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onsemi NCP1680/1 Totem Pole PFC Controller

NCP1680 with Critical Conduction Mode (CrM)
NCP1681 with Continuous Conduction Mode (CCM) / Multimode(CrM-CCM)

onsemi’s NCP1680 is a CrM PFC controller IC designed to drive the bridgeless totem-pole PFC topology. The bridgeless totem-pole PFC is a power factor correction architecture that consists of a fast switching leg driven at the PWM switching frequency and a second leg that operates at the AC line frequency. This topology eliminates the diode bridge present at the input of a conventional PFC circuit, allowing significant improvement in the power stage efficiency.

The NCP1681 can be configured to operate in Continuous Conduction Mode (CCM) or Multi-Mode (CrM-CCM) operation.


  • Totem Pole PFC Topology Eliminates Input Diode Bridge
  • Critical Conduction Mode (CRM) Operation for NCP1680
  • Discontinuous Conduction Mode (DCM) with Valley Turn On Under Light Load Condition for NCP1680
  • Continuous Conduction Mode (CCM) Operation At High Power Level for NCP1681
  • Optional Multi-mode Operation With CCM at High Power & CrM at Medium Power Level for NCP1681
  • Frequency Foldback in DCM With 25 kHz Minimum Frequency
  • Skip Mode in Very Light Load Condition
  • Proprietary Current Sense Scheme for NCP1680
  • Digital Voltage Loop Compensation
  • AC Line Monitoring Circuit & AC Phase Detection
  • Near Unity Power Factor in All Operating Modes
  • PFC OK Indicator


  • Enables High Efficiency & Compact Design
  • Optimized Efficiency For High Power Design
  • Optimized Performance Across Power Levels
  • Prevents Operation in Audible Range Complies with Energy Efficiency Regulatory Standards
  • Cycle-by-Cycle Current Limit Without Hall Effect Sensor
  • Simplifies Design & Reduces External Components
  • Complies with Energy Efficiency Regulatory Standards
  • Allows Communication with Downstream Converter to Optimize System Performance


  • Power Factor Correction
  • Offline Power Supply

End Products

  • Server Power
  • Industrial Power Supplies
  • Telecom 5G Power
  • Networking Power
  • Gaming Console Power Supplies
  • UHD TV Power Supplies
  • Computing Power Supplies

NCP1680 Block Diagram

onsemi — NCP1680 Block Diagram

Totem Pole v.s. Standard Boost PFC Efficiency Comparison

onsemi — Totem Pole v.s. Standard Boost PFC Efficiency Comparison
Bridgeless Totem Pole PFC provides 1.8% higher efficiency than standard boost PFC at full load, 90 Vac input condition equivalent to 9 W power loss reduction

Simplified Totem Pole PFC Topology

onsemi — Simplified Totem Pole PFC Topology


onsemi NCP1681 CCM 1KW Evaluation Board

onsemi — NCP1681 CCM 1KW Evaluation Board
NCP1681: Totem Pole PFC Controller


  • Rated output power is 500 W for 90 140 V AC and 1 kW for 180 265 V AC
  • Recommended minimum 500 LFM external airflow while operating EVB