Patent ID: 6839246

Claim:
A self-driving circuit of a DC/DC converter, said converter including at least a transformer having a primary winding and a secondary winding, and a rectification portion having at least a first and a second of synchronous rectifying MOS transistors, characterized in that said self-driving circuit comprises a resister, a capacitor, a transistor, and a diode, said resister and capacitor being connected in parallel, one of the ends of said parallel connection being connected with the positive end of the secondary winding, and the other connected to the base of said transistor; the emitter of said transistor being connected to the source end of the first synchronous rectifying MOS transistor, and the collector of said transistor connected with the cathode of said diode and the gate end of the second synchronous rectifying MOS transistor; and the anode of said diode being connected to the negative end of the secondary winding.