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