A PFC AC-to-DC power supply is disclosed. According to various embodiments, the PFC AC-to-DC power supply comprises a switching converter comprising at least one main power switch and a PFC controller for controlling the at least one main power switch. The PFC controller may comprise a processing unit comprising a processor and a memory having firmware stored thereon which, when executed by the processor, causes the processor to compute an input current set point for the AC-to-DC power supply based on the output voltage of the AC-to-DC power supply. The PFC controller may also comprise hardware circuitry in communication with the processing unit. The hardware circuitry may comprise a first a/d converter, such as a window a/d converter, for outputting a digital input current error value based on the input current of the AC-to-DC power supply and an analog form of the input current set point from the processing unit. The hardware circuitry may also comprise a digital current mode compensator in communication with the first a/d converter for determining the duty cycle for the at least one main power switch based on the digital input current error value from the a/d converter.