REV. 0

Information furnished by Analog Devices is believed to be accurate and

reliable. However, no responsibility is assumed by Analog Devices for its

use, nor for any infringements of patents or other rights of third parties

which may result from its use. No license is granted by implication or

otherwise under any patent or patent rights of Analog Devices.

a

ADP1173

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 617/329-4700

World Wide Web Site: http://www.analog.com

Fax: 617/326-8703

© Analog Devices, Inc., 1997

Micropower

DC-DC Converter

FUNCTIONAL BLOCK DIAGRAMS

SET

GAIN BLOCK/

ERROR AMP

COMPARATOR

SW2

FB

GND

SW1

AO

OSCILLATOR

DRIVER

A1

A2

1.245V

REFERENCE

ADP1173

SET

GAIN BLOCK/

ERROR AMP

COMPARATOR

SW2

SENSE

GND

SW1

AO

OSCILLATOR

DRIVER

A1

A2

1.245V

REFERENCE

ADP1173-3.3

ADP1173-5

ADP1173-12

R2

753k

Ω

R1

ADP1173-3.3: R1 = 456k

Ω

ADP1173-5: R1 = 250k

Ω

ADP1173-12: R1 = 87.4k

Ω

FEATURES

Operates From 2.0 V to 30 V Input Voltages

Only 110

A Supply Current (Typical)

Step-Up or Step-Down Mode Operation

Very Few External Components Required

Low Battery Detector On-Chip

User-Adjustable Current Limit

Internal 1 A Power Switch

Fixed or Adjustable Output Voltage Versions

8-Pin DIP or SO-8 Package

APPLICATIONS

Notebook and Palmtop Computers

Cellular Telephones

3 V to 5 V, 5 V to 12 V Converters

9 V to 5 V, 12 V to 5 V Converters

Portable Instruments

LCD Bias Generators

GENERAL DESCRIPTION

The ADP1173 is part of a family of step-up/step-down switching

regulators that operates from an input supply voltage of as little as

2 V to 12 V in step-up mode and to 30 V in step-down mode.

The ADP1173 consumes as little as 110

µA in standby mode,

making it ideal for applications that need low quiescent current.

An auxiliary gain amplifier can serve as a low battery detector,

linear regulator (under voltage lockout) or error amplifier.

The ADP1173 can deliver 80 mA at 5 V from a 3 V input in

step-up configuration or 100 mA at 5 V from a 12 V input in

step-down configuration. For input voltages of less than 2 V use

the ADP1073.