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TPS54334 - About difference between " Calculating formula of datasheet" and "WEBENCH of TPS54335A"

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Guru 21045 points

Hi Team,

 

Our customer calculate the loop compensation component(Rcomp , Ccomp , Ccomp2) using “WEBENCH of TPS54334A”.

(I received advice from John-san.)

https://e2e.ti.com/support/power_management/non-isolated_dcdc/f/196/t/440509

 

However, "Result of datasheet" does not accord with " Result of WEBENCH".

Could you please let us know if you know the reason?

And, Which is result most suitable?

 

[Our customer’s conditions]

-Vin=19.5V(typ)

-Vout=3.3V

-Iout=1.0A

-fsw=570kHz

 

[Result of WEBENCH]

-Rcomp=976ohm

-Ccomp=82nF

-Ccomp=1.3nF

 

 

[Result of datasheet]

-Rcomp(R4)=6.676kohm

-Ccomp=23.23nF

-Ccomp=0.02nF

 

 

Regards,

Kanemaru

  • 0
    TI__Guru**** 191445 points
    You weren't actually expecting to get the same results were you? Webench and the datasheet use two different methods (actually 3 different methods if you include the method of section 8.4.5 small signal model for frequency compensation and section 9.2.1.2.6 compensation components. I prefer and recommend the method of section 9.2.1.2.6. It is what I personally use. I suppose they are all valid, but I think pspice modeling is the most accurate, followed by webench and lastly the simple model of section 8.4.5
  • 0 in reply to JohnTucker
    Guru 21045 points

    Hi John-san,

     

    Thank you for your advice.

    I understood. thank you very much.

     

    Regards,

    Kanemaru