Adaptive algorithm for power control of a camera flash LED as a function of battery impedance, state of discharge (SoD), aging, temperature effects

摘要

A method for driving a light emitting semiconductor device. The method comprises: converting a primary supply voltage from a primary power supply to a secondary output voltage to provide the output voltage to the light emitting semiconductor device, measuring an initial primary supply voltage level at the beginning of a high current phase of the semiconductor light emitting device, determining a minimum threshold voltage level for the primary supply voltage level based on the measured primary supply voltage level, starting the high current phase thereby continuously comparing the measured primary supply voltage level with the minimum threshold voltage level and controlling an output current through the semiconductor light emitting device such that the measured primary supply voltage level does not fall below the minimum threshold voltage level.