Onsemi NCP1623 CrM power factor controller

     The onsemi NCP1623 Critical On-mode (CrM) power factor controller is designed to drive the PFC boost stage. The NCP1623 is based on an innovative valley synchronous frequency reentry (VSFF) method that operates in critical on-off mode (CrM) until the power drops below the threshold level. As the load attenuates and frequency retreats.

     The PFC controller enters discontinuous on-off mode (DCM) and the dead time increases. Under nominal and light loads, VSFF maximizes efficiency. In addition, the NCP1623's internal circuitry allows for a near-uniform power factor even when the switching frequency is reduced.

     The onsemi NCP1623 CrM power factor controller is packaged in SOP-6 and has all the features needed to build a robust and compact staggered PFC stage with minimal external components. The NCP1623A model has a follower boost capability that greatly improves low line efficiency. The device is also packaged in SOIC-8 with an ultra-low power mode controlled externally by disabled pins.