Product Specification

High-integrated Green-mode PWM Controller

SG6841

©System General Corp.

- 2 -

www.sg.com.tw

Version 2.1 (IRO33.0001.B5)

Jun.15,2006

MARKING DIAGRAMS

PIN CONFIGURATION

ORDERING INFORMATION

Part Number

Package

SG6841S

8-Pin SOP

SG6841D

8-Pin DIP

SG6841SZ

8-Pin SOP(Lead Free)

SG6841DZ

8-Pin DIP(Lead Free)

PIN DESCRIPTIONS

Pin No.

Symbol Function

Description

1

GND

Ground

Ground.

2

FB

Feedback

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

determined by this FB pin and current sense signal from Pin 6.

3

VIN

This pin is pulled high to the rectified line input through a resistor for start-up. Since the

start-up current requirement for SG6841 is very small, a large start-up resistance can be

used to minimize power loss. Under normal operation, this pin is also used to detect line

voltage to compensate for constant output power limit for universal AC input.

4

Ri

Reference Setting

A resistor from RI pin to ground will generate a constant current source forSG6841. This

current is used to charge an internal capacitor and hence the switching frequency are

determined. Increasing the resistance will decrease the current source and reduce the

65kHz switching frequency.

5

RT

Temperature

Protection

For over-temperature protection. An external NTC thermistor is connected from this pin

to ground. The impedance of the NTC will decrease under high temperature. Once the

voltage on RT pin drops below a fixed limit, the PWM output will be disabled.

6

SENSE

Current Sense

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

current limiting.

7

VDD

Power supply

Power Supply.

8

GATE

Driver Output

The totem-pole output driver for the power MOSFET. A soft driving waveform is

implemented to improve EMI.

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RI

VIN

GATE

VDD

SENSE

RT

GND

FB