Patent ID: 7791903
Filing Date: 2010-09-07
Classification: H02M,Y02B

Abstract:
1. A DC-DC flyback converter, which comprises: a three-winding transformer; a primary power circuit including a first MOSFET connected to a first winding of the transformer; a secondary power circuit connected to a second winding of the transformer, the secondary power circuit further including a synchronous rectifier comprising a second MOSFET having first and second output terminals; and a self-driven circuit including connected to a third winding of the transformer, wherein the self-driven circuit further includes a negative voltage removal circuit for removing negative voltage between the output terminals of the synchronous rectifier and a synchronous rectifier trigger switch-off circuit for switching the synchronous rectifier to an off condition, wherein the negative voltage removal circuit is formed by a third MOSFET and a resistor, while the synchronous rectifier trigger switch-off circuit includes the third MOSFET, the second winding of the transformer and a Zener diode.