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TPS7A85A: Temperature characteristic

Part Number: TPS7A85A

Hi

My Customer has question.

Can you tell me the thermal resistance between "junction TJ" and "ambient temperature TA" at forced air cooling 1 m / s?

Assuming worst case, load current 3.9 A, voltage difference 0.326 V, ambient temperature 75 ° C., forced air cooling 1 m/s.

I want to check if it can operate under this condition.


I think that it is difficult to deal with, but I want comments.

Best Regard

T Kishi

4 Replies

  • Hi T Kishi,

    We do not have thermal metrics for applications with forced air cooling so we will need to work with our thermal modeling team to get an estimate for you. However please note that our responses will be delayed due to the Christmas Holidays.

    In the meantime it would be good to get some more information from you on the board it will be placed on. For comparisons sake the JEDEC standard High-k board, which the thermal metrics are derived from, has approximately ~5500mm squared of 1 oz copper on the internal layers as well as ~1100mm squared of 2 oz copper on the external layer on the opposite side as the IC.

    Kyle Van Renterghem
    Application & Validation Manager
    LDO Product Line
  • In reply to Kyle Van Renterghem:

    Hi Kyle

    Thank you for reply!

    I understood that US can not be confirmed because it is holiday.
    Even if it takes time, is it possible to get some data?
    Customer is in a hurry but I will try to negotiate somehow.

    Best Regard
    T Kishi
  • In reply to T Kishi:

    Hi T Kishi,

    Based on the power dissipation and the thermal metrics in the PDS, which assumes no forced air flow and that the device is mounted on the JEDEC high-k board, we get a junction temp of 129.7°. Forced convection will reduce the junction temp but off the top of my head I don't have a good estimate for how much.

    We should be able to get an estimate from the modeling team for the high-k board but I cannot guarantee when we can get this since many people will be off the whole week of the 25th. There may be some online resources that you or the customer can use to get a quicker estimate of how much cooling the forced air will provide.

    Kyle Van Renterghem
    Application & Validation Manager
    LDO Product Line
  • In reply to Kyle Van Renterghem:

    Hi T Kishi,

    You should be able to use the webtherm simulator on webench for the TPS7A85. This does not have the exact same theta JA as the TPS7A85A. but it will give you a good estimate of the junction temperature for these boards.

    Best Regards,
    Mark

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