Synchronous rectifier control circuit with deadtime adjustment to prevent crossover conduction

Abstract

A synchronous rectification control circuit is connected with a secondary-side rectification circuit and includes a driving circuit, a dead-time acquisition circuit, and a zero-voltage detection circuit. The driving circuit includes a differentiating circuit, a first comparator, and a capacitor, wherein the differentiating circuit generates a signal to the first comparator and the capacitor functions to charge and discharge to form a cycle. The dead-time acquisition circuit includes a second comparator and a third comparator, wherein the second comparator has a positive input connected to an output of the first comparator of the driving circuit, the second comparator has an output connected to a positive input of the third comparator, and the third comparator has a negative input connected to the output of the first comparator to acquire a dead-time signal. The zero-voltage detection circuit includes a fourth comparator and a totem pole circuit, wherein the fourth comparator has a negative input connected to an input terminal of the driving circuit for detecting a potential present in the input terminal of the driving circuit and the fourth comparator has an output that is connected to the totem pole circuit to supply an output of a signal. With such an arrangement, shorting is prevented from occurring in the secondary-side rectification circuit.