Patent ID: 7382633

Claim:
A DC converter having a transformer, a main switch connected in series with a primary winding of the transformer, and a series circuit being connected to ends of one of the primary winding and main switch and including a clamp capacitor and an auxiliary switch, the main and auxiliary switches being alternately turned on/off so that a secondary winding of the transformer generates a voltage that is rectified and smoothed with a rectifying/smoothing circuit to provide a DC output, the DC converter comprising: a time difference detector configured to detect a time difference between a point around which the main switch provides a minimum level after the auxiliary switch turns off and a point at which the main switch turns on; an integrator configured to integrate the output of the time difference detector; and a delay controller configured to control a turn-on point of the main switch according to the outputs of the integrator and time difference detector, the delay controller operating to minimize the output of the time difference detector according to the output of the integrator and controlling a turn-on point of the main switch in a pulse-by-pulse manner according to a pulse-by-pulse control signal based on the output of the time difference detector.