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.

TPS82085: Thermal resistant VS characterization parameter

Part Number: TPS82085

Hi Team, 

Can you please explain the difference between the terms thermal resistance VS characterization parameter? 

Would it be effective to add heatsink at the top of this package? 


  • Hi Ohad,

    You can find detailed information about both parameters in this app note

    There is a difference in the setup for simulating/measuring both parameters. The RθJC(top) setup has a heat sink kept on top of the IC. Almost all power dissipated by the IC is guided to this heat sink on top of the IC. RθJC(top) is calculated by dividing the measured temperature delta between junction and case by the dissipated power. 

    The ΨJT setup is according to JESD51-2 specs. There is no heat sink used in this setup and in reality not all power dissipated in the IC flows to the top of the case. However the total power dissipated in the IC is still used in the calculation of ΨJT .

     ΨJT = (Junction temperature - case temperature)/ total power dissipated in IC. Even though the power used in the calculation is invalid,ΨJT is still useful for board designers as this experimental configuration is much like the application environment of the IC package. The amount of energy flowing from the die to the top of the package during this test is similar to what would be found in a real application

    Best regards,