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webench model for BQ54540

Timothy Starr
Expert 2445 points
Other Parts Discussed in Thread: TPS54540

Hello-

The data sheet for the TPS54540 says that it can do switching up to 2.5MHz. We plan to use an external clock at 1.25MHz, but the webench GUI won;t let us set it higher than 515KHz. Is there a way we canfind out our effiency at the higher switching frequency? Out input range is 4.5 - 40V and the output is 3.3V @ 5A. Thanks for your help.

-Tim Starr on behalf of KW@MC

  • 0
    TI__Guru 71526 points

    Hi TIm,

     MAX Switching Freq is determined by Eq(7) in the datasheet, and Webench uses this formula.  And as described on page 13: " . . which limits the maximum operating frequency in applications with high input to output step down ratios."   

    In this case, you have a high IN to OUT ratio.  If you reduce the VIN MAX, you'll see the switching freq changes;  for example, setting VIN MAX as 10v yields 2.1MHz as the MAX frequency.

    -Leonard