This application note describes an evaluation board consisting of the LM3421 controller configured as a SEPIC constant current LED driver. It is capable of converting input voltages from 8V to 18V and illuminating up to six LEDs with approximately 350 mA of drive current.
Additional features include analog and pulse-width modulated (PWM) dimming, over-voltage protection, under-voltage lockout and cycle-by-cycle current limit. A bill of materials is included that describes the parts used in this evaluation board. A schematic and layout have also been included along with measured performance characteristics.