Patent ID: 8134851

Claim:
A resonant converter comprising: a primary side switching stage having high- and low-side switches series connected at a switching node and controlled by a primary side controller; a transformer having a primary coil and a secondary coil, the secondary coil having at least one pair of portions series connected at a node, a resonant tank formed by series connecting the primary coil to the switching node with a first inductor and a first capacitor; at least one pair of first and second secondary side switches connected to the at least one pair of portions, respectively, the first and second secondary switches of each pair being used for synchronous rectification; and a secondary side controller to control and drive the first and second secondary side switches of each pair by sensing voltage across each secondary side switch, comparing said voltage across each secondary side switch with a programmable threshold, and determining a turn ON and turn OFF transition for the first and second secondary side switches in close proximity to a point in time when there is zero current through the secondary side switch to achieve synchronous rectification.