SG6859 Datasheet. Www.s Manuals.com. R1.2.1 Fairchild

User Manual: Marking of electronic components, SMD Codes AA, AA**, AA***, AA-, AA-**, AA-***, AA=***, AAA, AAA***, AAC, AAD, AAE, AAE**, AAF, AAFI, AAG, AAH**, AAHC, AAHO, AAI**, AAIK, AAJ**, AAJ***, AAJF*, AAJI, AAJJ, AAL***, AAM***, AAN***, AANC, AAP, AAQ, AAR, AAS, AASQ, AASR, AAT***, AATJ, AATK, AATL, AATM, AAU, AAU**, AAW, AAX, Aa. Datasheets 2N7002T, 2SD1757K, 74AHC1G00GW, AME8804AEEY, BCW60A, BCX51, BD48E23G, BD48K23G, BL3406B-1.0V, BL9641, LR9641, MAX1736EUT41-T, MAX1736EUT42-T, MAX2644, MAX4335EXT-T, MAX4336EXT

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Product Specification

SG6859

Low Cost Green-Mode PWM Controller for Flyback Converters

FEATURES
„
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„
„
„
„
„
„
„
„
„
„
„
„
„

Green-Mode PWM
Supports the “Blue Angel” Standard
Low Start-up Current (9uA)
Low Operating Current (3mA)
Leading-Edge Blanking
Constant Output Power Limit
Universal Input
Built-in Synchronized Slope Compensation
Current Mode Operation
Cycle-by-cycle Current Limiting
Under Voltage Lockout (UVLO)
Programmable PWM Frequency with Frequency
Hopping
VDD Over Voltage Protection (Auto Restart)
Gate Output Voltage Clamped at 17V
Low Cost
Few External Components Required
Small SOT-26 and Dip 8 Packages

APPLICATIONS
General-purpose switching mode power supplies and
flyback power converters, such as
„ Battery chargers for cellular phones, cordless
phones, PDAs, digital cameras, and power tools
„ Power adapters for ink jet printers, video game
consoles, and portable audio players
„ Open-frame SMPS for TV/DVD standby and other
auxiliary supplies, home appliances, and consumer
electronics
„ Replacements for linear transformers and RCC
SMPS
„ PC 5V standby power.

DESCRIPTION
This highly integrated PWM controller provides
several special enhancements designed to meet the low
standby-power needs of low-power SMPS. To minimize
standby power consumption, the proprietary green-mode
function provides off-time modulation to linearly
decrease the switching frequency under light-load
conditions. This green-mode function enables the power
supply to easily meet even the strictest power
conservation requirements.
The BiCMOS fabrication process enables reducing
the start-up current to 9uA, and the operating current to
3mA. To further improve power conservation, a large
start-up resistance can be used. Built-in synchronized
slope compensation ensures the stability of peak current
mode control. Proprietary internal compensation provides
a constant output power limit over a universal AC input
range (90VAC to 264VAC). Pulse-by-pulse current limiting
ensures safe operation even during short-circuits.
To protect the external power MOSFET from being
damaged by supply over voltage, the SG6859’s output
driver is clamped at 17V. SG6859 controllers can be used
to improve the performance and reduce the production
cost of power supplies. The SG6859 is the best choice for
replacing linear and RCC-mode power adapters. It is
available in 8-pin DIP and 6-pin SOT-26 packages.

