This document is a reference design that supports the use of FL6961 in LED illumination design. It should be used in conjunction with the FL6961 datasheet as well as Fairchild's application notes and technical support team. The design features a boundary mode PFC controller, low input current THD, controlled on-time PWM, zero current detection, cycle-by-cycle current limiting, leading-edge blanking instead of RC filtering, and other characteristics.