Patent ID: 11228239

Abstract:
An AC capacitor is coupled to a totem-pole type PFC circuit. In response to detection of a power input disconnection, the PFC circuit is controlled to discharge the AC capacitor. The PFC circuit includes a resistor and a first MOSFET and a second MOSFET coupled in series between DC output nodes with a common node coupled to the AC capacitor. When the disconnection event is detected, one of the first and second MOSFETs is turned on to discharge the AC capacitor with a current flowing through the resistor and the turned on MOSFET. Furthermore, a thyristor may be simultaneously turned on, with the discharge current flowing through a series coupling of the MOSFET, resistor and thyristor. Disconnection is detected by detecting a zero-crossing failure of an AC power input voltage or lack of input voltage decrease or input current increase in response to MOSFET turn on for a DC input.