Fairchild Semiconductor KA7525B Datasheet

www.fairchildsemi.com

Rev.1.0.1

Features

• Internal Start-up Timer

• Internal Current Sense Blanking 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 2.1V of Hysteresis

• Totem Pole Output with High State Clamp

• Low Start-up and Operating Current

• 8-Pin DIP or 8-Pin SOP.

Applications

• Electronic Ballast

•SMPS

Description

The KA7525B provides simple and high perform ance activ e power factor correction. KA7525B 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 current sense blanking (In ternal R,C) 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 pr event no load runawa y conditions. Outpu t drive clamps limiting power MOSFET gate drive independent of supply voltage greatly enhance the products practical application.

KA7525B

KA7525BKA7525B

KA7525B

Po wer Factor Correction Controller

Po wer Factor Correction ControllerPo wer Factor Correction Controller

Po wer Factor Correction Controller

8-DIP

8-SOP

KA7525B

Pin Assignments

Pin Definitions

Pin Number Pin Name Pin Function Description

1 INV

Inverting input of the error amplifier. The output of the Boost converter should be resistively divided to 2.5V and connected to this pin.

2EA_OUT

The output of the error amplifier. A feedback compensation network is placed between this pin and the INV pin.

3MULT

Input of the multiplier stage. The full-wave rectified AC is divided to less than 2V and is connected to this pin.

4CS

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

5 Idet

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

6 GND The ground potential of all the pins. 7OUT

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

8 Vcc The logic and control power supply connection.

8INV

EA OUT

MULT

Vcc

OUT

GND

Idet

(Top View)

KA7525B

Internal Block Diagram

Absolute Maximum Ratings

Temperature Characteristics (0°°°°C ≤

≤ ≤

≤ Ta ≤

≤ ≤

≤ 125°°°°C )

Parameter Symbol Value Unit

Supply Voltage V

30 V Peak Drive Output Current Ioh, IoI ±500 mA Driver Output Clamping Diodes

> VCC or VO < -0.3V

Iclamp ±10 mA

Detector Clamping Diodes Idet ±10 mA Error Amp, Multiplier and Comparator Input Voltage Vin -0.3 to 6 V Operating Temperature Range Topr 0 to 125 °C Storage Temperature Range Tstg -65 to 150 °C Power Dissipation Pd 0.8 W Thermal Resistance (Junction-to-Air) Rθja 100 °C/W

Characteristics Symbol Value Unit

Temperature Stability for Reference Voltage(Vref) ∆Vref (Typ) 20 mV Temperature Stability for Multiplier Gain(K) ∆K/∆T (Typ) -0.2 %/°C

2.5V Ref Internal

Bias

OUT

INV

EA OUT

GND

MULT

Idet

Vcc

Timer R

R,C Filter

Vref

Vea(-)

Error Amp

Vm2

Vref ~ Vref+1V

Multiplier

0 ~2V

Vm1

Vmo

Drive Output

Over Voltage Protection

1.8V

Current Sense Comparator

Vref

Zero Current Detector

240mV

Vcc

1.8V

7.5V

1.24V

10V

36V

2.1V

+ _

UVLO

K =

Vm1× (Vm2-Vref)

Pin4 Threshold(Vmo)

KA7525B

Electrical Characteristics

Unless otherwise specified, these specifications apply over the operating ambient temperatures for the KA7525B with 0°C ≤

Ta ≤

125°C and Vcc=12V.

Parameter Symbol Conditions Min. Typ. Max. Unit UNDER VOLTAGE LOCK OUT SECTION

Start Threshold Voltage V

th (st)

Vcc Increasing 9 10 11 V

UVLO Hysteresis H

Y(st)

-1.72.12.5V

Supply Zener Voltage Vz Icc=10mA 30 36 - V

SUPPLY CURRENT SECTION

Start-Up Supply Current Ist Vcc < Vth(st) - 0.2 0.3 mA Operating Supply Current Icc No Output Switching - 4 8 mA Dynamic Operating Supply Current Idcc 50kHz, CI =1nF - 5 10 mA

ERROR AMPLIFIER SECTION

Voltage Feedback Input Threshold Vref

Iref=0mA 2.465 2.5 2.535 V 0°C ≤ Ta ≤ 125°C 2.44 - 2.56 V

Line Regulation

∆

Vref1 12V ≤ Vcc ≤ 25V - 0.1 10 mV

Load Regulation

(Note1)

∆

Vref2 0mA ≤ Iref ≤ 2mA - 0.1 10 mV

Temperature Stability of Vref

(Note2)

