Standard Application

Cin = Required 560µF electrolytic

(See input filter note)

Cout = Required 2000µF electrolytic

L1

= Optional 1µH input choke

Series

15 AMP 24V INPUT “BIG-HAMMER III”

PROGRAMMABLE ISR

PT7750

The PT7750 series is a new +24V

input, 15 Amp output, high-perfor-

mance Integrated Switching Regulator

(ISR) housed in a 27-pin SIP package.

The 15A capability allows easy integra-

tion of the latest high-speed,

low-voltage µPs and bus drivers into

+24V distributed power systems.

The PT7750 series has been de-

signed to work in parallel with one or

For STBY* pin:

open = output enabled

ground = output disabled.

Pin-Out Information

Pin Function

1

VID0

2

VID1

3

VID2

4

VID3

5

STBY* - Stand-by

6

VID4

10

11

12

Remote Sense Gnd

13

GND

Pin Function

14

GND

15

GND

16

GND

17

GND

18

GND

19

GND

20

21

22

23

24

25

26

Remote Sense Vout

27

Sync Out

more of the PT7747 current boosters for

increased Iout in increments of 15A.

The output voltage of the PT7750

series can be easily programmed over a

wide range with a 5-bit input. A differ-

ential remote sense is provided which

automatically compensates for any

voltage drop from the ISR to the load.

2000µF of output capacitance is

required for proper operation.

Sense

PT7747 15A current boosters

Features

56

PT7750

7 - 11

13 - 19

20 - 25

27

V

IN

GND

1µH

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

Specifications

Characteristics

PT7750 SERIES

(T

Symbols

Conditions

Min

Typ

Max

Units

Output Current

A

A

Input Voltage Range

0.1A

20.0

—

28.0

V

Undervoltage Lockout Threshold

0.1A

—

18.7

—

V

Output Voltage Tolerance

—

—

±80

mV

0°C

PT7756

—

—

±160

mV

Line Regulation

20V

—

±15

—

mV

Load Regulation

—

±10

—

mV

—75

—

mV

Transient Response

—

100

—

µSec

—

200

—

mV

Efficiency

η

—

88

—

%

—

84

—

%

—

80

—

%

Switching Frequency

20V

300

350

400

kHz

0.1A

Absolute Maximum

Ta

0

—

+85

°C

Operating Temperature Range

Recommended Operating

Forced Air Flow = 200 LFM

0

—

+65***

°C

Temperature Range

Storage Temperature

—

-40

—

+125

°C

Weight

—

Vertical/Horizontal

—

53/66

—

grams

* ISR-will operate down to no load with reduced specifications. Please note that this product is not short-circuit protected.

** The PT7750 series can be easily paralleled with one or more of the PT7747 Current Boosters to provide increased output current in increments of 15A.

*** See safe operating area chart.

Output Capacitors:

The PT7750 series requires a minimum output capacitance of 2000µF for proper operation. Do not use Oscon type capacitors. The maximum allowable

output capacitance is (42,000 ÷ Vout)µF for the PT7751, (96,000 ÷ Vout)µF for the PT7756, or 15,000µF, whichever is less.

Input Filter:

An input inductor is optional for most applications. The input inductor must be sized to handle 9ADC with a typical value of 1µH. The input capacitance

must be rated for a minimum of 8.0 Arms of ripple current when operated at maximum output current and maximum output voltage. Contact an applications engi-

neer for input capacitor selection for applications at other output voltages and output currents.

Revised 1/12/99

Application Notes

Mechanical Outline

Product Selector Guide