 100. Japan
Tel: (03) 218-5800
Ashitate Denki Corp.
Higashi-Nagasaki Bldg.
1-14. Kanda-Iwamoto-Cho. Chiyoda-Ku
Tokyo 1D1 .. Japan
Tel: (03)255-5151
Ashltate Denki Corp.
Highness-Katahira 901
3-36. Katahira 1-Chome. Sendai-Shi
Miyagi 980. Japan
T91:(0222) 66-8951
Dairiichi Seigyo Kiki Corp.
Kouraku BI~g.
1-8. Kouraku 1-Chome. Bunkyo-Ku
TOkyo 112. Japan
Tel: (03) 811,-9205
Fuji Electronics Corp.

Fusou Bldg.

Hamilton Avnet Electronics Corp.
Yu and You Bldg.
1-4. Nihonbashi Horidome-Cho. Chuo-Ku
Tokyo 103. Japan
Tel: (03) 662-9911
lnaba Sangyo Kiki Corp.
4-6. Honda 1-Chome. Nishi-Ku
Osaka 550. Japan
Tel: (06) 582-8483
Kanematsu Semiconductor Corp.
Bingo-Cho Nomura Bldg.
2-5. Bingo-Cho. Higashi-Ku
Osaka 541. Japan
Tel: (06) 222-1851
Kanematsu Semiconductor Corp.
Daini-Nagaoka Bldg.
8-5. Hatchobori 2-Chome. Chuo-Ku
Tokyo 104. Japan
Tel: (03) 552-6091
Nakamura Denki Corp.
3-5. Soto-Kanda 1-Chome. Chiyoda-Ku
Tokyo 101. Japan
Tel: (03) 255-6831
Okamoto Musen Denki Corp.
7-28. Hatae Dohri. Nakarnura-Ku
Nagoya-Shi. Aichi 453. Japan
Tel: (052) 461-4111
Okamoto Musen Denki Corp.
2-7. Ohsumi 1-Chome. Higashi-Yodogawa-Ku
Osaka 533. Japan
Tel: (06) 327-1133

,

5-3. Nishi,tlonmallhi 1-Chome. Nishi-Ku
Osaka 550. Japan
Tel: (06)541-7112
Fuji Electronics Corp.
New-Kourakuen Bldg.
22-3. Hongo 1-Chome. Bunkyo-Ku
Tokyo 113. Japan
Tel: (03) 815-0830
Futaba Danki Corp.

SudOu Bldg.
3-9. Shimizu l-Chome
Matsumoto~Shi. Nagano 390 Japan
Tet: (02~)35-2329
i"utaba D8nki Corp.
ShUWIl-1BR Bldg.
5-7. KOhjimachi. Chiyoda-Ku
Tokyo 102. Japan
Tel: (03) 230-2171

Okamoto Musen Denki Corp.
2-17. Nozawa 3-Chome. Setagaya-Ku
Tokyo 154. Japan
Tel: (03) 412-8211

International
Radio Industrial Del Norte. S.A.
Calle Del Cerro No. 18
H. Del Parral. Chih.
Tel: 2-18-38
The Netherlands
Inelco Components
and Systems bv
Turfstekerstraat 63
1431 GD-Aalsmeer
Tel: (0031) 02977/28855 TWX: 14693
Rodelco Electronics
Verrijn Stuartlaan 29
2280 AG-RijSwijk ZH
Tel: (0031) 070/995750 TWX: 32506
Rodelco Electronics
Rue de Genave 4
1140 Bruxelles
Tel: (0032) 02/2166330 TWX: 61415
Norway
Datamatik NS
Jerikoveien 16
Oslo 10
Norway
Tel: 00947/230 17 30 TWX: 16967
Sweden
In Multikomponent
Box 1330
S-17125Solna
Sweden
Tel: 00946/8830020 TWX: 10516
Norqvist + Berg
Box 9145
S-102 72 Stockholm
Sweden
Tel: 00946/869 04 00 TWX: 10407
Switzerland
MoorAG
Bahnstr.58
8105 Regensdorf/Zurich
Tel: (0041) 01/8406644 TWX: 0045-52042
PrimotecAG
Wettinger Str. 23
5400 Baden
Tel: (0041) 056/265262 TWX: 0045-58949

Osaka T okiwa Shoko
13-3. Nipponbashi 5-Chome. Naniwa-Ku
Osaka 556. Japan
Tel: (06) 643-3521

United Kingdom
Barlec Ltd.
Foundry Lane
Horsham
Sussex RH 13 5PX
Tei: Horsham (0403) 51881 TWX: 877222

Mexico
Dicopel S.A.
Augusto Rodin No. 20
Mexico 18 D.F.
Tel: 687-18-00

Celdis Ltd.
37/39 Loverock Road
Reading
Berkshire RG3 1DZ
Tel: Reading (0734) 585171 TWX: 848370

