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Rainbow Electronics MAX1745 User Manual

General description, Applications, Features

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General Description

The MAX1744/MAX1745 are step-down DC-DC con-
trollers capable of handling up to 36V inputs. These
parts use a proprietary current-limited control scheme
for excellent light- and full-load efficiency, while their
330kHz (max) switching frequency permits small exter-
nal components for space-critical applications.
Operation to 100% duty cycle permits the lowest possi-
ble dropout voltage.

The MAX1744 contains an internal feedback network
that provides a pin-selectable output voltage of either
3.3V or 5V. The MAX1745 uses an external feedback
network to generate an adjustable output voltage
between 1.25V and 18V.

The MAX1744/MAX1745 are available in a space-sav-
ing 10-pin µMAX package.

________________________Applications

Automotive Electronics

Telecom Systems

Wall-Cube-Powered Devices

Industrial Control Systems

Firewire/IEEE1394

____________________________Features

High-Voltage Operation (up to 36V IN)
Efficiency >90%
Output Power Capability Exceeds 50W
10-Pin µMax Package
Low-Dropout Voltage
100% (max) Duty Cycle
90µA Quiescent Current
4µA Shutdown Current
Up to 330kHz Switching Frequency
Output Voltage

5V or 3.3V (MAX1744)

Adjustable 1.25V to 18V (MAX1745)

Current-Limited Control Scheme

MAX1744/MAX1745

High-Voltage, Step-Down DC-DC

Controller in µMAX

________________________________________________________________ Maxim Integrated Products

1

19-1776; Rev 1; 10/01

Ordering Information

PART

TEMP RANGE

PIN-PACKAGE

MAX1744EUB

-40

°C to +85°C

10 µMAX

MAX1744AUB

-40

°C to +125°C

10 µMAX

MAX1745EUB

-40

°C to +85°C

10 µMAX

MAX1745AUB

-40

°C to +125°C

10 µMAX

GND

OUT

REF

VL

CS

MAX1744

3/5

5V

3.3V

ON

OFF

SHDN

IN

VH

EXT

P

IN

4.5V TO 36V

OUT
3.3V
OR 5V

Typical Operating Circuit

1

2

3

4

5

10

9

8

7

6

IN

EXT

VH

3/5 (FB)

( ) ARE FOR MAX1745 ONLY.

REF

VL

GND

MAX1744
MAX1745

µMAX

TOP VIEW

CS

OUT

SHDN

Pin Configuration

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.