Ferrite beads DC current capacity

C

Chris Carlen

Guest
Hi:

Why don't wideband choke manufacturers ever specify DC current
capacities for these things, for ex.:


http://www.jwmiller.com/pdf2/FB2000.pdf


???

--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
crcarle@sandia.gov -- NOTE: Remove "BOGUS" from email address to reply.
 
On Wed, 13 Oct 2004 16:27:56 -0700, the renowned Chris Carlen
<crcarle@BOGUS.sandia.gov> wrote:

Hi:

Why don't wideband choke manufacturers ever specify DC current
capacities for these things, for ex.:


http://www.jwmiller.com/pdf2/FB2000.pdf


???
Click to expand...
It should be pretty much the current capacity of a 0.024" wire-
between AWG 22 and 24, no?


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
Hi Chris,

Why don't wideband choke manufacturers ever specify DC current
capacities for these things, for ex.:
Click to expand...
They should since these become nearly inefficient once the core
saturates. Above a certain current you end up with an inductance
equivalent to the number of turns in air, as if the core wasn't there.
Not a whole lot of nanohenrys. I always design in cores or chokes from
manufacturers that do specify limits, such as Philips, Amidon etc.

Regards, Joerg

http://www.analogconsultants.com
 
Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> says...
Chris Carlen <crcarle@BOGUS.sandia.gov> wrote:

Why don't wideband choke manufacturers ever specify DC current
capacities for these things, for ex.:

http://www.jwmiller.com/pdf2/FB2000.pdf

It should be pretty much the current capacity of a 0.024" wire-
between AWG 22 and 24, no?
Click to expand...
No. Ferrite beads have a current at which DC saturation makes
them ineffective. It us usually far above the carrying capacity
of the wire for such small beads though.

See: http://www.topmagnetics.com/ferriteproperties.htm
 
Joerg wrote:
Hi Chris,

Why don't wideband choke manufacturers ever specify DC current
capacities for these things, for ex.:


They should since these become nearly inefficient once the core
saturates. Above a certain current you end up with an inductance
equivalent to the number of turns in air, as if the core wasn't there.
Not a whole lot of nanohenrys. I always design in cores or chokes from
manufacturers that do specify limits, such as Philips, Amidon etc.
Click to expand...

Makes me wonder how many folks design these things in without ever
thinking about core saturation.



--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
crcarle@sandia.gov -- NOTE: Remove "BOGUS" from email address to reply.
 
Spehro Pefhany wrote:
On Wed, 13 Oct 2004 16:27:56 -0700, the renowned Chris Carlen
crcarle@BOGUS.sandia.gov> wrote:


Hi:

Why don't wideband choke manufacturers ever specify DC current
capacities for these things, for ex.:


http://www.jwmiller.com/pdf2/FB2000.pdf


???


It should be pretty much the current capacity of a 0.024" wire-
between AWG 22 and 24, no?
Click to expand...

Core saturation is what I am considering.


Thanks for the input.

Good day!


--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
crcarle@sandia.gov -- NOTE: Remove "BOGUS" from email address to reply.
 
On Thu, 14 Oct 2004 01:56:28 +0100, the renowned Guy Macon
<http://www.guymacon.com> wrote:

Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> says...

Chris Carlen <crcarle@BOGUS.sandia.gov> wrote:

Why don't wideband choke manufacturers ever specify DC current
capacities for these things, for ex.:

http://www.jwmiller.com/pdf2/FB2000.pdf

It should be pretty much the current capacity of a 0.024" wire-
between AWG 22 and 24, no?

No. Ferrite beads have a current at which DC saturation makes
them ineffective. It us usually far above the carrying capacity
of the wire for such small beads though.
Click to expand...
He didn't ask about the effective loss or inductance at high currents,
he asked about the current capacity. The ampacity is as I suggest.

