TL081A: Amplifier

Abhishek Kumar

Part Number: TL081A
Other Parts Discussed in Thread: TL081, TLV9052, TLV9051,

Tool/software:

I am using TL081 op- amp for voltage sensing. But, at some voltage level I can see that the output voltage of the op- amp is taking a dip to half the voltage level and then returns back to the original level. Kindly, suggest why this could be?

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 318030 points

Are you using an actual TL081, or some simulation? Some simulation models do this when the input voltage is outside the allowed range and the output would be undefined.

0 Gerasimos Madalvanos over 1 year ago in reply to Clemens Ladisch

TI__Mastermind 33151 points

Hello Abhishek,

Could you please provide a schematic, as well as oscilloscope probes of the inputs/outputs when this behavior is happening?

Best,
Jerry

0 Abhishek Kumar over 1 year ago in reply to Clemens Ladisch

Prodigy 20 points

Yes, I am using an actual TL081 op- amp.

0 Gerasimos Madalvanos over 1 year ago in reply to Abhishek Kumar

TI__Mastermind 33151 points

Hey Abhishek,

Are you able to supply a schematic as well as oscilloscope probes of the inputs and outputs when this behavior is happening?

Best,
Jerry

0 Abhishek Kumar over 1 year ago in reply to Gerasimos Madalvanos

Prodigy 20 points

Hello Jerry,

0 Gerasimos Madalvanos over 1 year ago in reply to Abhishek Kumar

TI__Mastermind 33151 points

Hello Abhishek,

Is the op amp in a valid common mode range and output range? Please see below table for +/-15V supply. Valid common mode range for schematic provided is 3V to 5V, and the valid output range is 1.5V to 3.5V. I would recommend a different amplifier for 5V single supply operation, like the TLV9052.

Best,
Jerry

0 Abhishek Kumar over 1 year ago in reply to Gerasimos Madalvanos

Prodigy 20 points

Hello Jerry,

Thank you for your reply.

How can I verify the Common mode voltage range?

Regards

Abhishek

0 Clemens Ladisch over 1 year ago in reply to Abhishek Kumar

Guru 318030 points

The required headroom from the power rails is constant, i.e., you need to keep 3 V away from both rails. This means that the TL0xx must be used with more than 6 V.

The TLV9051 has rail-to-rail inputs, i.e., the specified common-mode range includes both power rails.

0 Jacob Nogaj over 1 year ago in reply to Clemens Ladisch

TI__Genius 15406 points

Hi Abhishek,

Jerry and Clemens are correct, the easiest solution here would be to utilize the TLV9051. The TLV9051 device will have a much wider common mode input range than the TL081A.

Here is a training video which covers this concept in greater detail: TIPL Common Mode Voltage

Please let me know if you have any further questions.

Best,

Jacob

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TL081A: Amplifier