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Automotive integrated buck LED driver offers PWM dimming

Posted: 21 Jan 2016     Print Version  Bookmark and Share

Keywords:Allegro MicroSystems  PWM dimming  LED  driver  LDO 

Allegro MicroSystems has unleashed a couple of single-IC switching regulators that claim to deliver constant-current output to drive high-power LEDs. 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, noted the company.

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 applications where high quality and reliability are highly desired and essential, Allegro added.

A6214, A6216

Internal 5V, 10mA LDO provides added flexibility and cost savings for driving external loads if required by the system. User-selectable output current provides system design and application flexibility, PWM as well as analogue dimming capability provides precise LED current control, and automatic output voltage adjustment based on the number of LEDs in a single string ensures optimal system efficiency. LED dimming is accomplished by a direct logic input pulse-width-modulation (PWM) signal at the enable pin. Alternatively, an analogue 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 added 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 MCU or 555 timer.)

The A6214 is provided 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 per cent matte-tin lead frame plating.

Functional block diagram for A6214

Functional block diagram for A6214


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