Multi-Domain Modelling and Simulation of White CoB LEDs

The multi-domain operation of blue pump LEDs in a chip-on-board (CoB) device cannot be described properly by the existing chip level multi-domain compact models and a package compact thermal model because their operation is strongly affected by such parts of the environment as the substrate or the phosphor. In this case a mix of compact modelling and distributed modelling approaches need to be used. This paper presents a method that applies a chip level multi-domain LED compact model in a distributed way for the simulation of the LED chips and a Finite Volume Method based description for the whole package, including the temperature dependent light conversion taking place in the phosphor layer covering the entire LED chip array. The chip model describes the electrical, thermal and light output characteristics and their mutual dependence. This paper presents a new multi-domain phosphor model based on path tracing algorithms to describe the blue-to-yellow conversion, heat loss and light propagation in a distributed way for white CoB LEDs.