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TINA/Spice/OPA211: OPA211 model have strange comportment

Etienne Haenni
Prodigy 200 points
Part Number: OPA211
Other Parts Discussed in Thread: TINA-TI, , OPA313

Tool/software: TINA-TI or Spice Models

Dear Miss, Dear Mister,


I'm currently simulating a current source which use the OPA211.

Unfortunately, the behavior of the circuit is quite strange.

To compare I copy the schematic and replace the amplifier with an OPA313. The version with the OPA313 work as expected.

In green is the output current with the OPA211, in red the output current with the OPA313:

Could you please take a look at the OPA211 model?

Thanks in advance.

Kind regards.

Etienne

  • 0
    TI__Genius 9775 points

    Hi Etienne,

    Your application is unity gain follower that requires at least an opamp that its input can rail up to +Vsupply.

    By looking at the datasheet, OPA313 can approach around 0.2V from +Vsupply while OPA211 can only approach

    1.4V from supply.



    Thus OPA211 for your application will fail while OPA313 will not.


    Herman

  • 0 in reply to Herman Theodorus
    Prodigy 200 points

    Dear M. Theodorus,


    Thank you for your reply.

    In fact I have the habit to work with the other amplifier of the OPA3xx series which have rail to rail input. Due to this I didn't check the input limitation of the OPA211.

    I correct my design by applying a +/-15V supply at the OPA211 and everything works well now.

    Sorry for this unneeded request for model correction.

    Kind regards.

    Etienne