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Fairchild |
KA7526
Power Factor Correction Controller
www.fairchildsemi.com
Features
• Internal Startup Timer
• Internal R/C filter which eliminates the Need for an
External R/C filter
• Overvoltage Comparator eliminates Runaway Output
Voltage
• Zero Current Detector
• One Quadrant Multiplier
• Trimmed 1.5% Internal Bandgap Reference
• Under Voltage Lock Out with 5V of Hysteresis
• Totem Pole Output with High State Clamp
• Low Startup and Operating Current
• 8-Pin DIP or 8-Pin SOP
Applications
• Electronic Ballast
• SMPS
Descriptions
The KA7526 provides simple and high performance active
power factor correction. KA7526 is optimized for electronic
ballast and low power, high density power supplies requiring
a minimum board area, reduced component count and low
power dissipation. Addition of internal R/C filter eliminates
the need for an external R/C filter. Internal clamping of the
error amplifier and multiplier outputs improves turn on over-
shoot characteristics and current limiting. Special circuitry
has also been added to prevent no load runaway conditions.
The output drive clamping circuit limits overshoot of the
power MOSFET gate drive Independent of supply voltage,
so that it greatly enhance the system reliability.
8-DIP
8-SOP
1
1
©2000 Fairchild Semiconductor International
Rev. 5.0
KA7526
Internal Block Diagram
VCC
8
36V
5V
+
-
13V
UVLO
Idet 5
+ 240mV
7.5V
-
1.8V
Zero Current
Detector
40kΩ
CS 4
-
8pF
+ Current Sense
Comparator
2.5V Ref
Internal
Bias
Timer R
S
Q
R
VCC
Drive
Output
7 OUT
Over Voltage
Protection
+
- 1.8V
1.65V
Vref
MULT 3
Vm1
Vmo
0~3.8V
Multiplier
-+
Pin4 Threshold(Vmo)
K = Vm1 ⋅ (Vm2-Vref)
6
GND
Vm2
Vref~Vref+2V
+
-
2
EA OUT
Vref
Vea(-)
Error Amp
1 INV
IC Characteristics
Parmaeter
UVLO
Multiplier Input Range (Vm1)
Multiplier Input Range (Vm2)
Maximum Current Sense Voltage
KA7526
8/13V
0 ~ 3.8V
Vref ~ Verf + 2V
1.65V
2
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