Method for controlling power source switching circuit

摘要

The purpose of the present invention is to suppress generation of additional leak currents and harmonic components, and suppress deterioration in efficiency, even with a small load on a switching power source circuit. The operation modes of the circuit are respectively adopted in accordance with the magnitude of an output: a non-conducting mode for an output smaller than a threshold (P11); a discontinuous mode for an output between thresholds (P11-P21)(> P11); a critical mode for an output between thresholds (P21-P31)(> P21); and a continuous mode for an output greater than a threshold (P31). This allows for further suppression of increase in the leak current in the region where the power consumption of a load is small, compared to conventional techniques.