PROTECTION CIRCUIT APPLIED TO AN ALTERNATING CURRENT POWER SOURCE AND RELATED PROTECTION METHOD THEREOF

摘要

A protection circuit applied to an alternating current (AC) power source includes a sample-and-hold unit, a detection unit, and a discharge signal generation unit. The sample-and-hold unit samples a peak value of a direct current (DC) voltage during each period of a corresponding AC voltage, wherein the AC power source provides the AC voltage. The detection unit generates a detection signal when the DC voltage crosses a reference voltage corresponding to the peak value. The discharge signal generation unit generates a count signal when the discharge signal generation unit does not receive the detection signal within a predetermined time of a period of the AC voltage, accumulates the count signal, and generates a discharge signal to a discharge unit when a number of accumulated count signals is greater than a predetermined value, wherein the discharge unit discharges an X capacitor according to the discharge signal.

主权项

1. A protection circuit applied to an alternating current (AC) power source, comprising:
a sample-and-hold unit for sampling a peak value of a direct current (DC) voltage during each period of a corresponding AC voltage, wherein the AC power source provides the AC voltage; a detection unit coupled to the sample-and-hold unit for generating a detection signal when the DC voltage crosses a reference voltage corresponding to the peak value; and a discharge signal generation unit coupled to the detection unit for generating a count signal when the discharge signal generation unit does not receive the detection signal within a predetermined time of a period of the AC voltage, accumulating the count signal, and generating a discharge signal to a discharge unit when a number of accumulated count signals is greater than a predetermined value; wherein the discharge unit is used for discharging an X capacitor according to the discharge signal.