TYPICAL APPLICATION

SG6859

© System General Corp.
Version 1.2.1(IAO33.0067.B2)

-1-

www.sg.com.tw • www.fairchildsemi.com
September 28,2007

Product Specification

SG6859

Low Cost Green-Mode PWM Controller for Flyback Converters

MARKING DIAGRAMS

PIN CONFIGURATION

AAJ: SG6859
M: Mask Version
W: Week code A~Z=W1~W26
A~Z=W27~W52

AAJMW

: Lead Free Package

SOT-26
GATE

GND
FB

VDD

RI

SENSE
DIP-8

T: D=DIP
P: Z =Lead Free
Null=Regular Package
XXXXXXXX: Wafer Lot
Y: Year; WW: Week
V: Assembly Location

SG6859TP
XXXXXXXXYWWV

GND

GATE
VDD

FB

NC

NC

SENSE

RI

ORDERING INFORMATION
Part Number

Pb-Free

Package

SG6859TZ

6-Pin SOT-26

SG6859DZ

8-Pin DIP-8

PIN DESCRIPTIONS
Pin No.
DIP-8(SOT-26)

Name

Type

Function

GATE

1 / (6)

Driver Output

VDD

2 / (5)

Supply

NC

3

NC pin.

4 / (4)

Analog Input

Current sense. This pin senses the voltage across a resistor. When the voltage
reaches the internal threshold, PWM output is disabled. This activates
over-current protection. This pin also provides current amplitude information for
current-mode control.

Analog
Input/Output

A resistor connected from the RI pin to ground will generate a constant current
source for the SG6859. This current is used to charge an internal capacitor, to
determine the switching frequency. Increasing the resistance will reduce the
amplitude of the current source and reduce the switching frequency. A 95kΩ
resistor Ri results in a 50uA constant current Ii and a 70kHz switching frequency.

SENSE

The totem-pole output driver for driving the power MOSFET.
Power supply.

RI

5 / (3)

NC

6

NC pin.

FB

7 / (2)

Analog Input

Feedback. The FB pin provides the output voltage regulation signal. It provides
feedback to the internal PWM comparator, so that the PWM comparator can
control the duty cycle.

GND

8 / (1)

Supply

Ground.

© System General Corp.
Version 1.2.1(IAO33.0067.B2)

-2-

www.sg.com.tw • www.fairchildsemi.com
September 28, 2007

Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters

SG6859

BLOCK DIAGRAM

© System General Corp.
Version 1.2.1(IAO33.0067.B2)

-3-

www.sg.com.tw • www.fairchildsemi.com
September 28, 2007

Product Specification

SG6859

Low Cost Green-Mode PWM Controller for Flyback Converters

ABSOLUTE MAXIMUM RATINGS
Symbol

Parameter

Value

Unit

VVDD

DC Supply Voltage *

30

V

VFB

Input Voltage to FB Pin

-0.3 to 7

V

VSENCE

Input Voltage to Sense Pin

-0.3 to 7

V

TJ

Operating Junction Temperature

150

RθJA

Thermal Resistance (Junction to Air)

°C

SOT

208.4

°C/W

DIP

82.5

°C/W

TSTG

Storage Temperature Range

-55 to +150

°C

TL

Lead Temperature (Wave soldering or IR, 10 seconds)

260

°C

VESD-HBM

ESD Capability, HBM Model

3.5

kV

VESD-MM

ESD Capability, Machine Model

200

V

* All voltage values, except differential voltages, are given with respect to GND pin.
* Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device.

RECOMMENDED OPERATING CONDITIONS
Symbol

Parameter

Value

Unit

VDD

DC Supply Voltage

≦22

V

Operating Ambient Temperature

-20 to +85

°C

TA

* For proper operation.

ELECTRICAL CHARACTERISTICS (VDD = 15V; TA = 25°C)
VDD Section
Symbol

Parameter

VDD-OP

Continuously Operation Voltage

Max.

Unit

22

VDD-ON

Turn-On Threshold Voltage

15.5

V

16.5

17.5

VDD-OFF

Turn-Off Threshold Voltage

10.5

V

11.5

12.5

IDD-ST

Startup Current

V

VDD=VDD-ON – 0.1V

9

15

µA

Operating Supply Current

VDD=15V,
GATE with 1nF to GND

3

3.5

mA

VDD-OVP

VDD Over-voltage-protection level

(Auto Restart)

25

26

tD-VDDOVP

VDD Over-voltage-protection Debounce (Auto Restart)

125

µs

VDD-G OFF

VDD Low-threshold Voltage to Exit
Green-off Mode

VDD-OFF + 1

V

IDD-OP

© System General Corp.
Version 1.2.1(IAO33.0067.B2)

Test Condition

Min.

