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    LED Driver, LM3409

    The TI LM3409 is a DC-DC constant-current buck driver IC. This is a step down driver that can provide a constant current source to power LED(s). The circuit I designed around it is optimized for low ripple, fast switching capability, and current up to about 6A continuous. 

    Design specification as built:

    • Vin up to 20v
    • Vout 3v up to 17v (3v dropout max, 2v typical)
    • Output current up to 6A continuous (tested)
    • Less than 1% ripple (simulated and measured)
    • Clean switching up to 120kHz (measured)
    • Analog current adjust using ADJ pin (takes digital pwm inputs and filters using an RC)
    • Digital PWM/signal pin (turns off on pin HIGH)
    • Easily controllable using an arduino (or anything really...)

    Schematic on KiCad:

    PCB Layout on KiCad (BOM is included):

    And a build video:

    PSpice simulation circuit:

    Recommend you use a heatsink on the bottom of the board, and on the LM3409 itself as pictured. Also recommended you use my 3D printed mount:


    As pictured, I used a Cree XM-L2 (single 3.3v output), and a wall wart 6.5v 3A PSU. The LED is mounted on a CPU heatsink

    That's all for now :)