The NCP1632A 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 NCP1632A 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.

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