I’m looking to use MP28164 in an application that only requires 20 mA - a fraction of the part’s rating. When I run through the inductor sizing calculations from the datasheet, I get values that vary significantly from the examples in application circuits and the eval board schematics.
When I run through these calculations, I get 13-70 uH.
Could you provide some guidance on correct inductor sizing?
I see this problem sometimes when we look at applications with very low load currents. The calculations tell us to use a huge inductor! But sometimes these can be hard to source. Of course, you can find something like a 68uH inductor with maybe 200mA Isat and be ok.
However I typically see customers simply using a smaller inductor that they have more stock of or is easier to source. The draw back of smaller a inductance is that you’ll get more ripple current, but at such a low load current the ripple itself is often negligible.
You can always calculate the ripple you’re expecting with the smaller inductance and see if it’s within what you find acceptable.