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UCC27211A-Q1: Package thermal parameter

Chuqiang Wen
Expert 6040 points
Part Number: UCC27211A-Q1


Hi team, 

DDA package has thermal pad, while D package doesn't have. 

I can understand that DDA package has better junction to ambient thermal resistance. But why D package has better junction to case thermal resistance? 

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Thanks!

Ethan Wen

  • 0
    TI__Expert 3055 points

    Hi Ethan, 

    RθJC applies to the condition that the chip dissipated power conducts through the single surface of the device package (case top or bottom). This means that the RθJC parameter is generally suitable for the condition that the only heatsinking is attached at the top (or bottom) of the package where more than 90% of the heat is distributed from the top (or bottom), which is very similar to JEDEC test condition. 

    You can read more about evaluating junction temperature here: How to Evaluate Junction Temperature Properly with Thermal Metrics

    I am reaching out internally to get more information about this specific device. 

    Best,

    Amy

  • +1 in reply to Amy Wozniak
    TI__Expert 3055 points

    Hi Ethan,

    The lead frame in the DDA package has a deeper downset so that the thermal pad is exposed. This means the distance between the die and the top of the package is larger in the DDA package, and thus the thermal resistance over that distance is larger.

    Best,

    Amy