• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 47 subscribers
  • Views 194 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

OPA2991: Floating nodes in PSpice (Cadence 17.4)

Tim Harper
Prodigy 10 points
Part Number: OPA2991
Other Parts Discussed in Thread: TLE2142, , OPA991

Tool/software:

I recently downloaded the PSpice model for the OPA2991 (sbomb49b.zip) from the TI website and attempted to use in my simulation.  This sim works great with other TI models that I have and simulates just fine.  Most recently I used a model for the TLE2142 and it was very smooth.  However, when I pop that out and drop in the OPA2991, I get a bunch of floating node errors. 

The model seems to have some transconductance amplifiers around these failed nodes, so I'm guessing the Spice engine is somehow not seeing a good reference to ground in there and is freaking out.  

I cannot post my schematic for proprietary reasons, but suffice it to say that it DOES run just fine with several other opamp models, just not this one, and I am planning to use the OPA991 in my design.  

Has anyone else had this issue with the OPA2991 PSpice model, and did you find a workaround?  Additionally, perhaps you can recommend another opamp model that I can try that is very close to the OPA2991?  

Thanks! 

  • 0
    TI__Mastermind 23678 points

    Tim,

    • I ran the model in PSpice for TI and did not have any issues.  I have seen cases in the past where people used a different version of PSpice and had simulation issues.
    • Below is the exact procedure I used to import the model and run the simulation.
    • If you are using a different version of PSpice you may need to use PSpice for TI.

    opa2991-sim-model-test.pdf

    Best regards,

    Art

  • 0 in reply to Art Kay
    Prodigy 10 points

    Thank you Art!  

    I will give this a shot after lunch and see if it fixes my issue.  If not, I went ahead and downloaded PSpice for TI and will get it installed.  Do you happen to know if installing PSpice for TI will interfere with the existing Cadence installations on my computer?  Or is it completely separated?  

    Kind regards,

    Tim

  • +1 in reply to Tim Harper
    TI__Mastermind 23678 points

    Tim,

    My experience has been that the two version can both be present on your computer and will not interfere with each other.  In the past I had a full professional version of Cadence on my computer and was able to use both PSpice for TI and the full-Cadence version.  Other engineers have done the same without issue.  I suppose it is possible that some versions may not be compatible or cause issue but I have not heard of that happening yet.

    Another option is TINA spice.  While PSpice does have some advantages over TINA, most engineers I know prefer TINA as it is intuitive and easy to use.

    Best regards, Art

  • +1 in reply to Art Kay
    Prodigy 10 points

    Hi Art, 

    So, I wasn't successful in getting my simulation to run in PSpice for TI, but after loading it on my computer and bringing the TI models into my full version of PSpice, I was able to run my sim in the the full version of PSpice (Cadence 17.4) with the OPA2991 model. All seems to be fixed now.   Not sure why the model in the new application fixed it over the one I downloaded from TI's website, but it did and I'm not going to question or complain.  ;-)

    Thanks again for your help!  It was cool working with you on this.  I am looking at my personal copy of your 'Analog Engineer's Pocket Reference' right now...it always has a place on my desk.  

    Have a great afternoon!

    Cheers,

    Tim