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Original question:

TPS7H1111-SP: Unencrypted PSpice Models

TPS7H1111-SP: Unencrypted Spice Model

James Simons
Prodigy 10 points
Part Number: TPS7H1111-SP

Hi Sarah,

Are you sure about the KP parameter value? It being negative and so small seems strange.

James

  • 0
    TI__Expert 7870 points

    Hi James,

    To my knowledge, the KP parameter should be correct. Let me take a look and sanity check the assumptions made in the calculation and SPICE interpretation.

    Thanks,

    Sarah

  • 0 in reply to Sarah Koch
    Prodigy 10 points

    Sarah,

    Thank you for looking into this further for me. Just FYI, I went ahead and ran a simulation with the KP=-0.23u number given in the original post and the steady-state output goes to -38mV. If I give KP a value of +10, the output goes to the correct value of 1V for my particular design.

    -James

  • 0 in reply to James Simons
    TI__Expert 7870 points

    Hi James,

    It looks like there was a unit typo that was masked by other FET model parameters which were not previously shared. I have updated the guidance in this post to include all needed parameters and corrected the unit. Can you let me know if this resolves the basic behavior inaccuracy you had observed?

    Thanks,

    Sarah 

  • 0 in reply to Sarah Koch
    Prodigy 10 points

    Hi Sarah,

    That makes sense and yes, it did solve the basic behavior. There is one other thing I'm confused about and was hoping you could explain. I also noticed the STAB output is nearly zero under any circuit operating conditions. And, the Bode response is the same no matter what values are input for the RC compensation. Am I missing something?

    Thanks,

    James

  • 0 in reply to James Simons
    TI__Expert 7870 points

    Hi James,

    I would not expect changing COMP to have no impact on the frequency response and understand the motivation for wanting to simulate this scenario. I would need time to look into this further to truly understand the model's behavior. Ultimately the model does make simplifications and assumptions about the actual device - this may be one area that assumed default compensation would be used in order to produce nominal sim results. 

    Thanks,

    Sarah

  • 0 in reply to Sarah Koch
    Prodigy 10 points

    Ah, I see. That all makes sense. It would be nice to see the effects of the compensation, but I see that it's not absolutely necessary unless a worst-case analysis is required.  If that's the case, it might be nice to mention it in the model limitations. Thanks so much again for your help on this.

    Regards,

    James

  • 0 in reply to James Simons
    TI__Expert 7870 points

    No problem, thank you for the feedback here! I've noted this behavior in case there is a chance to flesh it out in a future revision or at least document the limitation in the model usage notes as you suggested. 

    All the best,

    Sarah