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Powering automotive lighting

Multi-pixel driver with CAN FD Light

STMicroelectronics’ L99LDLH32 linear current regulator delivers an integrated solution for dynamic automotive lighting controlled using the lightweight CAN FD Light protocol.

The L99LDLH32 is an all-in-one solution featuring CAN FD transceiver and CAN FD Light protocol handler as well as a precision oscillator for CAN synchronization (Source: STMicroelectronics)

Ideal for use with OLED lamps that provide bright, homogeneous, and high-contrast lighting from a small surface area, the driver lets designers produce complex light patterns and effects that enhance safety and styling, explained the company.

With 32 regulated current sources, independently programmable from 1 mA to 15 mA, the product can drive individual pixels in external and interior lighting applications. Global dimming is also provided, with 8-bit resolution. While powered at the vehicle battery voltage, the driver produces outputs of up to 35 V to cover an emitter forward-voltage spread.

The integrated CAN FD Light protocol handler and transceiver simplify connection to the vehicle’s communication infrastructure and controlling domain ECU (electronic control unit), explained the company. Based on industry standards, CAN FD Light’s synchronized commander/responder communication, conceived for controlling simple devices like lights and sensors, saves costly external components such as timing crystals, the company further continued. On the other hand, the data bandwidth of 1 Mbit/s enables designers to create animated light patterns and permits modulated transitions and dimming.

In addition, on-chip memory cells allow programming of parameters such as current level and PWM dimming for stand-alone operation, to provide a failsafe mode to cover malfunctioning of the communication bus or controller. Targeting roles including safety-critical lighting such as taillights, stoplights, and turn indicators, the L99LDLH32 provides features for a high level of functional safety, said the company. These include a fault-status pin, voltage and temperature monitors, a programmable timeout watchdog, and short-circuit and open-load detection. In addition, frequency dithering minimizes electromagnetic emissions, the company continued explaining in its press release. Monolithically integrated using ST’s BCD9sL process, the L99LDLH32 is AEC-Q100 qualified and ready to order on ST Estore. It is available as a 7mm x 7mm QFN48 device with wettable flanks and an exposed thermal pad to aid dissipation.

(Source: Logo Bosch/Photo Adobe Stock)

CiA 604-1 CAN FD Light

A CAN FD Light responder node is an implementation based on a subset of the CAN FD data link layer functionality as specified in ISO 11898 -1:2015. It is a concept for price-sensitive sensor and actuator networks that can be used under automotive conditions. The CiA 604-1 CAN FD Light document from CAN in Automation (CiA) specifies the requirements of the data link layer and the physical coding sub-layer of a responder node. It contains detailed requirements for: the logical link control sub-layer; the medium access control sub-layer; the physical coding sub-layer.

Currently, CiA 604-2 data link layer and physical coding sub-layer conformance test plan of responder nodes and CiA 604-3 are under preparation. The CiA 604-3 document provides CAN FD Light system design recommendations, e.g., how the CAN FD Light commander node communicates with CAN FD Light responder nodes. Responder nodes use the CAN FD transceivers as specified in ISO 11898 -2:2016 or CAN SIC transceivers as specified in CiA 601-4 version 2.0.0.


Publish date

CAN in Automation