EMRFD Message Archive 2605
Message Date From Subject 2605 2009-01-18 06:22:59 Steve Shielded inductors
manufactured by TDK. TDK's spec sheet indicates these components have
"ferrite core and magnetic shielding."
What are the implications of "ferrite core and magnetic shielding" with
respect to locating these inductors close to each other on a circuit board?
Is it OK to series them end-to-end or parallel them side-by-side in
order to achieve desired inductances? Does the shielding mean they will
not inductively couple to each other?
Thanks.
Steve K8JQ2607 2009-01-18 08:39:04 Graham Haddock Re: Shielded inductors
> I have some 0805 inductors in the 1-4uH range from the MLFThe smaller they are, the lower the "Q". So don't expect this
> series manufactured by TDK. TDK's spec sheet indicates these
> components have "ferrite core and magnetic shielding."
to act like a high "Q" circuit. If ferrite, also expect the
inductance value to walk around with frequency, a lot.
If the value is critical, measure it at the frequency of
operation. A lot of L-C meters measure values at around
100 kHz. Don't expect to get the same value at tens of MHz.
> What are the implications of "ferrite core and magneticIf the conductors pass thru the ferrite, then they are self
> shielding" with respect to locating these inductors close to
> each other on a circuit board?
shielding, like toroids, so there will be some, but little
external field. Probably OK to locate close to each other.
> Is it OK to series them end-to-end or parallel them side-by-Yes, recognizing the comments above.
> side in order to achieve desired inductances? Does the
> shielding mean they will not inductively couple to each other?
--- Graham / KE9H
==2608 2009-01-18 14:37:57 Steve Re: Shielded inductors
and I plan to look at it with a VNA following assembly.
Steve K8JQ
Graham Haddock wrote:
> Steve wrote:
>
> > I have some 0805 inductors in the 1-4uH range from the MLF
> > series manufactured by TDK. TDK's spec sheet indicates these
> > components have "ferrite core and magnetic shielding."
>
> The smaller they are, the lower the "Q". So don't expect this
> to act like a high "Q" circuit. If ferrite, also expect the
> inductance value to walk around with frequency, a lot.
> If the value is critical, measure it at the frequency of
> operation. A lot of L-C meters measure values at around
> 100 kHz. Don't expect to get the same value at tens of MHz.
>
> > What are the implications of "ferrite core and magnetic
> > shielding" with respect to locating these inductors close to
> > each other on a circuit board?
>
> If the conductors pass thru the ferrite, then they are self
> shielding, like toroids, so there will be some, but little
> external field. Probably OK to locate close to each other.
>
> > Is it OK to series them end-to-end or parallel them side-by-
> > side in order to achieve desired inductances? Does the
> > shielding mean they will not inductively couple to each other?
>
> Yes, recognizing the comments above.
>
> --- Graham / KE9H
>
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