Patent ID: 9369116
Filing Date: 2016-06-14
CPC Classification: H03K,H05B,Y02B

Claim Text:
1. A circuit for detecting a leading-edge phase-cut dimmer, comprising: an edge detector operable to receive an input signal, detect whether the input signal has a rapidly rising edge, and generate an edge detector output signal, wherein the edge detector output signal comprises a signal pulse if a rapidly rising edge is detected in the input signal; a pulse stretcher operable to receive the edge detector output signal and generate a pulse stretcher output signal, wherein if the edge detector output signal comprises a signal pulse, the pulse stretcher output signal comprises a stretched pulse having a duration that is longer than the signal pulse received from the edge detector; and a filter operable to receive the pulse stretcher output signal and generate a filter output signal, wherein if the pulse stretcher output signal comprises at least a predetermined number of stretched pulses within a predetermined amount of time, the filter output signal indicates the presence of a leading-edge phase-cut dimmer, the filter comprising a filter capacitor whose value in part determines the number of stretched pulses that must be received from the pulse stretcher before the presence of a leading-edge phase-cut dimmer is indicated.