Fairchild Semiconductor KA7526 Datasheet

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 Re fe rence

• Under Voltage Lock Out with 5V of Hystere si s

• 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 a nd 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 cou nt an d lo w 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 overshoot 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 suppl y volt a ge , so that it greatly enhance the system reliability.

8-DIP

8-SOP

Rev. 5.0

KA7526

Internal Block Diagram

Idet

MULT

36V

7.5V

1.8V

40k

Ω

Vm1

0~3.8V

Pin4 Threshold(Vmo)

K =

Vm1

13V

8pF

1.65V

Vmo

⋅

(Vm2-Vref)

240mV

Zero Current Detector

Current Sense Comparator

Multiplier

UVLO

Vref

GND

2.5V Ref V

Error Amp

Vref

Drive Output

Vea(-)

1.8V

OUT

INV

Internal Bias

Timer R

Vm2

Vref~Vref+2V

EA OUT

Over Voltage Protection

IC Characteristics

Parmaeter KA7526

UVLO 8/13V Multiplier Input Range (Vm1) 0 ~ 3.8V Multiplier Input Range (Vm2) Vref ~ Verf + 2V Maximum Current Sense Voltage 1.65V

PIN Assignments

KA7526

Vcc

8INV

OUT

GND

Idet

EA OUT

MULT

(Top View)

Pin Definitions

Pin Number Pin Name Pin Function Descrition

Inverting input of the error amplifier. The output of the boost

1 INV

2EA OUT

3MULT

4CS

5 Idet 6 GND The ground potential of all the pins. 7OUT 8V

converter should be resistively divided to 2.5V and con nected 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 is divided to less than 3.8V and is connected to this pin.

Input to the PWM comparator. The Current is sensed in the boost stage by a resistor in the source lead of MOSFET. An internal leading edge blanking circuitry has been included to reject any high frequency noise present on the current waveform.

The zero current detector senses the inductor current by monitoring when the boost inductor auxilary winding voltage falls below 1.8V.

The output of a high-current power driver capable of driving the gate of a power MOSFET.

The logic and control power supply connection.

KA7526

Absolute Maximum Ratings

Parameter Symbol Value Unit

Supply voltage V Peak drive output current I Driver output clamping diodes

O>VCC

or VO<-0.3V

, I

Iclamp ± 10 mA

Detector clamping diodes Idet ± 3mA Error amp, multiplier and

comparator input voltage

Operating temperature range Topr -25 to 125 Storage temperature range Tstg -65 to 150 Power dissipation Thermal resistance

(Junction-to-air)

Note : Based in 8-DIP

(Note)

Pd 0.8 W

qja 100

30 V

± 500 mA

-0.3 to 6 V

o o

C C

Temperature Characteristics (-25oC ≤

≤ Ta ≤

≤ 125oC )

≤ ≤

Parameter Symbol Value Unit

Temperature stability for reference voltage(Vref) ∆Vref (Typ) 20 mV Temperature stability for multiplier gain(K) ∆K/∆T (Typ)

-0.2

KA7526

Electrical Characteristics

Unless otherwise specified, for typical values Vcc=12V , Ta=25

with

-25

≤ Ta ≤ 125

Parameter Symbol Condition Min. Typ. Max. Unit

UNDER VOLTAGE LOCK OUT SECTION

Start Threshold Voltage Vth (st) V UVLO Hysteresis HY(st) - 4 5 6 V Supply Zener Voltage Vz I

SUPPLY CURRENT SECTION

Start Up Supply Current Ist V Operating Supply Current I

Dynamic Operating Supply Current Idcc 50kHz, CI=1nF - 5 10 mA

ERROR AMPLIFIER SECTION

Voltage Feedback Input Threshold Vref Line Regulation ∆Vref1 12V≤Vcc≤25V - 0.1 10 mV

Load Regulation Temperature Stability of Vref

(Note1)

(Note2)

∆Vref2 0mA≤Iref≤2mA - 0.1 10 mV ∆Vref3 -25

Input Bias Current Ib(ea) - -0.5 - 0.5 µA Output Source Current Isource Vm2=3V -2 -4.5 - mA Output Sink Current Isink Vm2=2V 3 4.5 - mA Output Voltage Range

(Note2)

∆Veao No Load on E.A Output 1.2 - 5.6 V

Slew Rate SR - - 0.6 - V/µs

MULTIPLIER SECTION

Input Bias Current (pin3) Ib(m) - -0.5 - 0.5 µA M1 Input Voltage Range (pin3) ∆Vm1 - 0 - 3.8 V M2 Input Voltage Range (pin2) ∆Vm2 - Vref - Vref+2 V

Multiplier Gain

(Note3)

Maximum Multiplier Output Voltage Vomax(m) Vea(-)=0V, Vm1=2V 1.55 1.65 1.75 V Temperature Stability of K

