Power control circuit and method

摘要

A light source with substantially constant intensity and power consumption is provided. The light source includes a controllable dc voltage and current source; a non-linear light-emitting load supplied with dc voltage and current from the controllable dc voltage and current source; a current sense circuit connected in series with the non-linear light-emitting load; a variable LED forward voltage (varying with temperature, binning batch, aging) sensor circuit; a multiplier operative to measure a power-representative signal; and a power consumption control feedback circuit through which the dc voltage and current source is controlled in relation to the variable forward voltage representative signal to adjust the dc voltage and then a current to amplitudes that keep the light intensity and power consumption produced by the light source substantially constant.