Zero current detecting circuit and method and related synchronous switching power converter

摘要

A zero current detecting circuit is disclosed. The zero current detecting circuit includes a first zero current comparator for determining current variation on an inductor of a synchronous switching power converter so as to output a zero current signal to turn off a down-bridge transistor of the synchronous power converter; a second zero current comparator for determining whether the first zero current comparator turns off the down-bridge transistor too early or too late and outputting a comparison result; a counter coupled to the second zero current comparator for ascending or descending a control bit according to the comparison result, and an adjustable delay unit coupled to the first zero current comparator and the counter for adjusting a delay time according to the control bit, and delaying and outputting the zero current signal according to the delay time, to compensate a negative offset voltage by delay.

主权项

1. A zero current detecting circuit, comprising:
a first zero current comparator for determining current variation on an inductor of a synchronous switching power converter so as to output a zero current signal to turn off a down-bridge transistor of the synchronous switching power converter; a second zero current comparator for determining whether the first zero current comparator turns off the down-bridge transistor too early or too late, and outputting a comparison result; a counter coupled to the second zero current comparator for ascending or descending a control bit according to the comparison result; and an adjustable delay unit coupled to the first zero current comparator and the counter for adjusting a delay time according to the control bit, and delaying and outputting the zero current signal according to the delay time, to compensate a negative offset voltage by delay.