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LM2840 Inductor Selection

Hi

My custome has question.The brink of adoption propriety, Please cooperate!

■Customer SPEC

 VIN=32V

 VOUT=5.0V

 MAX IOUT=50mA

 SWf=1.25MHz

Not the problem using the 15uH as of a circuit diagram of Inductor is DS P15?

Best Regards

T Kishi

  • Hello - The Team is presently on Holiday vacation, please allow us a couple of more days to answer to your post.
    Regards,
    -JPF
  • Hello,

    One aspect of the recommended inductor values in the data sheet is that it does not specify which frequency version of the device is in use as well as suggesting that all current versions can use the same inductance. While the data sheet does in fact show a value of 15uH, when you use Webench it suggests a value of 330uH for the 550kHz device. So for the 1.25MHz version a value in the 150uH to 180uH would be appropriate. I trust Webench to use more reliable formulas targeted for each version of the product. I would also recommend using the 550kHz version given the input voltage of 32V.

    Alan Martin