Achieving accurate electro-optical-thermal measurements of high-power LEDs

High-power Light Emitting Diode (LED) generates significant amount of heat fluxes that can affect the temperature-dependent properties of the device. This self-heating effect can upset the measurement setup and produce inaccurate readings, leading to misinterpretation of results such as electrical and thermal resistances. Optical, electrical and thermal performances of high-power LED packages were analysed under different temperature feedback controls. The results of these experiments demonstrate the importance of the temperature control module in the measurement setup affecting the device´s properties such as the series resistance Rs and the thermal resistance Rth. In the electrical current-voltage measurements, the temperature control module cannot control the self-heating effect effectively, resulting in a lower Rs compared to when the measurements are made manually. In transient thermal measurements, it was found that lower Rth values are obtained when the controller operates in closed-loop adaptive temperature control compared to when it operates in open-loop adaptive temperature control. This paper recommends the manual electrical and open-loop thermal measurement methods for accurate parametric LED analyses.