Patent ID: 6580626
Filing Date: 2003-06-17
Classification: H02M,Y02B

Abstract:
A switching power supply comprising a DC/DC converter in which a switching element connected to a primary winding of a transformer turns on or off to thereby take out an AC voltage from a secondary winding of the transformer, said AC voltage thus taken out being rectified by a synchronous rectifying switch element connected in series to the secondary winding so as to obtain a DC output voltage,wherein said switching power supply further comprises: a switch element which is connected between a control terminal of said rectifying switch element and a first terminal of said secondary winding where a positive voltage is induced when said switching element turns on; and a voltage regulation element for turning on said switch element by the voltage induced on the first terminal of the secondary winding when said switching element turns on so as to supply the voltage to the control terminal of said rectifying switch element.