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SG6858 — Low-Cost, Green-Mode, PWM Controller for Flyback Converters
September 2009
SG6858
Low-Cost, Green-Mode, PWM Controller for Flyback
Converters
Features
Green-Mode PWM
Supports the ”Blue Angel” Standard
Low Startup Current: 10µA (Maximum)
Low Operating Current: 2.5mA
Leading-Edge Blanking (LEB)
Constant Output Power Limit
Built-in Synchronized Slope Compensation
Current-Mode Operation
Cycle-by-Cycle Current Limiting
Under-Voltage Lockout (UVLO)
Programmable PWM Frequency
V
DD
Over-Voltage Protection with Auto-Restart
Gate Output Voltage Clamped at 17V
Few External Components Required
SSOT-26 and DIP-8 Packages Available
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 meet even the strictest power
conservation requirements.
The BiCMOS fabrication process enables reducing the
startup current to 10µA and the operating current to
2.5mA. To further improve power conservation, a large
startup resistance can be used. Built-in synchronized