The 6-pin PFC controller NCP1622 is designed to drive PFC boost stages. It is based on an innovative Valley Synchronized Frequency Fold-back (VSFF) method. In this mode, the circuit classically operates in Critical conduction Mode (CrM) when control voltage exceeds a programmable value Vctrl,FF.
Critical Conduction Mode with frequency foldback Valley Synchronized Frequency Fold-back (VSFF) Works with or without a transformer w/ ZCD winding Dynamic Response Enhancer Benefits: Optimizes conversion efficiency across load range Enhanced efficiency at light load conditions compared to CrM PFC Reduced inductor cost and simplified design Improved transient response for line and load steps