Patent ID: 9419511
Filing Date: 2016-08-16
CPC Classification: H02M

Claim Text:
1. A method of controlling a capacitor discharge for a switching power supply, the method comprising: a) generating a first voltage signal from a voltage at an X capacitor that is coupled between input terminals of said switching power supply, wherein said generating said first voltage signal comprises differentiating said voltage at said X capacitor to generate a differential signal, clamping said differential signal between an upper limit and a lower limit to generate a clamping signal, and converting said clamping signal to generate said first voltage signal; b) activating a detection signal in response to said first voltage signal being inactive for a duration of a predetermined time interval, wherein said detection signal being activated indicates a cut-off of said input terminals; and c) at least partially discharging the X capacitor after the cut-off and in response to activation of the detection signal.