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TPS76733 - Theta JA Value?

I am having trouble finding a specific piece of thermal data (theta JC) for the TPS76733QPWPR linear regulator.  The datasheet does not appear to have it nor do the documents the datasheet mentions for additional thermal information.  I need this information for thermal de-rating calculations and this particular part has very little margin so I need to be as accurate as possible.

There is some information for this data in Application Report APRA953B, but I am hoping for a more exact Theta JA Value.

Adam

  • To clarify, I am interested in the specific Theta JC values fro this part. We have done a full set of thermal calculations for this part but we cannot use the Theta JA numbers because of the complexity of our PCB and variations in the local ambient temperature in the vicinity of the part (there is no airflow and there are substantial thermal gradients within the module so even near this part there is not one ambient temperature number we can use.) We are measuring the component temperature by attaching a thermocouple to the top of the part so we know what the top-side case temperature is, and we know how much power is being dissipated by the part. With those two pieces of information we can derive the junction temperature if we have the Theta JC but there is nothing we can do with Theta JA, even if we could determine what the Theta JA is for our board.
  • Hi Adam,

    It looks like this device was released before we provided these thermal values. I will have the thermals rerun for this device and provide you the results. Please note that this can take up to two weeks.

    Very Respectfully,
    Ryan
  • Hi Adam,

    Good news, the results are in.

    Theta JA = 35.8 °C/W
    Theta JC, top = 26.1 °C/W
    Theta JB = 8.7 °C/W
    Psi JT = 0.4 °C/W
    Psi JB = 8.6 °C/W
    Theta JC, bottom = 2.6 °C/W

    Very Respectfully,
    Ryan