ON Semiconductor's NCL30100 is a compact switching regulator controller intended for space-constrained, constant current, high brightness LED driver applications where high efficiency and small size are important. The controller is based on a peak current, quasi-fixed OFF-time control architecture optimized for continuous conduction mode step-down (buck) operation. This allows the output filter capacitor to be eliminated. In this configuration, a reverse buck topology is used to control a cost effective N-channel MOSFET.