METHOD AND APPARATUS FOR DIGITAL DETECTION OF THE PHASE-CUT ANGLE OF A PHASE-CUT DIMMING SIGNAL

摘要

A device (220) implements a method (600) of controlling dimming of a light emitting diode (LED) light source (230) by: receiving a phase-cut dimming signal (105) produced from an AC line voltage (15), ascertaining the peak voltage level (109) of the AC line voltage (15); ascertaining the present value of a phase-cut duty cycle of the phase-cut dimming signal, employing the peak voltage level of the AC line voltage to ascertain the maximum phase-cut duty cycle for the phase-cut dimming signal, ascertaining the phase-cut angle (107) of the phase-cut dimming signal from the present value of the phase-cut duty cycle of the phase-cut dimming signal and the maximum phase-cut duty cycle for the phase-cut dimming signal; and controlling the dimming of the LED light source in response to the phase-cut angle.

主权项

1. A method, comprising:
receiving a phase-cut dimming signal produced from an AC line voltage; comparing the phase-cut dimming signal to a threshold voltage and in response thereto outputting a digital phase-cut dimming signal; ascertaining a peak voltage level of the AC line voltage; ascertaining a duty cycle of the digital phase-cut dimming signal; employing the peak voltage level of the AC line voltage to ascertain a maximum value of the duty cycle of the digital phase-cut dimming signal; ascertaining a phase-cut angle of the phase-cut dimming signal from the duty cycle of the digital phase-cut dimming signal and the maximum value of the duty cycle of the digital phase-cut dimming signal; and controlling a dimming of an LED-based lighting unit in response to the phase-cut angle of the phase-cut dimming signal.