Switching power supply device

摘要

A switching power supply device has a switching controller adapted to generate an output voltage from an input voltage by turning on and off a switching device by a non-linear control method according to a comparison signal and a timer signal, a main comparator adapted to generate the comparison signal by comparing a feedback voltage based on the output voltage with a predetermined reference voltage, a timer adapted to output the timer signal as a one-shot pulse when a predetermined fixed period elapses after the switching device is turned from on to off or vice versa, and a reverse current detector adapted to detect a reverse current to the switching device to forcibly turn off the switching device. The timer and the reverse current detector are turned on at a pulse edge in the comparison signal, and are turned off on ending their respective operation.

主权项

1. A switching power supply device comprising:
a switching control portion that generates an output voltage from an input voltage by performing on/off control of a switch device using a non-linear control method in accordance with a comparison signal and a timer signal; a main comparator that compares a feedback voltage corresponding to the output voltage and a predetermined reference voltage with each other to generate the comparison signal; a timer portion that performs a one-shot output of the timer signal at a time point when a predetermined fixed period elapses after the on/off of the switch device is switched; and a backward flow detection portion that detects a backward flow for the switch device to forcibly turn off the switch device; wherein the timer portion and the backward flow detection portion are turned on at a time point when a pulse edge of the comparison signal occurs and turned off at a time point when operation of each of the timer portion and backward flow detection portion is completed, the switching power supply device further comprising a delay portion that performs a one-shot output of a delay comparison signal at a time point when a predetermined delay period elapses after the pulse edge of the comparison signal occurs, wherein the switching control portion receives an input of the delay comparison signal instead of the comparison signal and performs the on/off control of the switch device using the non-linear control method in accordance with the delay comparison signal and the timer signal.