Controller IC with Zero-Crossing Detector and Capacitor Discharge Switching Element

摘要

An integrated circuit (IC) for controlling the discharge of a capacitor coupled across first and second input terminals of a power converter circuit, wherein the first and second terminals for receiving an ac line voltage. The IC includes a switching element coupled across the first and second input terminals and a detector circuit. The detector circuit including first and second comparators that produce first and second output signals responsive to a zero-crossing event of the ac line voltage. The first and second output signals being used to generate a reset signal coupled to a timer circuit responsive to the zero-crossing event. When the reset signal is not received within a delay time period, the timer circuit outputs a discharge signal that turns the switching element on, thereby discharging the capacitor.

主权项

1. An integrated circuit (IC) comprising:
a power converter controller to regulate an output of a power converter, the power converter having first and second input terminals to receive an ac line voltage, an x-capacitor being coupled across the first and second input terminals; a regulator circuit configured to regulate a supply voltage provided to the power converter controller; a discharge circuit, which includes:
a switching element for coupling across the first and second input terminals; anda detector Circuit coupled to the switching element the detector circuit comprising:
first and second comparators, each having a first input respectively coupled to the first and second input terminals, the first and second comparators respectively producing first and second output signals responsive to a zero-crossing event of the ac line voltage;circuitry coupled to receive the first and second output signals, the circuitry outputting a discharge signal when neither the first nor second output signals are received within a delay time period, the discharge signal being coupled to activate the switching element, when activated, the switching element providing a discharge path to discharge a voltage across the x-capacitor.