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FAN4800CS View Datasheet(PDF) - Fairchild Semiconductor

Part Name
Description
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FAN4800CS
Fairchild
Fairchild Semiconductor Fairchild
FAN4800CS Datasheet PDF : 19 Pages
1 2 3 4 5 6 7 8 9 10 Next Last
December 2010
FAN4800AS/CS/01S/2S
PFC/PWM Controller Combination
Features
ƒ Pin-to-Pin Compatible with ML4800 and FAN4800
and CM6800 and CM6800A
ƒ PWM Configurable for Current Mode or
Feedforward Voltage-Mode Operation
ƒ Internally Synchronized Leading-Edge PFC and
Trailing-Edge PWM in One IC
ƒ Low Operating Current
ƒ Innovative Switching-Charge Multiplier Divider
ƒ Average-Current Mode for Input-Current Shaping
ƒ PFC Over-Voltage and Under-Voltage Protections
ƒ PFC Feedback Open-Loop Protection
ƒ Cycle-by-Cycle Current Limiting for PFC/PWM
ƒ Power-on Sequence Control and Soft-Start
ƒ Brownout Protection
ƒ Interleaved PFC/PWM Switching
ƒ Improved Efficiency at Light Load
ƒ fRTCT=4•fPFC=4•fPWM for FAN4800AS/01S
ƒ fRTCT=4•fPFC=2•fPWM for FAN4800CS/02S
Applications
ƒ Desktop PC Power Supply
ƒ Internet Server Power Supply
ƒ LCD TV, Monitor Power Supply
ƒ UPS
ƒ Battery Charger
ƒ DC Motor Power Supply
ƒ Monitor Power Supply
ƒ Telecom System Power Supply
ƒ Distributed Power
Related Resources
ƒ AN-8027 - FAN480X PFC+PWM Combination
Controller Application
Description
The highly integrated FAN4800AS/CS/01S/02S parts
are specially designed for power supplies that consist of
boost PFC and PWM. They require very few external
components to achieve versatile protections /
compensation. They are available in 16-pin DIP and
SOP packages.
The PWM can be used in either current or voltage
mode. In voltage mode, feed-forward from the PFC
output bus can reduce the secondary output ripple.
Compared with older productions, ML4800 and
FAN4800, FAN4800AS/CS/01S/02S have lower
operation current that saves power consumption in
external devices. FAN4800AS/CS/01S/02S have
accurate 49.9% maximum duty of PWM that makes the
hold-up time longer. Brownout protection and PFC soft-
start functions available in this series are not available
in ML4800 and FAN4800.
To evaluate FAN4800AS/CS/01S/02S for replacing
existing FAN4800 and ML4800 boards, five things must
be completed before the fine-tuning procedure:
1. Change RAC resister from the old value to a higher
resister: between 6MΩ to 8MΩ.
2. Change RT/CT pin from the existing values to
RT=6.8kΩ and CT=1000pF to have fPFC=64kHz and
fPWM=64kHz.
3. The VRMS pin needs to be 1.224V at VIN=85 VAC
for universal input application from line input from
85VAC to 270VAC.
4. At full load, the average VVEA needs to be ~4.5V
and the ripple of VVEA needs to be less than
400mV.
5. For the Soft-Start pin, the soft-start current has
been reduced to half the FAN4800 capacitor.
There are two differences from FAN4800A/C/01/02 to
FAN4800AS/CS/01S/02S:
1. Under-voltage protection debounce time is
extended to one second.
2. PWM gate clamp voltage is raised to 19V.
© 2010 Fairchild Semiconductor Corporation
FAN4800AS/CS/01S/02S • Rev. 1.0.1
www.fairchildsemi.com
 

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