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From: Joerg on 9 Jul 2010 17:54
Hammy wrote:
> I'm looking for a 390uH inductor for a Boost PFC choke 250W output
> power.
>
> After spending some time browsing data sheets,I'm confused why only
> the DC current rating is shown. There is never any graph for current
> vs inductance or inductance vs frequency or max peak current to avoid
> saturation or graphs for core loss.
>

There is but you have to politely ask. Sometimes they'll have to measure
it and they only do that if you dangle a BIG carrot in the form of a fat
potential purchase order.

Usually they state several values. For excample current for 30C or 40C
temp rise, then current for 20% inductance loss and 30% loss. That's
usually enough to design with. I wouldn't want to push an inductor much
past -30% in the peaks although some folks go to -50%. Probably the same
guys who won't shift before 6000rpm :-)


> From looking at a data sheet on a Bourns vertical mount Toroid 560uH
> @1kHz They specify at rated DC current an inductance drop from the
> original 560uH to 314.18uH.
>
>
>
> My PFC choke specifications at 65kHz are 4.9Apk and 3Arms would the
> 2321 560uH 3.6A one here be a possible candidate?
>
> http://www.bourns.com/data/global/pdfs/2300_series.pdf
>

44% drop at I-rated? Yikes! Personally I wouldn't like to push that one
to 4.9A peaks.

>
> I could use a coilcraft part I have but its bigger then I would like
> to use part C1062-BL
>
> http://www.coilcraft.com/pdfs/c1061.pdf
>

Mucho mejor :-)


> Note the detailed specs compared to 99% of the other inductor
> datasheets.


You should see some oriental IC datasheets ...

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
From: Hammy on 9 Jul 2010 18:44
On Fri, 09 Jul 2010 14:54:13 -0700, Joerg <invalid(a)invalid.invalid>
wrote:

>Hammy wrote:
>> I'm looking for a 390uH inductor for a Boost PFC choke 250W output
>> power.
>>
>> After spending some time browsing data sheets,I'm confused why only
>> the DC current rating is shown. There is never any graph for current
>> vs inductance or inductance vs frequency or max peak current to avoid
>> saturation or graphs for core loss.
>>
>
>There is but you have to politely ask. Sometimes they'll have to measure
>it and they only do that if you dangle a BIG carrot in the form of a fat
>potential purchase order.
>
>Usually they state several values. For excample current for 30C or 40C
>temp rise, then current for 20% inductance loss and 30% loss. That's
>usually enough to design with. I wouldn't want to push an inductor much
>past -30% in the peaks although some folks go to -50%. Probably the same
>guys who won't shift before 6000rpm :-)

Almost every Inductor datasheet I have looked at is 1 maybe two pages
one page consist of packaging information. The other page just states
DC current rateing DCR and maybe SRF.

Usually its for the whole series.What are they trying to save money on
paper?
>
>> From looking at a data sheet on a Bourns vertical mount Toroid 560uH
>> @1kHz They specify at rated DC current an inductance drop from the
>> original 560uH to 314.18uH.
>>
>>
>>
>> My PFC choke specifications at 65kHz are 4.9Apk and 3Arms would the
>> 2321 560uH 3.6A one here be a possible candidate?
>>
>> http://www.bourns.com/data/global/pdfs/2300_series.pdf
>>
>
>44% drop at I-rated? Yikes! Personally I wouldn't like to push that one
>to 4.9A peaks.

Yep thats what I figured. I'm useing the coilcraft part. I started the
layout I'm just waiting for the parts to come for the supply its
provideing the bus voltage for.

>>
>> I could use a coilcraft part I have but its bigger then I would like
>> to use part C1062-BL
>>
>> http://www.coilcraft.com/pdfs/c1061.pdf
>>
>
>Mucho mejor :-)

If they could only all be like that.
>
>> Note the detailed specs compared to 99% of the other inductor
>> datasheets.
>
>
>You should see some oriental IC datasheets ...

Dont get me started.;-)
From: Joerg on 9 Jul 2010 19:55
Hammy wrote:
> On Fri, 09 Jul 2010 14:54:13 -0700, Joerg <invalid(a)invalid.invalid>
> wrote:
>
>> Hammy wrote:
>>> I'm looking for a 390uH inductor for a Boost PFC choke 250W output
>>> power.
>>>
>>> After spending some time browsing data sheets,I'm confused why only
>>> the DC current rating is shown. There is never any graph for current
>>> vs inductance or inductance vs frequency or max peak current to avoid
>>> saturation or graphs for core loss.
>>>
>> There is but you have to politely ask. Sometimes they'll have to measure
>> it and they only do that if you dangle a BIG carrot in the form of a fat
>> potential purchase order.
>>
>> Usually they state several values. For excample current for 30C or 40C
>> temp rise, then current for 20% inductance loss and 30% loss. That's
>> usually enough to design with. I wouldn't want to push an inductor much
>> past -30% in the peaks although some folks go to -50%. Probably the same
>> guys who won't shift before 6000rpm :-)
>
> Almost every Inductor datasheet I have looked at is 1 maybe two pages
> one page consist of packaging information. The other page just states
> DC current rateing DCR and maybe SRF.
>

There should always be at least one current for 20% or 30% or some other
percentage drop in inductance. Or an inductance given for the rated DC
current, like in one of the datasheets you posted.


> Usually its for the whole series.What are they trying to save money on
> paper?


They come from countries where there aren't many trees left?

But seriously, you can get more data, just not as a low volume user. For
example, I requested a specific additional datapoint on an inductor from
a Chinese manufacturer. They took it to the lab, ran tests and sent me
the actual plots. A lot more than I asked for.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
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