Re: inductor polarity

On Thu, 27 Feb 2025 21:24:23 -0800, Joerg <news@analogconsultants.com>
wrote:

On 2/27/25 7:50 PM, john larkin wrote:

I need to put 16 of these on a very dense PC board.
 
https://www.digikey.com/en/products/detail/murata-power-solutions-inc/19R476C/5798223
 
Each of the eight channels needs two of these. If I can put each pair
of inductors close together and with the same current but opposed
field direction, I'll get minimum mag field leakage to other channels
(and to other boards.)
 
I see that one lead is longer than the other. I wonder if that implies
a consistent winding direction, so my manufacturing people could use
that as the "pin1" indicator.
 

>
Typically that is the case.
>
>

If that's not dependable, I'll have to set up a rig to determine mag
field polarity, and mark one side with a red dot or something.
 

>
Best is to shoot off an Email to Murata. They are usually quite
responsive to technical inquiries. That one email could save your
production folks a lot of future grunt work.
>

I did fill out their inquiry form. I hate filling out forms.

Murata makes great stuff, like dc/dc converters and such.

>

I'd rather use surface-mount shielded inductors, but these tall
unshielded drum cores have way more L and less R than a shielded part,
for a given PCB footprint.
 

>
But those also talk a lot :-)

One could make a 10s of kilovolt isolated power supply with a pair of
"shielded" inductors separated by a sheet of plastic.