Wide Supply Range, Micropower,

Rail-to-Rail Instrumentation Amplifier

Data Sheet

AD8420

Rev. 0

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FEATURES

Maximum supply current: 80 μA

Minimum CMRR: 100 dB

Drives heavy capacitive loads: ~700 pF

Rail-to-rail output

Input voltage range goes below ground

Gain set with 2 external resistors

Can achieve low gain drift at any gain

Very wide power supply range

Single supply: 2.7 V to 36 V

Dual supply: ±2.7 V to ±18 V

Bandwidth (G = 100): 2.5 kHz

Input voltage noise: 55 nV/√Hz

High dc precision

Maximum offset voltage: 125 μV

Maximum offset drift: 1 μV/

°C

Maximum differential input voltage: ±1 V

8-lead MSOP package

APPLICATIONS

Bridge amplifiers

Pressure measurement

Medical instrumentation

Portable data acquisition

Multichannel systems

PIN CONFIGURATION

8

FB

7

REF

6

5

AD8420

TOP VIEW

(Not to Scale)

+

–

–

+

Figure 1.

General Purpose

Zero

Drift

Military

Grade

Low

Power

Digital

Gain

AD8221, AD8222

AD8231

AD620

AD8420

AD8250

AD8220, AD8224

AD8290

AD621

AD8235,

AD8236

AD8251

AD8226, AD8227

AD8293

AD524

AD627

AD8253

AD8228

AD8553

AD526

AD8226,

AD8227

AD8231

AD8295, AD8224

AD8556

AD624

AD623

AD8557

AD8223

GENERAL DESCRIPTION

The AD8420 is a low cost, micropower, wide supply range,

instrumentation amplifier with a rail-to-rail output and a novel

architecture that allows for extremely flexible design. It is optimized

to amplify small differential voltages in the presence of large

common-mode signals.

The AD8420 is based on an indirect current feedback architecture

that gives it an 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 rail-to-rail output, and the output

voltage swing is completely independent of the input common-

mode voltage.

Single-supply operation, micropower current consumption, and

rail-to-rail output swing make the AD8420 ideal for battery-

powered applications. Its rail-to-rail output stage maximizes

dynamic range when operating from low supply voltages. Dual-

supply operation (±15 V) and low power consumption make

the AD8420 ideal for a wide variety of applications in medical

or industrial instrumentation.

The AD8420 is available in an 8-lead MSOP package. Performance

is specified over the full temperature range of −40°C to +85°C,

and the part is operational from −40°C to +125°C.