November 2006
FAN4800
Low Start-Up Current PFC/PWM Controller Combos
Features
Description
Low start-up current (100µA typical)
Low operating current (2.5mA typical)
Low total harmonic distortion, high power factor
Pin-compatible upgrade for the ML4800
The FAN4800 is a controller for power-factor-corrected,
switched-mode power supplies. Power Factor Correction
(PFC) allows the use of smaller, lower-cost bulk capaci-
tors, reduces power line loading and stress on the
switching FETs, and results in a power supply that fully
complies with IEC-1000-3-2 specifications. Intended as a
BiCMOS version of the industry-standard ML4800, the
FAN4800 includes circuits for the implementation of
leading edge, average current, boost-type power factor
correction, and a trailing-edge Pulse Width Modulator
(PWM). A gate driver with 1A capabilities minimizes the
need for external driver circuits. Low-power require-
ments improve efficiency and reduce component costs.
Average current, continuous or discontinuous boost,
leading-edge PFC
Slew rate enhanced transconductance error amplifier
for ultra-fast PFC response
Internally synchronized leading edge PFC and trailing-
edge PWM
Reduction of ripple current in the storage capacitor
between the PFC and PWM sections
PWM configurable for current-mode or voltage-mode
An over-voltage comparator shuts down the PFC section
in the event of a sudden decrease in load. The PFC sec-
tion also includes peak current limiting and input voltage
brownout protection. The PWM section can be operated
in current or voltage mode, at up to 250kHz, and
includes an accurate 50% duty cycle limit to prevent
transformer saturation.
operation
Additional folded-back current limit for PWM section
20V BiCMOS process
VIN OK guaranteed turn-on PWM at 2.25V
VCC OVP comparator, low-power detect comparator
Current-fed gain modulator for improved noise
The FAN4800 includes a folded-back current limit for the
PWM section to provide short-circuit protection.
immunity
Brownout control, over-voltage protection, UVLO,
soft-start, and reference OK
Available in 16-DIP, 16-SOIC (wide) packages
16-PDIP
16-SOIC
Applications
Desktop PC Power Supply
Internet Server Power Supply
Uninterruptible Power Supply (UPS)
Battery Charger
DC Motor Power Supply
Monitor Power Supply
Telecom System Power Supply
Distributed Power
Ordering Information
Operating
Packing
Method
Marking
Part Number
FAN4800IN
Temp. Range
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
Pb-Free
Yes
Package
Code
FAN4800
FAN4800
FAN4800
16-PDIP
16-SOIC
16-SOIC
Rail
Rail
FAN4800IM
FAN4800IMX
Yes
Yes
Tape & Reell
© 2005 Fairchild Semiconductor Corporation
FAN4800 Rev. 1.0.5
www.fairchildsemi.com