First automotive integrated buck LED driver with internally-generated PWM dimming

20-01-2016 | Allegro | New Technologies

Allegro MicroSystems Europe has announced two new single-IC switching regulators that provide constant-current output to drive high-power LEDs in automotive applications. The devices are the industry’s first to allow LED dimming without the need for local microcontroller or timer-based or PWM dimming control, says the company. The 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 analogue dimming input can be used to calibrate the LED current, or implement thermal fold-back 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. The A6214 is housed in a compact 10-pin narrow SOIC package (suffix LK). The A6216 is available in a 16-pin TSSOP package (suffix LP), both with exposed pad for enhanced thermal dissipation. Both are lead (Pb) free, with 100% matte-tin lead frame plating.

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