Patent ID: 7375988

Claim:
A self-synchronized synchronous rectifier power supply circuit comprising: a transformer having a primary winding and a secondary winding; a primary circuit connecting an input alternating voltage to the primary winding; a secondary circuit comprising: a low pass output filter and a synchronous rectifier circuit connecting the secondary winding to the low pass output filter; wherein the synchronous rectifier circuit comprises: first and second synchronous rectifier switches each controlled by a signal applied to an included control electrode of the switch; first and second driver switches connected in series with the included control electrodes of the first and second synchronous rectifier switches such that the first and second driver switches control the voltage supplied from an external DC source to the included control electrodes of the first and second synchronous rectifier switches; a means for establishing a DC potential on the drain electrodes of the first and second driver switches; a driver date resistor connected between the DC potential and the gate electrodes of the first and second driver switches; the gate electrode of the first and second driver switch being controlled by a secondary winding such that when a voltage less than the threshold voltage of the MOSFET is presented on the winding, the gate of the driver switch is turned off and when a voltage greater than the threshold voltage of the MOSFET is present on the secondary winding, the gate electrode of the driver switch is allowed to float or be pulled to a higher voltage by the driver gate resistor turning the MOSFET on.