LED solutions in automotive lighting get an ever-increasing level of attention—not only on show cars, but also in the market where a continuously growing number of models is equipped with LED lighting. This DVN technical report on LEDs and their implementation in the electrical and thermal environment is a response to the increased prevalence and interest of LED lights on (and in) cars.
The target group for this report is not technical specialists, but rather persons who in their daily work are confronted with more general questions and decisions around LEDs and want to gain a solid basic understanding of this technology. We cover the various topics from a broader view by giving typical examples and data without going into too much detail or trying to account for each and every execution variant.
The chapters of the report focus on the LED itself and its interfaces to the electrical and thermal interfaces in the car.
First we describe the technology of the LED. The basic physical principles of light emission are outlined and related to the typical construction of LED products of the different integration levels. Additionally a sketch of the manufacturing processes of LED dies is discussed.
Secondly we focus on the electrical characteristics of LEDs. The consequences of this behaviour for the electronics driver circuitry are explained and design examples are discussed.
In a third step, the most important elements of the temperature dependence of an automotive LED are covered. It will become clear that the thermal management of an LED is paramount to the performance of the built lighting device overall. Especially also the characteristics and influences of the cooling by heat sinks is explained.
As a link to application examples we include photographs of the thermal components of various LED systems for rear lighting, signaling, DRLs and headlamps. The variety of different designs highlights the problem of non-modularity and reusability of technologies leading to growing engineering resource needs.
As an outlook to the future we present three expert opinions in the field on the development of LED systems and markets, and we conclude with some of our own (DVN) statements, predictions and forecasts about the future of LED automotive lighting.