Fairchild FAN4800ANY Pfc/pwm controller combination Datasheet

FAN4800A/C, FAN4801/1S/2/2L
PFC/PWM Controller Combination
Features
Description
ƒ
Pin-to-Pin Compatible with ML4800 and FAN4800
and CM6800 and CM6800A
ƒ
PWM Configurable for Current-mode or
Feed-forward Voltage-Mode Operation
ƒ
Internally Synchronized Leading-Edge PFC and
Trailing-Edge PWM in one IC
The
highly
integrated
FAN4800A/C
and
FAN4801/1S/2/2L 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.
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ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
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ƒ
ƒ
Low Operating Current
ƒ
fRTCT=4•fPFC=2•fPWM for FAN4800C and
FAN4802/2L
Innovative Switching-Charge Multiplier Divider
Average-Current-Mode for Input-Current Shaping
PFC Over-Voltage and Under-Voltage Protections
PFC Feedback Open-Loop Protection
Cycle-by-Cycle Current Limiting for PFC/PWM
Power-on Sequence Control and Soft-Start
Brownout Protection
Interleaved PFC/PWM Switching
FAN4801/1S/2/2L Improve Efficiency at Light Load
fRTCT=4•fPFC=4•fPWM for FAN4800A and
FAN4801/1S
Applications
ƒ
ƒ
ƒ
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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, FAN4800A/C and FAN4801/1S/2/2L have
lower operation current that save power consumption in
external devices. FAN4800A/C and FAN4801/1S/2/2L
have accurate 49.9% maximum duty of PWM that
makes the hold-up time longer. Specifically, the
brownout protection and PFC soft-start functions are not
in ML4800 and FAN4800.
To start evaluating FAN4800A/C, FAN4801/1S/2/2L for
replacing existing FAN4800 and ML4800 boards, five
things must be done 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,
fPWM=64KHz.
3.
VRMS pin needs to be 1.224V at VIN=85 VAC for
universal input application from line input from
85VAC to 270 VAC. Both poles for the Vrms of
FAN4801/1S/2/2L don’t need to substantially
slower than FAN4800; about 5 to 10 times.
4.
At full load, the average VEA needs to ~4.5V and
the ripple on the VEA needs to be less than 400mV.
5.
Soft-Start pin, the soft-start current has been
reduced to half from the FAN4800 capacitor.
Desktop PC Power Supply
Internet Server Power Supply
LCD TV, Monitor Power Supply
UPS
Battery Charger
DC Motor Power Supply
Monitor Power Supply
Telecom System Power Supply
Distributed Power
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
Related Resources
Complete design instructions are detailed in application
note AN-6078SC (available in Chinese only).
www.fairchildsemi.com
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
March 2009
Operating
Temperature Range
Eco
Status
FAN4800ANY
-40°C to +105°C
Green
FAN4800CNY
-40°C to +105°C
Green
16-pin Dual In-Line Package (DIP)
FAN4800AMY
-40°C to +105°C
Green
16-pin Small Out-Line Package (SOP)
Tape & Reel
FAN4800CMY
-40°C to +105°C
Green
16-pin Small Out-Line Package (SOP)
Tape & Reel
FAN4801NY
-40°C to +105°C
Green
16-pin Dual In-Line Package (DIP)
Tube
FAN4801SNY
-40°C to +105°C
Green
16-pin Dual In-Line Package (DIP)
Tube
FAN4802NY
-40°C to +105°C
Green
16-pin Dual In-Line Package (DIP))
Tube
FAN4802LNY
-40°C to +105°C
Green
16-pin Dual In-Line Package (DIP))
Tube
FAN4801MY
-40°C to +105°C
Green
16-pin Small Out-Line Package (SOP)
Tape & Reel
FAN4801SMY
-40°C to +105°C
Green
16-pin Small Out-Line Package (SOP)
Tape & Reel
FAN4802MY
-40°C to +105°C
Green
16-pin Small Out-Line Package (SOP)
Tape & Reel
FAN4802LMY
-40°C to +105°C
Green
16-pin Small Out-Line Package (SOP)
Tape & Reel
Part Number
Packing
Method
Package
16-pin Dual In-Line Package (DIP)
Tube
Tube
For Fairchild’s definition of “green” Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html.
Part Number
PFC:PWM Frequency Ratio
Brown Out / In
Range In / Out
FAN4800ANY
1:1
1.05V / 1.90V
N.A
FAN4800AMY
1:1
1.05V / 1.90V
N.A
FAN4800CNY
1:2
1.05V / 1.90V
N.A
FAN4800CMY
1:2
1.05V / 1.90V
N.A
FAN4801NY
1:1
1.05V / 1.90V
1.95V / 2.45V
FAN4801SNY
1:1
1.05V / 1.90V
2.80V / 3.35V
FAN4802NY
1:2
1.05V / 1.90V
1.95V / 2.45V
FAN4802LNY
1:2
0.90V / 1.65V
1.95V / 2.45V
FAN4801MY
1:1
1.05V / 1.90V
1.95V / 2.45V
FAN4801SMY
1:1
1.05V / 1.90V
2.80V / 3.35V
FAN4802MY
1:2
1.05V / 1.90V
1.95V / 2.45V
FAN4802LMY
1:2
0.90V / 1.65V
1.95V / 2.45V
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Ordering Information
www.fairchildsemi.com
2
IEA
VEA
IAC
FBPFC
ISENSE
VREF
VDD
VRMS
VDD
SS
OPFC
FBPWM
OPWM
RT/CT
GND
RAMP
ILIMIT
VREF
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Application Diagram
FAN4800A/C
FAN4801/1S/2/2L
Secondary
Figure 1.
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
Typical Application Current Mode
www.fairchildsemi.com
3
IEA
VEA
IAC
FBPFC
ISENSE
VREF
VDD
VRMS
VDD
SS
OPFC
FBPWM
OPWM
RT/CT
GND
RAMP
ILIMIT
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Application Diagram
VREF
FAN4800A/C
FAN4801/1S/2/2L
VREF
Secondary
Figure 2.
