Color fluctuations from LED binning and temperature variations corrected in real-time by MCU-embedded drivers

Infineon LITIX 'TLD4020-3ET', ECU-less down to compact vehicles…"30% growth within 5 years"

Vehicle interior lighting is breaking away from the role of 'auxiliary illumination.' As it becomes a core element of user experience (UX) that reveals brand identity through color and animation while reflecting driver preferences, the LED interior ambient market is rapidly expanding. On this subject, we met in advance with Choi Young-jae, Research Director at Davo Corporation, who will present a technical webinar session titled 'Intelligent LED Interior Lighting Solutions Illuminating Future Vehicles,' to discuss market momentum and shifts in design requirements.

From transportation to 'experience space'…RGB extends down to compact vehicles

Choi identified the change in automotive character as the primary growth driver. Specifically, "automobiles are transforming beyond mere transportation into spaces providing user experience." Automakers create brand-distinctive impressions through lighting color and motion, while drivers personalize their experience by changing colors or confirming driving modes, warnings, and climate control status through light. Behind this, the falling cost of semiconductors and LEDs fueled widespread adoption. RGB lighting, once exclusive to premium vehicles, is now filtering down to mid-range and compact cars. He noted that "most premium vehicles, and over half of mid-range brands, now use RGB LEDs," and with continued cost reduction, this trend will spread across most vehicle types, predicting "market growth of 30% or more within 5 years." However, he noted that the level of sophistication and concept will vary by country and brand.

"A single misaligned light mistaken for defect"…Color maintenance is the technology itself

Behind the brilliance lies sophisticated engineering. LED color shifts subtly due to binning (device variation), temperature, and degradation. Choi stated, "In areas like dashboards where multiple LEDs are clustered, a color change in even one can be immediately noticeable and mistaken for a vehicle defect." The 'color temperature' that must be maintained here refers not to actual temperature but to color coordinates. The problem is that simple current control alone cannot maintain these color coordinates. Drift caused by temperature, variation, and degradation must be corrected through software algorithms, which requires high-resolution PWM and an MCU to run it. As slim interior design narrows PCB space, the trend toward integrating the MCU into the driver rather than keeping it separate has solidified. He summarized: "Interior lighting is now an integrated solution organically linking optics, semiconductors, and software."

Intelligent driver integrating MCU and LIN…Single-chip zone-wide control

Infineon's answer to these requirements is the automotive LED driver brand 'LITIX.' The 'TLD4020-3ET' introduced at the webinar is an 'intelligent LED driver' that integrates an Arm-core MCU, LIN communication, a 16-bit PWM engine, and 32kB flash memory on a single chip. With an auto-addressing function, it implements dynamic control across wide areas such as door zones, center fascia, and footwells all at once. The 'ECU-less' in its name does not mean it does not control lighting. It means that rather than having a separate LED-dedicated controller, the BCM or zone control issues commands via LIN, while the TLD4020 controls the actual LEDs at the endpoint.

Hardware unchanged, software only…"Scalable to 4-channel, 12-channel"

While existing basic and multi-channel drivers focused on constant-current operation, PWM dimming, and protection/diagnostics, the TLD4020-3ET integrates MCU and LIN to encompass color control and software functions. Choi stated, "The biggest advantage is being able to create multiple derivative products by changing only software while keeping hardware the same," classifying this as a 'dedicated RGB local LED driver.' The future competitiveness, he diagnosed, will hinge on "the ability to uniformly control LEDs and software flexibility." The roadmap follows that direction. Starting with the current 3-channel (RGB) product, RGBW 4-channel products that control white as well, and even 12-channel products are in preparation. Ultimately, he forecast a transition toward a stage of controlling entire interior LEDs through zone-centric centralized communication protocols.