Automotive buck regulator LED driver has dimming feature

Allegro Microsystems Europe has introduced two switching regulator ICs for automotive LED lighting applications. As the first such devices in the industry they enable designers to implement dimming functionality without requiring a separate microcontroller or PWM circuit.

Both the A6214 and the A6216 contain a high-side n-channel DMOS switch for the DC/DC buck regulator functionality. A true average current is output using a cycle-by-cycle, controlled on-time method. The automotive-grade driver chips offer multiple timing and protection functions and are designed for dimmable interior lighting, daytime running lights, front and rear fog lights, turn and stop lights as well as for map lights.


Output current is user-selectable by an external current sense resistor. Output voltage is automatically adjusted to drive various numbers of LEDs in a single string. This ensures the optimal system efficiency.


The A6214 is a single-IC switching regulator that provides constant-current output to drive high-power LEDs. It integrates 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.


LED dimming is accomplished by a direct logic input pulse-width-modulation (PWM) signal at the Enable pin. Alternatively, an Analog Dimming input can be used to calibrate the LED current, or implement thermal foldback in conjunction with external NTC thermistor. The A6216 has the added capability to generate its own PWM dimming frequency and duty cycle in stand-alone mode.


The A6214 is provided in a compact 10-pin narrow SOIC package (suffix LK). The A6216 is in 16-pin TSSOP (suffix LP), both with exposed pad for enhanced thermal dissipation. It is lead (Pb) free, with 100% matte-tin leadframe plating.


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