Electro-thermal coupling and performance estimation of LEDs at system level

Abstract

The electro-thermal coupling is analyzed to describe the interaction between the electrical and thermal characteristics of light-emitting diodes (LEDs), which can be considered as an equilibrium process between electrical responses and altering thermal conditions. Based on that, a system-level estimation method of the electro-thermal performance of LEDs is introduced. For thermal management or optimization problems, the method tends to analyze the electro-thermal interaction rather than to take the LED chip as the constant heat source. Firstly, it is suggested to connect the electrical and thermal characteristics of LEDs by a current-voltage-junction temperature (I-V-Tj) relation, which logs the chip-level characteristics and reflects the electro-thermal coupling. Secondly, a modeling method of LED systems is introduced, including the equivalent of the chip layout, PCB substrate, heatsink, heat dissipation condition, etc. Thirdly, iterative analytical calculations are used to solve the electro-thermal coupling. By calculating the performance of sample chip arrays, each procedure of the method is illustrated in detail. The work may provide a further understanding of the electro-thermal coupling and contribute to the design work of LEDs.