Buck LED drivers streamline automotive lighting

July 26, 2019 //By Julien Happich
LED drivers
Diodes Incorporated’s (Nasdaq: DIOD) AL8860Q and AL8861Q automotive LED drivers combine robust performance, simplified design, and flexibility to address internal and external lighting applications, such as fog lamps, position lamps, rear lamps, and door lamps.

The chips operate from 4.5V to 40V to withstand load-dump events and operate correctly at low-cranking voltages in stop-start applications. Leveraging hysteretic-mode buck control simplifies the design of the feedback loop, enabling inherent stability with only four external components. Designers can save real estate and minimize the electronic bill of materials due to the integrated, main power MOSFET and a programmable switching frequency up to 1MHz that allows a small output inductor.

The devices can source 1.5A for powering loads up to 40W depending on supply voltage and external components. In addition, both drivers support 0.3V to 2.5V analog dimming as well as high-precision PWM dimming from 1% to 100% to allow various automatic or user-adjustable brightness controls. Such flexibility enables use in a wide variety of applications inside and outside the vehicle, permitting designers to create multiple lamp types efficiently using the same driver and streamline inventory management for manufacturing.

Comprehensive built-in protection features ensure reliability and safety, including short-circuit and open-LED protection as well as overtemperature shutdown. The AL8861Q additionally features current-sense resistor, short-circuit protection.

Both drivers are packaged in the high-power density MSOP-8EP with support for analog and PWM dimming via one control pin. This control pin, with its analog dimming function, can be used for soft-start of the LED current with only one capacitor.

Diodes – www.diodes.com


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