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a

ADP3050

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., 2000

200 kHz, 1 A High-Voltage

Step-Down Switching Regulator

FUNCTIONAL BLOCK DIAGRAM

200kHz

OSCILLATOR

FREQUENCY

AND CURRENT LIMIT

FOLDBACK

2.5V

REGULATOR

CURRENT SENSE

AMPLIFIER

BOOST

FB

SD

GND

BIAS

CURRENT

LIMIT

1.2V

CMP

R

SQ

DRIVER

SWITCH

IN

COMP

+

ADP3050

FEATURES

Wide Input Voltage Range: 3.6 V to 30 V

Adjustable and Fixed (3.3 V, 5 V) Output Options

Integrated 1 A Power Switch

Uses Small Surface-Mount Components

Cycle-By-Cycle Current Limiting

Peak Input Voltage (100 ms): 60 V

Thermally Enhanced 8-Lead SOIC Package

Configurable as a Buck, Buck-Boost and SEPIC

Regulator

APPLICATIONS

Industrial Power Systems

PC Peripheral Power Systems

Preregulator for Linear Regulators

Distributed Power Systems

Automotive Systems

Battery Chargers

GENERAL DESCRIPTION

The ADP3050 is a current-mode monolithic buck (step-down)

PWM switching regulator that contains a high current 1 A power

switch and all control, logic, and protection functions. It uses a

unique compensation scheme that allows the use of any type of

output capacitor (tantalum, ceramic, electrolytic, OS-CON).

Unlike some buck regulators, the design is not restricted to using

a specific type of output capacitor or ESR value.

A special boosted drive stage is used to saturate the NPN power

switch, providing a system efficiency higher than conventional

bipolar buck switchers. Further efficiency improvements are ob-

tained by using the low voltage regulated output to provide the

device's internal operating current. A high switching frequency

allows the use of small external surface-mount components. A

wide variety of standard off-the-shelf devices can be used, pro-

viding a great deal of design flexibility. A complete regulator

design requires only a few external components.

The ADP3050 includes a shutdown input that places the device

in a low-power mode, reducing the total supply current to under

20

µA. Internal protection features include thermal shutdown

circuitry and a cycle-by-cycle current-limit for the power switch

to provide complete device protection under fault conditions.

The ADP3050 provides excellent line and load regulation,

maintaining typically less than

±3% output voltage accuracy

over temperature and under all input voltage and output current

conditions.

The ADP3050 is specified over the industrial temperature range of

–40

°C to +85°C and is available in a thermally enhanced 8-lead

SOIC package.