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
Typical Application Voltage Mode
www.fairchildsemi.com
4
Figure 3. FAN4800A/C Function Block Diagram
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Block Diagram
Figure 4. FAN4801/1S/2/2L Function Block Diagram
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
www.fairchildsemi.com
5
F – Fairchild logo
Z – Plant code
X – 1 digit year code
Y – 1 digit week code
TT – 2 digits die run code
T – Package type (N:DIP, M:SOP)
P – Y: Green package
M – Manufacture flow code
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Marking Information
Figure 5. Top Mark
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
www.fairchildsemi.com
6
Figure 6. Pin Configuration (Top View)
Pin Definitions
Pin #
Name
Description
1
IEA
Output of PFC Current Amplifier. The signal from this pin is compared with an internal
sawtooth to determine the pulse width for PFC gate drive.
2
IAC
Input AC Current. For normal operation, this input provides current reference for the multiplier.
The suggested maximum IAC is 100µA.
3
ISENSE
4
VRMS
5
SS
6
FBPWM
7
RT/CT
Oscillator RC Timing Connection. Oscillator timing node; timing set by RT and CT.
8
RAMP
PWM RAMP Input. In current mode, this pin functions as the current sense input; when in
voltage mode, it is the feed forward sense input from PFC output 380V (feedforward ramp).
9
ILIMIT
Peak Current Limit Setting for PWM. The peak current limits setting for PWM.
10
GND
11
OPWM
PWM Gate Drive. The totem-pole output drive for PWM MOSFET. This pin is internally
clamped under 15V to protect the MOSFET.
12
OPFC
PFC Gate Drive. The totem pole output drive for PWM MOSFET. This pin is internally clamped
under 15V to protect the MOSFET.
13
VDD
Supply. The power supply pin. The threshold voltages for startup and turn-off are 11V and
9.3V, respectively. The operating current is lower than 10mA.
14
VREF
Reference Voltage. Buffered output for the internal 7.5V reference.
15
FBPFC
16
VEA
PFC Current Sense. The non-inverting input of the PFC current amplifier and the output of
multiplier and PFC ILIMIT comparator.
Line-Voltage Detection. Line voltage detection. The pin is used for PFC multiplier.
PWM Soft-Start. During startup, the SS pin charges an external capacitor with a 10µA
constant current source. The voltage on FBPWM is clamped by SS during startup. In the event
of a protection condition occurring and/or PWM disabled, the SS pin is quickly discharged.
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Pin Configuration
PWM Feedback Input. The control input for voltage-loop feedback of PWM stage.
Ground.
Voltage Feedback Input for PFC. The feedback input for PFC voltage loop. The inverting
input of PFC error amplifier. This pin is connected to the PFC output through a divider network.
Output of PFC Voltage Amplifier. The error amplifier output for PFC voltage feedback loop.
A compensation network is connected between this pin and ground.
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
www.fairchildsemi.com
7
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be
operable above the recommended operating conditions and stressing the parts to these levels is not recommended.
In addition, extended exposure to stresses above the recommended operating conditions may affect device
reliability. The absolute maximum ratings are stress ratings only.
Symbol
VDD
Parameter
Min.
DC Supply Voltage
Max.
Unit
30
V
VH
SS, FBPWM, RAMP, OPWM, OPFC
-0.3
30.0
V
VL
IAC, VRMS, RT/CT, ILIMIT, FBPFC, VEA
-0.3
7.0
V
7.5
V
0
VVREF+0.3
V
-5.0
0.7
V
VVREF
VREF
VIEA
IEA
VN
ISENSE
IAC
Input AC Current
1
mA
IREF
VREF Output Current
5
mA
IPFC-OUT
Peak PFC OUT Current, Source or Sink
0.5
A
IPWM-OUT
Peak PWM OUT Current, Source or Sink
0.5
A
Power Dissipation TA < 50°C
800
mW
PD
RΘ j-a
Thermal Resistance (Junction to Air)
TJ
TSTG
TL
DIP
80.80
°C/W
SOP
104.10
°C/W
+125
°C
Operating Junction Temperature
-40
Storage Temperature Range
-55
Lead Temperature (Soldering)
Electrostatic Discharge
Capability
ESD
Human Body Model
Charged Device Model
+150
°C
+260
°C
4.5
kV
1000
V
Notes:
1. All voltage values, except differential voltage, are given with respect to GND pin.
2. Stresses beyond those listed under “absolute maximum ratings “may cause permanent damage to the device.
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Absolute Maximum Ratings
Recommended Operating Conditions
The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended
operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not
recommend exceeding them or designing to Absolute Maximum Ratings.
Symbol
TA
Parameter
Min.
Operating Ambient Temperature
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
-40
Typ.
Max.
Unit
+105
°C
www.fairchildsemi.com
8
VDD=15V, TA=25°C, RT=6.8kΩ, CT=1000pF unless noted operating specifications.
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Units
30
80
µA
2.0
2.6
5.0
mA
11
12
V
1.9
V
VDD Section
IDD ST
Startup Current
VDD=VTH-ON-0.1V; OPFC OPWM Open
IDD-OP
Operating Current
VDD=13V; OPFC OPWM Open
VTH-ON
Turn-on Threshold
Voltage
10
Hysteresis
1.5
VDD OVP
27
ΔVTH
VDD-OVP
ΔVDD-OVP
VDD OVP Hysteresis
28
29
1
V
V
Oscillator
fOSC-RT/CT
RT/CT Frequency
RT=6.8kΩ, CT=1000pF
PFC & PWM Frequency
240
256
268
60
64
67
120
128
134
kHz
fOSC
FAN4800C,FAN4802/02L
PWM Frequency
RT=6.8kΩ, CT=1000pF
fDV
Voltage Stability
11V ≦ VDD ≦ 22V
2
%
fDT
Temperature Stability
-40°C ~ +105°C
2
%
fTV
Total Variation (PFC &
(1)
PWM)
Line, Temperature
70
kHz
fRV
Ramp Voltage
6.5
15.0
mA
50
75
kHz
(1)
58
Valley to Peak
IDischarge
Discharge Current
fRANGE
Frequency Range
tPFCD
PFC Dead Time
2.8
VRAMP=0V, VRT/CT=2.5V
(1)
kHz
V
RT=6.8kΩ, CT=1000pF
400
600
800
ns
7.4
7.5
7.6
V
30
50
mV
25
mV
0.5
%
7.35
7.65
V
25
mV
VREF
VVREF
Reference Voltage
IREF=0mA, CREF=0.1µF
ΔVVREF1
Load Regulation of
Reference Voltage
CREF=0.1µF, IREF=0mA to 3.5mA
VVDD=14V, Rise/Fall Time > 20µs
ΔVVREF2
Line Regulation of
Reference Voltage
CREF=0.1µF, VVDD=11V to 22V
ΔVVREF-DT
(1)
Temperature Stability
-40°C ~ +105°C
(1)
ΔVVREF-TV
Total Variation
Line, Load, Temp
(1)
ΔVVREF-LS
Long-Term Stability
TJ=125°C, 0 ~ 1000HRs
5
Maximum Current
VVREF > 7.35V
5
IREF-MAX.
