www.fairchildsemi.com

Rev.1.0.2

Features

· Wide operatimg frequency range up to (150kHz)
· Pulse by pulse over current limiting
· Over load protection
· Over voltage protecton (Min. 23V)
· Internal thermal shutdown function
· Under voltage lockout
· Internal high voltage sense FET
· External sync terminal
· Auto Restart Mode

Description

The Fairchild Power Switch(FPS) product family is specially
designed for an off line SMPS with minimal external
components. The Fairchild Power Switch(FPS) consist of
high voltage power SenseFET and current mode PWM
controller IC. controller IC features a trimmed oscillator,
under voltage lock out, leading edge blanking, optimized
gate turn-on/turn-off driver, thermal shut down protection,
over voltage protection, temperature compensated precision
current sources for loop compensation and fault protection
circuit. compared to discrete MOSFET and controller or
R

switching converter solution, a Fairchild Power

Switch(FPS) can reduce total component count, design size,
weight and at the same time increase & efficiency,
productivity, and system reliability. It has a basic platform
well suited for cost effective C-TV power supply.

TO-3PF-5L

1.DRAIN 2.GND 3.V

4.FB 5.Sync

TO-3P-5L

Internal Block Diagram

#3 V

32V

2.5R

1mA

0.1V

OVER VOLTAGE S/D

7.5V

25V

Thermal S/D

Power on reset

L.E.B

OSC

Vref

Internal

bias

Good

logic

SFET

#1 DRAIN

#2 GND

#4 FB

#5 Sync

6.4V

KA3S0680RB/KA3S0680RFB

Fairchild Power Switch(FPS)

KA3S0680RB/KA3S0680RFB

Absolute Maximum Ratings

Note:
1. Tj=25

C to 150

2. Repetitive rating: Pulse width limited by maximum junction temperature
3. L=24mH, starting Tj=25

Characteristic

Symbol

Value

Unit

Maximum Drain voltage

(1)

D,MAX

800

Drain Gate voltage (R

=1M

)

DGR

800

Gate source (GND) voltage

Drain current pulsed

(2)

24.0

Single pulsed avalanche energy

(3)

455

Continuous drain current (T

=25

6.0

Continuous drain current (T

=100

4.0

Maximum supply voltage

CC,MAX

Input voltage range

0.3 to V

Total power dissipation

(watt H/S)

150

Derating

1.21

Operating ambient temperature

25 to +85

Storage temperature

STG

55 to +150

KA3S0680RB/KA3S0680RFB

Electrical Characteristics (SFET part)

(Ta =

C unless otherwise specified)

Note:
Pulse test: Pulse width

300

S, duty cycle

Characteristic

Symbol

Test condition

Min.

Typ.

Max.

Unit

Drain source breakdown voltage

DSS

= 0V, I

= 50

800

Zero gate voltage drain current

DSS

= Max., Rating,

= 0V

= 0.8Max., Rating,

= 0V, T

= 125

200

Static drain source on resistance

(note)

DS(ON)

= 10V, I

= 4.0A

1.6

2.0

Forward transconductance

(note)

gfs

= 15V, I

= 4.0A

1.5

2.5

Input capacitance

Ciss

= 0V, V

= 25V,

f = 1MHz

1600

Output capacitance

Coss

140

Reverse transfer capacitance

Crss

Turn on delay time

d(on)

= 0.5BV

DSS

, I

= 6.0A

(MOSFET switching
time are essentially
independent of
operating temperature)

Rise time

150

Turn off delay time

d(off)

300

Fall time

130

Total gate charge
(gate-source+gate-drain)

=10V, I

= 6.0A,

= 0.5BV

DSS

(MOSFET

switching time are
essentially independent of
operating temperature)

Gate source charge

Qgs

Gate drain (Miller) charge

Qgd

----

KA3S0680RB/KA3S0680RFB

Electrical Charcteristics (SFET part) (Continued)

(Ta = 25

C unless otherwise specified)

Note:
1. These parameters, although guaranteed, are not 100% tested in production
2. These parameters, although guaranteed, are tested in EDS(water test) process
3.The amplitude of the sync. pulse is recommended to be between 2V and 3V for stable sync. function.

Characteristic

Symbol

Test condition

Min.

Typ. Max.

Unit

UVLO SECTION
Start threshold voltage

START

Stop operating voltage

STOP

After turn on

OSCILLATOR SECTION
Initial accuracy

OSC

Ta = 25

kHz

Frequency change with temperature

(2)

+85

Maximum duty cycle

MAX

FEEDBACK SECTION
Feedback source current

Ta = 25

C, Vfb = GND

0.7

0.9

1.1

Shutdown Feedback voltage

6.9

7.5

8.1

Shutdown delay current

delay

Ta = 25

C, 5V

Vfb

1.4

1.8

2.2

SYNC. & SOFT START SECTION
Soft start voltage

= 2V

4.7

5.0

5.3

Soft start current

Sync & S/S = GND

0.8

1.0

1.2

Sync threshold voltage

(3)

SYTH

Vfb = 5V

6.0

6.4

6.8

REFERENCE SECTION
Output voltage

(1)