24

-4-

Typ.

V

www.sg.com.tw • www.fairchildsemi.com
September 28, 2007

Product Specification

SG6859

Low Cost Green-Mode PWM Controller for Flyback Converters

Feedback Input Section
Symbol

Parameter

ZFB

Input Impedance

Test Condition

Min.

VFB-OPEN

FB Output High Voltage

5

VFB-OL

FB Open-loop Trigger Level

4.3

tD-OLP

The delay time of FB pin Open Loop Protection

VFB-N

Green-Mode Entry FB Voltage

VFB-G

Green-Mode Ending FB Voltage

SG

Green-Mode Modulation Slope

Typ.

Max.

5

KΩ
V

4.6

4.9

56
2.6

Unit

2.85

V
ms

3.1

2.20

V
V

RI=95KΩ

40

75

100

Hz/mV

Test Condition

Min.

Typ.

Max.

Unit

Current Sense Section
Symbol

Parameter

ZSENSE

Input Impedance

10

tPD

Delay to Output

40

55

100

ns

VSTHFL

Flat Threshold Voltage for Current Limit

0.91

0.96

1.01

V

VSTHVA

Valley Threshold Voltage for Current Limit

0.75

0.80

0.85

V

tLEB

Leading-Edge Blanking Time

250

300

350

ns

DCYSAW

Duty Cycle of SAW Limit

KΩ

40

%

Oscillator Section
Symbol
FOSC

Parameter
Normal PWM Frequency

Test Condition
Center Frequency
Hopping Range

RI=95KΩ

Min.

Typ.

Max.

65

70

75

±4.9

THOP

Hopping Period

RI=95KΩ

3.7

FOSC-G

Green-Mode Frequency

RI=95KΩ

22

FDV

Frequency Variation versus VDD Deviation

VDD=13.5 to 22V

FDT

Frequency Variation versus Temp. Deviation

TA=-20 to 85°C

0

0.02

Unit
KHz
ms
KHz

2

%

2

%

Output Section
Symbol

Parameter

DCYMAX

Maximum Duty Cycle

VGATE-L

Output Voltage Low

VDD=15V, Io=20mA

VGATE-H

Output Voltage High

VDD=13.5V, Io=20mA

tr

Rising Time

VDD=15V, CL=1nF

150

tf

Falling Time

VDD=15V, CL=1nF

55

VGATE-CLAMP

Output Clamp Voltage

VDD=22V

© System General Corp.
Version 1.2.1(IAO33.0067.B2)

Test Condition

-5-

Min.

Typ.

Max.

Unit

70

75

80

%

1.5
8

16

V
V

17

ns
ns
18

V

www.sg.com.tw • www.fairchildsemi.com
September 28, 2007

Product Specification

SG6859

Low Cost Green-Mode PWM Controller for Flyback Converters

TYPICAL CHARACTERISTICS
Turn-Off Threshold Voltage (VDD-OFF) vs Temperature
14

16.8

13

VDD-OFF (V)

VDD-ON (V)

Turn-On Threshold Voltage (VDD-ON) vs Temperature
17.0

16.6

16.4

16.2

12
11
10
9
8

16.0
-40

-25

-10

5

20

35

50

65

80

95

110

-40

125

-25

-10

5

35

50

65

80

95

110

125

110

125

110

125

Operating Supply Current (IDD-OP) vs Temperature

Startup Current (IDD-ST) vs Temperature
1.4

3.0

1.2

2.8

1.0

IDD-OP (mA)

IDD-ST (uA)

20

Temperature (℃)

Temperature (℃)

0.8
0.6

2.6

2.4

2.2

0.4
0.2

2.0

-40

-25

-10

5

20

35

50

65

80

95

110

125

-40

-25

-10

5

20

35

50

65

80

95

Temperature (℃)

