Does a Single Led Bin Really Represent a Single Led Type?

Abstract

In a recent H2020 European wide research project (Delphi4LED, www.delphi4LED.eu) extensive study for generating multi-domain compact LED models based on measurement data was concluded. In this context combination of the latest LED testing standards and recommendations of JEDEC and CIE have been applied in testing and new models and modelling methods have been developed in order to capture the multi -domain operation of LEDs for the purpose of simulation. A valid question is: how representative a model is for a type of an LED package, how to select a nominal LED device for modelling and how to capture the inherent variation of LED operating parameters. We had specific tasks dedicated to measure and model these variations. Findings related to capturing, quantif ying and modelling of the thermal features of the mechanical structure of LED packages have already been published. In this paper we report about the measured variances of the multi -domain chip level operation of LEDs and the way how to model them. During this analysis we were confronted with the issue of having various parameter distributions in a LED population purchased from the same bin. This raises the question: LEDs belonging to a given binning class really represents a single LED type if their multi -domain behaviour is different.

Multi-Domain Modelling of LEDs for Supporting Virtual Prototyping of Luminaires

“…A couple of issues still must be dealt with, such as the necessary number of LED samples to be characterized for the extraction of the parameter set that is representative of the given LED type; how to represent the sample-to-sample variations of the model parameters; how to include typical LED product parameters, such as the binning value of the forward voltage, etc. These are questions that are still the subject of research within the Delphi4LED project [49].…”

“…Elaboration of the right method for identification of the "median" LED is still an ongoing activity. Some results obtained so far are reported elsewhere [49].…”

“…Within this work, the properties of the junction-to-ambient heat-flow path of LED populations were investigated. The analysis was done on 11 royal blue and 10 phosphor converted white LEDs [46,47,49].…”

“…In terms of the IVL characteristics, nominating a median device is less straightforward [49]. In the study of the predictive power of the physics based multi-domain LED model, the median device was the one with an electrical characteristic closest to the average characteristic.…”

“…Elaboration of the right method for identification of the "median" LED is still an ongoing activity. Some results obtained so far are reported elsewhere [49]. For demonstration purposes, however, a model parameter set for the measured LED populations was established, see Figure 24.…”