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OPA348: spice model seems to be not inclued Zo behavior

yang fan
Prodigy 60 points
Part Number: OPA348
Other Parts Discussed in Thread: TINA-TI

Tool/software:

first,opa348 pspice project from TI cann't be opened, reported a mistake;

second,by opa348 spice model I cann't simulate correct Zo curve,which can be obtained through TINA.

I suspect that opa348 spice model and according project have a problem.

  • 0
    TI__Mastermind 28240 points

    Hi Yang,

    Thank you for reporting this! I have a few questions to see what needs to be fixed. 

    yang fan said:
    first,opa348 pspice project from TI cann't be opened, reported a mistake;

    Did you use the OPA348 from Pspice for TI's internal library or is it from the web? 

    yang fan said:
    second,by opa348 spice model I cann't simulate correct Zo curve,which can be obtained through TINA.

    Where did you pull this spice model? Was this on the web or from TINA-TI internal library? 

    Thank you,

    Robert Clifton 

  • 0 in reply to Robert Clifton56
    Prodigy 60 points

    I download Pspice project from this link https://www.ti.com.cn/cn/lit/zip/sboc001,which include these files as below,

    I use OrCAD capture to open opa348.opj,then a diabox appear like this,

    Then I establish a OrCAD Pspice project,input a schematic as below, include opa348.lib and opa348.olb in this zip file to project library,  then peform a AC simulation to get OPA348's Zo Curve,from curve ZO is about 1000 ohms at high frequency.

    Similarly,I peform a simulation in TINA like this,opa348 model can be searched directly  in TINA.

    IN TINA's output curve,OPA348's zo is about 35 ohms at high frequency.

    Through zo curve comparison,obvious difference can be seen,so I have confusion.Maybe I can compare two opa348 macromodel's internal  description  used in two simulation and find out difference,But sorry so far I don't konw how to do this.

  • 0 in reply to yang fan
    TI__Mastermind 28240 points

    Hi Yang,

    We had noticed a few versions of the OPA348 model weren't working properly so we went and got them fixed. However, it appears there's still a discrepancy. I'll investigate this further and try to get this corrected as soon as possible. 

    Thank you,

    Robert Clifton  

  • 0 in reply to Robert Clifton56
    Prodigy 60 points

    ok,thanks a lot.

  • 0 in reply to yang fan
    TI__Mastermind 28240 points

    Hi Yang,

    I've taken a look into this and I have confirmed there's a discrepancy between the TINA model and the Pspice model. Thank you for pointing this out. I'm working on getting this fixed. 

    Also I want to slightly correct your simulation circuit. You can find it here: https://www.ti.com/lit/an/snoa475f/snoa475f.pdf But basically to test output impedance I recommend building your circuit like this: 

    The results match closely with the datasheet 

    Also some of the older models might not properly simulate output impedance. If they do then the circuit shown above should make it work. 

    Best Regards,

    Robert Clifton

  • 0 in reply to Robert Clifton56
    Prodigy 60 points

    Thanak you very much,I will follow your advise.Yesterday I have opened opa348.lib with OrCAD Pspice which downloaded from TI,then compared it with opa348's macro model in TINA.They look different although I don't know spcific meaning each row,that need much advanced konwledge about spice only I can learn it in future.Maybe one could copy TINA internal macro model content to form a pspice model which behavior indentically as TINA.

    I'm Sorry to have consumed your a lot of valuable time,I'm very happy with your dissusion.

  • 0 in reply to yang fan
    TI__Mastermind 28240 points

    Hi Yang,

    There's no need to apologize for this. To be honest, I'm happy you caught this. I thought I fixed the models, but I missed the pspice version. The ones on TINA, both the one you can download on TI.com and the internal model for TINA are the correct version. The Pspice one is being changed to match TINA.

    If anything I'm sorry for consuming your valuable time! 

    Best Regards,

    Robert Clifton