Temperature (℃)

Normal PWM Frequency (FOSC) vs Temperature

Maximum Duty Cycle (DCYMAX) vs Temperature
75.0

72.0

74.8
DCYMAX (%)

FOSC (Khz)

71.5

71.0

70.5

74.6

74.4

74.2

74.0

70.0
-40

-25

-10

5

20

35

50

65

80

95

110

-40

125

© System General Corp.
Version 1.2.1(IAO33.0067.B2)

-25

-10

5

20

35

50

65

80

95

Temperature (℃)

Temperature (℃)

-6-

www.sg.com.tw • www.fairchildsemi.com
September 28, 2007

Product Specification

SG6859

Low Cost Green-Mode PWM Controller for Flyback Converters

Green-Mode Ending FB Voltage (VFB-G) vs Temperature
2.30

3.0

2.28

2.8

2.26

VFB-G (V)

VFB-N (V)

Green-Mode Entry FB Voltage (VFB-N) vs Temperature
3.2

2.6

2.4

2.24

2.22

2.2

2.20
-40

-25

-10

5

20

35

50

65

80

95

110

125

-40

-25

-10

5

20

35

50

65

80

95

110

125

23

24

Temperature (℃)

Temperature (℃)

Op er atin g Su p p ly C u r rent v s VDD v o ltag e

Leading-Edge Blanking Time (tLEB) vs Temperature
340

3.5

330
3.0

IDD-OP (mA)

tLEB (ns)

320
310
300

2.5

2.0

1.5

290
280

1.0

-40

-25

-10

5

20

35

50

65

80

95

110

125

12

Temperature (℃)

© System General Corp.
Version 1.2.1(IAO33.0067.B2)

13

14

15

16

17

18

19

20

21

22

VDD (V)

-7-

www.sg.com.tw • www.fairchildsemi.com
September 28, 2007

Product Specification

SG6859

Low Cost Green-Mode PWM Controller for Flyback Converters

OPERATION DESCRIPTION
SG6859 devices integrate many useful designs into
one controller for low-power switch-mode power supplies.
The following descriptions highlight some of the features
of the SG6859 series.

Start-up Current
The start-up current is only 9uA. Low start-up
current allows a start-up resistor with a high resistance
and a low-wattage to supply the start-up power for the
controller. A 1.5 MΩ, 0.25W, start-up resistor and a
10uF/25V VDD hold-up capacitor would be sufficient for
an AC-to-DC power adapter with a wide input range
(100VAC to 240VAC).

Operating Current
The operating current has been reduced to 3mA. The
low operating current results in higher efficiency and
reduces the VDD hold-up capacitance requirement.

Green-Mode Operation
The proprietary green-mode function provides
off-time modulation to linearly decrease the switching
frequency under light-load conditions. On-time is limited
to provide stronger protection against brownouts and
other abnormal conditions. The feedback current, which is
sampled from the voltage feedback loop, is taken as the
reference. Once the feedback current exceeds the
threshold current, the switching frequency starts to
decrease. This green-mode function dramatically reduces
power consumption under light-load and zero-load
conditions. Power supplies using the SG6859 can easily
meet even the strictest regulations regarding standby
power consumption.

Oscillator Operation
A resistor connected from the RI pin to ground will
generate a constant current source for the SG6859. This
current is used to charge an internal capacitor. The
charge-time determines the internal clock speed and the
switching frequency. Increasing the resistance will reduce
the amplitude of the input current and reduce the
switching frequency. A 95kΩ resistor Ri results in a 50uA
constant current Ii and a 70kHz switching frequency. The
relationship between Ri and the switching frequency is:

fPWM =

6650
R I (k Ω )

Each time the power MOSFET is switched on, a
turn-on spike will inevitably occur at the sense-resistor.
To avoid premature termination of the switching pulse, a
320nsec leading edge blanking time is built in.
Conventional RC filtering can therefore be omitted.
During this blanking period, the current-limit comparator
is disabled and it cannot switch off the gate driver.

