FreeLists / si-list / [SI-LIST] Re: Ferrite bead question

[steve weir <weirsi@xxxxxxxxxx>]

Joel, in theory, yes.  But being real physical things that cost 
money, for a given size device, the chemistry and winding 
configuration the values of the parameters you mention are 
interdependent.  Be careful with ferrite beads.  They can be quite 
useful.  However, misapplied, they can do a lot more harm than 
good.  Remember that at low frequencies they are linear inductors 
with very appreciable Qs.

Steve


At 11:33 AM 4/7/2006, Joel Brown wrote:
>I often see recommendations in application notes for ferrite beads on DC
>power lines. Sometimes a particular P/N is specified and sometimes just
>an impedance is given.
>Wouldn't I want to choose a ferrite bead that has the highest impedance
>possible at the frequencies of interest, and that the current rating and
>DC resistance are appropriate? Would the frequencies of interest be the
>fundamental switching frequency of the part and possibly the 3rd and 5th
>harmonics?
>Thanks - Joel
>
>
>
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