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TLV62585: Asking for the design TLV62585 package selection

SHH
Mastermind 30746 points
Part Number: TLV62585

Hi Team,

Customer is designing TLV62585.
TLV62585 has two packages SOT-5X3 and VQFN,

Would you please let me know which package has better efficiency? Which package has better thermal performance?

BR,
SHH

  • 0
    TI__Prodigy 720 points

    Hi SHH,

    I did a webench simulation, and the QFN package has a slightly better efficiency.

    The thermal performance of the two packages can be found in data sheet:

    I hope this helps.

    Thanks,
    Zain Riaz

  • 0 in reply to Zain Riaz
    TI__Mastermind 30746 points

    Hi Zain,

    thanks for feedback. Would you please share the simulation result? for the d/s, the efficiency chart did not mentioned the efficiency is related to the package. Would you please let me know why QFN has better efficiency?

    for thermal performance, junction to ambient thermal resistance and junction to case thermal resistance are in opposite direction.

    Would you please let me know why QFN has larger  junction to ambient thermal resistance, but lower junction to case thermal resistance?

    QFN and SOT, which one has better thermal performance?

  • 0 in reply to SHH
    TI__Prodigy 720 points

    Hi SHH,

    I have attached two Webench Simulations with this post. QFN package has 88.4% efficiency, whereas SOT has 88.1% (efficiency is on page 5 of document).

    For the thermal performance, I will look into it and get back to you soon.

    Thanks,

    Zain

    TLV62585-SOT.pdf

    TLV62585-QFN.pdf

  • 0 in reply to Zain Riaz
    TI__Mastermind 30746 points

    Hi Zain,

    thanks. would you please also help me check TLV625858 datasheet figure 6 efficiency is for which package?

    Why QFN has better efficiency?

    BR,

    SHH

  • 0 in reply to SHH
    TI__Prodigy 720 points

    Hi SHH,

    Can you please mention what is your key concern? Maybe I can help you answer what you are looking for. 

    The efficiency appears to be very similar for both packages. As far as thermal performance is concerned, each thermal resistance is based on a different test, and these tests are defined in the attached document. Generally we see that Junction-to-Case and Junction-to-board are commonly used thermal performance metrics, and based on this the QFN package should have a better thermal performance. 

    I hope this answers your query and I look forward to your reply.

    Regards,

    Zain

    4075.spra953c.pdf

  • 0 in reply to Zain Riaz
    TI__Mastermind 30746 points

    Hi Zain,

    thanks.

    two question here.

    1. why QFN has better efficiency instead of SOT? the chip die should be the same. it is confused for me.

    2. why QFN package ambient to case resistance is bigger than SOT package? I think bigger ambient to case resistance means worse temperature performance.

    as highlighted here, why RJA and RJC are not consistent?

    BR,

    SHH

  • 0 in reply to SHH
    TI__Prodigy 720 points

    Hi SHH,

    Please see my comments below:

    1. why QFN has better efficiency instead of SOT? the chip die should be the same. it is confused for me.

    The difference in efficiency of QFN and SOT is only 0.3% based on the simulations, this much tolerance in efficiency values is acceptable. It is safe to assume that both packages have the same efficiency

    2. why QFN package ambient to case resistance is bigger than SOT package? I think bigger ambient to case resistance means worse temperature performance.

    as highlighted here

    You are correct, bigger resistance means worse temperature performance. And I stand corrected, SOT package has a better thermal performance based on Junction-to-Case and Junction-to-Board resistance. Please also refer to attached article with this post discussing the superior thermal performance of SOT packages. SOT Thermal Performance.pdf

    why RJA and RJC are not consistent?

    As mentioned before, with reference to the attached document in an earlier reply, the two tests are performed with different setups. Generally speaking RJC and RJB are designed based on our devices, and are considered more reliable. RJA on the other hand is based on standard industry test and is done purely for the purpose of comparing various devices with each other (given that the test setup and conditions adhere to industry standards)

     

    I hope the information is helpful.


    Best Regards,
    Zain Riaz