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Automotive-compliant buck LED drivers

Diodes Incorporated has announced the AL8843Q and AL8862Q automotive-compliant DC-DC buck converters, designed for driving single LEDs and multiple LED strings in and around vehicles.

The company explains that applications include daytime running lights (DRL), which many manufacturers now offer as standard, as well as fog lights, turn lights, and brake/stop lights.

With a supply voltage from 4.5V and to at least 40V (AL8862Q up to 55V), the AL8843Q and AL8862Q can withstand severe voltage variations, such as load dumps during low cranking or stop-start operation, without suffering any corresponding degradation in the LED drive current.

A high level of integration delivers high performance while minimising the bill of materials. Both parts feature an integrated power MOSFET: 40V/0.2Ω for the AL8843Q and 55V/0.4Ω for the AL8862Q. Additionally, the devices feature hysteretic-mode buck LED driver control, which simplifies the feedback loop enabling engineers to realise highly stable buck converter designs using just four external components.

Differentiating features for the AL8843Q include an input voltage range of 4.5V to 40V and 3A output current, while the AL8862Q can operate at between 5V and 55V input voltage, delivering up to 1A at the output.

Both parts support full scale (0% to 100%) PWM dimming, controlled with either an analog input between 0.4V and 2.5V or a PWM signal generated by an external microcontroller or host processor. Safety features include overtemperature protection as well as LED short- and open-circuit protection. The AL8862Q incorporates an open-drain fault indication pin, which is asserted low to report faulty conditions.

The AL8843Q and AL8862Q in SO-8EP are qualified to AEC-Q100 Grade 1, support PPAP documents, and are manufactured in IATF16949 certified facilities.

Author
Charlotte Hathway

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