• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 37 subscribers
  • Views 572 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Results are different between WEBENCH and PSPICE average model for TPS54040

Denis Dessales48
Prodigy 20 points
Other Parts Discussed in Thread: TPS54040

Hi,

I want to calculate phase margin and cross over frequency ... for the TPS54040.

If I use the WEBENCH design center and the TPS54040 Pspice average model in order to compute the Bode plot.

There is some small differences between the 2 tools:

For example :10 kHz of gap for the cross over frequency.

Who have right ? Is it due to the LC necessary to inject the AC signal on the PSPICE model ?

Thanks for your help !

  • 0
    TI__Prodigy 680 points
    Hi Denis,

    The TPS54040 model in WEBENCH has been updated to be more accurate. I would recommend going with the numbers provided by WEBENCH.

    Another potential reason for the difference you are seeing is the actual value of the output cap. Internally, WEBENCH derates the output cap before calculating the loop response. Any difference between this computed value in WEBENCH and the value you are using in PSPICE could lead to a difference in crossover frequency and phase margin between the two.

    Regards,
    Lakshmi
  • 0 in reply to Lakshmi Holehonnur
    Prodigy 20 points

    The output cap derating is equal to 45% like the datasheet ?

    Another question regarding Pspice model, the output phase given by the simulation is automatically the phase margin ?

    Thank you !