do high current, high inductance inductors even exist (say 5A, 5mH)

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Hi - I need to find some fairly large inductors. They need to be able
to handle around 5A (10A would be better) and have a inductance of
about 5mH (20mH would be better). Does such a thing even exist? Would
it be just terribly huge/expensive? I couldn't find such a beast in the
Digi-key catalog - as soon as inductance went over 1mH current capacity
would fall to fractions of an A. Any suggestions? Thanks!

-Michael J Noone


Re: do high current, high inductance inductors even exist (say 5A,5mH)


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Yes.  And, yes.

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The size of an inductor is related to the energy stored within.
Energy stored in joules is 1/2*L*I^2, so a 10 ampere, 20 mHy inductor
stores 2 joules of energy in its magnetic field.  To reach that level,
there has to either be a lot of size or a lot of flux.  The wire also
has to look like something you wire a house with.  Think E-I
laminations and bolted construction that look at home in a big tube
amplifier.  Something you can prop a door open with.

Here is a catalog page covering something that goes to 10 mHy and 12.5
amperes.
http://www.newark.com/product-details/text/catalog/6025.html

Re: do high current, high inductance inductors even exist (say 5A, 5mH)


6 pounds!!! Crikey - back to the drawing board. The device that it is
intended for weighs just about a pound I believe. It would just get
crushed by that.


Re: do high current, high inductance inductors even exist (say 5A, 5mH)


Michael J. Noone wrote...
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 pick picky.  First you ask does such an inductor even exist?
 Then you ask that it come in pint size.  Do you need a rating
 for continuous full current?  It's in these fellows nature to
 have high thermal mass, so low-current-rated chokes can handle
 high-current surges for quite a long time.

 What's your application, maybe there's a work-around.


--
 Thanks,
    - Win

Re: do high current, high inductance inductors even exist (say 5A, 5mH)


I'm working on a LTC1735 based DC DC circuit - it will take 3 polymer
lithium ion batteries in series (so something around 9 -12.6V) and
bring it down to 6V at 0-10A or so.

I just wrote out my calculations for the inductor size, and then
realized I had accidentally forgotten I was switching in the Khz range,
not the hz range (I left out an E3). Argh. I now realize I need
something more like 4B5%H at 10A. Oops.

-Michael


Re: do high current, high inductance inductors even exist (say 5A, 5mH)



"Michael J. Noone" wrote:

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Look at an iron powder core for that.

Graham


Re: do high current, high inductance inductors even exist (say 5A, 5mH)


In the datasheet
(http://www.linear.com/pc/downloadDocument.do ;jsessionid=DQoz75T1G2b0GkR2X5Tq2FK7GjRY9e8F9B22ageNuz5C542YAvvF!1077717719?navId=H0,C1,C1003,C1042,C1032,C1092,P1733,D2172),
page 12, it specifically says that powdered iron cores shouldn't be
used...


Re: do high current, high inductance inductors even exist (say 5A, 5mH)



"Michael J. Noone" wrote:

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(http://www.linear.com/pc/downloadDocument.do ;jsessionid=DQoz75T1G2b0GkR2X5Tq2FK7GjRY9e8F9B22ageNuz5C542YAvvF!1077717719?navId=H0,C1,C1003,C1042,C1032,C1092,P1733,D2172),
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In which case pls try and find a compact lightweight ferrite core that doesn't
saturate at 10A for your design inductance !

You might find Epcos's Ferrite Magnetic Designer useful.
www.epcos.com


Graham



Re: do high current, high inductance inductors even exist (say 5A,5mH)


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saturate at 10A for your design inductance !
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Will you please provide a link that points directly to that program or
the page that shows it available for download?

I have tried many times to find it, and I think it simply isn't
available anymore.


Good day!


--
_____________________
Christopher R. Carlen
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Re: do high current, high inductance inductors even exist (say 5A, 5mH)


"Chris Carlen" wrote ...
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It appears to be the very first hit on Google:
http://www.epcos.com/web/generator/Web/Sections/DesignTools/Ferrites/Page,templateId=render,locale=en.html

Google is http://www.google.com
Try it. You'll like it.


