Secondary side synchronous rectifier for resonant converter

An integrated circuit for a resonant converter, wherein the resonant converter has:

• 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 side switches of each pair being used for synchronous rectification;
• the integrated circuit comprising:
• a secondary side controller for controlling and driving the first and second secondary side switches of each pair by sensing voltage across each secondary side switch, comparing the voltage 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, wherein the secondary side controller for controlling the at least one pair of first and second secondary side switches is contained in one IC package.

A secondary side synchronous rectifier for a resonant converter, the secondary side synchronous rectifier comprising:

• a sensing circuit to sense a voltage across a first secondary side switch and a second secondary side switch of the resonant converter;
• at least one comparison circuit using a programmable reference voltage to determine a zero current condition through the first secondary side switch and the second secondary side switch;
• and
• a driver circuit configured to switch the first secondary side switch and the second secondary side switch if the comparison circuit detects the zero current condition.