Fairchild SG6742DZ, SG6742SZ, SG6742DZ, SG6742SZ Schematic

Product Specification

Highly Integrated Green-Mode PWM Controller SG6742

FEATURES

 High-voltage start-up  Low operating current (4mA)  Linearly decreasing PWM frequency to 22KHz  Frequency jittering to reduce EMI emission  Fixed PWM frequency (65KHz)  Peak-current-mode control  Cycle-by-cycle current limiting  Leading-edge blanking  Synchronized slope compensation

To minimize standby power consumption, a proprietary green-mode function provides off-time modulation to linearly decrease the switching frequency at light-load conditions. To avoid acoustic noise problems, the minimum PWM frequency is set above 22KHz. This green-mode function enables the power supply to meet international power conservation requirements. With the internal high-voltage start-up circuitry, the power loss due to bleeding resistors is eliminated. To further reduce power consumption, SG6742 is manufactured using the BiCMOS process, which allows an operating current of 4mA.

 Internal open-loop protection  GATE output maximum voltage clamp (18V)  V  V

under-voltage lockout (UVLO)

DD

over voltage protection (OVP)

DD

 Programmable over-temperature protection (RT)  Internal latch circuit (OVP, RT)  Constant power limit (full AC input range)  Internal OTP sensor with hysteresis

SG6742 integrates a frequency a hopping function that helps reduce EMI emission of a power supply with minimum line filters. Also, its built-in synchronized slope compensation achieves stable peak-current-mode control. The proprietary internal line compensation ensures constant output power limit over a wide AC input voltages, from 90V

to 264VAC.

AC

SG6742 provides many protection functions. In addition

APPLICATIONS

General-purpose switch-mode power supplies and flyback power converters, including:

 Power Adapters  Open-Frame SMPS

DESCRIPTION

to cycle-by-cycle current limiting, the internal open-loop protection circuit ensures safety should an open-loop or output short-circuit failure occur. PWM output is disabled until V controller starts up again. As long as V

drops below the UVLO lower limit when the

DD

exceeds about

DD

26V, the internal OVP circuit is triggered.

SG6742 is available in an 8-pin DIP or SOP package.

The highly integrated SG6742 series of PWM controllers provides several features to enhance the performance of flyback converters.

TYPICAL APPLICATION

Product Specification

Highly Integrated Green-Mode PWM Controller SG6742

MARKING INFORMATION PIN CONFIGURATION

T: D = DIP, S = SOP

SG6742

XXXXXXXXYWWV

TP

P: Z =Lead Free

Null=regular package

XXXXXXXX: Wafer Lot Y

: Year; WW: Week

V

: Assembly Location

GND

FB

GATE

VDD

NC

HV

SENSE

RT

ORDERING INFORMATION

Part Number PWM Frequency Pb-Free Package

SG6742SZ 65KHz

SG6742DZ (Preliminary) 65KHz

SOP-8

DIP-8

PIN DESCRIPTIONS

Pin No. Symbol Function Description

1 GND Ground Ground.

2 FB Feedback

3 NC NA NC pin.

4 HV Start-up Input For start-up, this pin is pulled high to the line input or bulk capacitor via resistors.

5 RT

6 SENSE Current Sense

7 VDD Power Supply

8 GATE Driver Output The totem-pole output driver. Soft driving waveform is implemented for improved EMI.

Temperature

Detection

The signal from the external compensation circuit is fed into this pin. The PWM duty cycle is

determined in response to the signal on this pin and the current-sense signal on SENSE pin.

For over-temperature protection, an external NTC thermistor is connected from this pin to GND

pin. The impedance of the NTC decreases at high temperatures. Once the voltage of the RT

pin drops below a fixed limit, PWM output is disabled.

Current sense. The sensed voltage is used for peak-current-mode control and cycle-by-cycle

current limiting.

Power supply. The internal protection circuit disables PWM output as long as VDD exceeds the

OVP trigger point.