Constant Output Power Limit
When the SENSE voltage across the sense resistor Rs
reaches the threshold voltage (around 0.96V), the output
GATE drive will be turned off following a short
propagation delay tPD.
This propagation delay will introduce an additional
current proportional to tPD*Vin/Lp. The propagation delay
is nearly constant regardless of the input line voltage VIN.
Higher input line voltages will result in larger additional
currents. At high input line voltages, the output power
limit will be higher than at low input line voltages.
To compensate for this output power limit variation
across a wide AC input range, the threshold voltage is
adjusted by adding a positive ramp.
This ramp signal rises from 0.80V to 0.96V, and then
flattens out at 0.96V. A smaller threshold voltage forces
the output GATE drive to terminate earlier.
This reduces the total PWM turn-on time and makes
the output power equal to that of low line input. This
proprietary internal compensation ensures a constant
output power limit for a wide AC input voltage range
(90VAC to 264VAC).

Under Voltage Lockout (UVLO)
The turn-on and turn-off thresholds of the SG6859
are fixed internally at 16.5V/11.5V. During start-up, the
hold-up capacitor must be charged to 16.5V through the
start-up resistor, so that the SG6859 will be enabled. The
hold-up capacitor will continue to supply VDD until power
can be delivered from the auxiliary winding of the main
transformer. VDD must not drop below 11.5V during this
start-up process. This UVLO hysteresis window ensures
that hold-up capacitor will be adequate to supply VDD
during start-up.

(kHz )

Leading-Edge Blanking

© System General Corp.
Version 1.2.1(IAO33.0067.B2)

-8-

www.sg.com.tw • www.fairchildsemi.com
September 28, 2007

Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters

SG6859

Gate Output
The SG6859 BiCMOS output stage is a fast totem
pole gate driver. Cross conduction has been avoided to
minimize heat dissipation, increase efficiency, and
enhance reliability. The output driver is clamped by an
internal 17V Zener diode in order to protect power
MOSFET transistors against undesired over-voltage gate
signals.

Built-in Slope Compensation
The sensed voltage across the current sense resistor
is used for current mode control and pulse-by-pulse
current limiting. Built-in slope compensation will
improve stability and prevent sub-harmonic oscillations
due to peak-current mode control. The SG6859 has a
synchronized, positively-sloped ramp built-in at each
switching cycle. The slope of the ramp is:

0.36 × Duty
Duty (max .)

Noise Immunity
Noise from the current sense or the control signal can
cause significant pulse width jitter, particularly in
continuous-conduction mode. While slope compensation
helps alleviate these problems, further precautions should
still be taken. Good placement and layout practices should
be followed. Avoiding long PCB traces and component
leads, locating compensation and filter components near
the SG6859, and increasing the power MOS gate
resistance is advised.

© System General Corp.
Version 1.2.1(IAO33.0067.B2)

-9-

www.sg.com.tw • www.fairchildsemi.com
September 28, 2007

Product Specification

SG6859

Low Cost Green-Mode PWM Controller for Flyback Converters

REFERENCE CIRCUIT
F1

L1

1

2

1

L

BD1
C3
CX1

R3

R1
2

4

C1

C2
R5

R4

T1

10

N
3

1,2

L2

D4

2

1

1

2

VO

1

R2

1

9
R10

D1
2
2

3

FB

VDD

RI

SENSE

6

R7

C8

D5

C9

Q1

1

5

7

3

2

GND GATE

2

U1
1

C7

8
5

3,4

GND

R15

4

C6
C11

R9

R6

R8

1

D2

2
R11

R13

1

4

C4

U2

2
CY1

C10
3

3

R14

U3
1

2

R12

BOM
Reference
BD1

Component
BD 1A/500V

Reference
L2

Component
10uH 6mm

CX1

(Optional)

