CIRCUITS AND METHODS FOR SYNCHRONOUS RECTIFICATION IN RESONANT CONVERTERS

摘要

PROBLEM TO BE SOLVED: To provide methods for realizing synchronous rectification in resonant converters, and methods for operating the same.SOLUTION: A resonant converter includes a primary stage having: first and second switches coupled in series; a controller coupled to the first switch and the second switch to control operation thereof; a first transformer comprising a primary coil coupled to a node between the first and second switches; and a resonant inductor coupled to the primary coil of the first transformer. The resonant converter also includes a secondary stage having: a second transformer formed of a primary coil coupled to the resonant inductor and a secondary coil comprising first and second coil sections; a third switch coupled to the first coil section of the secondary coil; and a fourth switch coupled to the second coil section of the secondary coil. A switch drive circuit is provided to drive the third and fourth switches for synchronous rectification, with the switch drive circuit comprising a secondary coil of the first transformer.SELECTED DRAWING: Figure 2