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.

Problems with Pspice model OPA335

Other Parts Discussed in Thread: OPA335, DXP

I have some problem in simulating this opamp in Altium pspice.

In the past i thought this model worked but there seems to be a problem in it.

6646.OPA335.zip

 I get an error message:

                Source  Message             Time      Date      No.

                 XSpice  singular matrix:  check nodes e39\xu1#branch and e42\xu1#branch   

 

This causes the iteration to hit the limits without results during Simulation.

 I need this model for stability analysis of a precision current source I am debugging.

I tried the tina model in TiNa and there it works. But that is a different spice dialect.

We are standardized on Altium spice and thi sis quite a problem at the moment.

Simulation in tina s no option because the FET I use(IRLL110PbF)is not in the tina library.

Any solution?

  • Hello Bert,

    The OPA335 model syntax was developed using a Cadence PSpice compatible simulator. Because of this, it runs on TINA Spice and other PSpice based simulators. I think that Altium uses the SIMetrix Spice simulator, but I am not certain about that. Both Altium and SIMetrix speak of their simulators using "enhanced" Spice which means there may be some subtle differences between them and others. That may create some issue for the OPA335 model. Unfortunately, we don't have the Altium simulator available for our use.

    The "singular matrix" error code you are receiving is one of several errors that indicate a convergence problem. Can you share the circuit diagram of the circuit you are attempting to simulate? If so, we can try and set up the circuit in one of our alternate PSpice compatible simulators and see if we can get the error.

    Regards, Thomas

    PA - Linear Applications Engineering

  • Hi Bert,

    We found the PSpice model listing for the IRLL110 MOSFET on line and set it up for TINA Spice. You can use this MOSFET model, along with the OPA335 model, and simulate your circuit using TINA.You'll find the TINA model contained within the attached TINA circuit file.

    Simply copy and past the IRL110 MOSFET symbol into your TINA circuit containing the OPA335 and wire it as needed.

    Regards, Thomas

    PA - Linear Applications Engineering

    IRLL110 Macro Test.TSC
  • Hi Thomas Thanks a lot. I will give it a try today.

    I have been told Altium uses Xspice.

    I assume you have altium at TI also as you acquired NSC

    At the time I worked for NSC Altium (a few years ago) was used for all application engineers world wide.

    And I understand that the workbench application is supporting altium also so maybe that will make it more adopted within  TI?

    Greets,\

    Bert

  • Hello Bert,

    We use Altium for PC board layout, but do not have access to its circuit simulation software - at least not in our group. Our primary simulation software is TINA Spice which is probably apparent.

    Let me know if the circuit simulates as in needed with TINA now that you have the MOSFET.

    Regards, Thomas

    PA - Linear Applications Engineering

  • Hi Thomas,

    I tried the model and it simulates OK in TINA. in practice both simulators have their own quality.

    And I got the current source stability  right with enough closed loop BW also so I succeeded.

    If you have altium layout you definitely have altium spice inside. Or only have to activate the option.

    All Altium licenses include simulation.

    If you are in Altium ,

    Click DXP and MyAccount.

    Then under the window with the available licenses you will see A Extensions and updates (3rd column)  There you can enable the Altium extension.

    There is also a first tie signal integrity extension.

    Greets

    Bert

  • Hi Bert,

    Glad to hear your OPA335 circuit is simulating okay using TINA. Indeed each of the simulators do have their own merits, and drawbacks.

    Thanks for the info regarding the Altium simulator. I will give it a look next time I am using the program.

    Regards, Thomas

    PA - Linear Applications Engineering