Constant current versus pulse current for power supplies on high power LED

Abstract

One of the major problems encountered in the use of high power LEDs is that they are not 100% efficient because much of the power consumed is converted into heat that requires additional costs to be evacuated. This paper investigates a method to supply the LED that tries to keep the LED junction temperature close to the ambient temperature. A comparison has been made between a LED supplied on DC “constant-current” and a LED supplied by constant-current pulses. The paper shows how constant-current pulses contribute on the optimal operation of LEDs maintaining the temperature at low values. Maintaining the junction temperature as low as possible will raise the reliability of the LED (Arrhenius Law). Finally, the paper presents the measurement results according to the developed vehicle test.