Patent ID: 7525822

Claim:
A DC converter, comprising: a transformer including primary and secondary windings that are loosely coupled with each other, and a tertiary winding tightly coupled with the primary winding; a main switch connected in series with the primary winding; and a series circuit connected to ends of one of the primary winding and the main switch, and including a clamp capacitor and an auxiliary switch, the main and auxiliary switches being alternately turned on/off so that a voltage of the secondary winding of the transformer is synchronously rectified with synchronous rectifiers and is smoothed with smoothing elements to provide a DC output, wherein the tertiary winding is configured to generate a voltage that drives the synchronous rectifiers, a winding start of the tertiary winding is connected to a first one of the synchronous rectifiers, and a winding end of the tertiary winding is connected to a second one of the synchronous rectifiers, and the tertiary winding is not connected to ground.