Patent ID: 9300204
Filing Date: 2016-03-29
CPC Classification: H02M

Claim Text:
1. A switching power supply comprising: a main body of the switching power supply that performs switching operation of input voltage through switching a switching element to obtain a specified output voltage; a control circuit that ON/OFF drives the switching element at a predetermined frequency; a noise detecting circuit that detects GND bounce noise developed on a ground line of the control circuit accompanying the switching of the switching element; and a canceling signal generating circuit that generates a canceling signal corresponding to the GND bounce noise and in a reversed phase with respect to the GND bounce noise and adds the canceling signal onto the ground line of the control circuit when the noise detecting circuit detects the GND bounce noise; wherein the noise detecting circuit detects the GND bounce noise based on an output voltage of a current transformer linked with the ground line exceeding a threshold level for noise detection a predetermined number of successive times.