The LM3434 is an adaptive constant on-time DC/DC buck constant current controller designed to drive a high brightness LED (HB LED) at high forward currents. It is a true current source that provides a constant current with constant ripple current regardless of the LED forward voltage drop. The board can accept an input voltage ranging from -9V to -30V w.r.t. GND. The output configuration allows the anodes of multiple LEDs to be tied directly to the ground referenced chassis for maximum heat sink efficiency when a negative input voltage is used.
The evaluation board is designed to provide a constant current in the range of 4A to 20A. The LM3434 requires two input voltages for operation. A positive voltage with respect to GND is required for the bias and control circuitry and a negative voltage with respect to GND is required for the main power input. This allows for the capability of using common anode LEDs so that the anodes can be tied to the ground referenced chassis. The evaluation board only requires one input voltage of -9V to -30V with respect to GND.