(1)
IOS
0.4
Output Short Circuit
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Electrical Characteristics
mA
25
mA
PFC OVP Comparator
VPFC-OVP
ΔVPFC-OVP
Over-Voltage Protection
2.70
2.75
2.80
V
PFC OVP Hysteresis
200
250
300
mV
0.2
0.3
0.4
V
Voltage Level on FBPFC
to Enable OPWM During
Startup
2.3
2.4
2.5
V
Hysteresis
1.15
1.25
1.35
V
Low-Power Detect Comparator
VEAOFF
VEA Voltage OFF OPFC
VIN OK Comparator
VRD-FBPFC
ΔVRD-FBPFC
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
www.fairchildsemi.com
9
VDD=15V, TA=25°C, RT=6.8kΩ, CT=1000pF unless noted operating specifications.
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Units
6
V
2.55
V
90
µmho
Voltage Error Amplifier
FBPFC
Input Voltage Range
Vref
Reference Voltage
AV
(1)
Gmv
IFBPFC-L
IFBPFC-H
IBS
Open-Loop Gain
(1)
0
at T=25°C
2.45
2.50
35
42
Transconductance
VNONINV=VINV, VVEA=3.75V at T=25°C
50
70
Maximum Source Current
VFBPFC=2V, VVEA=1.5V
40
50
Maximum Sink Current
VFBPFC=3V, VVEA=6V
-50
Input Bias Current
-1
VVEA-H
Output High Voltage on
VVEA
5.8
VVEA-L
Output Low Voltage on
VVEA
dB
µA
-40
µA
1
µA
6
0.1
V
0.4
V
0.7
V
100
µmho
10
mV
7.4
8.0
V
0.1
0.4
Current Error Amplifier
VISENSE
GmI
Input Voltage Range
(1)
(ISENSE pin)
-1.5
Transconductance
VNONINV=VINV, VIEA=3.75V
78
VOFFSET
Input Offset Voltage
VVEA=0V, IAC Open
-10
VIEA-H
Output High Voltage
VIEA-L
Output Low Voltage
IL
Source Current
IH
Sink Current
AI
6.8
VISENSE=-0.6V, VIEA=1.5V
35
VISENSE=+0.6V, VIEA=4.0V
Open-Loop Gain
(1)
88
50
-50
40
V
µA
-35
50
µA
dB
Tri-Fault Detect
(1)
tFBPFC_OPEN
Time to FBPFC Open
VPFC-UVP
PFC Feedback UnderVoltage Protection
VFBPFC=VPFC-UVP to FBPFC OPEN,
470pF from FBPFC to GND
0.4
2
4
ms
0.5
0.6
V
100
µA
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Electrical Characteristics (Continued)
Gain Modulator
IAC
GAIN
BW
Vo(gm)
Input for AC Current
GAIN Modulator
Bandwidth
(1)
(2)
(1)
Output Voltage=5.7kΩ ×
(1)
(ISENSE-IOFFSET)
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
Multiplier Linear Range
0
IAC=17.67µA, VRMS=1.080V
VFBPFC=2.25V, at T=25°C
7.50
9.00
10.50
IAC=20µA, VRMS=1.224V VFBPFC=2.25V,
at T=25°C
6.30
7.00
7.70
IAC=25.69µA, VRMS=1.585V
VFBPFC=2.25V, at T=25°C
3.80
4.20
4.60
IAC=51.62µA, VRMS=3.169V
VFBPFC=2.25V, at T=25°C
0.95
1.05
1.16
IAC=62.23µA, VRMS=3.803V
VFBPFC=2.25V, at T=25°C
0.66
0.73
0.80
IAC=40µA
2
IAC=20µA, VRMS=1.224V VFBPFC=2.25V,
at T=25°C
0.74
0.82
kHz
0.90
V
www.fairchildsemi.com
10
VDD=15V, TA=25°C, RT=6.8kΩ, CT=1000pF unless noted operating specifications.
