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www.fairchildsemi.com
FAN7527B
Power Factor Correction Controller
Features
• Internal start-up timer
• Internal R/C filter eliminates the need for an external
R/C filter
• Very precise adjustable output over voltage protection
• Zero current detector
• One quadrant multiplier
• Trimmed 1.5% internal band gap reference
• Under voltage lockout with 3V of hysteresis
• Totem pole output with high state clamp
• Low start-up and operating current
• 8-Pin DIP or 8-Pin SOP
Description
The FAN7527B provides simple and high performance
active power factor correction. The FAN7527B is optimized
for electronic ballasts and low power and high density power
supplies which require minimum board size, reduced
external components and low power dissipation. Because the
R/C filter is included in the current sense block, the external
R/C filter is not necessary. Special circuitry has also been
added to prevent no load runaway conditions. Regardless of
the supply voltage, the output drive clamping circuit limits
the overshoot of the power MOSFET gate drive. It greatly
enhances the system reliability.
8-DIP
Applications
• Electronic ballast
• SMPS
1
8-SOP
1
Rev 1.0.2
©2003 Fairchild Semiconductor Corporation
FAN7527B
Internal Block Diagram
Vcc
8
2.5V Ref
Vcc
+
−
11.5V
8.5V
UVLO
Internal
Bias
Drive
Output
Timer R
7 OUT
Idet
5
7.2V
2V 1.5V
+
−
Zero Current
Detector
S
Q
Static OVP
40k
CS
4
8pF
+
−
R
Current Sense
Comparator
Vref
Veao(L)=2.25V
+
−
2.25V
1.8V
Vmo
MULT 3
Vm1
0 ~ 3.8V
Multiplier
Vmo
K
=
Vm1
⋅
(
Vm2
−
Vref
)
−
+
0.25V
Vm2
Vref~Vref+2.5V
Isovp=30uA
Idovp=40uA
+
−
Vref
Vea(-)
1 INV
OVP
Current
Detector
6
GND
2
EA_OUT
Error Amp
2
FAN7527B
PIN Description
INV
1
2
3
4
(Top View)
8
7
6
5
Vcc
OUT
GND
ldet
EA_OUT
MULT
CS
Pin Number
1
2
3
4
5
6
7
8
Pin Name
INV
EA_OUT
MULT
CS
ldet
GND
OUT
Vcc
Pin Function Description
Inverting input of the error amplifier. the output of the boost converter
should be resistively divided to 2.5V and connected to this pin.
The output of the error amplifier. a feedback compensation network is
placed between this pin and the INV pin.
Input to the multiplier stage. the full-wave rectified ac voltage is
divided to less than 2V and is connected to this pin.
Input of the PWM comparator. the MOSFET current is sensed by a
resistor and the resulting voltage is applied to this pin. an internal R/C
filter is included to reject any high frequency noise.
Zero current detection input.
The ground potential of all the pins.
Gate driver output. the push pull output stage is able to drive the
power MOSFET with peak current of 500mA.
Supply voltage of driver and control circuits.
3
FAN7527B
Absolute Maximum Ratings (Ta=25°C)
Characteristics
Supply voltage
Peak drive output current
Driver output clamping diodes Vo > Vcc or Vo < -0.3V
Detector clamping diodes
Error amp, multiplier and comparator input voltages
Operating junction temperature
Operating temperature range
Storage temperature range
Power dissipation
8-DIP
8-SOP
Symbol
V
CC
I
OH
,I
OL
lclamp
ldet
Vin
Tj
Topr
Tstg
Pd
Value
30
±500
±10
±10
-0.3 to 6
150
-25 to 125
-65 to 150
1.1
0.8
Unit
V
mA
mA
mA
V
°C
°C
°C
W
Thermal Data
Characteristics
Thermal resistance junction-ambient Max.
8-DIP
8-SOP
Symbol
Rθja
Value
110
150
Unit
°C/W
Temperature Characteristics (-25°C
≤
Ta
≤
125°C)
Characteristics
Temperature stability for reference voltage (V
ref
)
Temperature stability for multiplier gain (K)
Symbol
∆Vref
∆K/∆T
Min.
-
-
Typ.
20
-0.2
Max.
-
-
Unit
mV
%/°C
4
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