Allegro MicroSystems adds buck-boost solution to automotive LED drivers

The launch of the ALT80802 expands the family of 62xx/808xx LED drivers for lighting from Allegro MicroSystems. The device addresses a key market trend of 3-4 white LEDs in a single string powered from 12V battery input, which is particularly suitable for fog, backup, DRL, side mirror and other automotive lighting applications.

The device provides 2 MHz operation, enhanced performance in PWM dimming capability and fault protection, reducing the external component count. It can be operated in buck mode up to 2A, to drive 1-2 WLEDs from the battery or up to 12 WLEDs from a pre-boost supply.

A high-frequency switching regulator that provides constant output current to drive high-power LEDs, this device is designed to aid in EMC/EMI design by frequency dithering, soft freewheel diode turn-off, and well controlled switch node slew rates.

A programmable oscillator allows the device to switch up to 2.5 MHz, outside EMI-sensitive frequency bands such as the AM band. It integrates a power MOSFET for step-down (buck) or inverting buck-boost conversion.

The 50 V-rated enable pin can be tied to Vin for automatic startup, to support battery-level PWM dimming common in legacy body controllers. The input range is 3.8 to 50 V.

With current-mode control and simple external compensation, the ALT80802 can achieve fast transient response. The control loop of the ALT80802 is designed for PWM dimming operation to achieve low dimming on-time, low turn-on overshoot, accurate PWM duty cycle, and wide dimming range.

Protection features of the ALT80802 include pulse-by pulse current limit, hiccup mode short-circuit protection, open/short freewheeling diode protection, BOOT open/short voltage protection, VIN under voltage lockout, and thermal shutdown.

The ALT80802 is AEC-Q100 automotive qualified and is available in a small 10 pin DFN package with thermal pad and wettable flank.

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