SWITCHING POWER SUPPLY APPARATUS FOR CORRECTING OVERCURRENT DETECTION POINT BASED ON GRADIENT OF SWITCHING CURRENT

摘要

A switching power supply apparatus has a switching device control circuit for performing overcurrent protection by controlling switching-on/off of a switching device, connected serially to a primary winding of a transformer, so as to make a voltage output from a rectifying and smoothing circuit, connected to a secondary winding of the transformer, have a specific value, and switching off the switching device when the electric current flowing through the switching device exceeds a value as an overcurrent detection point. This control circuit includes: a current variation measurement circuit for measuring a gradient of the electric current flowing through the switching device, based on a current measurement signal output from a circuit for measuring this electric current; and an overcurrent detection-point correction circuit for correcting the overcurrent detection point with respect to the electric current flowing through the switching device, based on a signal output from the current variation measurement circuit.