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TPSM84624: Thermal Modeling

Nick Rael
Prodigy 20 points
Part Number: TPSM84624

Hello,

I'm running a thermal analysis and this part is included in our design. Our setup is not the same as that used in JESD51-2A and therefore I am unable to use the theta value nor the characterization parameters. We want to ensure we aren't going to exceed this parts max IC temperature, but I have no detailed way to model my part, which is currently modeled as a ceramic block. The datasheet says that is has a max IC junction temperature. Is this junction located on the center of the QFM, and have any theta JB tests been ran to attempt to define this value? Also, is there significant thermal mass to the sealed inductor above the QFM? Any advice on how to best model this part would be appreciated.

Thanks,

Nick

  • 0
    TI__Guru 50120 points

    Hi Nick,

    To accurately generate a thermal model of the power module, you will need more details on the internal construction, routing, BOM and power dissipation numbers for IC and inductor. It is not a simple single material/black box since the power module has an internal IC, integrated inductor, and design construction to enable this product. Unfortunately the internal construction is proprietary information and can not be shared. Because of this it will be a bit tough to accurately create the thermal model.

    However, I can say that the max IC junction temperature is generally located at the center of the power module and heat will radiate outwards. It is also recommended to use the PsiJB and PsiJT specs. There is an app note that details the different thermal units and why the Psi units are used.

    Regards,

    Jimmy

  • 0 in reply to Jimmy Hua
    Prodigy 20 points

    Jimmy,

    I figured that might be the response. As such, my options are limited, even in regards to using Psi units, as our setup does not accurately represent the way the Psi values are obtained. I think I might be able to use notes 1-11 on page 9 of the datasheet to make a rough estimate model of the power module. 

    Thanks,

    Nick