topic Re: Loading SPICE models in Fusion Electronics Forum

Loading SPICE models

hupp — Mon, 18 Sep 2023 20:52:17 GMT

I am trying to load a SPICE model for a Texas Instruments opamp (OPA2863A) but having no luck. I was able to extract a simplified .CIR from the TINA model that was supplied by TI. I renamed this "OPA2863A.mdl" so it can be recognized by Fusion. Here is what happens:

- I select the op-amp and choose "Add Spice Model"
- I then click the "Map" button.
- In the Map To Model dialog window I hit the Load Model... button and chose the "OPA2863A.mdl" file. This is loaded in and the model name automatically changes to "OPA2863A". All good!
- Now if I click the "OK" button nothing happens. The dialog window doesn't go away and it does not switch to the "Map P..." tab. If I click on the "Map P..." tab there are no pins to map.

It seems to me that the ngspice engine is not happy with the model file but there is no error message reported. Is there some way to get Fusion to report any ngspice errors? I've attached a screenshot and the model file.

Thanks for any help!
Brian

Re: Loading SPICE models

jorge_garcia — Tue, 19 Sep 2023 22:55:23 GMT

Hi @hupp,

I hope you're doing well. I've passed this along to our developers for review.

Let me know if there's anything I can do for you.

Best Regards,

Re: Loading SPICE models

hupp — Wed, 20 Sep 2023 01:33:30 GMT

Thanks @jorge.garcia! I look forward to any help the team can give.

Re: Loading SPICE models

holger.vogt — Wed, 20 Sep 2023 13:38:56 GMT

Unfortunately my Fusion360 (updated today) ships with ngspice-26, which stems from 2014 and does not support this and other PSPICE compatible models. The most recent ngspice-41 (and several earlier versions) support these models (just tested it with ngspice-41).

You may ask Autodesk for an update (which should not be too difficult as the ngspice API did not change). A simple replacement of ngspice.exe, some libs required by ngspice, and an one line entry into .spiceinit to achieve PSPICE compatibility would be sufficient (and of course some testing would be due).

Re: Loading SPICE models

jorge_garcia — Wed, 20 Sep 2023 17:59:36 GMT

Hello @holger.vogt,

It is always good to hear from you.

@hupp,

Part of the issue is that there is a verification going on of the model, and issues are not reported to the user. This is a known gap in the workflow after and we need to address it. Regarding the upgrade, we are actively working on this and will release Fusion with the latest stable version of ngspice soon

For now we don't have a good way to get the model fixed, it's likely because of something in the SPICE that is proprietary to TINA. I'm personally excited to see the new version of ngspice in Fusion, I've been waiting on it for a while myself.

Let me know if there's anything else I can do for you.

Best Regards,

Betreff: Loading SPICE models

holger.vogt — Wed, 20 Sep 2023 19:48:05 GMT

It is not possible to run the model with ngspice-26. There is no reasonable fix available.

With ngspice-41 however it will run out-of-the-box, both the 'TINA' model as well as the original PSPICE model from TI (https://www.ti.com/lit/zip/sbombg1). PSPICE compatible models are preferred over TINA models, but the differences often are marginal.

Re: Loading SPICE models

hupp — Thu, 21 Sep 2023 04:29:28 GMT

Thanks @holger.vogt and @jorge.garcia! This is very helpful.

So I'll just have to wait until Fusion is updated with a newer ngspice version. @jorge_garcia will the new update use ngspice-41? It sure would be nice if any updates would include an error console showing which line of a SPICE model is causing an issue. Just a thought!

Thanks again!

Re: Loading SPICE models

holger.vogt — Thu, 21 Sep 2023 13:35:02 GMT

If you are courageous, and you are using MS Windows, and you have some know-how on files and folders, you may do an update yourself immediately.

Please have a look at https://ngspice.sourceforge.io/download.html#eagle.

Please note that this is neither endorsed by Autodesk, nor is there any warranty.

Re: Loading SPICE models

hupp — Thu, 21 Sep 2023 16:23:29 GMT

I'm running MacOS but not sure I'd be that daring in any case. But thanks!

Re: Loading SPICE models

jorge_garcia — Thu, 21 Sep 2023 19:27:59 GMT

Hello @hupp,

The new update we are planning will use ngspice41 or whatever the latest version may be at the time. The errors dialog is supposed to surface to show you what the issues are, so that's a bug that is also going to be addressed.

Let me know if there's anything else I can do for you.

Best Regards,

Re: Loading SPICE models

hupp — Fri, 22 Sep 2023 01:13:38 GMT

Thanks @jorge_garcia ! I'm looking forward to the update. I know you can't tell me when it will happen but I can only hope for sooner than later!

Best regards,
Brian

Re: Loading SPICE models

skupinBE26G — Tue, 14 Nov 2023 16:21:35 GMT

When can we expect the new update with the stable ngspice simulation?

My special problem is: I have downloaded .Lib files from Texas Industries and converted them to .mdl files for Fusion and none of them work in Fusion 360. I also tried .cir files from Analog Devices. They only work partially. I added them for reference. Maybe you could check them out.

How can I map them?

Re: Loading SPICE models

jorge_garcia — Tue, 14 Nov 2023 21:37:19 GMT

Hi @skupinBE26G,

I hope you're doing well. The new ngspice engine will be shipped in Fusion soon, keep an eye out for it. For now, unless they are plain SPICE models you can't use them without heavily altering them.

To give some idea, we are already testing the new version of ngspice in our internal betas.

Let me know if there's anything else I can do for you.

Best Regards,

Re: Loading SPICE models

panpan_fan — Tue, 30 Jan 2024 06:26:17 GMT

Hi @hupp @holger.vogt @skupinBE26G

I hope you are doing well!

Today we release Fusion V2.0.18220+ and it will support Pspice model for simulation.

Hope it can solve your problem.

Please upgrade and have a try, thanks!

Regards,

Panpan Fan

Re: Loading SPICE models

skupinBE26G — Fri, 07 Jun 2024 13:53:53 GMT

NICE