Patent ID: 9240727
Filing Date: 2016-01-19
CPC Classification: H02H,H02M

Claim Text:
1. A switching power supply device control circuit, being a control circuit of a flyback type switching power supply device that converts a voltage of an AC input into a predetermined direct current voltage by turning a switching element on and off and that supplies a voltage to a load, comprising: a current detecting circuit, connected to the switching element, that converts a current of the switching element into a voltage signal; an overcurrent protection circuit that detects an overcurrent with respect to the load based on the voltage signal converted by the current detecting circuit; a voltage correction circuit that corrects a reference voltage signal to the overcurrent protection circuit in response to a change in the voltage of the AC input; an oscillator circuit having a frequency modulating function whereby a switching frequency with respect to the switching element can be modulated; and a slope compensation circuit that generates a slope compensation signal increasing monotonically in proportion to an on-state period of the switching frequency including a frequency modulation period set by the oscillator circuit, wherein the voltage correction circuit corrects the reference voltage signal in accordance with the slope compensation signal.