AD8420 Datasheet, PDF (1/10 Pages) Analog Devices – Wide Supply Range, Rail-to-Rail Output Instrumentation Amplifier

Preliminary Technical Data
Wide Supply Range, Rail-to-Rail Output
Instrumentation Amplifier
AD8420
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
NC 1
+IN 2
–IN 3
–V_S 4
AD8420
8 _VOUT
7 FB
6 REF
5 +V_S
TOP VIEW
(Not to Scale)
Figure 1.
Table 1. Instrumentation Amplifiers by Category¹
General Zero
Military Low
Digital
Purpose Drift
Grade
Power
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
Rev. PrD
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