Patent ID: 9622315
Date: 2017-04-11
CPC Classifications: H05B

Claim:
1. A device comprising: a light emitting diode (LED) load having a light output responsive to a phase angle of a dimmer; a detection circuit configured to detect the dimmer phase angle and to output a pulse width modulation (PWM) control signal from a PWM output port, the PWM control signal having a duty cycle determined based on the detected dimmer phase angle; an open loop power converter configured to receive a rectified voltage from the dimmer and to provide an output voltage corresponding to the rectified voltage to the LED load; and a bleed circuit connected in parallel with the LED load, the bleed circuit comprising a resistor and a transistor comprising a gate connected to the PWM output port to receive the PWM control signal, the transistor turning on and off in response to the duty cycle of the PWM control signal, wherein a percentage of the duty cycle increases as the detected dimmer phase angle decreases below a predetermined low dimming threshold, causing an effective resistance of the bleed circuit to decrease and a bleed current through the bleed circuit to increase as the detected dimmer phase angle decreases.