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TPS745-Q1: Condition for Thermal resistance

NOBUO FUJIHARA
Genius 9335 points
Part Number: TPS745-Q1

Hi team,

My customer asks about board condition where thermal resistance was measured on datasheet for 8pin package.

I saw SLVAE85, but it describe information only for 6pin package.

Q.1) Thermal via condition for datasheet Thita-Ja spec for 8pin package

Could you provide number for thermal via?

Is it same as described in 8.1.6, 2x1 array ot thermal vias of 300-um diameter and 25-um Cu plating?

Q.2) For TPS745-Q1, can you share similar information in SLVAE85 with 8pin package?

Best regards,

  • 0
    TI__Mastermind 49970 points

    Hi Fujihara-san,

    For Q1, our thermal data is base on a JEDEC Standard High-K PCB. The application note http://www.ti.com/lit/an/slvae85/slvae85.pdf you refer to makes it clear that the JEDEC Standard High-K PCB is not optimal for thermal performance. The reason we use the JEDEC standard is that it is the best way to make a comparison between devices. 

    Fro Q2, I have been working to bring up a thermal tool for all of our devices that can help estimate the performance. An example of this is here. Until this tool is updated, the best way is to build a board and test the performance. 

    I hope this helps.



  • 0 in reply to JCHK
    TI__Genius 9335 points

    Hi John-san,

    Thanks a lot for prompt support.

    I understood JEDEC High-K board is used to generate thermal resistance described in the datasheet.

    According to description in Table 1 of SLVAE85–February 2019, JEDEC High-K board has no "Additional" thermal vias.

    Does this mean no thermal via is implemented in JEDEC High-K board?

    Best regards,

    Nobuo

  • 0 in reply to NOBUO FUJIHARA
    TI__Mastermind 49970 points

    Hi Fujihara-san,

    In SLVAE85, it shows the JEDEC High-K (2s2p 2 signal, 2 power planes), It is not easy to see, but there are no thermal vias under the package:

    The optimized layout shows thermal vias both underneath and in the copper plane surrounding the package:

    So to answer your question, yes, there are no thermal vias on the JEDEC board. 

    I hope this answers your question

  • 0 in reply to JCHK
    TI__Genius 9335 points

    Hi John-san,

    Thanks for the detailed explanation.

    Best regards,