Electronic Design

3.0 A Buck Regulator LED Drives High Power LEDs

Allegro_0924-AAllegro MicroSystems' A6211 switching buck regulator LED driver provides constant-current output to drive high-power LEDs. With a wide input supply voltage from 6 V to 48 V, the device integrates a high-side N-channel MOSFET switch for dc-to-dc stepdown (buck) conversion. A true average current is output using a cycle-by-cycle, controlled on-time method. Fault protection advantages include design techniques addressing pin-pin shorts, pin-ground shorts and open and shorted external components. It was designed for the consumer, industrial and architectural lighting markets in addition to light bars for scanners and multifunction printers. The LED current is user-configurable by an external current sense resistor, allowing the output voltage to be set to optimize constant-current supply for LED array configurations, including multiple LEDs in series, in a single string, or parallel strings. Provided in a compact 8-pin narrow SOIC package (suffix LJ) with exposed pad for enhanced thermal dissipation, the A6211GLJTR-T LED driver is priced at $0.38 each/1,000.
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