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

Product Specification

Low Cost Green-Mode PWM Controller for Flyback Converters SG6859

Version 1.2.1(IAO33.0067.B2) September 28,2007

FEATURES

 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

Product Specification

Low Cost Green-Mode PWM Controller for Flyback Converters SG6859

Version 1.2.1(IAO33.0067.B2) September 28, 2007

MARKING DIAGRAMS PIN CONFIGURATION

ORDERING INFORMATION

Part Number Pb-Free Package

SG6859TZ 6-Pin SOT-26

SG6859DZ 8-Pin DIP-8

PIN DESCRIPTIONS

Pin No.

Name DIP-8(SOT-26) Type Function

GATE 1 / (6) Driver Output The totem-pole output driver for driving the power MOSFET.

VDD 2 / (5) Supply Power supply.

NC 3 NC pin.

SENSE 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.

RI 5 / (3) 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.

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.

AAJ: SG6859

M: Mask Version

W: Week code A~Z=W1~W26

A~Z=W27~W52

: Lead Free Package

SOT-26

GND

FB

RI

GATE

VDD

SENSE

T: D=DIP

P: Z =Lead Free

Null=Regular Package

XXXXXXXX: Wafer Lot

Y: Year; WW: Week

V: Assembly Location

DIP-8

RI

NC

FB

GND

SENSE

N

C

VDD

GATE

AAJMW

XXXXXXXXYWWV

SG6859TP

Product Specification

Low Cost Green-Mode PWM Controller for Flyback Converters SG6859

Version 1.2.1(IAO33.0067.B2) September 28, 2007

BLOCK DIAGRAM

Product Specification

Low Cost Green-Mode PWM Controller for Flyback Converters SG6859

Version 1.2.1(IAO33.0067.B2) September 28, 2007

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 °C

SOT 208.4 °C/W

RθJA Thermal Resistance (Junction to Air) 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

TA Operating Ambient Temperature -20 to +85 °C

* For proper operation.

