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WEBENCH® Tools/TPS54531: getting different results when simulating Stability Analysis.

Robert Eschbach
Expert 6695 points
Part Number: TPS54531

Tool/software: WEBENCH® Design Tools

I'm getting different results when simulating Stability Analysis.

Once doing the simulation alone

Once when the tool offers me its stability components.

I inserted the components into my design, but I'm getting different results while simulating and when using the "Re Comp" tool

                I'm using 2 options for the feedback resistors. (2 feedback options)

·         Vout = 5.25

·         Vout = 4.00

 

 

The design has according to "Operating Values" DC Gain of 67[dB] and Phase Margin of 60[°] for Vout = 5.25[V]

The design has according to "Operating Values" DC Gain of 68[dB] and Phase Margin of 59[°] for Vout = 4.00[V]

 

Please see image attached (For the case of 5.25[V])

 

Can I ask you to check that, and if so how can I point you to the Link?

If not here is an image of my design (attached)

 

Input Voltage = 24[V]

Output Voltage Option A = 5.25[V]

Output Voltage Option A = 4.00[V]

Current Consumption 3[A]

If any information is needed please advise.

Webench Question TPS54531DDA.docx


  • 0
    TI__Expert 4795 points

    Hi Robert,

    I'm nut sure whether I understand your questions. So your question is you get different results by 1) Using the compensation component webench suggest 2) Using the compensation component from Re-Comp table, not questing the results with different output? I think it's normal the bode plot performance would be a little bit different at 4V and 5.25V output.

    Further I go to the simulation as you did and have some feedback for your reference.

    1. The results I get with Webench alone data are as below:

    5.25VOUT

    4VOUT

    The results I use the Re-Comp tool are as below:

    1. 5.25VOUT

    2. 4VOUT

    From the results it's very similar from Webench alone simulation and Re-COMP simulation. I think you need to double check whether the inductor and capacitor parameters are same.

    Best Regards,

    Vincent Zhang 

  • 0 in reply to Vincent Zhang(BSR)
    TI__Expert 6695 points
    Vincent, I need to forward this to my customer. Can you send me an email directly to robeschbach@ti.com so I can include you on it? Thanks
  • 0 in reply to Robert Eschbach
    TI__Expert 4795 points
    Hi Robert,

    Yes I see you have loop me in the email.
  • 0 in reply to Vincent Zhang(BSR)
    Prodigy 10 points
    Hello Vincent
    My name is Hezi Ben Or from Spectronix (i.e. the customer)
    What I'm saying that when I simulate with the "Sim" (looks line a Sine Wave) for Bode Plot, I get different results while using the "Operating Values" window while using the same "Re Comp" option.
    I will check again just to be sure
  • 0 in reply to HEZI BEN OR
    TI__Expert 4795 points
    Hi Hezi,

    As I present in previous post, I get both results either 5.25V or 4V output, the 'sim' and 'Re comp' are same. My advice is you could double check whether the inductor and capacitor parameters are same.

    Regards,
    Vincent