LED Technology
outside the typical headlight or fog light region. Likewise, numerous premium models now feature elaborate welcome or farewell animations for exterior lighting units. While these animations offer little functional advantage, they serve to exude a sense of luxury and capture the user’s attention. It is a similar story inside the vehicle. Interior lighting typically consisted of switchable cabin lights and auxiliary footwell and glove box lights. Then, over time static door sill and curb-side lights have been added to many models to enhance localised illumination, but manufacturers are now going further.
RGB LED lighting in cars is advancing and becoming more versatile. Both premium and standard models alike are deploying increasingly complex animated lighting. By employing high-performance LED drivers for precise control of individual LEDs at high speeds, these systems are capable of transmitting feedback from crucial vehicle and infotainment functions.
Moreover, dynamic and animated lighting systems also provide scope to actively or passively impact the mood of the driver or passengers. In many vehicles, users can freely customise the interior lighting drastically shifting the dominant interior hue to their tastes. Likewise, research has found that using cool colour hues in parallel with air conditioning can reduce the user’s demand for colder air, helping to save energy. Although no vehicles currently offer this functionality, it is easy to envision its introduction shortly.
Automotive lighting has, and continues to undergo, remarkable transformation, evolving from a mere necessity to a crucial element of a vehicle’s feedback systems and visual identity, and today’s automotive designers allocate considerable resources to both cabin and exterior lighting design.
Addressing the technical challenges of automotive lighting When it comes to incorporating smart animated lighting into consumer applications like homes or game PCs, the task is relatively simple – the power, bandwidth, and physical volume of lighting can all be integrated with ease. However, implementing RGB lighting in a moving vehicle is far more complex as there are strict power, weight, size, and data transmission limitations.
The integration of advanced LED systems in vehicles, accompanied by the growing need for visual animation, will inevitably result in the heightened complexity of electronic components.
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Continuous advancements in driving assists and infotainment functions are already burdening in-vehicle networks (IVNs) using CAN and LIN communication protocols. While these legacy protocols are well suited for simple static lighting, they cannot effectively control the large number of LEDs and frequent updates required for advanced animations in dynamic RGB automotive lighting. CAN and LIN networks place limitations on the number of light nodes and complexity of animations for designers of modern automotive lighting systems, essentially reducing the impact of additional LED lighting by lowering the number of diodes and complexity of animations. Standard CAN tops out at 1 Mbit/s while LIN is just 20 Kbit/sec.
Furthermore, the direct integration of lighting into IVNs can lead to a decrease in system flexibility, as the reprogramming of smart lighting takes place within body control modules (BCMs), which is less than ideal. Achieving complex lighting in automotive environments demands a solution that is targeted and efficient. This solution must deliver the required performance without overwhelming existing IVNs or introducing additional complexities in development and manufacturing. LED compatibility is yet another factor that must be kept in mind. To maintain a strong supply chain, automotive OEMs procure LEDs from various manufacturers, necessitating the ability to mix products without compromising colour accuracy in the final application.
A solution tailored to meet market demands
The CAN-FD protocol’s high speed is ideal for advanced RGB LED lighting. However, the number of nodes supported is far too low and the bill-of-material (BoM) costs associated with implementing this architecture to support lighting systems are far too high for more automotive models to permit.
Melexis is a company that possesses a deep understanding of automotive lighting. It has a proven track record in developing LIN-based LED systems and offers a wide range of smart automotive LIN integrated circuit (IC) drivers designed for static ambient lighting, exterior decorative lighting, and exterior safety lighting. These feature efficient and intelligent operations working within the limitations of LIN networks to drive lights such as interior trim LEDs or simple turn indicators. In order to tackle the technical hurdles associated with complex lighting deployments, Melexis developed a dedicated solution called MeLiBu (Melexis
Light Bus). MeLiBu utilizes the accessible and extendable protocol and hardware architecture of LIN with the speed and reliability of CAN communication. This technology is built upon the CAN-FD physical layer and utilizes UART communication to achieve high data rates of up to 4 Mbits/s. It offers self- synchronization and strikes the right balance between performance and costs in an environment that automotive engineers are familiar with.
of each lighting component into the vehicle’s overall lighting design, based on brand, model, platform, feature, or function, ensuring that additional functionality is only included when needed. The implementation of colour coding, colour changing, and blinking sequences is also straightforward and scalable.
With MeLiBu, the end result is a solution that not only offers high-speed and robust performance but also has the advantage of being effortlessly scalable to accommodate
The lighting-specific nature of MeLiBu means it offers the lowest cost per light node on the market and can support the latest smart interior and exterior lighting. It eliminates the need for manufacturers to adopt expensive lighting solutions to facilitate complex dynamic lighting. It lets automotive engineers add lighting features like sophisticated animated feedback, user LED customisation, or dynamic animated turn indicators without excessively driving up system complexity or BoM costs. In addition to meeting the performance requirements, Melexis made it a priority to ensure that MeLiBu could be easily deployed and minimise the overall size of the wiring harness. By adopting a differential bus structure, Melexis has simplified the architecture while also allowing any microcontroller in the vehicle to serve as a commander for MeLiBu communication, regardless of its location. The current MeLiBu 1.x protocol supports a network of up to 60 Melexis LED driver ICs. With the next-generation MeLiBu 2.0 protocol, up to 256 LED drivers can be addressed. Given one Melexis LED controller IC can drive up to 42 single LEDs, a MeLiBu network can allow for the control of some 2,500 to 10,000 LEDs.
Scalability and flexibility are other key elements in modern automotive lighting. MeLiBu allows for the selective integration
the requirements of future animated high- density LED applications. It takes what animated lighting needs from CAN-FD without the unwanted costs or complexity, and combines it with the simplicity of LIN, but without the performance limitations.
Conclusion: A brighter tomorrow Automotive lighting is an unusual blend of safety and aesthetics, surrounded by a web of complex technical hurdles that must be overcome to serve a diverse range of applications. Over time, the changing requirements of automotive lighting have created a need for adaptable, scalable, and affordable solutions that can be seamlessly integrated into the industry – this is what has shaped Melexis’ MeLiBu technology. Combining established technologies reduces the barrier to adoption while providing predictable integration and reliability. MeLiBu has been adopted by numerous manufacturers already, and the use of this technology in vehicles will keep expanding as automotive designs create innovative lighting applications. This could include new advanced hazard warning systems that make our roads safer or improved communication between autonomous vehicles and humans, which makes our lives easier.
https://www.melexis.com/ Components in Electronics November 2024 29
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