coupled-inductor vs common-mode choke

W

Winfield Hill

Guest
Compare & contrast: coupled-inductor vs common-mode choke
e.g., Pulse Eng PA4339 common-mode choke $1.23 qty 100.
https://products.pulseelex.com/files/product_files/P850.pdf

Not bifilar wound, higher insulation voltage.
Not bifilar wound, lower coupling.

But datasheet says insulation only 80 Vdc
max between windings (no spec to core),
and there's no coupling-factor spec.


--
Thanks,
- Win
 
On 1 Aug 2019 06:10:09 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

Compare & contrast: coupled-inductor vs common-mode choke
e.g., Pulse Eng PA4339 common-mode choke $1.23 qty 100.
https://products.pulseelex.com/files/product_files/P850.pdf

Not bifilar wound, higher insulation voltage.
Not bifilar wound, lower coupling.

But datasheet says insulation only 80 Vdc
max between windings (no spec to core),
and there's no coupling-factor spec.
Click to expand...

K = 0.5 maybe?

Do you have one to measure?


--

John Larkin Highland Technology, Inc

lunatic fringe electronics
 
Klaus Kragelund wrote...
Normally they are never bifilar would since
UL/IEC demand 2mm creepage phase to neutral.
Click to expand...

Yes, for AC-line units, but this one has a very
low 80V insulation rating, evidentially meant
for dc-dc converter input stage isolation, etc.


--
Thanks,
- Win
 
Normally they are never bifilar would since UL/IEC demand 2mm creepage phase to neutral

You can test this to circumvent the requirement, but that takes a lot more engineering effort

Advantage of separation is lower capacitance which results in higher self resonance frequency

Cheers

Klaus
 
The low inductance seems to indicate it would be used for signal or low power inputs
 
Klaus Kragelund wrote...
The low inductance seems to indicate it would
be used for signal or low power inputs
Click to expand...

Or high-current dc-dc converters, 5uH 4A max.
OK, not that much current. This doesn't look
like an exceptionally attractive 6x7mm part.
But maybe we should examine the competition,
before judging. It is quite small. I have
a possible application. Maybe I can squeeze
one onto my MPX-16H board, in place of L4.

https://www.dropbox.com/sh/41r9wwgqo7rk3lw/AACKDkCKKJRq8DUvSSfQWkv0a?dl=0


--
Thanks,
- Win
 
On 2 Aug 2019 06:19:59 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

Klaus Kragelund wrote...

The low inductance seems to indicate it would
be used for signal or low power inputs

Or high-current dc-dc converters, 5uH 4A max.
OK, not that much current. This doesn't look
like an exceptionally attractive 6x7mm part.
But maybe we should examine the competition,
before judging. It is quite small. I have
a possible application. Maybe I can squeeze
one onto my MPX-16H board, in place of L4.

https://www.dropbox.com/sh/41r9wwgqo7rk3lw/AACKDkCKKJRq8DUvSSfQWkv0a?dl=0
Click to expand...

I LOVE how tight you make your schematics, too ! I try to do that
too rather than spread them out over many pages.

I am guessing that DG-409 chips aren't available in SMT ?
 
boB wrote...
On 2 Aug 2019, Winfield Hill wrote:

Maybe I can squeeze one onto my MPX-16H board,
in place of L4.

https://www.dropbox.com/sh/41r9wwgqo7rk3lw/AACKDkCKKJRq8DUvSSfQWkv0a?dl=0


I LOVE how tight you make your schematics, too !
I try to do that too rather than spread them out
over many pages.
Click to expand...

I have been taken to task for it, folks reminding
me of other larger paper sizes.

> I am guessing that DG-409 chips aren't available in SMT ?

No, the DG409 is, as are most alternates. But I
intentionally chose DIP packages because these
parts are exposed to long wires off board, with
static-damage possibilities, etc. So the user
should be able to quickly self-repair. This has
long been my philosophy for off-board connections.

I remember the pain and suffering when a National
Instruments board failed due to one chip's static
damage, we had to rewire the signal to another
pin and change the software, what a pain!

BTW, I'm giving away free blank MPX-16H boards.
Next pass I'll have a batch machine assembled,
but they'll cost about $150 each.


--
Thanks,
- Win
 
Winfield Hill wrote:

But datasheet says insulation only 80 Vdc
max between windings (no spec to core),
and there's no coupling-factor spec.
Click to expand...

The 9uH unit has SRF of 77MHz, but they specify its impedance at 100MHz.
What's the point?

Best regards, Piotr
 
On 4 Aug 2019 03:03:49 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

boB wrote...

On 2 Aug 2019, Winfield Hill wrote:

Maybe I can squeeze one onto my MPX-16H board,
in place of L4.

https://www.dropbox.com/sh/41r9wwgqo7rk3lw/AACKDkCKKJRq8DUvSSfQWkv0a?dl=0


I LOVE how tight you make your schematics, too !
I try to do that too rather than spread them out
over many pages.

I have been taken to task for it, folks reminding
me of other larger paper sizes.

I am guessing that DG-409 chips aren't available in SMT ?

No, the DG409 is, as are most alternates. But I
intentionally chose DIP packages because these
parts are exposed to long wires off board, with
static-damage possibilities, etc. So the user
should be able to quickly self-repair. This has
long been my philosophy for off-board connections.
Click to expand...

OK, yes I definitely understand the resoning for through hole on those
then. Hopefully they are socketed.

We have used multiplexors like the CD4051 or 74HC4051 family and when
their pins are exposed directly to the outside world, would seem to
break quite a bit in the field. This is why I always add some series
resistance or buffering and at least small capacitor to ground on the
pins to reduce that possibility. That has worked for me for about 20
years now where before that, in other products, they would break quite
often.




I remember the pain and suffering when a National
Instruments board failed due to one chip's static
damage, we had to rewire the signal to another
pin and change the software, what a pain!
Click to expand...

Yep. PITA !

BTW, I'm giving away free blank MPX-16H boards.
Next pass I'll have a batch machine assembled,
but they'll cost about $150 each.
Click to expand...
 
On 8/4/19 9:26 AM, Piotr Wyderski wrote:
Winfield Hill wrote:

  But datasheet says insulation only 80 Vdc
  max between windings (no spec to core),
  and there's no coupling-factor spec.

The 9uH unit has SRF of 77MHz, but they specify its impedance at 100MHz.
What's the point?

    Best regards, Piotr
Click to expand...

Resonances are symmetrical when plotted on a log frequency scale. A
choke has the same reactance at 2*SRF as it does at 0.5*SRF.

Same with bypass caps.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
"Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message
news:vb6dnYzoL96-4trAnZ2dnUU7-eudnZ2d@supernews.com...
Resonances are symmetrical when plotted on a log frequency scale. A choke
has the same reactance at 2*SRF as it does at 0.5*SRF.

Same with bypass caps.
Click to expand...

Assuming there's only a single resonance, of course!

Which is an okay bet with any capacitor I've seen. Not as good of one with
inductors.

Typical CMCs will have a few peaks and valleys up in the 10s of MHz range,
where the windings resonate in helical waveguide modes (slowed by the
velocity factor of the core, and damped by its loss), at least when single
layer; multilayer windings of course are easier to model as inter-layer
capacitance.

Ferrite beads are usually simple, though they sometimes have anomalous humps
at medium frequencies, that you wouldn't expect from the shape of the main
peak.

Data line chokes are usually simple in common mode, but have peaks and
valleys in the differential mode; which is to say, they have reasonable
transmission line behavior up there, which is actually a good thing in this
case.

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top