Synchronous rectifying circuit for flyback converter

摘要

A synchronous rectifying circuit for a flyback converter includes a synchronous rectifying element (Q2) coupled to the secondary winding (N2) of a transformer (T) and performing a synchronous rectifying operation according to an on/off operation of the synchronous rectifying element; an auxiliary inductance circuit (L3) coupled to the secondary winding (N2) of the transformer (T) and having an energy discharge time period shorter than that of the secondary winding (N2); and a control element (Q3) for turning the synchronous rectifying element (Q2) off in response to the detection of termination of the energy discharge of the auxiliary inductance circuit (L3).