AC DISCHARGE CIRCUIT FOR AN AC-TO-DC SWITCHING POWER CONVERTER

摘要

An AC discharge circuit is disclosed to eliminate the need of bleeding resistors for an AC-to-DC switching power converter. The AC-to-DC switching power converter has two AC power input terminals to be connected to an AC power source, and an AC input capacitor connected between the two AC power input terminals. The AC discharge circuit has a rectifier circuit to rectify a first voltage across the AC input capacitor to be a second voltage applied to an input terminal of a JFET, and a power removal detector to monitor a third voltage at an output terminal of the JFET to trigger a power removal signal to discharge the AC input capacitor when the third voltage has been remained larger than a threshold for a de-bounce time.