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FAN4800 Low Start-Up Current PFC/PWM Controller Combos
November 2006
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
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.
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
Part Number
FAN4800IN
FAN4800IM
FAN4800IMX
Operating
Temp. Range
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
Pb-Free
Yes
Yes
Yes
Package
16-PDIP
16-SOIC
16-SOIC
Packing
Method
Rail
Rail
Tape & Reell
Marking
Code
FAN4800
FAN4800
FAN4800
© 2005 Fairchild Semiconductor Corporation
FAN4800 Rev. 1.0.5
www.fairchildsemi.com
FAN4800 Low Start-Up Current PFC/PWM Controller Combos
Block Diagram
16
1
13
V
CC
7.5V
REFERENCE
V
EAO
V
FB
I
EAO
POWER FACTOR CORRECTOR
V
CC
17.9V
0.5V
-1V
V
CC
OVP
2.78V
TRI-FAULT
S
R
PFC OVP
V
REF
14
15
0.3V
2.5V
I
AC
V
RMS
I
SENSE
RAMP1
GAIN
MODULATOR
Low Power
Detector
3.5k
Q
PFC OUT
2
4
3
7
3.5k
PFC CMP
PFC I
LIMIT
S
R
Q
12
OSCILLATOR
CLK
RAMP2
350
DUTY CYCLE
LIMIT
PWM DUTY
8
PFC
OUT
PWM
OUT
PWM CMP
6
V
DC
V
CC
20μA
5
SS
350
V
FB
2.25V
V
IN
OK
V
REF
DC I
LIMIT
PULSE WIDTH MODULATOR
0.9V
SS CMP
S
1.0V
DC I
LIMIT
GND
Q
S
R
V
CC
UVLO
FAN4800 Rev.02
PWM OUT
Q
11
R
10
9
Figure 1. Internal Block Diagram
© 2005 Fairchild Semiconductor Corporation
FAN4800 Rev. 1.0.5
2
www.fairchildsemi.com
FAN4800 Low Start-Up Current PFC/PWM Controller Combos
Pin Configuration
1
I
EAO
V
EAO
16
2
I
AC
V
FB
15
3
I
SENSE
V
REF
14
4
V
RMS
V
CC
13
5
SS
PFC OUT 12
6
V
DC
PWM OUT 11
7
RAMP1
GND 10
8
RAMP2
DC I
LIMIT
9
FAN4800 Rev.03
Figure 2. Pin Configuration (Top View)
Pin Definitions
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Name
I
EAO
I
AC
I
SENSE
V
RMS
SS
V
DC
RAMP1
(RtCt)
RAMP2
(PWM RAMP)
DC I
LIMIT
GND
PWM OUT
PFC OUT
V
CC
V
REF
V
FB
V
EAO
Description
PFC transconductance current error amplifier output
PFC gain control reference input
Current sense input to the PFC current limit comparator
Input for PFC RMS line voltage compensation
Connection point for the PWM soft-start capacitor
PWM voltage feedback input
Oscillator timing node; timing set by RT, CT
In current mode, this pin functions as the current sense input; in voltage mode,
it is the PWM input from the PFC output (feed forward ramp)
PWM current limit comparator input
Ground
PWM driver output
PFC driver output
Positive supply
Buffered output for the internal 7.5V reference
PFC transconductance voltage error amplifier input
PFC transconductance voltage error amplifier output
© 2005 Fairchild Semiconductor Corporation
FAN4800 Rev. 1.0.5
3
www.fairchildsemi.com
FAN4800 Low Start-Up Current PFC/PWM Controller Combos
Absolute Maximum Ratings
The “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed.
The device should not be operated at these limits. The parametric values defined in the Electrical Characteristics
tables are not guaranteed at the absolute maximum ratings.
Symbol
V
CC
I
EAO
V
ISENSE
I
REF
I
AC
I
PFC_OUT
I
PWM_OUT
T
J
T
STG
T
A
T
L
θ
JA
Parameter
Positive Supply Voltage
PFC transconductance current error amplifier
output
I
SENSE
Voltage
Voltage on Any Other Pin
I
REF
Current
I
AC
Input Current
Peak PFC OUT Current, Source or Sink
Peak PWM OUT Current, Source or Sink
PFC OUT, PWM OUT Energy per Cycle
Junction Temperature
Storage Temperature Range
Operating Temperature Range
Lead Temperature (Soldering,10 seconds)
Thermal Resistance (θ
JA
) Plastic DIP
Min.
Max.
20
Unit
V
V
V
V
mA
mA
A
A
µJ
°C
°C
°C
°C
°C/W
0
-3.0
GND-0.3
5.5
0.7
V
CC
+0.3
10
1
1
1
1.5
150
-65
-40
150
125
260
80
© 2005 Fairchild Semiconductor Corporation
FAN4800 Rev. 1.0.5
4
www.fairchildsemi.com
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