When you use the common mode type properly, the currents cancel out
and do not affect the inductance/loss. Also, in some applications
there are high current surges at start-up that require you to know the
current-carrying capacity, but they actually operate at lower currents
that don't reduce the effectivenes that much.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
Chris Carlen wrote:
Joerg wrote:

Hi Chris,

Why don't wideband choke manufacturers ever specify DC current
capacities for these things, for ex.:



They should since these become nearly inefficient once the core
saturates. Above a certain current you end up with an inductance
equivalent to the number of turns in air, as if the core wasn't there.
Not a whole lot of nanohenrys. I always design in cores or chokes from
manufacturers that do specify limits, such as Philips, Amidon etc.



Makes me wonder how many folks design these things in without ever
thinking about core saturation.
Click to expand...

445-1157-1-ND INDUCTOR 680UH

490-1057-1-ND FERRITE CHIP 600 OHM 1500MA

What would the main differences be for the above two inductors/ferrite
beads when using them to filter a 5V/100mA signal? I am trying to
decide which one to use on the board I am making.. :)

cheers,
Jamie Morken



 
On Wed, 13 Oct 2004 17:51:15 -0700, the renowned Chris Carlen
<crcarle@BOGUS.sandia.gov> wrote:

Spehro Pefhany wrote:
On Wed, 13 Oct 2004 16:27:56 -0700, the renowned Chris Carlen
crcarle@BOGUS.sandia.gov> wrote:


Hi:

Why don't wideband choke manufacturers ever specify DC current
capacities for these things, for ex.:


http://www.jwmiller.com/pdf2/FB2000.pdf


???


It should be pretty much the current capacity of a 0.024" wire-
between AWG 22 and 24, no?


Core saturation is what I am considering.
Click to expand...
Then, yes, they should provide graphs, not just the saturation number,
absolutely. It usually takes quite a bit of current with ferrite beads
to saturate the core, because there is only one or two turns.



Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
On Wed, 13 Oct 2004 16:27:56 -0700, Chris Carlen
<crcarle@BOGUS.sandia.gov> wrote:

Hi:

Why don't wideband choke manufacturers ever specify DC current
capacities for these things, for ex.:


http://www.jwmiller.com/pdf2/FB2000.pdf


???
Click to expand...
The Fair-rite catalog used to be good for bias info on beads.
This is a 6M download.

http://www.fair-rite.com/fr_catalog-14thed_rev3.pdf

A shorter, more general article:

http://www.fair-rite.com/CUP%20Paper.pdf

RL
 
On Wed, 13 Oct 2004 21:45:29 -0400, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:


Makes me wonder how many folks design these things in without ever
thinking about core saturation.

The chip ferrite beads I specify do not saturate at less than the
maximum current, according to the manufacturer's data. The maximum
current is quite high (0.5A to 2.2A)- probably limited by temperature
rise of the chip.
Click to expand...
The permeability of the material is affected by field strength and
temperature, particularly the low-temperature lossy materials used in
suppression.

As simple beads are generally ungapped, they will reflect the shift
indicated in the Hanna curves for the material. Chip inductors, using
a meander type conductor, will be difficult to evaluate, except by the
mfrs test data. This is not necessarily reflected in book L and I
tables.

RL
 
Chris Carlen wrote:
Hi:

Why don't wideband choke manufacturers ever specify DC current
capacities for these things, for ex.:

http://www.jwmiller.com/pdf2/FB2000.pdf
Fair-rite does give some information about the effect of DC on their
Click to expand...
shield beads, e.g. page 31-40, 45-49, 53-73, 76-77, 80-83 (similar to
the ones you mention , above) in their catalog:
http://www.fair-rite.com/fr_catalog-14thed_rev3.pdf

--
John Popelish
 
On Wed, 13 Oct 2004 22:47:20 -0400, the renowned John Popelish
<jpopelish@rica.net> wrote:

Chris Carlen wrote:

Hi:

Why don't wideband choke manufacturers ever specify DC current
capacities for these things, for ex.:

http://www.jwmiller.com/pdf2/FB2000.pdf
Fair-rite does give some information about the effect of DC on their
shield beads, e.g. page 31-40, 45-49, 53-73, 76-77, 80-83 (similar to
the ones you mention , above) in their catalog:
http://www.fair-rite.com/fr_catalog-14thed_rev3.pdf
Click to expand...
Nice. ~Page 176 has info on temperature effects.

