Patent ID: 7352160
Filing Date: 2008-04-01
Classification: H02M,Y02B

Abstract:
1. A synchronous-rectification step-down switching regulator capable of changing an output voltage, comprising: a first switching element configured to switch in accordance with a first control signal input to a control electrode thereof so as to perform output control of an input voltage; an inductor connected between an output end of the first switching element and an output terminal; a second switching element for synchronous rectification configured to release energy stored in the inductor in accordance with a second control signal input to a control electrode thereof; a switching controller circuit part configured to control switching of the first switching element, and cause the second switching element to perform switching opposite to the switching of the first switching element; a comparator circuit configured to compare a reference voltage to a divided voltage corresponding to said output voltage; and a reverse current detector circuit part configured to detect a reverse current flowing from the inductor to the second switching element, wherein when said comparator circuit detects no change in the reference voltage, the reverse current detector circuit part, upon detection of generation of the reverse current, outputs a control signal to the switching controller circuit part so as to turn off the second switching element for synchronous rectification, and when said comparator circuit detects a change in said reference voltage compared with said divided voltage, the reverse current detector circuit part stops, for a predetermined period of time, the switching controller circuit part from turning off the second switching element even if the reverse current detector circuit part detects the reverse current.