Patent ID: 7440295
Filing Date: 2008-10-21
Classification: H02J,H02M,Y02B,Y04S

Abstract:
1. A switching mode power supply with an active load detection function, the switching mode power supply comprising: a switching unit which switches an AC power input to a primary coil of a transforming element at a frequency determined by a time constant and supplies the switched AC power to a secondary coil of the transforming element; a branching unit which branches current output from the secondary coil and supplies the branched current to a dummy resistor when the rectified current or voltage output from the secondary coil is greater or smaller than a reference value; a detecting unit which detects the branched current flowing to the dummy resistor; and a controlling unit which controls switching frequency by changing the time constant of the switching unit depending on the detected branched current of the detecting unit and reducing the amount of power supplied to the primary coil of the transforming element.