Control circuit of synchronous rectification type power supply unit, synchronous rectification type power supply unit and control method thereof

摘要

The control circuit comprises: a detecting portion COMP1 for detecting a status transition of a first signal FR at the connecting point P which changes at a constant cycle corresponding to current flowing through the antiparallel diode D when the main switch device FET is turned OFF; and a phase difference adjusting portion 30, 40 for adjusting the phase difference by adjusting the output timing of the second signal FP corresponding to a phase difference between the phase of the first signal FR detected by the detecting portion COMP1 and the phase of the second signal FP generated based on the first signal of one cycle before and the rectification switch device FET2 is turned ON corresponding to the second signal FP whose output timing is adjusted by the phase difference adjusting portion 30, 40.