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Units
-1.25
-1.15
-1.05
V
PFC ILIMIT Comparator
VPFC-ILIMIT
Peak Current Limit
Threshold Voltage,
Cycle-by-Cycle Limit
IAC=17.67µA, VRMS=1.08V VFBPFC=2.25V,
at T=25°C
200
Gate Output Clamping
Voltage
VDD=22V
13
VGATE-L
Gate Low Voltage
VDD=15V; IO=100mA
VGATE-H
Gate High Voltage
VDD=13V; IO=100mA
8
tr
Gate Rising Time
VDD=15V; CL=4.7nF; O/P=2V to 9V
40
70
120
ns
tf
Gate Falling Time
VDD=15V; CL=4.7nF; O/P=9V to 2V
40
60
110
ns
DPFC-MAX
Maximum Duty Cycle
VIEA<1.2V
94
97
DPFC-MIN
Minimum Duty Cycle
VIEA>4.5V
ΔVpk
PFC ILIMIT-Gain
Modulator Output
mV
PFC Output Driver
VGATE-CLAMP
15
17
V
1.5
V
V
%
0
%
Brown Out
VRMS-UVP
VRMS Threshold Low
VRMS-UVP
VRMS Threshold High
ΔVRMS-UVP
tUVP
Hysteresis
FAN4800A/C, FAN4801/1S/2
1.00
1.05
1.10
V
FAN4802L
0.85
0.90
0.95
V
FAN4800A/C, FAN4801/1S/2
1.85
1.90
1.95
V
FAN4802L
1.60
1.65
1.70
V
FAN4800A/C, FAN4801/1S/2
750
850
950
mV
FAN4802L
650
750
850
mV
340
410
480
ms
9.5
10.0
10.5
Under-Voltage
Protection Delay Time
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Electrical Characteristics (Continued)
Soft Start
VSS-MAX
Maximum Voltage
ISS
Soft-Start Current
VDD=15V
10
V
µA
PWM ILIMIT Comparator
VPWM-ILIMIT
tPD
tPWM-Bnk
Threshold Voltage
0.95
Delay to Output
1.00
1.05
250
Leading-Edge Blanking
Time
V
ns
170
250
350
ns
Range (FAN4801/1S/2/2L)
VRMS-L
RMS AC Voltage Low
When VRMS=1.95V at132Vrms
1.90
1.95
2.00
V
VRMS-H
RMS AC Voltage High
When VRMS=2.45V at150Vrms
2.40
2.45
2.50
V
VEA Low
When VVEA=1.95V at 30% Loading,
When VVEA=2.80V at 60% Loading
1.90
1.95
2.00
2.75
2.80
2.85
2.40
2.45
2.50
3.30
3.35
3.40
18
20
22
VEA-L
VEA-H
Itc
VEA Low (FAN4801S)
VEA High
VEA High (FAN4801S)
When VVEA=2.45V at 40% Loading,
When VVEA=3.35V at 70% Loading
Two-Level Current
FBPFC Two-Level Current
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
V
V
µA
www.fairchildsemi.com
11
VDD=15V, TA=25°C, RT=6.8kΩ, CT=1000pF unless noted operating specifications.
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Units
13
15
17
V
1.5
V
PWM Output Driver
VGATE-CLAMP
Gate Output Clamping Voltage VDD=22V
VGATE-L
Gate Low Voltage
VGATE-H
Gate High Voltage
VDD=13V; IO=100mA
8
tr
Gate Rising Time
VDD=15V; CL=4.7nF
30
60
120
ns
tf
Gate Falling Time
VDD=15V; CL=4.7nF
30
50
110
ns
Maximum Duty Cycle
49.0
49.5
50.0
%
PWM Comparator Level Shift
1.3
1.5
1.8
V
DPWM-MAX
VPWM-LS
VDD=15V; IO=100mA
V
Notes:
3. This parameter, although guaranteed by design, is not 100% production tested.
2 -1
-1
4. Gain=K × 5.3 × (VRMS ) ; K=( ISENSE - IOFFSET) × [IAC × (VEA - 0.7V)] ; VEA (MAX.)=5.6V.
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Electrical Characteristics (Continued)
www.fairchildsemi.com
12
20.0
2.96
18.0
2.94
16.0
2.92
2.90
IDD-OP(uA)
IDD-ST(uA)
14.0
12.0
10.0
8.0
6.0
2.88
2.86
2.84
4.0
2.82
2.0
2.80
0.0
2.78
-40℃ -25℃ -10℃
5℃
20℃
35℃ 50℃
65℃ 80℃ 95℃ 110℃ 125℃
-40℃ -25℃ -10℃
Figure 7. IDD-ST vs. Temperature
2.0
11.3
1.9
△VTH(V)
VTH-ON (V)
95℃ 110℃ 125℃
1.8
11.2
11.1
11.0
1.7
1.6
1.5
10.9
1.4
1.3
10.8
-40℃ -25℃ -10℃
5℃
20℃
35℃
50℃
65℃
80℃
-40℃ -25℃ -10℃
95℃ 110℃ 125℃
28.04
65.0
28.02
64.9
28.00
FOSC-FAN4801/1S(kHz)
27.96
27.94
27.92
27.90
35℃
50℃
65℃
80℃
95℃ 110℃ 125℃
64.7
64.6
64.5
64.4
64.3
27.88
27.86
5℃
20℃
35℃
50℃
65℃
80℃
95℃
64.2
-40℃
110℃ 125℃
Figure 11. VDD-OVP vs. Temperature
-25℃
-10℃
5℃
20℃
35℃
50℃
65℃
80℃
95℃
110℃ 125℃
Figure 12. fOSC-FAN4801/1S vs. Temperature
655
129.8
650
129.6
645
129.4
640
tPFCD(ns)
130.0
129.2
129.0
635
630
128.8
625
128.6
620
128.4
-40℃ -25℃ -10℃
20℃
64.8
27.98
-40℃ -25℃ -10℃
5℃
Figure 10. ΔVTH vs. Temperature
Figure 9. VTH-ON vs. Temperature
VDD-OVP(V)
20℃ 35℃ 50℃ 65℃ 80℃
Figure 8. IDD-OP vs. Temperature
11.4
FOSC-FAN4802/2L(kHz)
5℃
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Typical Characteristics
615
5℃
20℃ 35℃
50℃ 65℃
80℃ 95℃ 110℃ 125℃
-40℃ -25℃ -10℃
Figure 13. fOSC-FAN4802/2L vs. Temperature
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
5℃
20℃
35℃
50℃
65℃
80℃
95℃ 110℃ 125℃
Figure 14. tPFCD vs. Temperature
www.fairchildsemi.com
13
7.520
6
7.515
5
7.510
△ VVREF1(mV)
VVREF(V)
7.505
7.500
7.495
7.490
4
3
2
7.485
1
7.480
7.475
0
-40℃ -25℃ -10℃
5℃
20℃ 35℃ 50℃ 65℃ 80℃
95℃ 110℃ 125℃
-40℃ -25℃ -10℃
0.18
50℃
65℃
80℃
95℃ 110℃ 125℃
21.0
0.16
0.14
20.5
IREF-MAX.(mA)
△ VVREF2(mV)
35℃
21.5
0.20
0.12
0.10
0.08
0.06
20.0
19.5
19.0
0.04
0.02
18.5
0.00
-0.02
18.0
-40℃ -25℃ -10℃
5℃
-40℃ -25℃ -10℃
20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃
Figure 17. ΔVVREF2 vs. Temperature
2.742
252.2
2.740
