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Visitor II
March 20, 2018
Question

Fixed heatsink Zth

  • March 20, 2018
  • 1 reply
  • 787 views
Posted on March 20, 2018 at 15:09

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    1 reply

    ST Employee
    March 21, 2018
    Posted on March 21, 2018 at 11:23

    Ciao Jed, thanks for your question!

    The parameters in the red circle are related to the 4th degree Foster model fitting the heatsink thermal impedance (it is a RC network, as infigure 21 of the UM).

    You have to fill the R fields with the R1,...,R4 values and the

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    fields with thefour time constants (

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    1= R1*C1,...,

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    4=R4*C4).

    You can also set a lower degree Foster model for the heatsink thermal impedance, filling the first R-

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    couple (for 1st degree Foster model), the firsttwo

    R-

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    couple (for2nd degree Foster model), or the first threeR-

    https://wikimedia.org/api/rest_v1/media/math/render/svg/38a7dcde9730ef0853809fefc18d88771f95206c

    couple (for3rd degree Foster model).

    The thermal impedance you have set for the heatsink will be used to simulate the case temperature in all the steps (t1-t5 in your example).