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ADP3171

Synchronous Buck Controller with Dual Linear Regulator Controllers

Analog Devices 

a

Synchronous Buck Controller

with Dual Linear Regulator Controllers

ADP3171

FEATURES

Fixed 1.2 V N-Channel Synchronous Buck Driver

Two On-Board Linear Regulator Controllers

Total Accuracy ±1% over Temperature

High Efficiency Current-Mode Operation

Short Circuit Protection

Power Good Output

Overvoltage Protection Crowbar Protects Switching

Output with No Additional External Components

APPLICATIONS

Auxiliary System Supplies for Desktop

Computer Systems

General-Purpose Low Voltage Supplies

FUNCTIONAL BLOCK DIAGRAM

VCC

UVLO

AND BIAS

REFERENCE

CT

8

SET

OSCILLATOR

RESET

CROWBAR

REF

PWM

LOGIC

DRVH

DRVL

GND 1

1.5V

LRFB1 3

DAC +20%

PWRGD

LRDRV1 4

LRFB2

LRDRV2

1.8V

COMP

ADP3171

CMP

DAC –20%

CS–

7 CS+

5 FB

gm

1.2V

GENERAL DESCRIPTION

The ADP3171 is a highly efficient output synchronous buck

switching regulator controller optimized for converting a 5 V

main supply into the auxiliary supply voltages required by

processors and chipsets. The ADP3171 provides a fixed

output voltage of 1.2 V at up to 15 A, depending on the

power ratings of the external MOSFETs and inductor. The

ADP3171 uses a current-mode, constant off time architecture to

drive two N-channel MOSFETs at a programmable switching

frequency that can be optimized for regulator size and efficiency.

The ADP3171 provides accurate and reliable short circuit

protection and adjustable current limiting. It also includes an

integrated overvoltage crowbar function to protect the load in

case the output voltage exceeds the nominal programmed

voltage by more than 20%.

The ADP3171 contains two fixed output voltage linear regulator

controllers that are designed to drive external N-channel

MOSFETs. These linear regulators are used to generate the

auxiliary voltages required in most motherboard designs and have

been designed to provide a high bandwidth load-transient response.

The ADP3171 is specified over the commercial temperature

range of 0°C to 70°C and is available in a 14-lead SOIC package.

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 that

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

www.analog.com

Fax: 781/326-8703

© Analog Devices, Inc., 2002

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