XC 0.1uF

Q1

MOSFET 1A/600V

CY1

(Optional)

YC 102P/400V (Y1)

R1,R2

R 750KΩ 1206

C1

CC 103P/500V

R3,R4

R 47KΩ 1206

C2

EC 10µF/400V 105°C

R5

R 47Ω 1206

C3

CC 102P/500V

R6

R 4.7Ω 1206

C4

EC 10µ/50V

R7

R 100Ω 0805

C6

CC 472P 0805

R8

R 10Ω 1206

C7

CC 102P/100V 1206

R9

C8

(Optional)

EC 470µ/10V 105°C

R10

R 100KΩ 0805

C9

EC 220µ/10V 105°C

R11

C10

CC 222P 0805

R12

R 33KΩ 0805

C11

N.C.

R13

R 33KΩ 1/8W

(Optional) R 10Ω 1206
R 100Ω 1/8W

D1

Diode FRI07

R14

R 4.7KΩ 0805

D2

Diode FR102

R15

R 0Ω 0805

D4
D5

(Optional)

Diode SB360

T1

EE-16

ZD 6.8V 0.5W

U1

IC SG6859

F1

R 1Ω/0.5W

U2

PC817

L1

20mH 6*8mm

U3

TL431

© System General Corp.
Version 1.2.1(IAO33.0067.B2)

- 10 -

www.sg.com.tw • www.fairchildsemi.com
September 28, 2007

Product Specification

SG6859

Low Cost Green-Mode PWM Controller for Flyback Converters

PACKAGE INFORMATION
8 PINS - DIP (D)
D

Θ ¢X

5

E1

8

B

A

A2

4

A1

1

e

E

L
b1
b

e

Dimensions
Symbol

Millimeters
Min.
Typ.

A
0.381

A2

3.175

b

0.015
3.302

3.429

0.125

E

9.271

6.223

6.350

0.135

0.018
10.160

0.355

7.620

e

0.130
0.060

0.457
9.017

Max.
0.210

1.524

b1

E1

Typ.

5.334

A1

D

Inches
Min.

Max.

0.365

0.400

0.300
6.477

0.245

2.540

0.250

0.255

0.100

L

2.921

3.302

3.810

0.115

0.130

0.150

eB

8.509

9.017

9.525

0.335

0.355

0.375

θ˚

0˚

7˚

15˚

0˚

7˚

15˚

© System General Corp.
Version 1.2.1(IAO33.0067.B2)

- 11 -

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September 28, 2007

Product Specification

SG6859

Low Cost Green-Mode PWM Controller for Flyback Converters

6 PINS - SOT (T)
D

Detail A

b
4

E

E1

6

1

e

c

3

1
R
R

θ
A

A2

1

L2

e1

L

θ

A1

L1
1

θ

Detail A

Dimensions
Symbol

Millimeters
Min.
Typ.

A

Inches
Min.

Max.

Typ.

1.45

A1

0.15

A2

0.90

b
c

0.006

1.30

0.036

0.30

0.50

0.011

0.08

0.22

0.003

D

1.15

2.90

0.045

0.009
0.114

2.80

0.110

E1

1.60

0.063

e

0.95

0.037

e1

1.90

0.075

0.30

L1

0.45

0.60

0.020

0.60

L2

0.051
0.020

E

L

Max.
0.057

0.018

0.024

0.024

0.25

0.010

R

0.10

R1

0.10

0.25

0.004

θ°

0°

4°

8°

0°

4°

8°

θ1°

5°

10°

15°

5°

10°

15°

© System General Corp.
Version 1.2.1(IAO33.0067.B2)

0.004

- 12 -

0.010

www.sg.com.tw • www.fairchildsemi.com
September 28, 2007

Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters

© System General Corp.
Version 1.2.1(IAO33.0067.B2)

- 13 -

SG6859

www.sg.com.tw • www.fairchildsemi.com
September 28, 2007

www.s-manuals.com



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