252.0
2.738
2.736
2.734
2.732
50℃ 65℃ 80℃ 95℃ 110℃ 125℃
251.8
251.6
251.4
251.2
250.8
5℃
-40℃ -25℃ -10℃
20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃
5℃
20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃
Figure 20. ΔVPFC-OVP vs. Temperature
Figure 19. VPFC-OVP vs. Temperature
1.275
2.400
1.270
△ VRD-FBPFC(V)
2.398
2.396
2.394
2.392
2.390
1.265
1.260
1.255
1.250
1.245
2.388
-40℃ -25℃ -10℃
20℃ 35℃
251.0
2.730
-40℃ -25℃ -10℃
5℃
Figure 18. IREF-MAX. vs. Temperature
△ VPFC-OVP(mV)
VPFC-OVP(V)
20℃
Figure 16. ΔVVREF1 vs. Temperature
Figure 15. VVREF vs. Temperature
VRD-FBPFC(V)
5℃
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Typical Characteristics
1.240
5℃
-40℃ -25℃ -10℃
20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃
20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃
Figure 22. ΔVRD-FBPFC vs. Temperature
Figure 21. VRD-FBPFC vs. Temperature
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
5℃
www.fairchildsemi.com
14
74
2.502
2.500
73
Gmv(umho)
Vref(V)
2.498
2.496
2.494
73
72
2.492
72
2.490
2.488
71
-40℃ -25℃ -10℃
5℃
20℃ 35℃
50℃ 65℃ 80℃ 95℃ 110℃ 125℃
-40℃
Figure 23. Vref vs. Temperature
4.5
94
4.0
92
5℃
20℃
35℃
50℃
65℃
80℃
95℃
110℃ 125℃
90
3.0
Gm I(umho)
VOFFSET(mV)
-10℃
Figure 24. GmV vs. Temperature
3.5
2.5
2.0
1.5
88
86
84
82
1.0
80
0.5
0.0
78
-40℃ -25℃ -10℃
5℃
20℃
35℃
50℃
65℃
80℃
95℃ 110℃ 125℃
-40℃ -25℃ -10℃
Figure 25. VOFFSET vs. Temperature
5℃
20℃
35℃
50℃
65℃
80℃
95℃ 110℃ 125℃
Figure 26. GmI vs. Temperature
7.10
6.1
7.05
6.0
7.00
5.9
Rmul(kΩ)
6.95
GAIN2
-25℃
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Typical Characteristics
6.90
6.85
5.8
5.7
5.6
6.80
5.5
6.75
6.70
5.4
-40℃ -25℃ -10℃
5℃
20℃
35℃
50℃
65℃
80℃
-40℃ -25℃ -10℃
95℃ 110℃ 125℃
Figure 27. GAIN2 vs. Temperature
20℃
35℃
50℃
65℃
80℃
95℃ 110℃ 125℃
Figure 28. Rmul vs. Temperature
-1.1775
295
-1.1780
290
-1.1785
285
-1.1790
△ Vpk(mV)
VPFC-ILIMIT(V)
280
-1.1795
-1.1800
-1.1805
275
270
265
-1.1810
-1.1815
260
-1.1820
255
250
-1.1825
-40℃ -25℃ -10℃
5℃
5℃
20℃ 35℃ 50℃
-40℃ -25℃ -10℃
65℃ 80℃ 95℃ 110℃ 125℃
20℃
35℃
50℃
65℃
80℃
95℃ 110℃ 125℃
Figure 30. ΔVpk vs. Temperature
Figure 29. VPFC-ILIMIT vs. Temperature
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
5℃
www.fairchildsemi.com
15
10.1
1.010
10.0
1.009
9.9
9.8
1.007
ISS(uA)
VPWM-ILIMIT (V)
1.008
1.006
1.005
9.7
9.6
9.5
9.4
1.004
9.3
1.003
9.2
1.002
9.1
-40℃ -25℃ -10℃
5℃
-40℃ -25℃ -10℃
20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃
Figure 31. VPWM-ILIMIT vs. Temperature
1.048
867.5
1.047
867.0
1.046
866.5
△ VRMS-UVP(mV)
VRMS-UVP(V)
1.044
1.043
1.042
1.041
50℃ 65℃
80℃ 95℃ 110℃ 125℃
866.0
865.5
865.0
864.5
864.0
863.5
1.040
863.0
1.039
862.5
1.038
862.0
-40℃ -25℃ -10℃
5℃
-40℃ -25℃ -10℃
20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃
5℃
20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃
Figure 34. ΔVRMS-UVP vs. Temperature
Figure 33. VRMS-UVP vs. Temperature
1.940
2.446
1.939
2.445
2.444
1.938
2.443
1.937
VRMS-H(V)
VRMS-L(V)
20℃ 35℃
Figure 32. ISS vs. Temperature
1.045
1.936
1.935
1.934
2.442
2.441
2.440
2.439
1.933
2.438
1.932
2.437
2.436
1.931
-40℃ -25℃ -10℃
5℃
2.435
20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃
-40℃ -25℃ -10℃
Figure 35. VRMS-L vs. Temperature
5℃
20℃ 35℃ 50℃
65℃ 80℃ 95℃ 110℃ 125℃
Figure 36. VRMS-H vs. Temperature
1.942
2.436
1.940
2.434
1.938
2.432
VEA-H(V)
VEA-L(V)
5℃
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Typical Characteristics
1.936
1.934
2.430
2.428
1.932
2.426
1.930
2.424
1.928
-40℃ -25℃ -10℃
-40℃ -25℃ -10℃
5℃
5℃
20℃ 35℃ 50℃ 65℃ 80℃ 95℃
20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃
Figure 37. VEA-L vs. Temperature
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
110
℃
125
℃
Figure 38. VEA-H vs. Temperature
www.fairchildsemi.com
16
14.4
14.6
14.3
14.5
14.2
VGATE-CLAMP-PWM(V)
VGATE-CLAMP-PFC(V)
14.7
14.4
14.3
14.2
14.1
14.1
14.0
13.9
13.8
14.0
13.7
13.9
-40℃ -25℃ -10℃
5℃
20℃
35℃ 50℃ 65℃
13.6
80℃ 95℃ 110℃ 125℃
-40℃ -25℃ -10℃
Figure 39. VGATE-CLAMP-PFC vs. Temperature
5℃
20℃
35℃
50℃
65℃
80℃
95℃ 110℃ 125℃
Figure 40. VGATE-CLAMP-PWM vs. Temperature
96.06
49.80
96.04
49.75
DPWM-MAX(%)
DPFC-MAX(%)
96.02
96.00
95.98
95.96
95.94
49.70
49.65
49.60
49.55
95.92
95.90
49.50
95.88
-40℃ -25℃ -10℃
-40℃ -25℃ -10℃
5℃
20℃
35℃ 50℃
5℃
20℃ 35℃ 50℃ 65℃ 80℃ 95℃
65℃ 80℃ 95℃ 110℃ 125℃
Figure 41. DPFC-MAX vs. Temperature
110
℃
125
℃
Figure 42. DPWM-MAX vs. Temperature
1.460
21.0
20.8
1.455
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Typical Characteristics
VPWM-LS(V)
20.6
Itc(uA)
