Patent ID: 8884537

Claim:
A light emitting device power supply circuit, comprising: a tri-electrode AC switch (TRIAC) dimmer circuit, for generating a phase-cut AC dimming signal, wherein the phase-cut AC dimming signal has an OFF phase and an ON phase; a rectifier circuit, which is coupled to the TRIAC dimmer circuit, for generating a rectified dimming signal according to the phase-cut AC dimming signal, wherein the rectified dimming signal has an OFF phase and an ON phase corresponding to the OFF phase and the ON phase of the phase-cut AC dimming signal; a light emitting device driver circuit, for driving a light emitting circuit according to the rectified dimming signal; and an active bleeder circuit, including: a detection circuit, which is coupled to the rectifier circuit, for generating a detection signal and accumulating the detection signal in the OFF phase; and a current sinker circuit, which is coupled to the detection circuit, for generating a latching current to trigger the TRIAC dimmer circuit by operating a switch therein when the detection signal exceeds a predetermined level; wherein the detection circuit includes: a conversion device, for converting the rectified dimming signal to the detection signal; a storage device, for storing and accumulating the detection signal; and an OFF control circuit, for turning OFF the switch of the current sinker circuit in the ON phase, wherein the OFF control circuit includes a Zener diode, which has a reverse end coupled to the detection signal, and a forward end coupled to a relatively lower level, such that when a voltage difference between the detection signal and the relatively lower level exceeds a reverse breakdown voltage of the Zener diode, the Zener diode turns ON reversely.