Automotive-Compliant LED Driver Supports Multiple Topologies with Fault Reporting
The AL8866Q, an automotive-compliant LED driver from Diodes Inc., is designed to drive an external MOSFET. The DC-switching LED driver-controller supports buck, boost, buck-boost, and SEPIC topologies for high-power LED lighting systems. Applications include daytime running lights (DRL), high/low beams, fog lights, turn lights, brake/stop lights, and more.
Built with a fixed-frequency (400 kHz) peak current-mode control architecture, the AL8866Q can operate across a wide input voltage range from 4.7 to 85 V, covering the common 12-, 24-, and 48-V battery power rails. 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 pulse-width-modulation (PWM) dimming of the LED current via its DIM pin and maintains 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.
A soft-start function gradually increases the inductor and switch current to minimize potential overvoltage and overcurrent at the output. And an open-drain fault output indicates fault conditions such as 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 comes in SO-8EP and U-DFN3030-10 packages, with an operating temperature range of −40 to +125°C, and is priced at $0.50 and $0.48 in 1,000-piece quantities, respectively. A standard compliance version, the AL8866, is also available; it’s targeted at industrial and commercial applications.
