Design of Compensation Circuits for Quasi-Resonant PWM Controllers

摘要

The quasi-resonant converters can significantly reduce the turn-on losses,but the line voltage feed-forward characteristics are sacrificed in order to get the good transient response in current mode quasi-resonant converters. In this paper,a voltage feed-forward compensation circuit is proposed which effectually resolved above-mentioned problem.Simultaneity,to prevent the possible unstable operation at the large load conditions,an internal synchronized slop compensation circuit is added to the current loop to ensure system stable operation.Based on 1 um 40V BCD process,the voltage feed-forward compensation and adaptive slop compensation circuits were designed,the excellent transient response and system stability are obtained eventually.When the output system is 12V/30W,the voltage regulation can be reduced to 0.17% from 0.5% (without voltage feed-forward compensation) and the load regulation is 7.5mV/A with these modules in chip in the same power supply system.