I suppose the TDK stuff is stuck in some manual that's not available
online. They have info online on their core materials, but not the EMI
suppression materials.



Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
In article <i2mrm01lk0ru0pi7oorpo62bmn3vmqup0g@4ax.com>,
Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> wrote:
[...]
Then, yes, they should provide graphs, not just the saturation number,
absolutely. It usually takes quite a bit of current with ferrite beads
to saturate the core, because there is only one or two turns.
Click to expand...
The core material has a really-really high mu so that kind of works
against the low number of turns. Inductances up to about 1uH are not
uncommon.

I've seen saturation happen somewhere near one amp in a pulsed application.
I think that was a Fair-Rite type 73 material.


--
--
kensmith@rahul.net forging knowledge
 
Hi Jamie,

The first inductor (TDK) is rated at 35mA so it wouldn't work in your
application. The 600Ohm Murata is the kind of choke that I believe
Spehro was talking about and this one should be fine as it is rated for
300mA. Either one will drop rapidly in inductance and become nearly
inefficient when you exceed the rated current. EMI chokes usually go a
bit more gracefully while regular chokes can be pretty abrupt in core
saturation.

Regards, Joerg

http://www.analogconsultants.com
 
Guy Macon wrote:
Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> says...

Chris Carlen <crcarle@BOGUS.sandia.gov> wrote:


Why don't wideband choke manufacturers ever specify DC current
capacities for these things, for ex.:

http://www.jwmiller.com/pdf2/FB2000.pdf

It should be pretty much the current capacity of a 0.024" wire-
between AWG 22 and 24, no?


No. Ferrite beads have a current at which DC saturation makes
them ineffective. It us usually far above the carrying capacity
of the wire for such small beads though.

See: http://www.topmagnetics.com/ferriteproperties.htm
Click to expand...

That's a good one. Thanks.


--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
crcarle@sandia.gov -- NOTE: Remove "BOGUS" from email address to reply.
 
legg wrote:
On Wed, 13 Oct 2004 16:27:56 -0700, Chris Carlen
crcarle@BOGUS.sandia.gov> wrote:


Hi:

Why don't wideband choke manufacturers ever specify DC current
capacities for these things, for ex.:


http://www.jwmiller.com/pdf2/FB2000.pdf


???


The Fair-rite catalog used to be good for bias info on beads.
This is a 6M download.

http://www.fair-rite.com/fr_catalog-14thed_rev3.pdf

A shorter, more general article:

http://www.fair-rite.com/CUP%20Paper.pdf
Click to expand...

I actually have the catalog, just buried in a pile of datasheets, so
hadn't read it for a while.

Thanks for the input.


--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
crcarle@sandia.gov -- NOTE: Remove "BOGUS" from email address to reply.
 
Hi Ken,

I've seen saturation happen somewhere near one amp in a pulsed application.
I think that was a Fair-Rite type 73 material.


I have actually seen a VK200 (six-holer core) unsolder itself under
Click to expand...
heavy RF exposure.

Regards, Joerg

http://www.analogconsultants.com
 
"Chris Carlen" <crcarle@BOGUS.sandia.gov> wrote in message
news:ckm7er02noc@news4.newsguy.com...
Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> says...
Chris Carlen <crcarle@BOGUS.sandia.gov> wrote:

Why don't wideband choke manufacturers ever specify DC current
capacities for these things, for ex.:

http://www.jwmiller.com/pdf2/FB2000.pdf

It should be pretty much the current capacity of a 0.024" wire-
between AWG 22 and 24, no?

No. Ferrite beads have a current at which DC saturation makes
them ineffective. It us usually far above the carrying capacity
of the wire for such small beads though.

See: http://www.topmagnetics.com/ferriteproperties.htm
Click to expand...

The good information page is from a handbook.

Look out for the people at "Topmagnetics" though, they tried to get me to work
for free for them and IMHO are not to be trusted.

Clarence
 
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