NCP1623 CrM Power Factor Controller

onsemi NCP1623 Critical Conduction Mode (CrM) Power Factor Controller is designed to drive PFC boost stages. Based on an innovative Valley Synchronized Frequency Foldback (VSFF) method, the NCP1623 operates in critical conduction mode (CrM) until the power drops below a threshold level. The PFC controller enters discontinuous conduction mode (DCM) with increased dead-time as the load decays using frequency foldback. VSFF maximizes the efficiency at both nominal and light loads. In addition, the internal circuitry of the NCP1623 ensures a near-unity power factor even when the switching frequency is reduced.