Preliminary Technical Data

ADP3088

a

REV. PrK

3/28/02

Information furnished by Analog Devices is believed to be accurate and reli-

able. 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.

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

Tel: 781/329-4700

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

Fax: 781/326-8703

Analog Devices, Inc., 2002

1MHz,750mABuckRegulator

PRELIMINARY TECHNICAL DATA

FEATURES

1 MHz PWM Frequency

Automatic PWM to Power Saving Mode at Light Load

Fully Integrated 1 A Power Switch

3% Output Regulation Accuracy over Temperature,

Line, and Load

100% Duty Cycle Operation

Simple Compensation

Output Voltage: 1.25 V to 10.5 V

Small Inductor and MLC Capacitors

Low Quiescent Current while Pulse Skipping

Thermal Shutdown

Fully Integrated Soft Start

Cycle-by-cycle Current Limit

APPLICATONS

PDAs and Palmtop Computers

Notebook Computers

PCMCIA Cards

Bus Products

Portable Instruments

GENERAL DESCRIPTION

The ADP3088 is a high frequency, non-synchronous PWM

step-down DC-DC regulator with an integrated 1A power

switch in a space-saving MSOP8 package. It provides high

efficiency, excellent dynamic response, and is very simple

to use.

The ADP3088’s 1 MHz switching frequency allows for

small, inexpensive external components, and the current

mode control loop is simple to compensate and eases noise

filtering. It operates in PWM current mode under heavy

loads and saves energy at lighter loads by switching auto-

matically into Power Saving mode. Soft start is integrated

completely on chip, as is the cycle-by-cycle current limit.

Capable of operating from 2.5 V to 11 V input, it is ideal for

many applications, including portable, battery power appli-

cations, where local point-of-use power regulation is re-

quired. Supporting output voltages down to 1.25 V, the

ADP3088 is ideal to generate low voltage rails, providing

the optimal solution in its class for delivering power effi-

ciently, responsively, and simply with minimal printed cir-

cuit board area.

The device is specified over the industrial temperature

range of -40 °C to +85°C.

FUNCTIONAL BLOCK DIAGRAM

Figure 1. Typical Application

SW

DRV

FB

IN

GND

COMP

ADP3088

VOUT

1.8V

3.3

µH

10.0k

Ω

22.4k

Ω

20k

Ω

4.7pF

1N5817

IN

GND

VIN

3.3V

10µF

0.1µF

10µF

220pF

SW

FB

COMP

GND

IN

DRV

CURRENT

SENSE

AMP

PWM

COMPARATOR

REF

1.245V

ERROR

AMP

gm

SOFT-START

TIMER

+

R

SQ

RUN/STOP

COMPARATORS

1MHz

PROTECTION

LOGIC

(ILIM, OT)

IN

GND