Automotive LED driver has PWM dimming capability

January 20, 2016 // By Paul Buckley
Allegro MicroSystems Europe has introduced two single-IC switching regulators that provide constant-current output to drive high-power LEDs in automotive applications.

The devices claim to be the industry’s first to allow LED dimming without the need for local microcontroller or timer-based or PWM dimming control.

Allegro’s A6214 and A6216 devices integrate a high-side N-channel DMOS switch for DC-to-DC step-down (buck) conversion. A true average current is output using a cycle-by-cycle, controlled on-time method. Combined with automotive-grade quality and feature-rich functionality, a host of safety and robust protection features makes the A6214 and A6216 devices ideal for automotive lighting where high quality and reliability are essential.

User-selectable output current provides system design and application flexibility, and automatic output voltage adjustment based on the number of LEDs in a single string ensures optimal system efficiency. An internal 5 V, 10 mA LDO provides added flexibility and system cost savings for driving local circuitry if required.

LED dimming is accomplished by a direct logic input pulse-width-modulation (PWM) signal at the enable pin. An analog dimming input can be used to calibrate the LED current, or implement thermal foldback in conjunction with an external NTC thermistor. The A6216 has the unique capability to generate its own PWM dimming frequency and duty cycle in stand-alone mode that provides LED light dimming control without the need of a micro-controller or timer.