METHOD AND APPARATUS TO PROVIDE SYNCHRONOUS RECTIFYING CIRCUIT FOR FLYBACK POWER CONVERTERS

摘要

A method and an apparatus to provide synchronous rectifying circuit for flyback power converters. A Synchronous rectifying circuit for flyback power converter includes a pulse generator (100), an isolation device (70) and a synchronous rectifier (50). The pulse generator (100) is utilized to generate a pulse signal in response to a leading edge and a trailing edge of a switching signal (SIN). The switching signal (SIN) is used for switching a transformer (10) of the power converter. The isolation device such as a pulse transformer (75) is coupled to the pulse generator for transferring the pulse signal. The synchronous rectifier (50) includes a power switch (400) and a control circuit (200). The power switch (400) is connected between the secondary side of the transformer (10) and the output of the power converter for rectifying operation. The control circuit (200) having a latch is operated to receive the pulse signal for controlling the power switch (400).