Re: do high current, high inductance inductors even exist (say 5A,5mH)


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http://www.epcos.com/web/generator/Web/Sections/DesignTools/Ferrites/Page,templateId=render,locale=en.html
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Heh heh.  Well what do you know.  I never heard of that before ;-)


Thanks.


--
_____________________
Christopher R. Carlen
We've slightly trimmed the long signature. Click to see the full one.
Re: do high current, high inductance inductors even exist (say 5A, 5mH)


Quoted text here. Click to load it
(http://www.linear.com/pc/downloadDocument.do ;jsessionid=DQoz75T1G2b0GkR2X5T
q2FK7GjRY9e8F9B22ageNuz5C542YAvvF!1077717719?navId=H0,C1,C1003,C1042,C1032,C
1092,P1733,D2172),
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doesn't saturate at 10A for your design inductance !
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Hello Michael,

Here are some inductors with 10A and more.

http://www.we-eisos.de/we_web/emc/eisos/layout/frameset.php?sector=2&selmenu=2&katid=3&lan=0

Choose the WE-HCA type.
They have 10A and more current capability depending on the inductance.

Best regards,
Helmut




Re: do high current, high inductance inductors even exist (say 5A, 5mH)




**  This struck me as funny:


  http://www.linear.com.cn/prod/datasheet.html?datasheet65%0







..........  Phil



Re: do high current, high inductance inductors even exist (say 5A,5mH)


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Don't know if you're still searching but
Sumida returns some hit for ~4ÁH at >10H. Here is one of them :

http://www.sumida.com/en/products/pdf/CDEP147.pdf

Though you say you must avoid "powdered iron cores" in another post
and I have no idea what type that one is.


    Sylvain

Re: do high current, high inductance inductors even exist (say 5A, 5mH)



Michael J. Noone wrote:
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As far as I know, switchers operating in the tens of kiloherz always
use ferrites as the main inductor.  Iron powder is for filters.  Air
core has lots of stray inductance, too lossy, also probably
impractically big.


Re: do high current, high inductance inductors even exist (say 5A,5mH)


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except when they dont.

most iron powder cores are too lossy for SMPS applications - the trend
nowadays if for fairly high frequencies and fairly large ripple
currents, so large dB.

MPP and KoolMu cores are, however, extremely low loss at HF. whereas a
micrometals #26 iron powder core will fry.

Vishay have a lovely range of SMT inductors, up to about 100A - eg IHLP
series, 4.7uH 37mOhms Rdc, 10Adc Isat, 6.5x6.9x3mm

Cheers
Terry

Re: do high current, high inductance inductors even exist (say 5A,5mH)



Terry Given wrote:

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I just found out what happens to a #26 care ! Not often I've seen parts smoke
like that.

Useful experience though. I have some parts in #2 coming.


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I looked at vishay.com and couldn't find it. Care to post a link ? It looks
very small. Oh hang on - 10A Isat ? Not continuous thermally rated though is
it ?


Graham


Re: do high current, high inductance inductors even exist (say 5A,5mH)


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http://www.vishay.com/docs/34104/ih25cz01.pdf

I typed IHLP into the search box. Damn, I'm glad I got that tertiary
education :)

Cheers
Terry

Re: do high current, high inductance inductors even exist (say 5A,5mH)



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Well.... the site's own search facility didn't find it ! ( search term was 4.7uH
)

I got the IHLP prefix - ( some other sizes ) - but not this series. Websites act
funny sometimes.


Graham



Re: do high current, high inductance inductors even exist (say 5A,5mH)


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4.7uH )
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act
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yep. I have had trouble almost every time I use the IRF search engine.
Sorry about being a smartarse. Its genetic - thats my excuse, and Im
sticking ot it.

Cheers
Terry

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