FAN9611_1112 Datasheet, PDF (1/36 Pages) Fairchild Semiconductor – Interleaved Dual BCM PFC Controllers

December 2011
FAN9611 / FAN9612
Interleaved Dual BCM PFC Controllers
Features
 Sync-Lock™ Interleaving Technology for 180°
Out-of-Phase Synchronization Under All Conditions
 Automatic Phase Disable at Light Load
 Dead-Phase Detect Protection
 2.0A Sink, 1.0A Source, High-Current Gate Drivers
 High Power Factor, Low Total Harmonic Distortion
 Voltage-Mode Control with (V_IN)² Feedforward
 Closed-Loop Soft-Start with User-Programmable
Soft-Start Time for Reduced Overshoot
 Minimum Restart Frequency to Avoid Audible Noise
 Maximum Switching Frequency Clamp
 Brownout Protection with Soft Recovery
 Non-Latching OVP on FB Pin and Latching Second-
Level Protection on OVP Pin
 Open-Feedback Protection
 Power-Limit and Current Protection for Each Phase
 Low Startup Current of 80µA Typical
 Works with DC and 50Hz to 400Hz AC Inputs
Applications
 100-1000W AC-DC Power Supplies
 Large Screen LCD-TV, PDP-TV, RP-TV Power
 High-Efficiency Desktop and Server Power Supplies
 Networking and Telecom Power Supplies
 Solar Micro Inverters
Description
The FAN9611/12 family of interleaved dual Boundary-
Conduction-Mode (BCM) Power-Factor-Correction (PFC)
controllers operate two parallel-connected boost power
trains 180° out of phase. Interleaving extends the
maximum practical power level of the control technique
from about 300W to greater than 800W. Unlike the
continuous conduction mode (CCM) technique often
used at higher power levels, BCM offers inherent zero-
current switching of the boost diodes, which permits the
use of less expensive diodes without sacrificing
efficiency. Furthermore, the input and output filters can
be smaller due to ripple current cancellation and effective
doubling of the switching frequency.
The converters operate with variable frequency, which is
a function of the load and the instantaneous input /
output voltages. The switching frequency is limited
between 16.5kHz and 525kHz. The Pulse Width
Modulators (PWM) implement voltage-mode control with
input voltage feedforward. When configured for PFC
applications, the slow voltage regulation loop results in
constant on-time operation within a line cycle. This PWM
method, combined with the BCM operation of the boost
converters, provides automatic power factor correction.
The controllers offers bias UVLO (10V / 7.5V for
FAN9611 and 12.5V / 7.5V for FAN9612), input
brownout, over-current, open-feedback, output over-
voltage, and redundant latching over-voltage protections.
Furthermore, the converters’ output power is limited
independently of the input RMS voltage. Synchronization
between the power stages is maintained under all
operating conditions.
© 2008 Fairchild Semiconductor Corporation
FAN9611 / FAN9612 • Rev. 1.1.4
Figure 1. Simplified Application Diagram
www.fairchildsemi.com