Inductor Nightmares

[itsmoked]

I have been looking high and low for an inductor that is:
~8-9uH
~24A Isat
~14A IDC
Shielded or at least low leakage. (toroid)

And at this point I don't care if it's thru hole or SMD although I would prefer SMD.

I am starting to wonder if I am missing some point because NO ONE seems to have product in this realm. Everybody's offerings start to crap out in the 15A region or they go to 50A but conversely the inductance is far too low like: ~0.something.

Also do you know of any inductor companies that have willing and helpful staff I can run numbers by?

So far I have checked product catalogs for:
Datatronic
Bourns
JW Miller
Coilcraft
TOKO
TDK

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[ScottyUK]

Tried Ferroxcube? The Philips soft ferrites business changed name (and possibly owner?) a while ago. They have low leakage cores in fairly large sizes, maybe a couple of pounds in weight, plus core sections which can be built up for just about any application - I built a liquid-cooled HF power transformer using their stuff while at university. From memory one of the bigger gapped E cores or maybe a PM core should be able to meet that spec although you'll be winding it by hand.

http://www.ferroxcube.com/

They have a useful databook in .pdf format:

http://www.ferroxcube.com/appl/info/HB2005.pdf

See if you can track down a book called 'Soft Ferrites' by Edgar Snelling. It is a real oldie but is a fantastic reference for anyone working with HF inductor and transformer design. It is possibly out of print - mine is a really old copy.


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Sometimes I only open my mouth to swap feet...

 

[Madcow]

The helical wound are cool.Lots of current

http://www.hirelsystems.com/products.php?industry=8

The 100 series has 9u at 30 amps.
Do you need off the shelf or will a custom do?

 

[OutToLunch]

first, go to the micrometals website and download the inductor design software:

http://www.micrometals.com/software_index.html

if you go the toroidal route, you'll likely have to go bi or tri-filar. Order the cores and some wire to make your own prototypes.

Next, call Falco Electronics, their number is on their website they will work with you to get you what you need. They've always been helpful with custom parts - especially if you put them on your bom when your done.

http://www.falcomex.com/

 

[BobbyNewmark]

If it isn't too late, take a look at the Coilcraft SER2817H-103KL: 10 uH, 28 A Isat, 28 A RMS.

"I am starting to wonder if I am missing some point because NO ONE seems to have product in this realm."

This part of the market is driven by DC-DC converters for big digital chips like CPUs. (A typical load might be 1.1 V, 90 A, and 30 mV of ripple.) The ripple voltage requirement is stringent and generally means a polyphase switcher, at least for cheap mass market products. If the number of phases is N, the control loop response time decreases by a factor of 1/N, the capacitor size decreases by 1/N, and the capacitor and MOSFET heating decreases by 1/(N^2). (That last one is a godsend to the engineer designing the converter.)

The cut off seems to be around 10 to 20 A. For higher output currents, mass market products tend to use a polyphase switching converter that has the ~1 uH, low-parasitic-capacitance inductors.

 

[itsmoked]

Well... That makes a helluvalotta sense. Most interesting.

I am using the LT3780 controller which costs an arm and a leg,(like all of Linear's stuff), so I can just imagine the cost of a polyphase controller made by them. Yikes.

As for the SER2817H-103KL. I have one in my left hand! I looked at their site and ran their parametric search stuff and it never came up. I then called them and they said, "nope got nothing that hefty". They called back an hour later and said their search was missing that part and that they had the above part that would do the job. They then sampled me 3. Now I need a board.

Thanks for the help. I hope you hang around as I can easily see myself in some corner needing help. I am laying out the board to accept 1" toroids too in case I need one instead.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[BobbyNewmark]

Hey, talk about synchronicity!

It is just pathetic how useless so many manufacturer's websites are. They don't have a classic selection guide, and the parametric search either doesn't list all the products or is just plain broken. It's as if they are trying to drive the customers away. Except for a few specialty parts, my first stop these days is digikey.com just because of their search engine.

 

[itsmoked]

Their search engine has been pretty good but at times unpredictable. Lately they replaced it and I think the replacement is a lot better. NOW the "only parts in stock" really works!

Sadly Mouser's search engine is damn near worthless. The criteria are often obtuse and some are utterly useless. When you're done with a search you may be faced with a laborious 20 page mess.

National Semi's site was really bad up to a month ago. It has improved quite a bit lately.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[nbucska]

RE: Search engine.

Once I was looking for a HI-fr. power transistor.
Among others one "hit" produced St. Jerome's (?) letter
to the pope from the 3rd century...

I think it would be worth a new Manhattan -project
to develop a more useful search engine...


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