Patent ID: 7589982
Filing Date: 2009-09-15
Classification: H02M,Y02B

Abstract:
1. A synchronous rectifier forward converter comprising: a transformer having a primary winding and a secondary winding; a main switch connected in series with the primary winding, wherein the energy stored in the primary winding is transferred to the secondary winding according to on/off operations of the main switch; a synchronous rectifier including a forward switch and a freewheel switch and connected to the secondary winding, and configured to convert the energy received by the secondary winding into a regulated output voltage; and a reverse current suppressor having an input terminal for receiving a control input signal and an turn-off signal generator circuit configured to be driven by the control input signal to generate a turn-off signal to turn off the freewheel switch when the synchronous rectifier forward converter is shut down, wherein the control input signal has a characteristic that the control input signal stands in a first level when the synchronous rectifier forward converter is normally operating and the control input signal transits to a second level in a while after the input power of the synchronous rectifier forward converter is interrupted.