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