REV. 0

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a

ADP3170

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

VRM 8.5 Compatible

Single Phase Core Controller

FUNCTIONAL BLOCK DIAGRAM

OSCILLATOR

PWM

LOGIC

SET

RESET

CROWBAR

3.0V

REFERENCE

1.8V

DAC +20%

DAC –20%

CMP

REF

VID

DAC

REF

VID25

VID0

VID1

VID2

VID3

UVLO

AND BIAS

SD

DRVH

VCC

GND

REF

LRFB

LRDRV

COMP

DRVL

PGND

PWRGD

CS–

CS+

FB

CT

ADP3170

FEATURES

Optimally Compensated Active Voltage Positioning

with Gain and Offset Adjustment (ADOPT™) for

Superior Load Transient Response

Complies with VRM 8.5 Specifications with Lowest

System Cost

5-Bit Digitally Programmable 1.05 V to 1.825 V Output

N-Channel Synchronous Buck Controller

Onboard 1.8 V Linear Regulator Controller

Total Accuracy

1% Over Temperature

High Efficiency Current-Mode Operation

Short Circuit Protection

Power Good Output

Overvoltage Protection Crowbar Protects

Microprocessors with No Additional External

Components

APPLICATIONS

Core and 1.8 V Standby Supplies for Next Generation

GENERAL DESCRIPTION

The ADP3170 is a highly efficient output synchronous buck

switching regulator controller optimized for converting a 5 V

main supply into the core supply voltage required by next

generation Intel Celeron processors. The ADP3170 uses an

internal 5-bit DAC to read a voltage identification (VID)

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

output voltage between 1.05 V and 1.825 V. The ADP3170

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 ADP3170 also uses a unique supplemental regulation tech-

nique called Analog Devices Optimal Positioning Technology

(ADOPT) to enhance load transient performance. Active

voltage positioning results in a dc/dc converter 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 that it is always

optimally positioned for a system transient. The ADP3170 also

provides accurate and reliable short circuit protection and

adjustable current limiting. It also includes 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 ADP3170 contains a 1.8 V linear regulator controller that

is designed to drive an external N-channel MOSFET. This linear

regulator can be used to generate auxiliary voltages (such as 1.8 V

standby power) required in most motherboard designs, and has

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

The ADP3170 is specified over the commercial temperature range

of 0

°C to 70°C and is available in a 20-lead TSSOP package.

ADOPT is a trademark of Analog Devices, Inc.

Pentium is a registered trademark of Intel Corporation