© 2005 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN4800 Low Start-Up Current PFC/PWM Controller Combos
November 2006
FAN4800 Rev. 1.0.5
FAN4800
Low Start-Up Current PFC/PWM Controller Combos
Features
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
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
operation
Additional folded-back current limit for PWM section
20V BiCMOS process
V
IN
OK guaranteed turn-on PWM at 2.25V
V
CC
OVP comparator, low-power detect comparator
Current-fed gain modulator for improved noise
immunity
Brownout control, over-voltage protection, UVLO,
soft-start, and reference OK
Available in 16-DIP, 16-SOIC (wide) packages
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
Description
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.
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.
The FAN4800 includes a folded-back current limit for the
PWM section to provide short-circuit protection.
Ordering Information
16-PDIP
16-SOIC
Part Number
Operating
Temp. Range
Pb-Free Package
Packing
Method
Marking
Code
FAN4800IN -40°C to +125°C Yes 16-PDIP Rail FAN4800
FAN4800IM -40°C to +125°C Yes 16-SOIC Rail FAN4800
FAN4800IMX -40°C to +125°C Yes 16-SOIC Tape & Reell FAN4800
