LMP7721: LMP7721 as voltage follower

Nirav Gadhiya

Prodigy 205 points

Part Number: LMP7721
Other Parts Discussed in Thread: OPA376, OPA316, OPA320, OPA365

Hello,

I am using LMP7721 in three electrode potentiostat (homemade) as a voltage follower.

I have tested the same but getting negative voltage output.

I have attached the circuit diagram for same.

How can I test the LMP7721, whether it is ok or not??

Which op-amp are best to use in potentiostat application???

over 7 years ago

0 Marek Lis over 7 years ago

TI__Guru 60480 points

Nirav,

The LMP7721 has a non-standard pinout but your circuit should work the way your schematic shows it. What output voltage do you see? I suspect that you may have inadvertently swapped input or supply pins - please double check your connections. Please be aware that on +/-2.5V supply, linear input common-mode voltage range extends only up to 1.5V (but Vcm of 1V you show should be fine.) As an alternative, you may also consider, OPA316, OPA320, OPA376, or OPA365 - however, thay all come in a standard pinout (different than LMP7721).

0 Nirav Gadhiya over 7 years ago in reply to Marek Lis

Prodigy 205 points

Thanks Marek Lis.
I want to use CA3140 op-amp in my application of potentiostat.
Is it fine in the application??

0 Marek Lis over 7 years ago in reply to Nirav Gadhiya

TI__Guru 60480 points

CA3140 is not TI part thus I cannot comment on its performance.

0 Nicholas Schlensky over 7 years ago in reply to Marek Lis

Prodigy 120 points

I have used this amp as a follower for a similar application and it is a nice device which does work as shown. I remember the Vcm spec requires carefull attention however

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LMP7721: LMP7721 as voltage follower