Patent ID: 9673727
Date: 2017-06-06
CPC Classifications: H02M

Claim:
1. A switching power supply control circuit that causes a switching element connected to an input voltage source to perform switching to generate and output a predetermined direct-current voltage to a load and that changes an operating frequency of the switching based on the load, the switching power supply control circuit comprising: an oscillator that determines the operating frequency by charging a capacitor with a predetermined current based on a magnitude of the load or discharging the capacitor; and a jitter control circuit that is included in the oscillator and that performs frequency diffusion by modulating the operating frequency with a modulation frequency based on a changeable bit number of a counter, wherein the jitter control circuit switches the bit number of the counter at an operating frequency corresponding to a point of intersection of calculated curves each of which indicates a conducted electromagnetic interference reduction effect with respect to an operating frequency for each bit number.