Hi Chas and the group,
It was the design layout of the PCB of the POE, and it was easy to see
(no PHY used). The magnetics may have played a part but the layout is
terrible in some of these devices. They are not designed by engineers
of any competence. In my article, I was very careful to make sure the
end points of the Ethernet connection and cable were not a factor,
described in the article.
There is no PHY in this case, just inductors to inject the DC onto the
Ethernet connection. No active circuitry was involved as I remember.
Doug
Department for Continuing Education
Oxford, Oxfordshire, United Kingdom
--------------------------------------------------
Doug Smith
P.O. Box 60941
Boulder City, NV 89006-0941
TEL/FAX: 702-570-6108/570-6013
Mobile: 408-858-4528
Email: [email protected]
Web: http://www.dsmith.org
--------------------------------------------------
On Mon, 19 Oct 2015 21:29:14 +0000, "Grasso, Charles" wrote:
Hello Doug – in your tidbit you indicated that the pwb layout
was (likely) responsible for the
increased emissions at the below 100MHz range. It has been my
experience that when
the magnetics are placed inside a connector, that the emissions are
more influenced from
the imbalance in the cores and assembly that the layout. Nowadays
there is literally
no ambiguity in the layout – the traces go from the phy in the SoC to
the connector -
that’s it! [I am assuming that the design guidelines from the
connector/phy manufacturer
are being followed] Also how do you isolate the influence of the cable
in your measurements?
After all the internal signal wires could be twisted differently as you
move the cable... Y/N??
Best Regards
Charles Grasso
Compliance Engineer
Echostar Communications
(w) 303-706-5467
(c) 303-204-2974
(t) [email protected]
(e) [email protected]
(e2) [email protected]
From: Doug Smith [mailto:[email protected]]
Sent: Sunday, October 18, 2015 1:49 PM
To: [email protected]
Subject: Re: [PSES] PoE Injectors
Hi Bill,
Keep in mind that many POE adapters on the market will cause an
emissions problem because they are poorly designed and unbalance the
Ethernet pairs creating common mode currents.
See my Technical Tidbit at http://www.emcesd.com/tt2011/tt080111.htm
When you open some of them and look at the design, it is obvious they
were not designed by engineers.
Doug
Department for Continuing Education
Oxford, Oxfordshire, United Kingdom
--------------------------------------------------
Doug Smith
P.O. Box 60941
Boulder City, NV 89006-0941
TEL/FAX: 702-570-6108/570-6013
Mobile: 408-858-4528
Email: [email protected]
Web: http://www.dsmith.org
--------------------------------------------------
On Sun, 18 Oct 2015 18:50:30 +0000, Bill Owsley wrote:
Somewhere in the references at the end, you might find which
devices that these standards apply to.
There are number of exceptions. And there may have been changes since
doc was published.
In the past I have emailed Victor with questions.
- Bill
-------------------------
From: Scott Douglas
To: [email protected]
Sent: Sunday, October 18, 2015 2:04 AM
Subject: [PSES] PoE Injectors
Hello All,
I am wondering if PoE injectors need to be ErP compliant? If so, what
efficiency level? Does anyone know of any such injectors that are compliant?
The injector would be used to power a product and not a switch, router,
or access point.
Any and all comments appreciated.
Regards,
Scott
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