Interleaved 2-Phase Power Factor Controller

The NCP1632 from ON Semiconductor integrates a dual MOSFET driver for interleaved PFC applications. Interleaving consists of paralleling two small stages in lieu of a bigger one, more difficult to design. This approach has several merits like the ease of implementation, the use of smaller components or a better distribution of the heating.

Also, Interleaving extends the power range of Critical Conduction Mode that is an efficient and cost−effective technique (no need for low trr diodes). In addition, the NCP1632 drivers are 180° phase shifted for a significantly reduced current ripple.

Housed in a SOIC16 package, the circuit incorporates all the features necessary for building robust and compact interleaved PFC stages, with a minimum of external components. Typical applications are expected to include computer power supplies, LCD and plasma flat panels, and any line-powered appliances needing power factor correction.

General features include:

  • Near−Unity Power Factor
  • Substantial 180° Phase Shift in All Conditions Including Transient Phases
  • Frequency Clamped Critical Conduction Mode (FCCrM) i.e., Fixed Frequency, Discontinuous Conduction Mode Operation with Critical Conduction Achievable in Most Stressful Conditions
  • FCCrM Operation Optimizes the PFC Stage Efficiency Over the Load Range
  • Out−of−phase Control for Low EMI and a Reduced rms Current in the Bulk Capacitor
  • Frequency Fold−back at Low Power to Further Improve the Light Load Efficiency
  • Accurate Zero Current Detection by Auxiliary Winding for Valley Turn On
  • Fast Line / Load Transient Compensation
  • High Drive Capability: −500 mA / +800 mA
  • Signal to Indicate that the PFC is Ready for Operation (“pfcOK” Pin)
  • VCC Range: from 10 V to 20 V

Safety features include:

  • Output Over and Under Voltage Protection
  • Brown−Out Detection with a 500−ms Delay to Help Meet Hold−up Time Specifications
  • Soft−Start for Smooth Start−up Operation
  • Programmable Adjustment of the Maximum Power
  • Over Current Limitation
  • Detection of Inrush Currents
ON Semiconductor
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