The FAN6921BMRMY with Power Factor Correction (PFC)/QR COMBO CONTR is a highly efficient PFC controller manufactured by ON Semiconductor. It is designed to combine PFC with QR' switching techniques. This integrated circuit includes a high-voltage current-mode PFC controller, a high-voltage, low-side driver for the QR' switch, and a charge pump for driving an external gate driver. It also features a programmable voltage level for the soft-start, multiple level frequency folding, and programmable operating frequencies. Additionally, the FAN6921BMRMY implements an Auto-Restart function with programmable threshold. Its built-in protection features include a soft start for inrush current limit, over-voltage protection and short-circuit protection for both overload and over-voltage, and open loop protection for burst mode and single-line approach.