Patent ID: 7907425
Filing Date: 2011-03-15
Classification: H02M,Y02B

Abstract:
1. A circuit for predicting a valley timing for a voltage across a switching device, comprising: a voltage detector for detecting the voltage across the switching device to produce a detection voltage as a function of the voltage across the switching device; a first comparator for comparing the detection voltage with a first threshold to produce a first comparison signal; a second comparator for comparing the detection voltage with a second threshold to produce a second comparison signal; a logic circuit for producing a first logic signal and a second logic signal according to the first and second comparison signals; a timer for predicting a valley timing for the detection voltage according to the first and second logic signals, to thereby determine a valley signal used to trigger turn on of the switching device; and, a blanking signal for selectively blanking the valley signal; wherein the logic circuit further provides a third logic signal and a fourth logic signal according to the first and second comparison signals; wherein the logic circuit further comprises: