Inductor Voltage Rating?

I have to make low power SMPS operable up to several hundred volts. For 
obvious reasons, it would be good to use off the shelf SMT inductors.
In datasheets, they always specify inductor max. current, however they 
don't say anything about max. voltage.

Any advice or relevant experience?

Vladimir Vassilevsky
DSP and Mixed Signal Designs
www.abvolt.com

On May 5, 5:57=A0pm, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
> I have to make low power SMPS operable up to several hundred volts. For
> obvious reasons, it would be good to use off the shelf SMT inductors.
> In datasheets, they always specify inductor max. current, however they
> don't say anything about max. voltage.
>
> Any advice

  First I'd make sure the pads are far enough apart to stand off
whatever voltage you expect to create (+ safety factor of three or
so).

  Then, have you looked here:

http://www.digikey.com/product-search/en/transformers/switching-converter-s=
mps-transformers/787670


  Mark L. Fergerson

On Sun, 05 May 2013 19:57:27 -0500, Vladimir Vassilevsky wrote:

> I have to make low power SMPS operable up to several hundred volts. For
> obvious reasons, it would be good to use off the shelf SMT inductors. In
> datasheets, they always specify inductor max. current, however they
> don't say anything about max. voltage.
> 
> Any advice or relevant experience?

Yes.  If you're going to ask the the electronics equivalent of a question 
that would earn you a "Stupident" title change from some guy named 
Vladimir Vassilevsky on comp.dsp -- change your ways.

-- 
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

"Vladimir Vassilevsky"
>
> I have to make low power SMPS operable up to several hundred volts. For 
> obvious reasons, it would be good to use off the shelf SMT inductors.
> In datasheets, they always specify inductor max. current, however they 
> don't say anything about max. voltage.
>
> Any advice or relevant experience?


** Why not get a few likely candidates and test them to destruction ?

Then you will know the absolute max and can de-rate from there.

Eg: place the DUT in series with a high voltage ceramic cap and drive the 
combo at resonance with a sine wave from an amplifier -  should be easy 
enough to get a few hundred volts RMS across the inductor.



....  Phil

On Sun, 05 May 2013 21:04:21 -0500, Tim Wescott
<tim@seemywebsite.please> wrote:

>On Sun, 05 May 2013 19:57:27 -0500, Vladimir Vassilevsky wrote:
>
>> I have to make low power SMPS operable up to several hundred volts. For
>> obvious reasons, it would be good to use off the shelf SMT inductors. In
>> datasheets, they always specify inductor max. current, however they
>> don't say anything about max. voltage.
>> 
>> Any advice or relevant experience?
>
>Yes.  If you're going to ask the the electronics equivalent of a question 
>that would earn you a "Stupident" title change from some guy named 
>Vladimir Vassilevsky on comp.dsp -- change your ways.

  >:-}
		
                                        ...Jim Thompson
-- 
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

On May 5, 8:57=A0pm, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
> I have to make low power SMPS operable up to several hundred volts. For
> obvious reasons, it would be good to use off the shelf SMT inductors.
> In datasheets, they always specify inductor max. current, however they
> don't say anything about max. voltage.
>
> Any advice or relevant experience?
>
> Vladimir Vassilevsky
> DSP and Mixed Signal Designswww.abvolt.com

If you had a sample, the insulation rating of the wire would be a good
starting point for the upper limit...

--
Cheers,
James Arthur

On 5/5/2013 7:05 PM, Phil Allison wrote:
> "Vladimir Vassilevsky"
>>
>> I have to make low power SMPS operable up to several hundred volts. For
>> obvious reasons, it would be good to use off the shelf SMT inductors.
>> In datasheets, they always specify inductor max. current, however they
>> don't say anything about max. voltage.
>>
>> Any advice or relevant experience?
>
>
> ** Why not get a few likely candidates and test them to destruction ?
>
> Then you will know the absolute max and can de-rate from there.
>
> Eg: place the DUT in series with a high voltage ceramic cap and drive the
> combo at resonance with a sine wave from an amplifier -  should be easy
> enough to get a few hundred volts RMS across the inductor.
>
>
>
> ....  Phil
>
>
I call that the "diode" method.  Good for weeding out devices that
definitely won't work...but says nothing about those that pass,
out of the next batch...and the batch two years from now after
the vendor quits making 'em.
Certainly better than nothing, but nowhere near as helpful as contacting
the vendors.

Having a clear goal, like "several hundred volts" helps a lot.

Several people really hate this method.
The purchasing agent who has to source the thing.
The safety compliance agent who's looking at something potentially
unsafe with no specification.
The manufacturing manager waiting for you to get the line back up.
The guy in Field Returns who has to fix 'em.
Your successor saddled with your comfort with risk taking.

But, at least, you had fun smoking some.

<dagmargoodboat@yahoo.com>

If you had a sample, the insulation rating of the wire would be a good
starting point for the upper limit...

** That assumes the ends of the coil are adjacent.

Normally, the voltage between adjacent turns is divided by the number of 
turns, for a single layer coil.

Real tests need to be done on a real example -  cos insulation to the 
ferrite may be the first to fail.


.... Phil

"mike"
 Phil Allison wrote:

>> ** Why not get a few likely candidates and test them to destruction ?
>>
>> Then you will know the absolute max and can de-rate from there.
>>
>> Eg: place the DUT in series with a high voltage ceramic cap and drive the
>> combo at resonance with a sine wave from an amplifier -  should be easy
>> enough to get a few hundred volts RMS across the inductor.
>>
>>
>>
> I call that the "diode" method.  Good for weeding out devices that
> definitely won't work...but says nothing about those that pass,
> out of the next batch...and the batch two years from now after
> the vendor quits making 'em.


** My idea is to test *every example* at several times the max expected peak 
voltage - assuming this gives you a high pass rate.


> Certainly better than nothing, but nowhere near as helpful as contacting
> the vendors.


** When using an un-speced parameter - one is on ones own.



...   Phil

On 5/5/2013 8:28 PM, Phil Allison wrote:
> <dagmargoodboat@yahoo.com>
>
> If you had a sample, the insulation rating of the wire would be a good
> starting point for the upper limit...
>
> ** That assumes the ends of the coil are adjacent.
>
> Normally, the voltage between adjacent turns is divided by the number of
> turns, for a single layer coil.
>
> Real tests need to be done on a real example -  cos insulation to the
> ferrite may be the first to fail.
>
>
> .... Phil
>
>
>
Tests good, but you're missing the point...SPECS BETTER!

Shoot-From-The-Hip designers are a nightmare.
Back in the day, there was a whole building full of engineers
who did nothing but verify components met their specs.
Hard to do when they don't have a spec.
They would not let us do unspecified things that seemed to
over-stress the technology...unless we didn't tell 'em.
My engineers were trained to create reliable stuff.
YMMV