Melexis chip improves car cabin lighting


Car interior wood and leather decoration and blue ambient light

Each MLX81120 connects as a LIN slave on the main LIN bus and is controlled directly from the vehicle’s Body Control Module (BCM). The new device allows for up to 16 LIN RGB slave modules on a private LIN bus, thereby permitting up to 196 LED lighting devices to be connected to a single BCM via a LIN bus.

The fully featured, second generation, LIN-to-LIN gateway is based upon the MLX16 RISC CPU application controller.

The 16-bit MCU includes 32kB Flash (with ECC), 16kB ROM, 2kB RAM and a 380b EEPROM (with ECC). The ROM comes pre-loaded with a LIN driver, bootloader, math library and an RGB colour mix algorithm.

The LIN slave protocol controller operated up to 19.2kBaud and is compliant with LIN 2.x and SAE J2602. This block processes frames autonomously; ensuring that there are very few interrupts to the main application.

Also included in the MLX81120 are a master and slave LIN transceiver, both of which are also compliant with LIN 2.x and SAE J2602.

The 2nd master transceiver enables a decentralised ambient lighting architecture within a car, which makes it possible to easily add and/or change lighting functions for different car models or equipment options without changing the complex body control module or light ECU.

Extensive I/O capability is built in including four high voltage I/O lines, 16-bit PWM outputs, interrupt capable inputs and a 10-bit ADC with an integrated pre-driver.

The chip’s voltage regulator consumes 20μA in sleep mode. Other features include LED temperature compensation, LED leakage compensation / control and an integral battery and temperature monitor.

The chip can be configured to meet customer needs via the flash memory and requires only three external components for LIN RGB, thereby saving board space and reducing the solution cost.

“Cabin designers have told us they need a simple way to overcome the architectural limits of the LIN bus,” says Melexis’ Michael Bender, “the MLX81120 does exactly that, allowing lighting bus segmentation and extension for future use cases.”

Offering an automotive temperature range of -40°C to +125°C and housed in a small DFN4x4 12-pin package the MLX81120 is available as PPAP samples, along with a demo board and development software


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