SYNCHRONOUS RECTIFICATION DRIVE CIRCUIT USED IN LLC RESONANT CONVERTER

摘要

A synchronous rectification drive circuit used in an LLC resonant converter comprises: a power circuit, a main control circuit and a synchronous rectification control circuit. The power circuit comprises a primary LLC resonant circuit and a secondary LLC rectification circuit. An end of the main control circuit is connected to main switching transistors (Q1, Q2, Q3, Q4) in the power circuit, and the other end is connected to the synchronous rectification control circuit, and is configured to generate a first control signal for controlling the main switching transistor and a second control signal (B) for controlling the synchronous rectification control circuit. An end of the synchronous rectification control circuit is connected to synchronous switching transistors (Q5, Q6, Q7, Q8), and is configured to perform anti-interference protection with respect to the synchronous rectification circuit through a combination of an inductive module and a capacitive module, and perform processing on a third control signal (D) and the second control signal to obtain a signal (C) for driving the synchronous switching transistor, wherein the third control signal is required by the synchronous switching transistor and is obtained when performing detection on current flowing through the synchronous switching transistor.