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AD8221 Production
The AD8221 is a gain programmable, high performance instrumentation amplifier that delivers the industry’s highest CMRR over frequency in its class. The...
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AD8221 on Analog.com

AD82221 Single Supply Operation

wolfhorton

on Mar 21, 2023

Category: Hardware

Product Number: AD8221

I would like to use the AD8221 with +Vs = 10V and -Vs = 0V.

The AD8221 datasheet has the following statement:

This implies that the configuration I am targetting is valid.

Unfortunately if I try to simulate this in LTSpice, the simulation fails unless I tie -Vs to at least about -2.5V. So is the single supply configuration not actually valid, despite what the datasheet claims?

Thanks,

Eric

0 wolfhorton
on Mar 21, 2023 3:46 PM
Minor update -- the simulation runs well so long as I tie -Vs to at least -1V. It also runs (very, very slowly) with Vs = -0.5V.

So... Is the -Vs more negative than GND just a simulation limitation? Or is the datasheet statement (single supply supported) incorrect?
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0 wolfhorton
on Mar 21, 2023 3:54 PM
Additional update -- the simulation runs well with +Vs=10V and -Vs tied to ground through a 1p Ohm resistance, but fails if -Vs is tied directly to ground. A 1pico-Ohm resistance is arbitrarily small, so I am happy with these simulation results.

That being said, it would still be nice for an ADI expert / applications engineer to confirm that the single supply operation is a valid operating condition. It is suggested that it is in the single datasheet statement, however there is no other statements / references to this configuration listed.
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0 ADIApproved

on Mar 22, 2023 10:35 PM
Hi Eric,

Good day! I will be working on this. Please let me get back to you once I have an update.

Best regards
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AD82221 Single Supply Operation