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OPA2188 and LTSpice: Incorrect DC solution

Christian Kuhlmann
Prodigy 20 points
Other Parts Discussed in Thread: OPA2188, OPA320, TINA-TI

Hi,

I'm trying to simulate a small circuit using the OPA2188 model file and LTSpice.
I've set up a transient simulation and noticed that the DC solution is not reasonable while the transient response looks ok. At DC, I get a current of 5 kA drawn from the supplies.

I have attached the simulation files for reference.

I wasn't able to find any mistake in the simulation and the same circuit simulates without any problems when I use the TI model of the OPA320 instead.

Any help would be very much appreciated.

4452.OPA2188_LTSpice.zip

  • 0
    TI__Expert 6275 points

    See attached modified OPA2188.lib file.  Replace it with what you are using.  I fixed the net list by removing some IC=0 initial conditions which do not belong in there.  Let us know if any other problems.

    OPA2188.lib
  • 0 in reply to Tim Green1
    Prodigy 20 points

    Hi Tim,

    thanks for your help, the updated file solved the issue with the DC operating point. Unfortunately after this change there seems to be some convergence issue. After a few nanoseconds the solvers step size goes down to fsec. I'm using the latest version of LTSpice with convergence hacks enabled. The schematic is the same that I've attached to my previous post.

  • 0 in reply to Christian Kuhlmann
    TI__Expert 6275 points

    We have developed our newer op amp macro models to run best in our free SPICE simulator TINA-TI available at:

    http://www.ti.com/tool/tina-ti

    It has an intuitive easy-to use GUI interface.  Because TINA has an advanced math engine for convergence compared with other standard SPICE simulators we are seeing some issues with the macro models in other PSPICE based simulators.  We are working on a version of the model which will be more compatible in other PSPICE based simulators.  This will not be immediate so I would encourage you to consider TINA-TI for your SPICE simulations.    

  • 0 in reply to Tim Green1
    Expert 1220 points

    This is a thread hijack!

    I would like to comment and say I would encourage PSpice models to always be generic or at least offer a generic version with the release of the TINA version.

    There is a movement in the industry for companies to provide their own flavor of Spice. TI works with DesignSoft, ADI works with National Instruments, Intersil works with Simetrix. It's a little annoying for each company to say, "Well, please download OUR spice." I do not want to have 5 different versions of Spice when I am designing a circuit.

    LTSpice is from Linear, and I know they are a competitor to everyone, but LTSpice is a fantastic tool that is a *full* version and best of all it's *free*. Not to mention a strong support group on Yahoo. It's been ported to OSX too! 
    A-MAZING.

    -Ken

  • 0 in reply to Ken Dillinger
    Prodigy 55 points

    I want to second what Ken said.

    I work at Honeywell Aerospace, and ALL of the top circuits gurus are using LTSpice for analysis.  LT is winning the war with the people that matter.

    Love TI products, support, and development kits! Keep up the great work

  • 0 in reply to Dave Johnson
    Prodigy 30 points
    LTspice IV works just fine with the original circuit and model posted by Christian if the Engine Solver is set to Alternate and in the Transient menu the option "Start external DC supply voltages at 0V:" is activated. I didn't check the modified model posted by Tim.