LIN Bus gateway chip for automotive lighting

July 10, 2017 //By Graham Prophet
Melexis (Tessenderlo, Belgium) has added a LIN-to-LIN gateway that overcomes the limitation of only handling 16 devices on a typical LIN bus. Each MLX81120 connects as a LIN slave on the main LIN bus and is controlled directly from the vehicle's Body Control Module (BCM).

This 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 second generation, LIN-to-LIN gateway is based on the MLX16 RISC CPU application controller. The 16-bit MCU includes 32 kB Flash (with ECC), 16 kB ROM, 2 kB 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 19.2 kBaud 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 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 MLX81120 has a highly efficient voltage regulator that consumes just 20 μA in sleep mode. Other features include LED temperature compensation, LED leakage compensation / control and an integral battery and temperature monitor.

 

The flexible and configurable MLX81120 can be configured to meet designer needs via the flash memory and requires only three external components for LIN RGB, thereby saving board space and reducing the solution cost.

 

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

 

Melexis; www.melexis.com/en/product/MLX81120/LIN-Slave-IC-Ambient-Light-Applications