For technical support and more information, see inside back cover or visit www.ti.com/powertrends

Standard Application

For STBY* pin:

open = output enabled

ground = output disabled.

Pin-Out Information

Pin Function

1

VID0

2

VID1

3

VID2

4VID3

5

STBY* - Stand-by

6

Do Not Connect

Pin Function

10

11

12

13

GND

14GND

15

GND

16

GND

17

GND

18

GND

Description

The PT7708 is a next generation

“Big Hammer”, a high-performance

Integrated Switching Regulator (ISR),

which is made available in Power

Trends’ aluminum 27-pin SIP pack-

age. The PT7708 improves on the

popular PT7706 with 20A of output

current and short circuit protection.

The PT7708 is suitable for exist-

ing 5V system designs that require

power for the latest high-speed, low-

voltage µPs, and bus drivers.

The PT7708 output is program-

mable from 1.3V to 2.05V with a

4-bit input, which is compatible with

ential remote sense is also provided to

compensate for voltage drop between

the ISR and load.

Only 330µF of output capacitance

are required for proper operation.

Cin = Required 1500µF electrolytic

Cout= Required 330µF electrolytic

L1 = Optional 1µH input choke

Pin Function

19

GND

20

21

22

23

25

26

27

Sync Out

C

IN

+

C

OUT

+

LOAD

V

IN

VID0

VID1

VID2

VID3

V

OUT

GND

GND

SYNC OUT

STBY*

L1

1H

REMOTE SENSE ( )

REMOTE SENSE (+)

PROGRAMMING PINS

PT7708

4

321

26

20-25

12

5

13-19

27

7-11

Vo

Vin

GND

SNS(+)

SNS(-)

Synch

Out

STBY

VID3 - VID0

PT7708—3.3V

20 Amp Programmable

Next Generation “Big Hammer”

SLTS083

(Revised 6/30/2000)

Specifications

Characteristics

PT7708 SERIES

(T

Symbols

Conditions

Min

Typ

Max

Units

Output Current

—19

A

—20

Input Voltage Range

0.1A

3.1

—

3.6

V

Output Voltage Tolerance

—

V

0°C

Line Regulation

3.1V

—

±10

—

mV

Load Regulation

—

±10

—

mV

—

50

—

mV

Transient Response

—

50

—

µSec

—

100

—

mV

Efficiency

η

—

85

—

%

—

82

—

—

78

—

%

—

74—

Switching Frequency

3.1V

300

350

400

kHz

0.1A

Absolute Maximum

°C

Operating Temperature Range

Storage Temperature

—

–40

—

+125

°C

Mechanical Shock

Per Mil-STD-883D, Method 2002.3

1 msec, Half Sine, mounted to a fixture

—

500

—

G’s

Mechanical Vibration

Per Mil-STD-883D, Method 2007.2,

—

10

—

G’s

20-2000 Hz, Soldered in a PC board

Weight

—

Vertical/Horizontal

—

31/41

—

grams

Notes: (1) ISR-will operate down to no load with reduced specifications.

(2) For operation below 0°C, Cin and Cout must have stable characteristics. Use either low ESR tantalum or Oscon® capacitors.

(3) See Safe Operating Area curves or contact the factory for the appropriate derating.

(4) If the Remote Sense Ground is not used, pin 12 must be connected to pin 13 for optimum output voltage accuracy.

External Capacitors: The PT7708 requires a minimum output capacitance of 330µF for proper operation. The PT7708 also requires an input capacitance of 1500µF,

which must be rated for a minimum of 1.4Arms of ripple current. For transient or dynamic load applications, additional capacitance may be required. For more

information refer to the application note regarding capacitor selection for this product.

Input Filter: An input filter inductor is optional for most applications. The inductor must be sized to handle 20ADC with a typical value of 1µH.