Multi pixel driver has CAN FD Light interface

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By Christoph Hammerschmidt

The L99LDLH32 linear current controller from STMicroelectronics is a practical, integrated solution for controlling dynamic automotive lighting using the lean CAN FD Light protocol. The new driver is ideal for use with OLED lights that emit flat and homogeneous light. It thus enables the design of complex light patterns and effects that benefit both safety and styling.

With 32 regulated current sources that can be independently programmed to values between 1 mA and 15 mA, the L99LDLH32 can control individual pixels in outdoor and indoor lighting applications. In addition, a global dimming function with a resolution of 8 bits is included. Powered from the vehicle’s electrical system, the driver provides output voltages up to 35 V to cover light emitters with widely varying forward voltages.

Integrated handlers and transceivers for the CAN FD Light protocol facilitate the connection of the driver to the vehicle’s communication infrastructure as well as to the responsible domain ECU. CAN FD Light is based on proven industry standards and ensures synchronised communication between the commander and responder. Designed to control simple components such as lights and sensors, the protocol does not require complex external components such as frequency reference crystals, but with its data bandwidth of 1 MBit/s it still allows the implementation of complex, animated light patterns as well as evenly modulated transitions and dimming processes.

For stand-alone operation, memory cells integrated on the chip enable the programming of parameters such as currents or PWM dimming. This in turn allows the implementation of a failsafe mode in the event of a malfunction on the communication bus or in the controller. The L99LDLH32 is intended, among other things, for safety-relevant functions such as tail, brake or indicator lights and is therefore equipped with features that result in a high degree of functional safety. These include a fault status pin, voltage and temperature monitors, a watchdog with programmable timeout and a function for detecting short circuits and line interruptions. Last but not least, frequency dithering minimises the emission of electromagnetic interference.

Manufactured using ST’s BCD9sL process, the monolithically integrated L99LDLH32 is qualified to AEC-Q100 and can be ordered from the ST eStore. It is offered in a 7 mm x 7 mm Wettable Flank package of the QFN48 package design, which provides better heat dissipation with its thermal pad led out.


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