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TL1963A-Q1: Difference between RθJA ofTL1963AKTTR

Dice-K
Mastermind 7570 points
Part Number: TL1963A-Q1



Hi support team,
Why are the RθJA of TL1963AQKTTRQ1 and TL1963AKTTR different?

TL1963AQKTTRQ1   RθJA=22.8℃/W
TL1963AKTTR           RθJA=32.9℃/W

Regards,
Dice-K

  • 0
    TI__Genius 14245 points

    Hi Dice-K,

    Automotive devices often use different Bill Of Materials (BOM) during the assembly process in order to meet stricter quality standards. These BOM changes result in different thermal dissipation values since the various materials each play a part in dissipating heat from the die. 

    If you want to improve the thermal dissipation of any IC, you can use better PCB routing to do so. We have an App Note which shows how the thermal dissipation (θja) can be affected by board layout and it shows that with an optimized PCB layout the θja listed in our datasheets can be reduced by 35%-55%.

    https://www.ti.com/lit/an/slvae85/slvae85.pdf

  • 0 in reply to Kyle Van Renterghem
    Mastermind 7570 points

    Hi Kyle,
    Thank you for your reply.

    I have understood that TL1963AQKTTRQ1 and TL1963AKTTR have different BOM and PCB measurement conditions.
    Does that mean that the heat dissipation ability of the IC itself is the same?

    Best regards,
    Dice-K

  • 0 in reply to Dice-K
    TI__Genius 14245 points

    Hi Dice-K,

    The thermal metrics provided  both use the same standard PCB as defined by the JEDEC High-K Board, so the conditions are the same. The different BOMs mean that the heat that can be dissipated by the devices are different. 

  • 0 in reply to Kyle Van Renterghem
    Mastermind 7570 points

    Hi Kyle,
    Thank you for your support.

    So, if I measure TL1963AKTTR with the same BOM as TL1963AQKTTRQ1, will the results be the same?

    The reason I'm asking this question is that I'm looking for a device with low thermal resistance.
    I would like to confirm whether it is necessary to choose Q1 even though it is not an automotive application.

    Best regards,
    Dice-K

  • 0 in reply to Dice-K
    TI__Genius 14245 points

    Hi Dice-K,

    yes, if the BOMs matched then the results would be the same. 

    If you want the lowest thermal resistance possible I would recommend choosing the Q1 version to take advantage of the more thermally dissipative BOM. 

    I hope that helps. 

  • 0 in reply to Kyle Van Renterghem
    Mastermind 7570 points

    Hi Kyle,
    Thank you for your answer.

    I'm sorry and a little confused.

    The BOM of the Q1 version of your test has not been made public.
    So, whether I design with TL1963AKTTR or TL1963AQKTTRQ1, I think the BOM will be the same.
    So I don't see any reason to choose the more expensive Q1 version.

    Best regards,
    Dice-K

  • +1 in reply to Dice-K
    TI__Genius 14245 points

    Hi Dice-K,

    I'm sorry for the confusion. When I mention BOM above, I'm talking about the materials used to build the IC in the package, not the components on the PCB.

    The leadframe, mold compound, mount compound, etc...make up the materials used to create the packaged IC and these are what is affecting the thermal dissipation because we use different materials for the catalog version of the part compared to the automotive grade version of the part.