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Электронный компонент: FAN4800IN

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2005 Fairchild Semiconductor Corporation
www.fairchildsemi.com
Rev. 1.0.0
Features
Low start-up current(100
A typ.)
Low operating current(2.5mA typ.)
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
VIN OK guaranteed turn on PWM at 2.25V
Vcc OVP Comparator, Low Power Detect
Comparator
Current-Fed gain modulator for improved noise
immunity
Brown out control, over-voltage protection, UVLO,
soft start, and Reference OK
Available in a 16-DIP Package
Applications
Desktop PC Power Supply
Internet Server Power Supply
Un-interruptible Power Supply UPS
Battery Charger
DC Motor Power Supply
Monitor Power Supply
Telecom System Power Supply
Distributed Power
General Description
The FAN4800 is a controller for power
factor
corrected,
switched
mode power supplies. Power Factor Correc-
tion (PFC) allows the use of smaller, lower cost bulk
capacitors, reduces power line loading and stress on
the switching FETs, and results in a power supply that
fully complies with the IEC-1000-3-2 specifications.
Intended as a Bi-CMOS version of the industry-stan-
dard ML4800, the FAN4800 includes circuits for the
implementation of leading edge, average current, boost
type power factor correction and a trailing edge, pulse
width PWM (Pulse Width Modulator). A gate driver with
1A capabilities minimizes the need for external driver
circuits. Low power requirements improve efficiency
and reduce component costs.
An over voltage comparator shuts down the PFC sec-
tion in the event of a sudden decrease in load. The
PFC section 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 a short circuit protection
function
.
16-DIP
FAN4800
FAN4800
FAN4800
FAN4800
Low Start-Up Current PFC/PWM Controller Combos
FAN4800
2
Internal Block Diagram
RAMP2
V
FB
V
REF
RAMP1
V
RMS
20uA
OSCILLATOR
2.25V
4
3
15
PFC I
LIMIT
DUTY CYCLE
LIMIT
2
POWER FACTOR CORRECTOR
8
GAIN
MODULATOR
V
FB
I
SENSE
7.5V
REFERENCE
7
S
R
Q
S
R
Q
I
AC
IEAO
VEAO
Vcc
V
REF
PFC OUT
S
R
Q
UVLO
V
DC
SS
DC I
LIMIT
PWM OUT
Vcc
PULSE WIDTH MODULATOR
Vcc
0.95V
V
IN
OK
1.0V
DC I
LIMIT
3.5k
3.5k
2.5V
0.5V
2.78V
-1V
GND
6
5
9
10
11
12
14
0.3V
Low Power
Detector
Vcc
17.9V
TRI-FAULT
Vcc OVP
350
PWM CMP
SS CMP
S
R
Q
PFC OVP
PFC CMP
PWM DUTY
350
CLK
CLK
CLK
CLK
PFC
PFC
PFC
PFC
OUT
OUT
OUT
OUT
PWM
PWM
PWM
PWM
OUT
OUT
OUT
OUT
13
1
16
FAN4800
3
Pin Configuration
Pin Descriptions
Pin No.
Symbol
Description
1
IEAO
PFC transconductance current error amplifier output
2
I
AC
PFC gain control reference input
3
I
SENSE
Current sense input to the PFC current limit comparator
4
V
RMS
Input for PFC RMS line voltage compensation
5
SS
Connection point for the PWM soft start capacitor
6
V
DC
PWM voltage feedback input
7
RAMP1
(RtCt)
Oscillator timing node; timing set by RT, CT
8
RAMP2
(PWM RAMP)
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)
9
DC I
LIMIT
PWM current limit comparator input
10
GND
Ground
11
PWM OUT
PWM driver output
12
PFC OUT
PFC driver output
13
V
CC
Positive supply
14
V
REF
Buffered output for the internal 7.5V reference
15
V
FB
PFC transconductance voltage error amplifier input
16
VEAO
PFC transconductance voltage error amplifier output
16
16
16
16-
-
-
-Pin PDIP
Pin PDIP
Pin PDIP
Pin PDIP
F
F
F
F
A
A
A
A
N
N
N
N
6
6
6
6
8
8
8
8
0
0
0
0
0
0
0
0
1
1
1
1
4
4
4
4
1
1
1
1
3
3
3
3
1
1
1
1
6
6
6
6
1
1
1
1
5
5
5
5
V
V
V
V
C
C
C
C
C
C
C
C
G
G
G
G
N
N
N
N
D
D
D
D
V
V
V
V
F
F
F
F
B
B
B
B
V
V
V
V
E
E
E
E
A
A
A
A
O
O
O
O
P
P
P
P
F
F
F
F
C
C
C
C
O
O
O
O
U
U
U
U
T
T
T
T
P
P
P
P
W
W
W
W
M
M
M
M
O
O
O
O
U
U
U
U
T
T
T
T
V
V
V
V
R
R
R
R
E
E
E
E
F
F
F
F
D
D
D
D
C
C
C
C




I
I
I
I
L
L
L
L
I
I
I
I
M
M
M
M
I
I
I
I
T
T
T
T
9
9
9
9
1
1
1
1
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
1
1
1
1
2
2
2
2
1
1
1
1
3
3
3
3
1
1
1
1
2
2
2
2
1
1
1
1
6
6
6
6
1
1
1
1
4
4
4
4
4
4
4
4
5
5
5
5
I
I
I
ISENSE
SENSE
SENSE
SENSE
SS
SS
SS
SS
V
V
V
VRMS
RMS
RMS
RMS
IEAO
IEAO
IEAO
IEAO
VEAO
VEAO
VEAO
VEAO
Vcc
Vcc
Vcc
Vcc
GND
GND
GND
GND
3
3
3
3
I
I
I
IAC
AC
AC
AC
1
1
1
1
5
5
5
5
6
6
6
6
7
7
7
7
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
V
V
V
VDC
DC
DC
DC
RAMP
RAMP
RAMP
RAMP1
1
1
1
9
9
9
9
8
8
8
8
RAMP
RAMP
RAMP
RAMP2
2
2
2
DC I
DC I
DC I
DC ILIMIT
LIMIT
LIMIT
LIMIT
PWM OUT
PWM OUT
PWM OUT
PWM OUT
PFC OUT
PFC OUT
PFC OUT
PFC OUT
V
V
V
VREF
REF
REF
REF
V
V
V
VFB
FB
FB
FB
FAN4800
4
Absolute Maximum Ratings
Absolute maximum ratings are those values beyond which the device could be permanently damaged.
