The NCP1631 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 NCP1631 drivers are 180° phase shift 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.
General Features • 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 • Output Over and Under Voltage Protection • Brown−Out Detection with a 50−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
Typical Applications • Computer Power Supplies • LCD / Plasma Flat Panels • All Off Line Appliances Requiring Power Factor Correction
