LED Characterization for Combined Electrical-Optical-Thermal LED Modeling

Abstract

Traditionally incandescent and fluorescent light sources were mostly used in a single operation point and their relevant characteristics was described by a few parameters in a datasheet. The emitted light of LED products depends on current and temperature heavily and the behavior of LEDs in actual use can be predicted only by complex models of physical roots. The paper summarizes the elaboration of the methodology and also actual measurements for identifying parameters of electrical-optical-thermal LED models, all these carried out in the framework of the European Delphi4LED project. Measurement examples of high power LEDs are shown and the state-of-art of the modeling efforts is demonstrated in case studies. First, a model is proposed for separating the recombination effects in the LED junction to radiative and heat generating components. Then a two-diode Spice-like electro-thermal-optical model of LEDs is proposed, extended with a serial resistor in the branch which describes the light emission.