Putting the spotlight on LED lighting
“Through the development of fully adjustable ambient lighting,” says Michael Bender, LIN Product Line Manager at Melexis, “vehicle occupants will, in the near future, have the ability to adjust the color of the interior to anything they choose, altering this whenever they wish, as well as being able to set a number of specific lighting profiles to suit their individual tastes.
“They will be able to set specific lighting characteristics for different parts of the vehicle interior, create a particular start up lighting sequence, change the mood (perhaps when music by a particular artist is playing on the audio system for example). It also means that the driver (or passengers) can adapt the lighting system in response to diurnal and seasonal alterations in external illumination to maximize the overall lighting effect,” he says.
When it was launched the company’s MLX81106 was the industry’s first LIN RGB LED slave to be incorporated onto a single semiconductor die. The freely-programmable IC addresses the emergence of automotive LIN RGB ambient lighting systems and is capable of driving up to 4 LEDs directly thanks to its integrated constant current sources. Every output can be programmed to a maximum current of 35mA through the built-in Flash memory. All necessary components like physical layer LIN transceiver, LIN controller, voltage regulator, and 16-bit RISC-based microcontroller, as well as supporting functions like ADC, 16-bit PWM generation, constant current high voltage capable outputs and LED threshold monitoring capability are integrated into the chip.
Belgium-based Melexis is a major player in the automotive electronics market. The company’s mixed signal semiconductors, sensor ICs and programmable sensing systems are used not only in the automotive sector but also consumer, industrial and wireless industries. The 25-year old company has seen sales grow 11% in the fiscal year 2013-14 to EUR 275.4 million and is optimistic that 2014 will see a similar rate of growth. Says CEO Françoise Chombar: “Over the past year new product launches have continued at the expected pace, on the one hand strengthening our core in magnetic sensors and LIN, and equally adding some new avenues in optical sensing. All of these newly launched products are engineered to contribute in one or the other way to reducing the environmental footprint of our customers and our customers’ customers.”
One of the areas in which Melexis’ technologies have been particularly popular is automotive lighting. In 2013, for example, the company launched the MLX75031, which is a universal active light sensor interface designed to allow easy implementation of robust multi-channel, close range optical sensing systems into difficult operational environments. It incorporates four independent simultaneously operating light measurement channels: two taking care of reflection and the other two for ambient light measurement. This makes the device highly optimized for inclusion in humanmachine interfaces (HMI) requiring proximity detection or touch-less gesture recognition in environments subject to wide variation in background lighting levels, especially in automotive infotainment systems, white goods and consumer electronics devices.
“Rudimentary ambient lighting mechanisms first started to be included in vehicles about four years ago,” says Bender. “At that stage, however, they were very limited in terms of the functionality, plus they often proved fairly expensive to implement. The degree of customer adjustability needed to be increased markedly if such a feature was to ever have serious market appeal.
Melexis’ Avocet series of wide-VGA image sensors offers functions such as automotive driver assistance and night vision applications, security/surveillance applications, fleet safety cameras, truck blind spot cameras, transportation/heavy vehicle cameras, and other outdoor and all weather cameras. With a 1024 x 512 pixel resolution, these devices each feature an extended high dynamic range (HDR) up to 154dB in every single frame with a full resolution frame rate up to 60fps. Sensitivity in terms of SNR10 is 25nW/cm2 (at 25°C and 535nm). This low light performance combined with the extended HDR offers superior picture quality during day and night time and thus enhances safety for driver assistance systems”.
Automotive Industries (AI) asked Bender to list some of the breakthroughs in automotive lighting made by Melexis.
Bender: Melexis was among the first to develop cost-effective LIN and single-wire CAN system basis ICs. This has allowed inexpensive bus networking and opened the door to innovative ambient lighting control options. Applications for Melexis ICs have included high brightness LED control for signaling lamps and interior lighting applications. Integrated actuator driver ICs for control of steerable headlamp modules are another area where Melexis has supported automotive lighting advances.
AI: How receptive are automotive manufacturers in keeping up with the latest lighting technologies and incorporating them quickly in new models?
Bender: Manufacturers are very receptive. The pace of development runs faster than ever and providing drivers with compelling features, while reducing emissions is critical to a brand’s success. Market forces reward collaboration among IC suppliers possessing strong experience of working with vehicle manufacturers and their Tier 1 suppliers. It takes coordinated teamwork and collaborative innovation to minimize the time needed to field lighting advances into actual production platforms.
AI: How have lighting applications in automobiles changed in the recent past?
Bender: In a word, LEDs. The incandescent bulb is obsolete for new designs. LEDs so far are just replacements for incandescent bulbs, but there is so much more potential to be realized with this technology in automotive lighting.
AI: What role does LIN play in lighting?
Bender: Traditional ambient lighting with incandescent bulbs requires point-to-point wiring between switches and controls. Incandescent bulbs are inefficient and produce waste heat because of this inefficiency. LEDs are great problem solvers, but simply wiring them up in the circuit like a bulb replacement ignores their potential By integrating ambient lighting on a bus, like LIN, the ability to gain new functionality becomes a software exercise. Equally important is the fact that the size and cost benefits allow placement for accent and convenience lighting into locations impractical without the LIN bus and LEDs. Providing the driver and passengers with individualization options in all classes of cars, not just luxury vehicles.
AI: What do products like the MLX81106 and others offer automotive manufacturers?
Bender: The MLX81106 brings to automotive manufacturers a single chip, fully-compliant driver IC with best in class EMC robustness and the minimum footprint for an LED lighting module. With this device it is possible to make the lowest cost, smallest and best performing ambient LED controller. The flexibility of the ICs design allows use of the same IC for actuators and controls too.
AI: How effective and important is your Avocet series – how popular has it been with automotive OEMs?
Bender: Avocet is continuing to secure wins with its highly dynamic range and true automotive grade design and quality levels. When put head-to-head with competitive products the Autobright™ and Autoview™ functions provide designers with compelling performance advantages.
AI: How customizable are Melexis’ automotive solutions?
Bender: Melexis takes pride in its innovative engineered application-specific standard products (ASSPs), which make up more than 50% of our sales. Since introducing many of the world’s first programmable sensors for automotive applications the company has focused on ICs with software customizable functionality that enables our clients to create differentiated products and deliver value solutions to the markets they serve. In the event that a Melexis ASSP is not available and the economic and strategic conditions align then, we delight in collaborating on ASIC solutions with our customers.