Product Specification

Highly Integrated Green-Mode PWM Controller SG6742

BLOCK DIAGRAM

Product Specification

Highly Integrated Green-Mode PWM Controller SG6742

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

VDD Supply Voltage 30 V

VHV Input Voltage to HV Pin 500 V

VL Input Voltage to FB, SENSE, CS Pin -0.3 to 7.0 V

PD Power Dissipation TA < 50°C

Thermal Resistance (Junction-to-Air）

R

Θ

JA

DIP

SOP 400

DIP 82.5

SOP 141.0

TJ Operating Junction Temperature -40 to +125 °C

T

Storage Temperature Range -55 to +150 °C

STG

T

L

ESD

Lead Temperature (Wave Soldering or Infrared, 10 Seconds) 260 °C

Electrostatic Discharge Capability, Human Body Model All pins except HV pin 4 KV

Electrostatic Discharge Capability, Machine Model All pins except HV pin 400 V

* All voltage values, except differential voltages, are given with respect to the GND pin.

* Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device.

800

mW

°C/W

ELECTRICAL CHARACTERISTICS

VDD 󰦚 15V; TA 󰦚 25°C, unless otherwise noted.

VDD Section

Symbol Parameter Test Condition Min. Typ. Max. Unit

V

Continuously Operating Voltage 22 V

DD-OP

V

Start Threshold Voltage 15.5 16.5 17.5 V

DD-ON

V

Minimum Operating Voltage 9.5 10.5 11.5 V

DD-OFF

I

Start-up Current V

DD-ST

I

Operating Supply Current VDD = 15V, GATE open 4 5 mA

DD-OP

I

Internal Sink Current V

DD-OLP

V

I

TH-OLP

V

VDD Over-Voltage Protection 25 26 27 V

DD-OVP

t

VDD Over-Voltage Protection Debounce Time 75 125 200 µs

D-VDDOVP

Off Voltage 6.5 7.5 8.0 V

DD-OLP

– 0.16V 30 µA

DD-ON

+0.1V 50 70 90 µA

TH-O LP

HV Section

Symbol Parameter Test Condition Min. Typ. Max. Unit

IHV Supply Current Drawn from HV Pin

I

Leakage Current After Start-up

HV-LC

VAC=90V (VDC=120V)󰦘

V

=10µF

DD

HV = 500V,

VDD = V

DD-OFF

+1V

1.2

mA

1 20 µA

Product Specification

Highly Integrated Green-Mode PWM Controller SG6742

Oscillator Section

Symbol Parameter Test Condition Min. Typ. Max. Unit

F

Frequency in Nominal Mode

OSC

t

Hopping Period 4.4 ms

HOP

F

Green-Mode Frequency 18 22 25 KHz

OSC-G

FDV Frequency Variation vs. VDD Deviation VDD=11V to 22V 5 %

FDT Frequency Variation vs. Temp. Deviation TA=-20 to 85°C 5 %

* Hopping off at green-mode.

Center Frequency 62 65 68

Hopping Range ±3.7 ±4.2 ±4.7

KHz

Feedback Input Section

Symbol Parameter Test Condition Min. Typ. Max. Unit

AV Input Voltage to Current-Sense Attenuation 1/4.5 1/4.0 1/3.5 V/V

ZFB Input Impedance 4 7 kΩ

V

Output High Voltage FB pin open 5.5 V

FB-OPEN

V

FB Open-Loop Trigger Level

FB-OLP

t

Delay Time of FB Pin Open Loop Protection 53 56 59 ms

D-OLP

V

Green-Mode Entry FB Voltage 1.9 2.1 2.3 V

FB-N

V

Green-Mode Ending FB Voltage V

FB-G

5.0 5.2 5.4 V

-0.5 V

FB-N

PWM Frequency

F

OSC

F

OSC-G

V

FB-G

V

FB-N

FB

Fairchild SG6742DZ, SG6742SZ, SG6742DZ, SG6742SZ Schematic [ru]