Vref

Ta = 25

4.80

5.00

5.20

Temperature Stability

(1)(2)

Vref/

+85

0.3

0.6

mV/

CURRENT LIMIT (SELF-PROTECTION) SECTION
Peak Current Limit

OVER

Max. inductor current

3.52

4.00

4.48

PROTECTION SECTION
Thermal shutdown temperature (Tj)

(1)

140

160

Over voltage protection voltage

OVP

TOTAL DEVICE SECTION
Start Up current

START

= 14V

0.1

0.3

0.55

Operating supply current
(control part only)

Ta = 25

zener voltage

= 20mA

32.5

KA3S0680RB/KA3S0680RFB

Typical Performance Characteristics (control part)

(These characteristic graphs are normalized at Ta = 25

Fig.1 Operating Frequency

0.8

0.85

0.9

0.95

1.05

1.1

1.15

1.2

-25

100 125 150

Fosc

Fig.2 Feedback Source Current

0.8

0.85

0.9

0.95

1.05

1.1

1.15

1.2

-25

100 125 150

Ifb

Fig.3 Operating Current

0.8

0.85

0.9

0.95

1.05

1.1

1.15

1.2

-25

100 125 150

Iop

Fig.4 Max Inductor Current

0.8

0.85

0.9

0.95

1.05

1.1

-25

100 125 150

Ipeak

Fig.5 Start up Current

0.5

0.7

0.9

1.1

1.3

1.5

-25

100 125 150

Istart

Fig.6 Start Threshold Voltage

0.85

0.9

0.95

1.05

1.1

1.15

-25

75 100 125 150

Vstart

Temperature [

]

Temperature [

]

Temperature [

]

Temperature [

]

Temperature [

]

Temperature [

]

Figure 1. Operating Frequency

Figure 2. Feedback Source Current

Figure 3. Operating Supply Current

Figure 4. Peak Current Limit

Figure 5. Start up Current

Figure 6. Start Threshold Voltage

over

KA3S0680RB/KA3S0680RFB

Typical Performance Characteristics (continued)

(These characteristic graphs are normalized at Ta = 25

Fig.7 Stop Threshold Voltage

0.85

0.9

0.95

1.05

1.1

1.15

-25

100 125 150

Vstop

Fig.8 Maximum Duty Cycle

0.85

0.9

0.95

1.05

1.1

1.15

-25

75 100 125 150

Dmax

Fig.9 Vcc Zener Voltage

0.8

0.85

0.9

0.95

1.05

1.1

1.15

1.2

-25

100 125 150

Fig.10 Shutdown Feedback Voltage

0.85

0.9

0.95

1.05

1.1

1.15

-25

100 125 150

Vsd

Fig.11 Shutdown Delay Current

0.8

0.85

0.9

0.95

1.05

1.1

1.15

1.2

-25

100 125 150

Idelay

Fig.12 Over Voltage Protection

0.85

0.9

0.95

1.05

1.1

1.15

-25

100 125 150

Vovp

Temperature [

]

Temperature [

]

Temperature [

]

Temperature [

]

Temperature [

]

Temperature [

]

Figure 7. Stop Threshold Voltage

Figure 8. Maximum Duty Cycle

Figure 9. V

Zener Voltage

Figure 10. Shutdown Feedback Voltage

Figure 11. Shutdown Delay Current

Figure 12. Over Voltage Protection

th(H)

KA3S0680RB/KA3S0680RFB

Typical Performance Characteristics (continued)

(These characteristic graphs are normalized at Ta = 25

Figure13. Soft Start Voltage

Figure 14. Static Drain-Source on Resistance

Fig.13 Soft Start Voltage

0.85

0.9

0.95

1.05

1.1

1.15

-25

100 125 150

Vss

Fig.14 Drain Source Turn-on

Resistance

0.5

1.5

2.5

-25

75 100 125 150

Rdson

( )

KA3S0680RB/KA3S0680RFB

10/17/01 0.0m 001

Stock#DSxxxxxxxx

2001 Fairchild Semiconductor Corporation

LIFE SUPPORT POLICY
FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES

OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR

CORPORATION. As used herein:

1. Life support devices or systems are devices or systems

which, (a) are intended for surgical implant into the body,

or (b) support or sustain life, and (c) whose failure to

perform when properly used in accordance with
instructions for use provided in the labeling, can be

reasonably expected to result in a significant injury of the

user.

2. A critical component in any component of a life support

device or system whose failure to perform can be

reasonably expected to cause the failure of the life support

device or system, or to affect its safety or effectiveness.

www.fairchildsemi.com

DISCLAIMER
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY

PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY
LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER

DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.

Ordering Information

TU : Non Forming Type
YDTU : Forming Type

Product Number

Package

Operating Temperature

KA3S0680RB-TU

TO-3P-5L

-25

C to +85

KA3S0680RB-YDTU

TO-3P-5L(Forming)

KA3S0680RFB-TU

TO-3PF-5L

-25

C to +85

KA3S0680RFB-YDTU TO-3PF-5L(Forming)

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