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TINA/Spice/OPA4188: Convergence issues with even simple circuits using OPA4188

Paul Goodwin
Prodigy 80 points
Part Number: OPA4188
Other Parts Discussed in Thread: TINA-TI, , OPA188

Tool/software: TINA-TI or Spice Models

I’m have convergence issues using this model in even simple circuits - for example a simple inverting amplifier with unity gain ( Rf= 20K, Rin = 20K, OA (+) input to god = 10K, load = 100K. I’m running the OA of a +/- 12 V supply.

I’m able to get this circuit to converge in DC and transient analysis by varying the load resistance - reduced it to 10K.

I also increased the supply voltage from +/-12 to +/-15 volts

I took this simple circuit when it converted and change the input resistor from a singe resistor to two series resistors with a slightly different value and it no longer converged.

Is the OPA4188 model inherently hard to use?

  • 0
    TI__Guru* 93105 points

    Hi Paul,

    The OPA4188 simulation model is a complex model and an early version of what we refer to as our Green-Lis model. This early version can present a conversion challenge under some conditions, and with some Spice simulators.

    A newer version of the OPA188 simulation model has been in development. We refer to this version as the OPA188_GLW model. It is still a beta version, but once it is fully tested and veted it will replace the OPA4188 model currently on the web page. Note we use the OPA188 model for the single, dual, and quad version of the product.

    I am sending you the TINA Spice circuit using the new, OPA188_GLW beta model. You can copy and paste it into any TINA circuit. Give it a try and see if it converges more readily for you. If you still have problems, let us know.

    Regards, Thomas

    Precision Amplifiers Applications Engineering

    OPA188_GLW_Test_01.TSC

  • 0 in reply to Thomas Kuehl
    Prodigy 80 points
    Thank you very much
  • 0 in reply to Thomas Kuehl
    Prodigy 80 points
    I'm not skilled enough yet in TINA-TI Spice to know how to incorporate a model downloaded from the TI website. I downloaded it OK - it's an unzipped folder on my desktop with 3 files in it: OPA188.lib, OPA188.tld, and OPA188.TSM
  • 0 in reply to Paul Goodwin
    Prodigy 80 points
    Sorry - I downloaded the schematic: OPA188_GLW_Test_01.TSC. I've got it running now. Thanks.

    If you could lead me to the simplest explanation of how to incorporate this model into the TINA-TI Spice library, it would be greatly appreciated
  • 0 in reply to Paul Goodwin
    Prodigy 80 points

    I played around with the circuit I was having problems with and it works fine with the OPA188 model. I was doing unit step response analysis, and things look like they should. Thanks again.

  • 0 in reply to Paul Goodwin
    TI__Guru* 93105 points

    Hi Paul,

    I am glad to hear the OPA188_GLW model is working well for you.

    New simulation models are normally added to the TINA library by our Webench Simulation Models team. I haven't done that on my own. What I most often do when I get a new model is save it to a designated "new model" folder on my computer. Then, when I need to use it I simply use the Insert > Macro functions in TINA. TINA will then have you provide the file location information and the model will appear in the workspace.

    There has been some discussion about adding simulation files to the library on the Webench Simulation Models E2E forum. That may be of some help with your question:

    Most often, I simply access the xxxx.TSC TINA circuit file available inder the product page TOOLS tab and open it in TINA. Then, I simply click on the model's icon and copy and paste it into the new circuit I am working on.

    Once I have used the new simulation model in the new TINA circuit I save it for next time.

    I hope this helps!

    Regards, Thomas

    Precision Amplifiers Applications Engineering

  • 0 in reply to Thomas Kuehl
    Prodigy 80 points
    Thanks. When I opened the schematic you gave me with the beta model, it auto-saved that schematic on the c-drive. I did the copy/paste method you described into my schematic and saved it. Again, it worked great, and thanks.