85V LED driver for multiple topologies with fault reporting

Diodes has launched a DC-switching LED driver-controller that drives an external MOSFET and supports multiple technologies in high-power LED lighting systems.

Applications for the AL8866Q include daytime running lights (DRL), high/low beams, fog lights, turn lights, brake/stop lights, and more.

The LED driver supports buck, boost, buck-boost, and single-ended primary-inductance converter (SEPIC) topologies and operates within a wide input power supply range from 4.7V to 85V, covering the common 12V, 24V, and 48V battery power rails. This flexibility and multi-mode operation enables lighting designers to standardize on a single component type, streamlining inventory and simplifying design processes.

The AL8866Q has a 400kHz fixed-frequency peak current-mode control architecture. It incorporates a spread spectrum frequency modulation technique to enhance EMI performance, which is compliant with the most stringent CISPR 25 Class 5 standard.

The device supports analog and PWM dimming of the LED current via its DIM pin and has a 1% reference tolerance, enabling better brightness control and matching between lamps. With an over 100:1 analog dimming range, it achieves ±12% output current accuracy at low (20%) analog dimming levels, making it more precise than similar LED drivers available. Alternatively, PWM dimming (0.1 to 1kHz) achieves a 100:1 dynamic range.

The AL8866Q integrates a soft-start function, gradually increasing the inductor and switch current to minimize potential overvoltage and overcurrent at the output. It features an open-drain fault output to indicate various fault conditions, which include LED output-overvoltage, LED output-open/-short, cycle-by-cycle overcurrent protection, sense-resistor and shorted-inductor/-diode detection, diode-open circuit, and thermal shutdown.

The AL8866Q is available in the SO-8EP and U-DFN3030-10 packages, with an operating temperature range of -40°C to +125°C. The AL8866QSP-13 (SO8-EP) and AL8866QFN-7 (U-DFN3030-10) are available at $0.50 and $0.48 in 1,000-piece quantities, respectively.

A standard compliance version, AL8866, is available and suitable for industrial and commercial applications.