Precision Instrumentation Amplifier

AD8221

Rev. A

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FEATURES

Available in space-saving MSOP package

Gain set with 1 external resistor (gain range 1 to 1000)

Wide power supply range:

±2.3 V to ±18 V

Temperature range for specified performance:

–40°C to +85°C

Operational up to 125°C1

EXCELLENT AC SPECIFICATONS

80 dB min CMRR to 10 kHz ( G = 1)

825 kHz –3 dB bandwidth (G = 1)

2 V/µs slew rate

LOW NOISE

8 nV/√Hz, @ 1 kHz, max input voltage noise

0.25 µV p-p input noise (0.1 Hz to 10 Hz)

HIGH ACCURACY DC PERFORMANCE (AD8221BR)

90 dB min CMRR (G = 1)

25 µV max input offset voltage

0.3 µV/°C max input offset drift

0.4 nA max input bias current

APPLICATIONS

Weigh scales

Industrial process controls

Bridge amplifiers

Precision data acquisition systems

Medical instrumentation

Strain gages

Transducer interfaces

GENERAL DESCRIPTION

The AD8221 is a gain programmable, high performance instru-

mentation amplifier that delivers the industry’s highest CMRR

over frequency. The CMRR of instrumentation amplifiers on

the market today falls off at 200 Hz. In contrast, the AD8221

maintains a minimum CMRR of 80 dB to 10 kHz for all grades

at G = 1. High CMRR over frequency allows the AD8221 to

reject wideband interference and line harmonics, greatly

simplifying filter requirements. Possible applications include

precision data acquisition, biomedical analysis, and aerospace

instrumentation.

Low voltage offset, low offset drift, low gain drift, high gain

accuracy, and high CMRR make this part an excellent choice in

applications that demand the best dc performance possible,

such as bridge signal conditioning.

CONNECTION DIAGRAM

8

7

6

5

1

2

3

4

–IN

REF

+IN

TOP VIEW

AD8221

Figure 1. SOIC and MSOP Connection Diagram

40

50

60

70

80

90

100

110

120

FREQUENCY (Hz)

100

10

1k

10k

100k

AD8221

COMPETITOR 1

COMPETITOR 2

Figure 2. Typical CMRR vs. Frequency for G = 1

Programmable gain affords the user design flexibility. A single

resistor sets the gain from 1 to 1000. The AD8221 operates on

both single and dual supplies, and is well suited for applications

where ±10 V input voltages are encountered.

The AD8221 is available in low cost 8-lead SOIC and MSOP

packages, both of which offer the industry’s best performance.

The MSOP requires half the board space of the SOIC, making it

ideal for multichannel or space-constrained applications.

Performance is specified over the entire industrial temperature

range of –40°C to +85°C for all grades. Furthermore, the

AD8221 is operational from –40°C to +125°C1.