Patent ID: 7948219

Claim:
A control circuit of a synchronous rectification type power supply unit, the control circuit comprising: a detecting portion detecting a status transition of a first signal at a connecting point, the status transition changing in each of constant cycles corresponding to current flowing through an antiparallel diode when a main switch device is turned OFF, the connecting point coupling to a coil and being between the main switch device and a rectification switch device having the antiparallel diode wherein the main switch device and the rectification switch device are turned ON and OFF alternately in the constant cycles; and a phase difference adjusting portion adjusting a phase difference by adjusting output timing of a second signal which is a delayed signal of the first signal outputted one cycle before, corresponding to the phase difference between a phase of the first signal detected by the detecting portion and a phase of the second signal, wherein the rectification switch device is turned ON corresponding to the second signal whose output timing is adjusted by the phase difference adjusting portion.