Patent ID: 7068023
Filing Date: 2006-06-27
Classification: G05F,H02M

Abstract:
1. A switching power supply circuit having a switching element for controlling on/off state of an input power supply according to a drive pulse generated on the basis of a clock pulse having a prescribed period, wherein an electric current is allowed to flow from the input power supply to a load by controlling the switching element to be in on state, and a flywheel current is allowed to flow to the load by controlling the switching element to be in off state; the switching power supply circuit comprising: overcurrent detecting means for detecting that the current flowing through the switching element has reached a first reference value; flywheel current detecting means for detecting that the flywheel current has reached a second reference value; and an overcurrent protection circuit for performing an overcurrent protection operation of turning the switching element off based on a detected output of the overcurrent detecting means, and for turning the switching element on during the overcurrent protection operation at a timing of the clock pulse after the flywheel current detected by the flywheel current detecting means has reached the second reference value.