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

Standard Application

Cin = Required 2400µF electrolytic

Cout = Required 2400µF electrolytic

L1

= Optional 1µH input choke

32 Amp “Sledge Hammer”

Programmable ISR

PT7771—5V

The PT7771 is a high-output Inte-

grated Switching Regulator (ISR)

housed in a 27-pin SIP package. The

PT7771 operates off a standard 5V bus

to provide a 32 amp low-voltage power

source for the industry’s latest high-

speed µPs, ASICs, DSPs.

The PT7771 has been designed to

work in parallel with one or more of

the PT7746 -32A current boosters to

increase the load current capability in

increments of 32A.

The output voltage is program-

mable from 1.3V to 3.5V via a 5-bit

Pro Processor. A differential remote

sense is also provided to compensate

for voltage drop between the ISR and

load.

An output capacitance of 2400µF is

required for proper operation.

Note that this product does not

include short circuit protection.

For STBY* pin; open = output enabled;

ground = output disabled.

Pin-Out Information

PT7770

7 - 11

13 - 19

20 - 25

27

V

IN

GND

1H

GND

V

OUT

C

OUT

+

C

IN

+

12

26

1

L1

SYNC OUT

LOAD

REMOTE SENSE (+)

REMOTE SENSE (-)

VID1

VID2

VID3

VID4

PROGRAMMING PINS

2

3

4

STBY*

5

6

VID0

Pin

Function

in

in

in

in

in

Pin

Function

SLTS054A

(Revised 6/30/2000)

Specifications

Characteristics

PT7771

(T

Symbols

Conditions

Min

Typ

Max

Units

Output Current

= +60°C, 200 LFM, pkg N

—32

A

= +25°C, natural convection

—26

A

Input Voltage Range

0.1A

—

5.5

V

Output Voltage Tolerance

—

V

0°C

Line Regulation

4.5V

—

±10

—

mV

Load Regulation

—

±10

—

mV

—

50

—

mV

Transient Response

—

100

—

µSec

—

200

—

mV

Efficiency

η

—

90

—

%

Switching Frequency

4.5V

650

700

750

kHz

0.1A

Absolute Maximum

0

—

°C

Operating Temperature Range

Storage Temperature

—

-40

—

+125

°C

Weight

—

Vertical/Horizontal

—

53/66

—

grams

Notes: (1) ISR-will operate down to no load with reduced specifications. Please note that this product is not short-circuit protected.

(3) Consult the SOA curves or contact the factory for the appropriate derating.

Output Capacitors: The PT7771 regulator requires a minimum output capacitance of 2400µF for proper operation. Do not use Oscon type capacitors.

The maximum allowable output capacitance is 30,000µF.

Input Filter: An input filter is optional for most applications. The input inductor must be sized to handle 32ADC with a typical value of 1µH.

The input capacitance must be rated for a minimum of 2.6Arms of ripple current. For transient or dynamic load applications, additional

capacitance may be required.