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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.
Applications
• Electronic Ballast • SMPS
8-DIP
1
8-SOP
1
Rev 1.0.1
©2002 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.
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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 Symbol VCC IOH,IOL lclamp ldet Vin Tj Topr Tstg Pd Value 30 ±500 ±10 ±10 -0.3 to 6 150 -25 to 125 -65 to 150 0.8 Unit V mA mA mA V °C °C °C W
Temperature Characteristics (-25°C ≤ Ta ≤ 125°C)
Characteristics Temperature Stability for Reference Voltage (Vref) Temperature Stability for Multiplier Gain (K) Symbol ∆Vref ∆K/∆T Min. Typ. 20 -0.2 Max. Unit mV %/°C
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FAN7527B
Electrical Characteristics
VCC= 14V, -25°C ≤ Ta ≤ 125°C, unless otherwise stated. Characteristics Start Threshold Voltage UVLO Hysteresis < SUPPLY CURRENT SECTION > Start-up Supply Current Operating Supply Current Operating Current at OVP Dynamic Operating Supply Current < ERROR AMPLIFIER SECTION > Voltage Feedback Input Threshold Line Regulation Temperature Stability of Vref (Note1) Input Bias Current Output Source Current Output Sink Current Output Upper Clamp Voltage (Note2) Output Lower Clamp Voltage (Note3) Large Signal Open Loop Gain (Note4) Power Supply Rejection Ratio (Note5) Unity Gain Bandwidth (Note6) Slew Rate (Note7) < MULTIPLIER SECTION> Input Bias Current (Pin3) M1 Input Voltage Range (Pin3) M2 Input Voltage Range (Pin2) Multiplier Gain (Note8) Maximum Multiplier Output Voltage Temperature Stability of K (Note9) Ib(m) ∆Vm1 ∆Vm2 K ∆K/∆T Vm1 = 1V, Vm2 = 3.5V -25 ≤ Ta ≤ 125°C -0.5 0 Vref 0.36 1.65 0.44 1.8 -0.2 0.5 3.8 Vref+2.5 0.52 1.95 uA V V 1/V V %/°C Vref ∆Vref1 ∆Vref3 Ib(ea) Isource Isink Veao(H) Veao(L) Gv PSRR GBW SR Vm2 = 4V Vm2 = 4V Isource = 0.1mA Isink = 0.1mA 14V ≤ Vcc ≤ 25V Iref = 0mA, Ta = 25°C -25 ≤ Ta ≤ 125°C 14V ≤ Vcc ≤ 25V -25 ≤ Ta ≤ 125°C 2.465 2.44 -0.5 -2 2 60 60 2.5 2.5 0.1 20 -4 4 6 2.25 80 80 1 0.6 2.535 2.56 10 0.5 V V mV mV uA mA mA V V dB dB MHz V/us Ist Icc Icc(ovp) Idcc Vcc = Vth(st) -0.2V Output not switching Vinv = 3V 50kHz, CI = 1nF 10 60 3 1.7 4 100 6 4 8 uA mA mA mA Symbol Vth(st)
HY(st)
Test Condition Vcc Increasing -
Min. 10.5 2
Typ. 11.5 3
Max. 12.5 4
Unit V V
< UNDER VOLTAGE LOCKOUT SECTION>
Vomax(m) Vinv =0V, Vm1 = 4V
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FAN7527B
Electri.