FAN9612 Datasheet, PDF (1/37 Pages) Fairchild Semiconductor – Interleaved Dual BCM PFC Controller

PRELIMINARY
February 2009
FAN9612
Interleaved Dual BCM PFC Controller
Features
ƒ Low Total Harmonic Distortion, High Power Factor
ƒ 180° Out of Phase Synchronization
ƒ Automatic Phase Disable at Light Load
ƒ 1.8A Sink, 0.8A Source, High Current Gate Drivers
ƒ Trans-conductance (gM) Error Amplifier
ƒ Voltage-Mode Control with (VIN)² Feed Forward
ƒ Closed-Loop Soft-Start with User-Programmable
Soft-Start Time for Reduced Overshoot
ƒ Minimum Restart Timer Frequency to Avoid Audible
Noise
ƒ Maximum Switching Frequency Clamp
ƒ Brown-Out Protection with Soft-Recovery
ƒ Non-Latching OVP on FB pin and Latching Second
Level Protection on OVP Pin
ƒ Open Feedback Protection
ƒ Over-Current & Power-Limit Protection for Each
Phase
ƒ Low Start-Up Current of 80-µA Typical
ƒ Works with DC, 50Hz to 400Hz ac Inputs
Applications
ƒ 100-1000W Off-line Power Supplies
ƒ Large Screen LCD-TV, PDP-TV, RP-TV Power
ƒ High-End Desktop PC and Server Power Supplies
ƒ 80-PLUS Certified Equipment
Description
The FAN9612 Interleaved Dual Boundary-Conduction-
Mode (BCM) Power-Factor-Correction Controller
operates two parallel-connected boost power trains 180º
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 (no reverse-recovery losses), which
permits the use of less expensive diodes without
sacrificing efficiency. Furthermore, the input and output
filters can be made 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 implement voltage-mode control with input
voltage feed forward. 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 FAN9612 offers bias UVLO, input brown-out, input
over-voltage, over-current, open feedback, over-
temperature, 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. The FAN9612
is available in Lead(Pb)-Free 16-lead SOIC package.
Simplified Application Diagram
© 2008 Fairchild Semiconductor Corporation
FAN9612 • Rev. 0.9.1E
www.fairchildsemi.com