20.4
20.2
20.0
1.450
1.445
1.440
19.8
1.435
19.6
19.4
1.430
-40℃ -25℃ -10℃
5℃
20℃ 35℃
50℃ 65℃ 80℃ 95℃ 110℃ 125℃
-40℃ -25℃ -10℃
Figure 43. Itc vs. Temperature
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
5℃
20℃
35℃
50℃
65℃
80℃
95℃ 110℃ 125℃
Figure 44. VPWM-LS vs. Temperature
www.fairchildsemi.com
17
The FAN4800A/C and FAN4801/1S/2/2L consist of an
average current controlled, continuous boost Power
Factor Correction (PFC) front-end and a synchronized
Pulse Width Modulator (PWM) back-end. The PWM
can be used in current or voltage mode. In voltage
mode, feed forward from the PFC output bus can be
used to improve the line regulation of PWM. In either
mode, the PWM stage uses conventional trailing-edge,
duty-cycle modulation. This patented leading/trailing
edge modulation results in a higher usable PFC error
amplifier bandwidth and can significantly reduce the
size of the PFC DC bus capacitor.
IGAINMOD =
VRMS 2
×K
(1)
Note that the output current of the gain modulator is
limited around 159μA and the maximum output voltage
of the gain modulator is limited to 159μA x
5.7K=0.906V. This 0.906V also determines the
maximum input power.
However, IGAINMOD cannot be measured directly from
ISENSE. ISENSE=IGAINMOD – IOFFSET and IOFFSET can
only be measured when VEA is less than 0.5V and
IGAINMOD is 0A. Typical IOFFSET is around 31μA ~ 48μA.
The synchronization of the PWM with the PFC
simplifies the PWM compensation due to the controlled
ripple on the PFC output capacitor (the PWM input
capacitor). The PWM section of the FAN4800A,
FAN4801/1S operates at the same frequency as the
PFC; and FAN4800C, FAN4802/2L operates at double
with PFC.
Selecting RAC for IAC Pin
The IAC pin is the input of the gain modulator and also
a current mirror input and requires current input.
Selecting a proper resistor RAC provides a good sine
wave current derived from the line voltage and helps
program the maximum input power and minimum input
line voltage. RAC=VIN peak x 56KΩ. For example, if the
minimum line voltage is 75VAC, the RAC=75 x 1.414 x
56KΩ=6MΩ.
In addition to power factor correction, a number of
protection features are built into this series. They
include soft-start, PFC over-voltage protection, peak
current limiting, brownout protection, duty cycle limiting,
and under-voltage lockout (UVLO).
Current Amplifier Error, IEA
Gain Modulator
The current error amplifier’s output controls the PFC
duty cycle to keep the average current through the
boost inductor a linear function of the line voltage. At
the inverting input to the current error amplifier, the
output current of the gain modulator is summed with a
current, which results in a negative voltage being
impressed upon the ISENSE pin.
The gain modulator is the heart of the PFC, as the
circuit block controls the response of the current loop to
line voltage waveform and frequency, RMS line voltage,
and PFC output voltages. There are three inputs to the
gain modulator:
1. A current representing the instantaneous input
voltage (amplitude and wave shape) to the PFC.
The rectified AC input sine wave is converted to a
proportional current via a resistor and is fed into the
gain modulator at IAC. Sampling current in this way
minimizes ground noise, required in high-power,
switching-power conversion environments. The gain
modulator responds linearly to this current.
The negative voltage on ISENSE represents the sum of
all currents flowing in the PFC circuit and is typically
derived from a current sense resistor in series with the
negative terminal of the input bridge rectifier.
The inverting input of the current error amplifier is a
virtual ground. Given this fact, and the arrangement of
the duty cycle modulator polarities internal to the PFC,
an increase in positive current from the gain modulator
causes the output stage to increase its duty cycle until
the voltage on ISENSE is adequately negative to
cancel this increased current. Similarly, if the gain
modulator’s output decreases, the output duty cycle
decreases to achieve a less negative voltage on the
ISENSE pin.
2. A voltage proportional to the long-term RMS AC line
voltage, derived from the rectified line voltage after
scaling and filtering. This signal is presented to the
gain modulator at VRMS. The output of the gain
modulator is inversely proportional to VRMS (except
at unusually low values of VRMS, where special gain
contouring takes over to limit power dissipation of
the circuit components under brownout conditions).
