Power Integrations, Inc.
Method and apparatus for implementing a power converter input terminal voltage discharge circuit

Abstract:

A circuit for use in a power converter includes a control circuit capable of detecting whether an AC voltage source is coupled to an input of the power converter, and whether the AC voltage source is uncoupled from the input within a first period of time. A control circuit is coupled to drive a switch in a first operating mode when the control circuit detects that the AC voltage source is coupled to the input, and drive the switch in a second operating mode when the control circuit detects that the AC voltage source is uncoupled from the input. The control circuit is capable of discharging a capacitance coupled between input terminals of the power converter to a SELV level through a discharge path and the switch within a second period of time. An RC time constant of the discharge path is less than or equal to one second.