(Note2)

∆K/∆T-25

C, for Min/Max values Ta is the operating ambient tempe rature range

Increasing 12 13 14 V

=10mA 30 36 - V

<Vth(st) - 0.3 0.4 mA

Output not switching - 4 8 mA

Iref=0mA,25

≤Ta≤125

Vm1=1V, ∆Vm2=2.7 to 3.3V

≤Ta≤125

2.44 - 2.56 V

-20 - mV

0.49 0.62 0.74 1/V

--0.2 - %/

KA7526

Electrical Characteristics (Continued)

Parameter Symbol Condition Min. Typ. Max. Unit

CURRENT SENSE SECTION

Input Offset Voltage

(Note2)

Input Bias Current Ib(cs) 0V≤V Current Sense Delay to Output

(Note2)

DETECT SECTION

Detect Input Threshold Vth(det) Vdet Increasing 1.5 1.8 2.1 V Detect Hysteresis HY(det) - 180 240 400 mV Input Low Clamp Voltage Vclamp(I) Idet=-100µA 0.45 0.75 1 V Input High Clamp Voltage Vclamp(h) Idet=3mA 6.7 7.5 8.3 V Input Bias Current Ib(det) 1V≤Vdet≤6V -1 -0.2 1 µA Input High/low Clamp Diode Current

(Note2)

OUTPUT DRIVER SECTION Output Voltage High V Output Voltage Low V Rising Time Falling Time

(Note2)

Maximum Output Voltage Vomax(o) V Output Voltage With Uvlo Activated Vomin(o) V RESTART TIMER SECTION Restart Time Delay td(rst) Vm1=1V, Vm2=3.5V - 300 - µs

OVERVOLTAGE PROTECTION SECTION

Voltage Feedback Input Threshold Vth(ovp)

Notes :

1. Because the reference is not b rou ght out externally, this specification ca nnot be tested on th e p ac kage part. It is guar anteed by design.

2. This parameter, although guaranteed, is not tested in production.

Vio(cs) Vm1=0V, Vm2=2.2V -10 3 10 mV

≤1.7V -1 -0.3 1 µA

td(cs) - - 200 500 ns

Iclamp - - - ± 3mA

IO=-10mA, VCC=12V 8.5 9 - V

IO=10mA, VCC=12V - 0.8 1 V tr CI=1nF - 130 200 ns tf CI=1nF - 50 120 ns

=20V 12 13 15 V

=5V, IO=100µA--1V

Vcs=-0.5V, Vm1=1V

Vdet=0V

1.7 1.8 1.9 V

3. K =

Pin4 Threshold

Vm1×(Vm2-Vref)

(Vm1=Vpin3, Vm2=Vpin2)

Typica l Perfo rma nce Characteristics

KA7526

Fig1. E.A. Output Voltage vs C.S. Threshold

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

C.S Threshold Voltage [V]

0.2

0.0

-0.2

2.5 3.0 3.5 4.0 4.5 5.0

Vm1=4V

Vm1=1.5V

Vm1=1V

Vm1=0.5V

EA Output Voltage [V]

Figure 1. EA Output Voltage vs C.S. Threshold

Fig3. Supply Current VS Supply Voltage

20.0

17.5

15.0

12.5

10.0

7.5

Supply Current [mA]

5.0

2.5

0.0 0 5 10 15 20 25 30 35 40 45

Supply Voltage [v]

Fig2. Multiplier Input Voltage vs C.S. Threshold

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

C.S. Threshold Voltage [V]

0.2

0.0

-0.2

Veao=5V

012345

Multiplier Input Voltage [V]

Veao=3.25V

Veao=3V

Veao=2.75V

Veao=2.5V

Figure 2. Multiplier Input Voltage vs C.S. Threshold

Fig4. Reference Voltage vs Temperature

2.54

2.53

2.52

2.51

2.50

2.49

2.48

Reference Voltage(V)

2.47

2.46

2.45

-40 -20 0 20 40 60 80 100 120 140 Ambient Temperat ure(℃)

Figure 3. Supply Current vs Supply Voltage

Fig5. Start-up Thres hold vs Tempe ra tur e

13.4

13.3

13.2

13.1

13.0

12.9

12.8

Start-Up Threshold Voltage(V)

12.7

12.6

12.5

-40 -20 0 20 40 60 80 100 120 140 Ambient Temperature(℃)

Figure 5. Start-Up Threshold vs Temperature

Figure 4. Reference Voltage vs Temperature

Fig6. UV Lockout Hysteresis vs Temperature

6.5

6.0

5.5

5.0

4.5

UV Lockout H ys te resis(V)

4.0

3.5

-40-200 20406080100120140 Ambient Temperature (℃)

Figure 6. UV Lockout Hysteresis vs Temperature

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