Distele S.A.
Obrero Mundila 736
Mexico 13 D.F.
Tel: 538-05-00

Comway Electronics Ltd.
Market Street
Bracknell
Berkshire RG12 1QP
Tel: Bracknell (0344) 24765 TWX: 847201

Proveedora Electronica S.A.
Prolongacion Moctezuma Ote. No. 24
Mexico 21 D.F.
Tel: 554-83-00

6-10

In Electronic Services
Edinburgh Way
Harlow CM20 2DF
Tel: Harlow (0279) 26777 TWX: 81525

FAIRCHILD
A Schlumberger Company

Jermyn-Mogul
Vestry Estate
Sevenoaks

KentTN145EU
Tel: Sevenoaks (0732) 50144 TWX: 95142

Franchised
Distributors
Lock Distribution

Neville Street
Chadderton
Oldham
lancashire Ol9 6lF
Tel: Manchester 061-652 0431 TWX: 669619

Sales
Representatives

International
Macro Marketing LId.
Burnham lane
Slough
Berkshire Sl1 6lN
Tel: Burnham (062 86) 4422 TWX: 847945

International

Argentina

Brazil

Uruguay

Electroimpex SA
Guatemala 5991
1425 Buenos Aires, Argentina
Tel: 771-3773

Sinchy Rokka's Do Brazil Com E Rep Llda.
Rua Cambauba, 6 S/203, Rio De Janeiro, Brazil
Tel: (021) 393-1496

Ricagni Importaciones Llda.
Av. 18 De Julio, 1216
Montevideo, Uruguai
Tel: 90-3671

Transcontinental Marketing Llda.
R. Correa Vasques, 58
Sao Paulo, Brazil
Tel: (011) 71-3607

6-11

A Schlumberger Company

Sales
Offices

International

Austria
Fairchild Electronics GmbH
Meidlinger Hauptstr. 46
1120Wien
Tel: (0043) 0222/858682 TWX: 075096

Japan
Pol a Shibuya Bldg.,
15-21, Shibuya l-Chome, Shibuya-Ku,
Tokyo 150, Japan
Tel: (03) 400-8351

Scandinavia
Fairchild Semiconductor AB
Svartensgatan 6
S-11620 Stockholm, Sweden
Tel: 46/8/449255 TWX: 854-17759

Brazil
Fairchild Semicondutores Ltda.
R. Alagoas, 663
01242 Sao Paulo, Brazil
Tel: (011) 66-9092 (011) 67-3224

Yotsubashi Chuo Bldg.,
4-26, Shinmachi l-Chome, Nishi-Ku,
Osaka 550, Japan
Tel: (06) 541-6138

Switzerland
Fairchild Camera & Instrument GmbH
Baumackerstr. 4
8050 Zurich
Tel: (0041) 01/3114230 TWX: 0045-58311

I=AIRCHIL.C

France
Fairchild
121 Avenue D'italie
75013 Paris, France
Tel: 584-55-66
Germany
Fairchild Camera & Instrument
(Deutschland) GmbH
8046 Garching
Daimlerstr. 15
Tel: (0049) 089/320031 TWX: 0524831
Italy
Fairchild Semiconduttori S.P.A.
Viale Corsica, 7 - 20133 Milano
Tel: (02) 296001/5 - 2367741/5
Telegr: Fairsemco TWX: 330522 Fair I

Korea
Fairchild Semiconductor (Korea) Ltd.
No. 219-6, Gari Bong-Dong,
Guro-Ku, Seoul, Korea,
Tel: 855-0067, 6751
Mexico
Blvb. Pte. Adolfo Lopez Mateos No. 163
Col. Mixcoac
Delegacion B. Juarez
03910 Mexico D.F.
Tel: 563-54-11 Ext: 152, 153, 154, 155

The Netherlands
Fairchild Camera & Instrument GmbH
Ruysdaelbaan 35
5613 OX-Eindhoven
Tel: (0031) 040/446909 TWX: 51024

Fairchild Semiconduttori S.P.A.
Via Francesco Saverio Nitti, 11 - 00191 Roma
Tel: (06) 3287548-3282717 TWX: 612046 Fair Rom

6-12

United Kingdom
Fairchild Camera and Instrument (UK) Ltd.
230 High Street
Potters Bar
Hertfordshire En6 5BU, England
Tel: Potters Bar (0707) 51111
TWX: 262835
Fairchild Camera and Instrument (UK) Ltd.
17 Victoria Street
Craigshill
Livingston
West Lothian EH54 5BG, Scotland
Tel: Livingston (0506) 32891 TWX: 72629

FAIRCHILD
A Schlumberger Company

Fairchild reserves the nght to make changes in the circuitry
or specifications in this book at any time without notice.
Fairchild cannot assume responsibility for use of
any circuitry described other than circuitry embodied
in a Fairchild product a other circuit patent licenses
are implied ,
Printed in U.S.A.l214-12-0002-116/50M



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