OPA2626: Input of OPA2626

user4090349

Part Number: OPA2626

Tool/software:

Hello

I perform a simulation to check the output of OPA2626 when the input voltage is out of range. But the result is not what I expected.

Here I use 3.3V to supply OPA2626, so VCM should be less than 3.3-1.15 = 2.15V. The transfer ratio is I perform a DC sweep of V3 from 1.5V to 2.6V.

And the curve start to turn at 1.6V, at I expect it to change at (3.3-1.5)/13.4+1.5 = 1.63V. Could you tell me why?

10 months ago

0 user4090349 10 months ago

Intellectual 971 points

0 user4090349 10 months ago in reply to user4090349

Intellectual 971 points

For a non rail to rail input, does that mean when the input voltage exceed the VCM range, the output is similar as the input voltage at VCM range.

+1 Vikas Jeevannavar 10 months ago in reply to user4090349

TI__Expert 3186 points

Hi,

I replicated the schematic in TINA, and I found the curve turns at 1.63V. I have given a step size of 26mV in DC sweep, and it looks like your simulation has considered 0.05V step and connected the datapoints later. I recommend you decrease the step size or increase the datapoints in the simulation to get accurate results.

Thanks
Vikas J

0 user4090349 10 months ago in reply to Vikas Jeevannavar

Intellectual 971 points

Thanks a lot for your explanation. You are right. And for an Op Amp without rail to rail input as OPA2626, supply voltage 3.3V. So VCM is 3.3-1.15=2.15V.

If the input VCM higher than 2.15V. Does the output stay with the status of VCM = 2.15V?

Thanks!

+1 Vikas Jeevannavar 10 months ago in reply to user4090349

TI__Expert 3186 points

Hi,

We do not recommend any voltage outside the specified operations in electrical table. The output of the amplifier will be undetermined and depends on the internal architecture of the inputs.

Thanks
Vikas J

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OPA2626: Input of OPA2626