OPA140: input common-mode voltage specification

John Gray

Part Number: OPA140
Other Parts Discussed in Thread: OPA192, OPA828, OPA1677, OPA4192

I would like to verify that the common-mode input voltage range is correct on the datasheet, (V-)-0.1 min, (V+)-3.5 max. For a ±15 power system that limit the common mode to -15.1V to 11.5V. For a +5V power system that would limit the common mode to -0.1 to 1.5V.

Thanks, John

6 months ago

+1 Clemens Ladisch 6 months ago

Guru 244360 points

Yes, the datasheet is correct. Also see figure 6-5.

0 John Gray 6 months ago in reply to Clemens Ladisch

Intellectual 310 points

Clemens, thanks. I was hoping there was a mistake or I missed something.

have a good day!

0 Zach Olson 6 months ago in reply to John Gray

TI__Expert 7285 points

Hi John,

There is no mistake, this is the correct common-mode input range. Typically, the OPA140 is used in gain configurations in which the input common-mode range is not a limiting factor. If you require a wider common-mode input range for something like a voltage-follower circuit, we can recommend a more suitable device for the application.

Regards,

Zach

0 Michael Hartshorne 6 months ago in reply to Zach Olson

TI__Genius 10680 points

Hi John,

Is this still looking looking for a replacement for OPA192? I am still looking into the composite amp., but, I do think it will be difficult to end up with a solution that isn't overly complicated. I'll get back to you on this tomorrow.

Regards,
Mike

0 Michael Hartshorne 5 months ago in reply to Michael Hartshorne

TI__Genius 10680 points

John,

An update on the composite amp. design: I cannot find a good combination of amplifiers (OPA192 + a fast, low-Iq amplifier) that give much of a settling time benefit with a lower Iq than OPA828; I did manage to get a lower settling time with 3 mA total (using OPA192 input + OPA1677 as the output amplifier), but I know you were also looking for a design that works at 5 V, which this would not (OPA1677 does not have RRIO). My general feeling is that the composite amp. will not yield a great solution.

Sorry but I don't have anything to offer regarding the composite.

Regards,
Mike

0 John Gray 5 months ago in reply to Michael Hartshorne

Intellectual 310 points

Thanks Michael Hartshorne, Zach Olson, and Clemens Ladisch .

I'm going to do a slight change on the discussion. I wonder if a single ended to differential output would be a better fit? Needs a gain of 0.4V/V and again going from a ±12V max signal range to about ±4.082V range centered around 2.5V differential. Is there an area of components that might work for ADC conversion?

Thanks,

-John Gray

0 Zach Olson 5 months ago in reply to John Gray

TI__Expert 7285 points

Hi John,

I see there was a lot of discussion about your specific circuit requirements on this thread: OPA4192: Settling Time circuit topology for Data sheet and Typical Characteristics

For simplicity, I will suggest that we continue the conversation on the original thread. This will make it easier for us to support, as all of the information will be available to us on that post.

As the question about OPA140 input common-mode has been resolved, I will go ahead and close this thread for now.

Please post your follow-up question to the original OPA4192 thread, linked above, and we will continue to support.

Thanks,

Zach

0 John Gray 5 months ago in reply to Zach Olson

Intellectual 310 points

Zach Olson the question on the CM range of the OPA140 has been resolved. Thank you all.

-John Gray

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OPA140: input common-mode voltage specification