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LMR51635: WEBENCH design report reliability

JH Shin
Guru 11050 points
Part Number: LMR51635

Tool/software:

Hello,

Here is a report of the results that my customer verified using TI WEBENCH.

How similar is this WEBENCH report to the actual behavior of the device?

LMR51635_48Vin_28Vout(1.2A).pdf

Thank you.

JH

  • 0
    TI__Mastermind 31125 points

    Hi JH,

    Webench results are typically generated from bench data, and the model results are compared against bench results and deviations are checked. For efficiency data, sometimes it can be off by about 5% at most. 

    I would recommend cross-checking with the quickstart calculator.

    LMR51635-DESIGN-CALC.xlsm

    Thanks,

    Richard

  • 0 in reply to Richard Fu22
    Guru 11050 points

    Hi Richard,

    Thank you for your reply.

    When the customer tested using LMR51635EVM, they got the following results:

      - VIN = 50V, 0.61A / VOUT = 28V Load = 1A

      - Operation efficiency =28W / 30.5W = 91.8%

    This is different from the 98% efficiency of the Webench result above. Is the EVM test result correct?

    Regards,

    JH

  • 0 in reply to JH Shin
    TI__Mastermind 31125 points

    Hi JH,

    Bench test is correct, but I noticed that there's difference in the inductor. The EVM utilizes a 10uH inductor instead of the 22uH inductor. Possibly the extra inductor ripple current changes the RMS and can affect the loss.

    The other thing to consider is Webench results are based off of extrapolated model, so there will be some inaccuracies. In either way, bench test is the closest to reality.

    Thanks,

    Richard

  • 0 in reply to Richard Fu22
    Guru 11050 points

    Hi Richard,

    For reference, they said they tried changing to a 22uH Inductor and it didn't make much of a difference from the 10uH.

    Thanks,

    JH

  • 0 in reply to JH Shin
    TI__Mastermind 31125 points

    Hi JH,

    Understood, in any case, would recommend checking the EVM model for expected results.

    Thanks,

    Richard