Redefining automotive lighting with digital LED

This will be the first product developed under the umbrella of ISELED, an open alliance formed to provide a full ecosystem for the new digital LED right from its very inception.

The ISELED Alliance
The mission of the ISELED Alliance 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.

Robert Isele, Manager, Ambient Light, Modular System, Interior Lighting at BMW AG explained: “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.”

The founding partners of the open ISELED Alliance are Inova, Dominant Opto Technologies, NXP, TE Connectivity (early application prototypes) and Pforzheim University.

As the market inexorably moves towards autonomously driven vehicles, lighting will become more and more important and challenging. Professor Karlheinz Blankenbach, at Pforzheim University, said: “My role in this important project has been in systems definition and in the characterisation 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 recognised as very important from a safety standpoint. Of course, we should not limit our outlook to purely automotive applications.”

Sophisticated control dynamics
This upcoming generation of in-car lighting will typically consist of 10-30 LEDs mounted on a flexible strip. Each group of one red, green, and blue LED will form a ‘pixel’, which at 24-bit resolution (3x8-bit) can be set to more than 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. Hence, 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.

Now, the vanguard IseLED concept is set to change the automotive LED paradigm by creating an amazingly compact smart LED driver that is directly integrated with three color LEDs into a tiny 3x4mm package.

“The processing power is provided by a microcontroller from NXP, perfectly suited for the project,” said Manuel Alves, VP & GM, Product Line General Purpose and Integrated Solutions at NXP Semiconductors. “As NXP has a clear focus on system-level challenges, 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.”

Leveraging 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 an impressive 2Mbit/s, the new protocol enables blisteringly 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 eight 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 color 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.

“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.”

Product features
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. The color of each RGB LED ‘trio’ can be set with 24-bit resolution (3x8 bit). For temperature and manufacturing tolerance compensation, the brightness of each individual LED can be controlled with 12-bit resolution.

“Our business supplies qualified LEDs to the automotive market, and so we are thrilled to have had the fortune to take part in such a prestigious, exciting and paradigm-shifting project," commented Tek Beng Low, Senior Vice President at Dominant Opto Technologies. He added: "We see ISELED as a new boon in the automotive LED segment, and look forward to when this innovation really goes mainstream.”

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.