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