• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 40 subscribers
  • Views 521 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Datasheet vs Webench (Which is correct?)

Bart Dinger
Prodigy 40 points
Other Parts Discussed in Thread: LMR14203, LM2841

Is this a bug in webench for some devices or are the values just more optimised?

For example, the inductor chosen by Webench for a LM2841 using parameters similar to the examples in the datasheet gives an inductor that is 10x larger than the datasheet, example 150uH vs 15uH. It does this for other similar devices like LMR14203 as well. I've not done the maths myself yet so won't comment on its accuracy just yet. Was curious if others are finding discrepancy between datasheet recommendations and webench designs.

  • 0
    TI__Intellectual 2155 points

    Hi Bart,

    For the LM2841 design case, what was the output current for the design?  In the calculations, we often size the inductor based on the ripple current, which is a percentage (typically 30%) of the output current.  If you specify a smaller output current, you may end up with a larger inductor than specified in the datasheet.

    The reasoning behind is that the algorithm by default will try to design for CCM (Continuous Conduction Mode), but with low output current designs you may end up with a larger inductor value.

  • 0 in reply to Kevin Ip
    Prodigy 40 points
    Ah yes, that makes sense. I ended up with similar figures doing the calculations myself. Faith in Web bench restored :)