Digital LED lighting control for automotive applications

Digital LED lighting control for automotive applications

Market news |
By Graham Prophet

The open ISELED Alliance curently comprises Inova Semiconductors, Dominant Opto Technologies, NXP, TE Connectivity, and Pforzheim University. Its aim is to create LED-related products and solutions for the automotive market. These solutions are to be based on an entirely new in-car LED lighting concept that drives down costs, simplifies control, and expands the functionality of LED lighting and display solutions.


This generation of in-car lighting will typically consist of 10 to 30 LEDs mounted on a flexible strip. Each group of one red, green, and blue LED will form a ‘pixel’, with at 24-bit resolution/16 million colours.


At the present time, in order to individually control LEDs, a microcontroller containing LED-specific data is needed for each individual RGB LED. Such a solution is typically too cumbersome and expensive to be viable. Also, it is not feasible to capture individual LED life parameters such as functionality and temperature. The IseLED concept is to create a compact smart LED driver that is directly integrated with three colour LEDs into a 3 x 4 mm package.


The first solution consists of a driver from Inova with a bidirectional serial interface and daisy-chain capability integrated by Dominant Opto Technologies into a single compact package with three LEDs (red, green and blue). The new package will come with pre-calibration of the required white point from the factory. The driver includes three constant current mode (CCM) drivers to control the red, green and blue LEDs. For temperature and manufacturing tolerance compensation, the brightness of each individual LED can be controlled with 12-bit resolution.


The extremely low thermal resistance of the housing, which is 30% lower than in comparable products, reduces the power consumption of the LED by delivering better light efficiency with cooler LEDs. A built-in temperature sensor ensures accuracy, whilst the calibration values of the CCM LED drivers and temperature compensation parameters are securely stored in non-volatile memory, an indispensable prerequisite for safety-related applications.


The processing power is provided by a microcontroller from NXP, perfectly suited for the project; NXP comments, “…this IseLED concept fits right into what we’re aiming for with the recently announced S32K microcontroller product line. We are taking a new concept to market as a complete solution including hardware, software and developing the ecosystem around it.”


Using the experience it gained during the development of its APIX communications standard, Inova has built a high-speed communications protocol that allows every LED to be individually addressed. By supporting data rates up to 2 Mbit/sec, the protocol enables fast, dynamic lighting effects. Thus, the straightforward scalability of the solution will enable remarkable cost savings and open up new market opportunities.


Robert Kraus, CEO at Inova said, “The past 8 years have shown the power of an ecosystem, like our APIX link concept, to rapidly deploy new technology in an unsaturated market – and we hope to repeat this success with ISELED; perhaps we are now witnessing the inception phase of a another new automotive LED industry standard.”


The smart LED driver from Inova provides sophisticated calibration features, ensuring every LED will render the same colour and brightness over the full temperature range, thereby guaranteeing automotive-level illumination consistency, even accepting greater LED manufacturing tolerances than are currently attainable. A single microcontroller can now manage an LED strip containing 4,096 LEDs.


Robert Isele, Manager, Ambient Light, Modular System, Interior Lighting at BMW AG explains, “We have been listening to our customers, and the feedback has resoundingly indicated a demand for this new platform. We believe that we need an innovation which provides a cost-effective way of creating inspiring products of the future, which will assist with in-car information, corporate branding and communications. This new LED technology has to provide a very viable, easy-to-use solution to the in-car LED dilemma – it would have simply been impossible if every LED had to be calibrated individually.”


Prof. Karlheinz Blankenbach, professor at Pforzheim University., said, “My role in this important project has been in systems definition and in the characterization phase, setting the theoretical framework for implementation. Not only will interior lighting play a major role in future design, it is essential that vehicles are able to better communicate with the world around them, for instance, I see the ability of autonomous vehicles to inform pedestrians that they have been recognized as very important from a safety standpoint. Of course, we should not limit our outlook to purely automotive applications.”


“If interior lighting evolves as indicated by BMW and Prof. Blankenbach, there will be a strong demand for higher integration of optical parts, electronics and connectivity,” said Hajo Wetzel, Director, Global Advanced Engineering, TE Connectivity. “Since we have previously partnered with BMW and Inova in the field of connectivity, we decided to support this project by producing the early application prototypes. Due to the short timeline this was definitely a great challenge for our advanced engineering teams which were closely supported by our global lighting hubs in Europe and Canada.”





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