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FAN9611 Datasheet, PDF (1/35 Pages) Fairchild Semiconductor – Interleaved Dual BCM PFC Controllers | |||
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October 2009
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 (VIN)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 18kHz and 600kHz. 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, input over-voltage, over-current, open-
feedback, output over-voltage, and redundant latching
over-voltage protections. Furthermore, the convertersâ
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. 1.0.1
Figure 1. Simplified Application Diagram
www.fairchildsemi.com
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