Electrical Characteristics
Unless otherwise stated, these specifications apply: VCC=15V, RT=52.3K
,
CT=470pF, TA= -40
C to 125
C
Parameter
Min.
Max.
Unit
V
CC
-
20
V
IEAO
0
5.5
V
I
SENSE
Voltage
-5
0.7
V
Voltage on Any Other Pin
GND-0.3
VCC+0.3
V
I
REF
-
10
mA
I
AC
Input Current
-
1
mA
Peak PFC OUT Current, Source or Sink
-
1
A
Peak PWM OUT Current, Source or Sink
-
1
A
PFC OUT, PWM OUT Energy per Cycle
-
1.5
J
Junction Temperature
-
150
C
Storage Temperature Range
-65
150
C
Operating Temperature Range
-40
125
C
Lead Temperature (Soldering,10 sec.)
-
260
C
Thermal Resistance(
JA
)
Plastic DIP
-
80
C/W
Parameter
Symbol
Test Conditions
Min.
Typ.
Max.
Unit
VOLTAGE ERROR AMPLIFIER
Input Voltage Range
Vfb
Note3
0
-
6
V
Transconductance gm1
-
50
70
90
mho
Feedback Reference Voltage
Vref(PFC)
T
A
=25
C
2.45
2.5
2.55
V
Input Bias Current
Ib(Veao)
Note1
-1.0
-0.05
-
Output High Voltage
Veao(H)
-
5.8
6.0
-
V
Output Low Voltage
Veao(L)
-
-
0.1
0.4
V
Sink Current
Isink(V)
T
A
=25
C,
V
FB
=
3V
VEAO = 6.0V
-
-35
-20
A
Source Current
Isource(V)
T
A
=25
C,
V
FB
=
1.5V
VEAO = 1.5V
30
40
-
A
Open Loop Gain
Gv
Note2, Note3
50
60
-
dB
Power Supply Rejection Ratio
PSRR1
11V < V
CC
< 16.5V(Note3)
50
60
-
dB
FAN4800
5
Electrical Characteristics
(Continued)
Unless otherwise stated, these specifications apply: VCC=+15V, RT=52.3K
,
CT=470pF, TA= -40
C to 125
C
.
Parameter
Symbol
Test Conditions
Min.
Typ.
Max.
Unit
CURRENT ERROR AMPLIFIER
Input Voltage Range
Vieao
Note3
-1.5
-
0.7
V
Transconductance gm2
-
50
85
100
mho
Input Offset Voltage
Voffset
T
A
=25
C
-
-
25
mV
Input Bias Current
I
beao
Note3
-1
-
-
A
Output High Voltage
Ieao(H)
-
4.0
4.25
-
V
Output Low Voltage
Ieao(L)
-
-
1.0
1.2
V
Sink Current
Isink(I)
I
SENSE
= +
0.5
,
IEAO = 4.0V
-
-65
-35
A
Source Current
Isource(I)
I
SENSE
= -
0.5
,
IEAO = 1.5V
35
75
-
A
Open Loop Gain
Gi
Note3
60
70
-
dB
Power Supply Rejection Ratio
PSRR2
11V < V
CC
<16.5V(Note3)
60
75
-
dB
PFC OVP COMPARATOR
Threshold Voltage
Vovp
T
A
=25
C
2.70
2.78
2.9
V
Hysteresis
HY(ovp)
T
A
=25
C
230
-
350
mV
LOW POWER DETECT COMPARATOR
Threshold Voltage
Vth(lp)
T
A
=25
C
0.15
0.3
0.4
V
VCC OVP COMPARATOR
Threshold Voltage
Vcc_ovp
T
A
=25
C
17.5
17.9
18.5
V
Hysteresis
HY(Vcc_ovp)
T
A
=25
C
1.40
1.5
1.65
V
TRI-FAULT DETECT
Time to Fault Detect High
Td(F)
V
FB
=V
Fault Detect LOW
to
V
FB
=Open. 470pF
from V
FB
to GND(Note3)
-
2
4
ms
Fault Detect Low
F(L)
-
0.4
0.5
0.6
V
PFC I
LIMIT
COMPARATOR
Threshold Voltage
Vth(cs)
-
-1.10 -1.00 -0.90
V
(PFC I
LIMIT
V
TH
- Gain
Modulator Output)
Vth(cs)-Vgm
-
5
100
-
mV
Delay to Output(Note 3)
Td(pfc_off)
-
-
250
-
ns
DC I
LIMIT
COMPARATOR
Threshold Voltage
Vth(DC)
-
0.95
1.0
1.05
V
Delay to Output(Note 3)
Td(pwm_off)
-
-
250
-
ns
V
IN
OK COMPARATOR
Threshold Voltage
Vth(OK)
-
2.10
-
2.45
V
Hysteresis
HY(OK)
-
0.8
1.0
1.2
V