Patent ID: 9137880
Filing Date: 2015-09-15
Classification: H05B,Y02B

Abstract:
1. A circuit for a dimming system, the circuit comprising: an input for receiving a phase-cut dimmer output signal, the phase-cut dimmer output signal having a period and complementary cut and un-cut parts; an output for outputting a dimming control level signal; a comparator, connected to the input and arranged to produce a pulse-modulated signal from the phase-cut dimmer output signal, the pulse-modulated signal having an on-time which varies in dependence on the duration of the un-cut part; and a converter configured to determine the dimming level control signal directly from the pulse-modulated signal, such that the dimming level control signal has a non-linear but piece-wise linear relationship with the un-cut part; and wherein the converter is configured to determine the dimming level control signal by means of a variable frequency clock which increments or decrements a counter at each clock cycle during the on-time, and to determine the dimming level control signal from the counter.