Circuit and method for protecting a switching power supply from a fault condition

摘要

A switching regulator (18) for use in a switching power supply (10) detects a fault condition by looking for asserted feedback signal during a timer period. If feedback is asserted during the timer period, then the switching power supply (10) is operating normally. If feedback is not asserted during the timer period, then the switching power supply is in a fault condition. One way of implementing the timer is to charge and discharge by-pass capacitor (23). The timer period is the time for the VCC voltage to drop from a maximum value to a predetermined threshold. A counter (102) can also be used as the timer. When a fault is detected, the gate drive signal from the switching regulator is disabled for a period of time before attempting auto-restart.