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

VDD Section

Symbol Parameter Test Condition Min. Typ. Max. Unit

VDD-OP Continuously Operation Voltage 22 V

VDD-ON Turn-On Threshold Voltage 15.5 16.5 17.5 V

VDD-OFF Turn-Off Threshold Voltage 10.5 11.5 12.5 V

IDD-ST Startup Current VDD=VDD-ON – 0.1V 9 15 µA

IDD-OP Operating Supply Current VDD=15V,

GATE with 1nF to GND 3 3.5 mA

VDD-OVP VDD Over-voltage-protection level (Auto Restart) 24 25 26 V

tD-VDDOVP VDD Over-voltage-protection Debounce (Auto Restart) 125 µs

VDD-G OFF VDD Low-threshold Voltage to Exit

Green-off Mode V

DD-OFF + 1 V

Product Specification

Low Cost Green-Mode PWM Controller for Flyback Converters SG6859

Version 1.2.1(IAO33.0067.B2) September 28, 2007

Feedback Input Section

Symbol Parameter Test Condition Min. Typ. Max. Unit

ZFB Input Impedance 5 KΩ

VFB-OPEN FB Output High Voltage 5 V

VFB-OL FB Open-loop Trigger Level 4.3 4.6 4.9 V

tD-OLP The delay time of FB pin Open Loop Protection 56 ms

VFB-N Green-Mode Entry FB Voltage 2.6 2.85 3.1 V

VFB-G Green-Mode Ending FB Voltage 2.20 V

SG Green-Mode Modulation Slope RI=95KΩ 40 75 100 Hz/mV

Current Sense Section

Symbol Parameter Test Condition Min. Typ. Max. Unit

ZSENSE Input Impedance 10 KΩ

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 40 %

Oscillator Section

Symbol Parameter Test Condition Min. Typ. Max. Unit

Center Frequency 65 70 75

FOSC Normal PWM Frequency Hopping Range RI=95KΩ ±4.9 KHz

THOP Hopping Period RI=95KΩ 3.7 ms

FOSC-G Green-Mode Frequency RI=95KΩ 22 KHz

FDV Frequency Variation versus VDD Deviation VDD=13.5 to 22V 0 0.02 2 %

FDT Frequency Variation versus Temp. Deviation TA=-20 to 85°C 2 %

Output Section

Symbol Parameter Test Condition Min. Typ. Max. Unit

DCYMAX Maximum Duty Cycle 70 75 80 %

VGATE-L Output Voltage Low VDD=15V, Io=20mA 1.5 V

VGATE-H Output Voltage High VDD=13.5V, Io=20mA 8 V

tr Rising Time VDD=15V, CL=1nF 150 ns

tf Falling Time VDD=15V, CL=1nF 55 ns

VGATE-CLAMP Output Clamp Voltage VDD=22V 16 17 18 V

Product Specification

Low Cost Green-Mode PWM Controller for Flyback Converters SG6859

Version 1.2.1(IAO33.0067.B2) September 28, 2007

TYPICAL CHARACTERISTICS

Turn-On Threshold Voltage (V

DD-ON

) vs Temperature

16.0

16.2

16.4

16.6

16.8

17.0

-40 -25 -10 5 20 35 50 65 80 95 110 125

Temperature (℃)

V

DD-ON

(V)

Turn-Off Threshold Voltage (V

DD-OFF

) vs Temperature

8

9

10

11

12

13

14

-40 -25 -10 5 20 35 50 65 80 95 110 125

Temperature (℃)

V

DD-OFF

(V)

Startup Current (I

DD-ST

) vs Temperature

0.2

0.4

0.6

0.8

1.0

1.2

1.4

-40 -25 -10 5 20 35 50 65 80 95 110 125

Temperature (℃)

I

DD-ST

(uA)

Operating Supply Current (I

DD-OP

) vs Temperature

2.0

2.2

2.4

2.6

2.8

3.0

-40 -25 -10 5 20 35 50 65 80 95 110 125

Temperature (℃)

I

DD-OP

(mA)

Normal PWM Frequency (F

OSC

) vs Temperature

70.0

70.5

71.0

71.5

72.0

-40 -25 -10 5 20 35 50 65 80 95 110 125

Temperature (℃)

F

OSC

(Khz)

Maximum Duty Cycle (DCY

MAX

) vs Temperature

74.0

74.2

74.4

74.6

74.8

75.0

-40-25-10 5 203550658095110125

Temperature (℃)

DCY

MAX

(%)

Product Specification

Low Cost Green-Mode PWM Controller for Flyback Converters SG6859

Version 1.2.1(IAO33.0067.B2) September 28, 2007

Green-Mode Entry FB Voltage (V

FB-N

) vs Temperature

2.2

2.4

2.6

2.8

3.0

3.2

-40 -25 -10 5 20 35 50 65 80 95 110 125

Temperature (℃)

V

FB-N

(V)

Green-Mode Ending FB Voltage (V

FB-G

) vs Temperature

2.20

2.22

2.24

2.26

2.28

2.30

-40 -25 -10 5 20 35 50 65 80 95 110 125

Temperature (℃)

V

FB-G

(V)

Leading-Edge Blanking Time (t

LEB

) vs Temperature

280

290

300

310

320

330

340

-40 -25 -10 5 20 35 50 65 80 95 110 125

Temperature (℃)

t

LEB

(ns)

Operating Supply Current vs VDD voltage

1.0

1.5

2.0

2.5

3.0

3.5

12 13 14 15 16 17 18 19 20 21 22 23 24

VDD (V)

IDD-OP (mA

)

Product Specification

Low Cost Green-Mode PWM Controller for Flyback Converters SG6859

Version 1.2.1(IAO33.0067.B2) September 28, 2007

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:

)(kHz

)(kR

6650

I

PWM

fΩ

=

Leading-Edge Blanking

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.

