The LM3405A demo board is configured to drive a series string of high power, high brightness LEDs at a forward current of 1A using the LM3405A constant current buck regulator. The board can accept a full input operating range of 3V to 22V. The converter output voltage adjusts as needed to maintain a constant current through the LED array. The LM3405A is a step-down regulator with an output voltage range extending from a VO(MIN) of 205mV (the reference voltage) to a VO(MAX) determined by the maximum duty cycle (typically 94%). It can drive up to 5 LEDs in series at 1A forward current, with the single LED forward voltage of approximately 3.7V (Typical of white, blue, and green LEDs using InGaN technology).