Data Sheet

AD8422

High Performance, Low Power, Rail-to-Rail Precision Instrumentation Amplifier

Rev. C

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FEATURES

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Low power: 368 µA maximum quiescent current

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Rail-to-rail output

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Low noise and distortion

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8 nV/√Hz maximum input voltage noise at 1 kHz

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0.15 µV p-p RTI noise (G = 100)

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0.5 ppm nonlinearity with 2 kΩ load (G = 1)

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Excellent ac specifications

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80 dB minimum CMRR at 10 kHz (G = 1)

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2.2 MHz bandwidth (G = 1)

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High precision dc performance (AD8422BRZ)

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150 dB minimum CMRR (G = 1000)

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0.04% maximum gain error (G = 1000)

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0.3 µV/°C maximum input offset drift

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0.5 nA maximum input bias current

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Wide supply range

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4.6 V to 36 V single supply

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±2.3 V to ±18 V dual supply

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Input overvoltage protection: 40 V from opposite supply

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Gain range: 1 to 1000

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Available in 8-lead LFCSP, 8-lead MSOP, and 8-lead SOIC_N

APPLICATIONS

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Medical instrumentation

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Industrial process controls

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Strain gages

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Transducer interfaces

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Precision data acquisition systems

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Channel-isolated systems

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Portable instrumentation

TYPICAL APPLICATION DIAGRAM

Figure 1. Bridge Amplifier with Output Zero Adjust

GENERAL DESCRIPTION

The AD8422 is a high precision, low power, low noise, rail-to-rail

instrumentation amplifier that delivers the best performance per unit

microampere in the industry. The AD8422 processes signals with

ultralow distortion performance that is load independent over its full

output range.

The AD8422 is the third generation development of the industry-

standard AD620. The AD8422 employs new process technologies

and design techniques to achieve higher dynamic range and lower

errors than its predecessors, while consuming less than one-third

of the power. The AD8422 uses the high performance pinout

introduced by the AD8221.

Very low bias current makes the AD8422 error free with high source

impedance, allowing multiple sensors to be multiplexed to the

inputs. Low voltage noise and low current noise make the AD8422

an ideal choice for measuring a Wheatstone bridge.

The wide input range and rail-to-rail output of the AD8422 bring

all of the benefits of a high performance in-amp to single-supply

applications. Whether using high or low supply voltages, the power

savings make the AD8422 an excellent choice for high channel

count or power sensitive applications.

The AD8422 uses robust input protection that ensures reliability

without sacrificing noise performance. The AD8422 has high ESD

immunity, and the inputs are protected from continuous voltages up

to 40 V from the opposite supply rail.

A single resistor sets the gain from 1 to 1000. The reference pin

can be used to apply a precise offset to the output voltage.

The AD8422 is specified from −40°C to +85°C for the 8-lead MSOP

and the 8-lead SOIC_N and from −40°C to +125°C for the 8-lead

LFCSP.