Product Specification

Low Cost Green-Mode PWM Controller for Flyback Converters SG6859

Version 1.2.1(IAO33.0067.B2) September 28, 2007

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:

.)(max

36.0

Duty

Duty×

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.

Product Specification

Low Cost Green-Mode PWM Controller for Flyback Converters SG6859

Version 1.2.1(IAO33.0067.B2) September 28, 2007

REFERENCE CIRCUIT

F1

R7

R6

R3

R1

R5 R4

R9

R10

R11

R13

R12

R14

R8

R2

C3

C7

CY1 C10

C1

CX1

C2

C9

C4

C8

C6

1 2

L1

10

5

73,4

1,2

8

9

T1

2 1

D1

1

23

Q1

GND

1

FB

2

RI

3SENSE 4

VDD 5

GATE 6

U1

21

D2

12

3 4

U2

2 1

D4

2 1

D5

1 2

L2

2 3

1

U3

1

4

3

2

BD1

VO

GND

L

N

R15

C11

BOM

Reference Component Reference Component

BD1 BD 1A/500V L2 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 (Optional) CC 102P/100V 1206 R9 R 100KΩ 0805

C8 EC 470µ/10V 105°C R10 (Optional) R 10Ω 1206

C9 EC 220µ/10V 105°C R11 R 100Ω 1/8W

C10 CC 222P 0805 R12 R 33KΩ 0805

C11 N.C. R13 R 33KΩ 1/8W

D1 Diode FRI07 R14 R 4.7KΩ 0805

D2 Diode FR102 R15 R 0Ω 0805

D4 Diode SB360 T1 EE-16

D5 (Optional) ZD 6.8V 0.5W U1 IC SG6859

F1 R 1Ω/0.5W U2 PC817

L1 20mH 6*8mm U3 TL431

Product Specification

Low Cost Green-Mode PWM Controller for Flyback Converters SG6859

Version 1.2.1(IAO33.0067.B2) September 28, 2007

PACKAGE INFORMATION

8 PINS - DIP (D)

41

85

D

E1

EeB

A1

A2

A

b

b1

L

e

¢X

Θ

Dimensions

Millimeters Inches

Symbol Min. Typ. Max. Min. Typ. Max.

A 5.334 0.210

A1 0.381 0.015

A2 3.175 3.302 3.429 0.125 0.130 0.135

b 1.524 0.060

b1 0.457 0.018

D 9.017 9.271 10.160 0.355 0.365 0.400

E 7.620 0.300

E1 6.223 6.350 6.477 0.245 0.250 0.255

e 2.540 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˚

Product Specification

Low Cost Green-Mode PWM Controller for Flyback Converters SG6859

Version 1.2.1(IAO33.0067.B2) September 28, 2007

6 PINS - SOT (T)

13

64

E

e1

E1

e

D

b

A2

A1

A

θ

R1

R

L2

L1

L

θ

Detail A

c

1

Dimensions

Millimeters Inches

Symbol Min. Typ. Max. Min. Typ. Max.

A 1.45 0.057

A1 0.15 0.006

A2 0.90 1.15 1.30 0.036 0.045 0.051

b 0.30 0.50 0.011 0.020

c 0.08 0.22 0.003 0.009

D 2.90 0.114

E 2.80 0.110

E1 1.60 0.063

e 0.95 0.037

e1 1.90 0.075

L 0.30 0.45 0.60 0.020 0.018 0.024

L1 0.60 0.024

L2 0.25 0.010

R 0.10 0.004

R1 0.10 0.25 0.004 0.010

θ° 0° 4° 8° 0° 4° 8°

θ1° 5° 10° 15° 5° 10° 15°

Product Specification

Low Cost Green-Mode PWM Controller for Flyback Converters SG6859

Version 1.2.1(IAO33.0067.B2) September 28, 2007

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

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