WEBENCH® Tools/LMP8672: LMP8672

Michael Steffes

Part Number: LMP8672

Tool/software: WEBENCH® Design Tools

I was trying to get a demo design out of the LP Webench tool, I was able to get a design, and even got it to export to TINA, but when I run it the response is not close to target - can't see anything wrong, DC nodes simulate correctly - something wrong with the TINA model for theLMP8672? Or maybe I am missing something, here is the response where I modified a known working file the filter designer output. That -65dBc is not close.

here is this file,

LMP8671 webench MFB new model.TSC

Here is the webench exported file,

Exported Webench LMP8671 design.TSC

over 6 years ago

0 Michael Steffes over 6 years ago

Guru 48395 points

Oh and actually, I just went into the op amp macro's and the product folder model is the same as the TINA library I think. But, the Webench download reverses the supplies and says the model is encrypted?? Why? you can see it on the product folder pretty easily.

0 Jacob Freet over 6 years ago in reply to Michael Steffes

TI__Expert 8680 points

Hi Michael,

I'm going to get someone from WEBENCH to help out here.

Regards,

0 Michael Steffes over 6 years ago in reply to Jacob Freet

Guru 48395 points

Not likely to go anywhere,

I did just remove the MFB elements from the exported Webench TINA sim. Still doesn't work, likely a LMP8672 model problem - if so, the message for webench is to make sure their candidate devices operate correctly in simulation.

0 Alfred Chong over 6 years ago

TI__Expert 3482 points

Michael,

Could you please provide the input spec for your design?

Regards,

Alfred

0 Michael Steffes over 6 years ago in reply to Alfred Chong

Guru 48395 points

Hey Alfred, I am thinking this is a bad model on the LMP8672, the exported Webench TINA file is in the first post here, you can run it yourself - I can't find any errors and if I adapt a known working MFB design to this design, it gives the same result.

0 Alfred Chong over 6 years ago in reply to Michael Steffes

TI__Expert 3482 points

Michael,

I agreed with you that this is a model issue as the design works fine with other op-amp model.

I will reach out to the stakeholder for this issue.

Thanks for bringing this issue to us!

Regards,

Alfred

0 Michael Steffes over 6 years ago in reply to Alfred Chong

Guru 48395 points

Yea Alfred, I already did that, but

It might be prudent for your team to assign someone the task of vetting the models for the device subset you are including in the tool. Many have been recently updated, so you skip testing those - but if you run into an older (non-updated) device like this one - a quick test will suggest removing them for now from the solution universe. I kind of doubt a part like this will get any priority for updating the model, but it looks like a pretty good device physically.

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WEBENCH® Tools/LMP8672: LMP8672