Description

The highly integrated SG6742ML/MR PWM controller provides several features to enhance the performance of flyback converters.

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. The green-mode function enables the power supply to meet international power conservation requirements. With the internal high-voltage startup circuitry, the power loss due to bleeding resistors is also eliminated. To further reduce power consumption, SG6742ML/MR is manufactured using the BiCMOS process, which allows an operating current of only 2.7mA.

Features

ƒ High-Voltage Startup

ƒ Low Operating Current: 2.7mA

ƒ Linearly Decreasing PWM Frequency to 22KHz

ƒ Frequency Hopping to Reduce EMI Emission

ƒ Fixed PWM Frequency: 65KHz

ƒ Peak-Current-Mode Control

ƒ Cycle-by-Cycle Current Limiting

ƒ Leading-Edge Blanking

ƒ Synchronized Slope Compensation

ƒ Internal Open-Loop Protection

ƒ GATE Output Maximum Voltage Clamp: 18V

ƒ VDDUnder-Voltage Lockout (UVLO)

ƒ VDDOver-Voltage Protection (OVP)

ƒ Programmable Over-Temperature Protection (OTP)

ƒ Internal Latch Circuit (OVP, OTP)

ƒ Internal Sense Short-Circuit Protection

ƒ Build-in 5ms Soft-Start Function

ƒ Constant Power Limit (Full AC Input Range)

ƒ Internal OTP Sensor with Hysteresis

Applications

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

ƒ Power Adapters

ƒ Open-Frame SMPS