3. The output of the voltage error amplifier, VEA. The
gain modulator responds linearly to variations in this
voltage.
PFC Cycle-By-Cycle Current Limiter
As well as being a part of the current feedback loop,
the ISENSE pin is a direct input to the cycle-by-cycle
current limiter for the PFC section. If the input voltage
at this pin is less than -1.15V, the output of the PFC is
disabled until the protection flip-flop is reset by the
clock pulse at the start of the next PFC power cycle.
The output of the gain modulator is a current signal, in
the form of a full wave rectified sinusoid at twice the
line frequency. This current is applied to the virtual
ground (negative) input of the current error amplifier. In
this way, the gain modulator forms the reference for the
current error loop and ultimately controls the
instantaneous current draw of the PFC from the power
line. The general form of the output of the gain
modulator is:
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
IAC × (VEA − 0.7)
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Functional Description
www.fairchildsemi.com
18
Error Amplifier Compensation
To improve power supply reliability, reduce system
component count, and simplify compliance to UL 1950
safety standards, the FAN4800A/C, FAN4801/1S/2/2L
includes TriFault Detect. This feature monitors FBPFC
for certain PFC fault conditions.
The PWM loading of the PFC can be modeled as a
negative resistor because an increase in the input
voltage to the PWM causes a decrease in the input
current.
This
response
dictates
the
proper
compensation of the two transconductance error
amplifiers. Figure 45 shows the types of compensation
networks most commonly used for the voltage and
current error amplifiers, along with their respective
return points. The current-loop compensation is
returned to VREF to produce a soft-start characteristic
on the PFC: As the reference voltage increases from
0V, it creates a differentiated voltage on IEA, which
prevents the PFC from immediately demanding a full
duty cycle on its boost converter. Complete design is
referred in application note AN-6078SC.
In a feedback path failure, the output of the PFC could
exceed safe operating limits. With such a failure,
FBPFC exceeds its normal operating area. Should
FBPFC go too low, too high, or open, TriFault Detect
senses the error and terminates the PFC output drive.
TriFault detect is an entirely internal circuit. It requires
no external components to serve its protective function.
PFC Over-Voltage Protection
There is an RC filter between Rsense and ISENSE pin.
There are two reasons to add a filter at the ISENSE pin:
In the FAN4800A/C, FAN4801/1S/2/2L, the PFC OVP
comparator serves to protect the power circuit from
being subjected to excessive voltages if the load
changes suddenly. A resistor divider from the highvoltage DC output of the PFC is fed to FBPFC. When
the voltage on FBPFC exceeds 2.75V, the PFC output
driver is shut down. The PWM section continues to
operate. The OVP comparator has 250mV of hysteresis
and the PFC does not restart until the voltage at
FBPFC drops below 2.50V. VDD OVP can also serve as
a redundant PFC OVP protection. VDD OVP threshold is
28V with 1V hysteresis.
1. Protection: During startup or inrush current
conditions, there is a large voltage across Rsense,
which is the sensing resistor of the PFC boost
converter. It requires the ISENSE filter to attenuate
the energy.
2. To reduce L, the boost inductor: The ISENSE filter
also can reduce the boost inductor value since the
ISENSE filter behaves like an integrator before the
ISENSE pin, which is the input of the current error
amplifier, IEA.
The ISENSE filter is an RC filter. The resistor value of
the ISENSE filter is between 100Ω and 50Ω because
IOFFSET x RFILTER can generate a negative offset voltage
of IEA. Selecting an RFILTER equal to 50Ω keeps the
offset of the IEA less than 3mV. Design the pole of
ISENSE filter at fPFC/6, one sixth of the PFC switching
frequency, so the boost inductor can be reduced six
times without disturbing the stability. The capacitor of
the ISENSE filter, CFILTER, is approximately 100nF.
Selecting PFC Rsense
Rsense is the sensing resistor of the PFC boost
converter. During the steady state, line input current x
Rsense equals IGAINMOD x 5.7KΩ.
At full load, the average VEA needs to around 4.5V and
ripple on the VEA needs to be less than 400mV.
Choose the resistance of the sensing resistor:
Rsense =
( 4.5 − 0.7 ) × 5.7K Ω × IAC × Gain × VIN ×
2 × ( 5.6 − 0.7 ) × Line input Power
2
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
TriFault Detect™
(2)
where 5.6 is VEA maximum output.
PFC Soft-Start
PFC startup is controlled by VEA level. Before FBPFC
voltage reaches 2.4V, the VEA level is around 2.8V. At
90VAC, the PFC soft-start time is 90ms.
PFC Brownout
The AC UVP comparator monitors the AC input
voltage. The FAN4800A/C, FAN4801/1S/2 disables
PFC as lower AC input that the VRMS is less than
1.05V. The brownout voltage of FAN4802L is lower
than FAN4801/1S/2 that the VRMS is less than 0.9V.
Figure 45. Compensation Network Connection for the
Voltage and Current Error Amplifiers
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
www.fairchildsemi.com
19
Pulse Width Modulator (PWM)
To improve the efficiency, the system can reduce PFC
switching loss at low line and light load by reducing the
PFC output voltage. The two-level PFC output of
FAN4801/1S/2/2L can be programmable.
The operation of the PWM section is straightforward,
but there are several points that should be noted.
Foremost among these is the inherent synchronization
of PWM with the PFC section of the device, from which
it also derives its basic timing. The PWM is capable of
current-mode or voltage-mode operation. In currentmode applications, the PWM ramp (RAMP) is usually
derived directly from a current sensing resistor or
current transformer in the primary of the output stage. It
is thereby representative of the current flowing in the
converter’s output stage. ILIMIT, which provides cycle-bycycle current limiting, is typically connected to RAMP in
such applications. For voltage-mode operation and
certain specialized applications, RAMP can be
connected to a separate RC timing network to generate
a voltage ramp against which FBPWM is compared.
Under these conditions, the use of voltage feed-forward
from the PFC bus can assist in line regulation accuracy
and response. As in current-mode operation, the ILIMIT
input is used for output stage over-current protection.
