REV. A

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a

ADP3159/ADP3179

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., 2001

4-Bit Programmable

Synchronous Buck Controllers

FUNCTIONAL BLOCK DIAGRAM

CMP

DRVH

LRDRV2

LRFB2

LRFB1

LRDRV1

COMP

DRVL

CS–

CS+

PWM

DRIVE

VCC

CT

OSCILLATOR

UVLO

& BIAS

REFERENCE

REF

REF

VID DAC

DAC+20%

ADP3159/ADP3179

GND

FB

VID3

VID2

VID1

VID0

SET

RESET

CROWBAR

DAC–20%

PWRGD

+

–

FEATURES

Optimally Compensated Active Voltage Positioning

with Gain and Offset Adjustment (ADOPT™) for

Superior Load Transient Response

Complies with VRM 8.4 Specifications with Lowest

System Cost

4-Bit Digitally Programmable 1.3 V to 2.05 V Output

N-Channel Synchronous Buck Driver

Two On-Board Linear Regulator Controllers

Total Accuracy

0.8% Over Temperature

High Efficiency Current-Mode Operation

Short Circuit Protection

Power Good Output

Overvoltage Protection Crowbar Protects Micro-

processors with No Additional External Components

APPLICATIONS

Core Supply Voltage Generation for:

Intel Celeron™

GENERAL DESCRIPTION

The ADP3159 and ADP3179 are highly efficient output syn-

chronous buck switching regulator controllers optimized for

converting a 5 V main supply into the core supply voltage

required by high-performance processors. These devices use an

internal 4-bit DAC to read a voltage identification (VID) code

directly from the processor, which is used to set the output

voltage between 1.3 V and 2.05 V. They use 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 ADP3159 and ADP3179 also use a unique supplemental

regulation technique called Analog Devices Optimal Position-

ing Technology (ADOPT) to enhance load transient

performance. Active voltage positioning results in a dc/dc con-

verter that meets the stringent output voltage specifications

for high-performance processors, with the minimum number

of output capacitors and smallest footprint. Unlike voltage-

mode and standard current-mode architectures, active voltage

positioning adjusts the output voltage as a function of the load

current so it is always optimally positioned for a system tran-

sient. The devices also provide accurate and reliable short

circuit protection and adjustable current limiting. They also

include an integrated overvoltage crowbar function to protect

the microprocessor from destruction in case the core supply

exceeds the nominal programmed voltage by more than 20%.

The ADP3159 and ADP3179 contain two fixed-output volt-

age linear regulator controllers that are designed to drive

external N-channel MOSFETs. The outputs are internally

fixed at 2.5 V and 1.8 V in the ADP3159, while the ADP3179

provides adjustable output, which is set using an external

resistor divider. These linear regulators are used to generate

the auxiliary voltages (AGP, GTL, etc.) required in most moth-

erboard designs, and have been designed to provide a high

bandwidth load-transient response.

The ADP3159 and ADP3179 are specified over the commercial

temperature range of 0

°C to 70°C and are available in a 20-lead

TSSOP package.

ADOPT is a trademark of Analog Devices, Inc.

Pentium is a registered trademark of Intel Corporation.

Celeron is a trademark of Intel Corporation.