∆

Vref3 0°C ≤ Ta ≤ 125°C-20-mV

Input Bias Current Ib(ea) - -0.5 - 0.5

A 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 EA Out 1.2 - 3.6 V

Slew Rate (Note2) SR - - 0.6 - V/µs

MULTIPLIER SECTION

Input Bias Current(Pin3) Ib(m) - -0.5 - 0.5

A M1 Input Voltage Range (Pin3)

∆

Vm1 - 0 - 2 V

M2 Input Voltage Range (Pin2)

∆

Vm2 - Vref - Vref+1 V Multiplier Gain(Note3) K Vm1=1V, ∆Vm2= 2.7 to 3.3V 0.55 0.68 0.8 1/V Maximum Multiplier Output Voltage Vomax(m) Vea(-) = 0V, Vm1=2V 1.1 1.24 1.45 V Temperature Stability of K (Note2)

∆K/∆

T0°C ≤ Ta ≤ 125°C--0.2-%/

KA7525B

Electrical Characteristics

(Continued)

Notes :

1. Because the reference is no t b rou gh t out externally, this specification cann ot b e tested on the packa ge pa rt. It is guaranteed by design.

2. These parameters, although guaranteed, are not 100% tested in production.

3. K =

Parameter Symbol Conditions Min. Typ. Max. Unit CURRENT SENSE SECTION

Input Offset Voltage (Note2) Vio(cs) Vm1 = 0V, Vm2 = 2.2V -10 3 10 mV Input Bias Current Ib(cs) 0V ≤ Vcs ≤ 1.7V -1 -0.3 1

Current Sense Delay to Output (Note2) td(cs) - - 200 500 ns

ZERO CURRENT DETECT SECTION

Detect Input Threshold Vth(det) Vdet Increasing 1.65 1.8 1.95 V Detect Hysteresis HY(det) - 180 240 300 mV Input Low Clamp Voltage Vclamp(I) Idet = -100uA 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

Input High/Low Clamp Diode Current(Note2)

Iclamp(d) - - -

3mA

OUTPUT DRIVER SECTION Output Voltage High Voh I

= -10mA, V

= 12V 8.5 9 - V

Output Voltage Low Vol I

= 10mA, V

= 12V - 0.8 1 V Rising Time(Note2) tr CI = 1nF - 130 200 ns Falling Time(Note2) tf CI = 1nF - 50 120 ns Maximum Output Voltage Vomax(o) V

= 20V 12 13 15 V

Output Voltage With UVLO Activated Vomin(o) V

= 5V, IO = 100µA--1V RESTART TIMER SECTION Restart Time Delay td(rst) Vm1 = 1V, Vm2 = 3.5V - 300 -

OVER VOLTAGE PROTECTION SECTION

Voltage Feedback Input Threshold Vth(ovp) Vcs= -0.5V, Vm1=1V , Vdet=0V 1.7 1.8 1.9 V

Pin4 Threshold

Vm1×(Vm2-Vref)

(Vm1=Vpin3, Vm2=Vpin2)

KA7525B

Typical Performance Characteristics

2.5 3.0 3.5 4.0 4.5

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6 Vm1=2.5V

Vm1=2.0V

Vm1=1.5V

Vm1=1.0V

Vm1=0.5V

Vm1=3.0V

Vm1=0V

C.S. Threshold Voltage[V]

E.A. Output Voltage[V]

0.0 0.5 1.0 1.5 2.0 2.5 3.0

-0 . 2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4 Veao=3. 75V

Veao=3. 5V

Veao=4. 0V

Veao=3. 25V

Veao=3. 0V

Veao=2. 75V

Veao=2. 5V

C.S. Threshold Voltage[V]

Multiplier Input Voltage[V]

0 5 10 15 20 25 30 35 40 45

0.00

2.50m

5.00m

7.50m

10.00m

12.50m

15.00m

17.50m

20.00m

Supply Current[A]

Supply Voltage[V]

-20 0 20 40 60 80 100 120 140

2.45

2.46

2.47

2.48

2.49

2.50

2.51

2.52

Reference Voltage[V]

Temperature['C]

-20 0 20 40 60 80 100 120 140

9.4

9.5

9.6

9.7

9.8

9.9

10.0

10.1

10.2

Start-up Threshold[V]

Ambient Temperature['C]

-20 0 20 40 60 80 100 120 140

1.7

1.8

1.9

2.0

2.1

2.2

2.3

2.4

2.5

VU Lockout Hysteresis[V]

Ambient Temperature['C]

Figure 1. E.A. Output Voltage vs C.S. Thre shold

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

Figure 3. Supply Current vs Supply Voltage

Figure 4. Reference Voltage vs Temperature

Figure 5. Start-up Threshold vs Temperature

Figure 6. UV Lockout Hysteresis vs Temperature

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