Effects of saturation current rating of inductor in buck circuit

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MrSoftware

Joined Oct 29, 2013
2,015
Is there any reason that an inductor with a relatively high saturation current rating would be less desirable than an otherwise equivalent inductor with a lower saturation current rating in a buck circuit?

I was tasked with building a buck circuit and a preferred 10uH inductor was spec'd. Using the TI Switcher Pro software (free download, requires free account), other 10uH inductors were given as options, but our preferred inductor was not. It became apparent that the one difference was our preferred inductor had a higher saturation current rating then the others, and sure enough after editing (fudging) the specs for our preferred inductor to lower the saturation rating, it was suddenly listed as an option! So this brings the question; is there a potential down fall to using an inductor with higher than required saturation current rating, or is there a bug in the software that filters out inductors that really would be OK?

I went ahead and built the circuit using our preferred inductor and initial testing shows that it works OK, but I'm trying to determine if there is a hidden gotcha that I need to be aware of. Here's the circuit:

upload_2019-1-11_10-15-27.png
 

dl324

Joined Mar 30, 2015
13,574
The only disadvantages I can think of are that the higher saturating inductor would cost more and be larger. Circuit-wise, it wouldn't have any negative effect.
 

crutschow

Joined Mar 14, 2008
28,227
I agree with dl324.
The higher saturation current could allow you to run the converter at a lower switching frequency, which likely would give slightly higher conversion efficiency.
 
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