ON Semiconductor's onsemi NCP1623 Critical Conduction Mode (CrM) power factor controller is designed to drive a PFC boost stage. Based on an innovative Valley Synchronous Frequency Foldback (VSFF) method, the NCP1623 operates in Critical Conduction Mode (CrM) until the power drops below a threshold level. As the load decays, using frequency foldback, the PFC controller enters discontinuous conduction mode (DCM) and the dead time increases. At nominal and light loads, VSFF maximizes efficiency. Additionally, the NCP1623's internal circuitry allows the power factor to approach unity even when the switching frequency is reduced
Available in a TSOP-6 package, the ON Semiconductor NCP1623 CrM power factor controller has all the features required to build a robust and compact interleaved PFC stage with minimal external components. The NCP1623A model features follower boost capability, which greatly improves low line efficiency. The device is also available in a SOIC-8 package and features an ultra-low power mode controlled externally by a disable pin.