No voltage error amplifier is included in the PWM
stage, as this function is generally performed on the
output side of the PWM’s isolation boundary. To
facilitate the design of opto-coupler feedback circuitry,
an offset has been built into the PWM’s RAMP input
that allows FBPWM to command a 0% duty cycle for
input voltages below typical 1.5V.
As Figure 46 shows, FAN4801/1S/2/2L detect VEA pin
and VRMS pin to determine the system operates low
line and light load or not. At the second-level PFC,
there is a current of 20µA through RF2 from FBPFC pin.
So the second-level PFC output voltage can be
calculated as.
RF 1 + RF 2
× (2.5V − 20uA × RF 2 )
(3)
RF 2
For example, if the second-level PFC output voltage is
expected as 300V and normal voltage is 387V,
according to the equation, RF2 is 28kΩ RF1 is 4.3MΩ.
Output ≅
The programmable range of second level PFC output
voltage is 340V ~ 300V.
PWM Cycle-By-Cycle Current Limiter
The ILIMIT pin is a direct input to the cycle-by-cycle
current limiter for the PWM section. Should the input
voltage at this pin ever exceed 1V, the output flip-flop is
reset by the clock pulse at the start of the next PWM
power cycle. When the ILIMIT triggers the cycle-by-cycle
bi-cycle current, it limits the PWM duty cycle mode and
the power dissipation is reduced during the dead-short
condition.
Figure 46. Two-Level PFC Scheme
Oscillator (RT/CT)
The oscillator frequency is determined by the values of
RT and CT, which determine the ramp and off-time of
the oscillator output clock:
VIN OK Comparator
1
fRT / CT =
(4)
tRT / CT + tDEAD
The dead time of the oscillator is derived from the
following equation:
The VIN OK comparator monitors the DC output of the
PFC and inhibits the PWM if the voltage on FBPFC is
less than its nominal 2.4V. Once the voltage reaches
2.4V, which corresponds to the PFC output capacitor
being charged to its rated boost voltage, the soft-start
begins.
⎛ VREF − 1 ⎞
tRT / CT = CT × RT × ln ⎜
⎟
⎝ VREF − 3.8 ⎠
at VREF=7.5V and tRT/CT=CT x RT x 0.56.
PWM Soft-Start (SS)
(5)
PWM startup is controlled by selection of the external
capacitor at soft-start. A current source of 10µA
supplies the charging current for the capacitor and
startup of the PWM begins at 1.5V.
The dead time of the oscillator is determined using:
2.8V
× CT = 360 × CT
(6)
7.78mA
The dead time is so small (tRT/CT>>tDEAD) that the
operating frequency can typically be approximated by:
tDEAD =
fRT / CT =
1
tRT / CT
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Two-Level PFC Function
(7)
www.fairchildsemi.com
20
Leading/Trailing Modulation
When the PWM section is used in current mode, RAMP
is generally used as the sampling point for a voltage,
representing the current in the primary of the PWM’s
output transformer. The voltage is derived either from a
current sensing resistor or a current transformer. In
voltage mode, RAMP is the input for a ramp voltage
generated by a second set of timing components
(RRAMP, CRAMP) that have a minimum value of 0V and a
peak value of approximately 6V. In voltage mode, feed
forward from the PFC output bus is an excellent way to
derive the timing ramp for the PWM stage.
Conventional PWM techniques employ trailing-edge
modulation, in which the switch turns on right after the
trailing edge of the system clock. The error amplifier
output is then compared with the modulating ramp up.
The effective duty cycle of the trailing edge modulation
is determined during the on-time of the switch.
In the case of leading-edge modulation, the switch is
turned off exactly at the leading edge of the system
clock. When the modulating ramp reaches the level of
the error amplifier output voltage, the switch is turned
on. The effective duty-cycle of the leading-edge
modulation is determined during off-time of the switch.
Generating VDD
After turning on the FAN4800A/C, FAN4801/1S/2/2L at
11V, the operating voltage can vary from 9.3V to 28V.
The threshold voltage of the VDD OVP comparator is
28V and its hysteresis is 1V. When VDD reaches 28V,
OPFC is LOW, and the PWM section is not disturbed.
There are two ways to generate VDD: use auxiliary
power supply around 15V or use bootstrap winding to
self-bias the FAN4800A/C, FAN4801/1S/2/2L system.
The bootstrap winding can be taped from the PFC
boost choke or the transformer of the DC-to-DC stage.
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
PWM Control (RAMP)
www.fairchildsemi.com
21
19.68
18.66
16
A
9
6.60
6.09
1
8
(0.40)
TOP VIEW
0.38 MIN
5.33 MAX
8.13
7.62
3.42
3.17
3.81
2.92
2.54
0.35
0.20
0.58 A
0.35
1.78
1.14
15
0
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Physical Dimensions
8.69
17.78
SIDE VIEW
NOTES: UNLESS OTHERWISE SPECIFIED
A THIS PACKAGE CONFORMS TO
JEDEC MS-001 VARIATION BB
B) ALL DIMENSIONS ARE IN MILLIMETERS.
C) DIMENSIONS ARE EXCLUSIVE OF BURRS,
MOLD FLASH, AND TIE BAR PROTRUSIONS
D) CONFORMS TO ASME Y14.5M-1994
E) DRAWING FILE NAME: N16EREV1
Figure 47. 16-pin Dual In-Line Package (DIP)
Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner
without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify
or obtain the most recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically
the warranty therein, which covers Fairchild products.
Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings:
http://www.fairchildsemi.com/packaging/.
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
www.fairchildsemi.com
22
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
Physical Dimensions (Continued)
Figure 48. 16-Pin Small Outline Package (SOIC)
Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner
without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify
or obtain the most recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically
the warranty therein, which covers Fairchild products.
Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings:
http://www.fairchildsemi.com/packaging/.
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
www.fairchildsemi.com
23
FAN4800A/C, FAN4801/1S/2/2L — PFC/PWM Controller Combination
© 2008 Fairchild Semiconductor Corporation
FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1
www.fairchildsemi.com
24
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