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.

FEATURES

Maximum supply current: 90 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