Discharge circuits of discharge paths for electromagnetic interference filters

摘要

A discharge circuit for an electromagnetic interference (EMI) filter is provided. The discharge circuit includes a switch circuit, a control circuit, and a detection circuit. The switch circuit is coupled to an X-capacitor of the EMI filter. The control circuit is coupled to the switch circuit and configured to turn on the switch circuit in a predetermined period to provide a discharge path. The detection circuit is coupled to the discharge path. In the predetermined period, the detection circuit detects whether a cross point occurs between a discharge voltage signal on the discharge path and a reference voltage signal to generate a detection signal which is provided to the control circuit. When the detection circuit detects that the cross point does not occur, the control circuit continuously turns on the switch circuit according to the detection signal after the predetermined period has elapsed.

主权项

1. A discharge circuit for an electromagnetic interference (EMI) filter, comprising:
a switch circuit coupled to an X-capacitor of the EMI filter; a control circuit, coupled to the switch circuit, for turning on the switch circuit in a predetermined period to provide a discharge path; and a detection circuit, coupled to the discharge path, for, in the predetermined period, detecting whether a cross point occurs between a discharge voltage signal on the discharge path and a reference voltage signal to generate a detection signal which is provided to the control circuit, wherein when the detection circuit detects that the cross point does not occur between the discharge voltage signal and the reference voltage signal, the control circuit continuously turns on the switch circuit according to the detection signal after the predetermined period has elapsed.