Wide Supply Range, Rail-to-Rail Output

Instrumentation Amplifier

Preliminary Technical Data

AD8420

Rev. PrD

Information furnished by Analog Devices is believed to be accurate and reliable. However, no

responsibilityisassumedbyAnalogDevicesforitsuse,norforanyinfringementsofpatentsorother

rightsofthirdpartiesthatmayresultfromitsuse.Specificationssubjecttochangewithoutnotice.No

license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.

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

Tel: 781.329.4700

www.analog.com

Fax: 781.461.3113

©2011 Analog Devices, Inc. All rights reserved.

FEATURES

Gain set with 2 external resistors

Gain range: 1 to 1000

Input voltage goes below ground

Very wide power supply range

Single supply: 2.7V to 36V

Dual supply: +/-2.7V to+/-18V

Bandwidth (G=100): 2.5 kHz

Input noise: 50 nV/√Hz

Max supply current: 90 µA

Max offset voltage: 200 uV

Max differential input voltage: 1V

Min CMRR: 100 dB

MSOP-8 package

APPLICATIONS

Bridge amplifiers

Pressure Measurement

Medical instrumentation

Portable data acquisition

Multichannel systems

PIN CONFIGURATION

TOP VIEW

(Not to Scale)

–IN

1

NC

2

3

+IN

4

8

7

REF

6

5

AD8420

FB

Figure 1.

General

Purpose

Zero

Drift

Military

Grade

Low

Power

Digital

Gain

AD8221/2

AD8231

AD620

AD8420

AD8250

AD8220/4

AD8290

AD621

AD8235/6

AD8251

AD8228

AD8293

AD524

AD627

AD8253

AD8295

AD8553

AD526

AD8226/7

AD8231

AD8556

AD624

AD623

AD8557

AD8223

1

See www.analog.com for the latest instrumentation amplifiers.

GENERAL DESCRIPTION

The AD8420 is a low cost, wide supply range amplifier that uses

two resistors to set any gain between 1 and 1000. It is optimized

to amplify small differential voltages in the presence of large

common mode signals.

The AD8420 is based on a current mode architecture that gives

it excellent input common mode range. Unlike conventional

instrumentation amplifiers, the AD8420 can easily amplify

signals at or even slightly below ground without requiring dual

supplies. The AD8420 has a full rail to rail output, and the

output voltage is completely independent of the input common

mode voltage.

The AD8420 can operate off both single or dual supplies. It

works well for a portable system with a limited single supply

voltage and equally well for a system using large dual supplies.

Gain is set using the ratio of two resistors. A reference pin

allows the user to offset the output voltage. This feature is useful

when the output signal needs to be centered around a specific

voltage, such as mid-supply.

The AD8420 is available in an 8 pin MSOP package.

Performance is specified over the full temperature range of

−40°C to +85°C. Part is operational from −40°C to +125°C