[SI-LIST] Re: RJ-45 Connector
- From: "Lee Ritchey" <leeritchey@xxxxxxxxxxxxx>
- To: "Curt McNamara" <CurtM@xxxxxxxxxxx>, "Joel Brown" <joel@xxxxxxxxxx>
- Date: Fri, 9 Jun 2006 11:53:24 -0700
I have received CE approvals on dozens of products with having to resort to
removing the planes from under the RJ-45 connectors or the magentics. Same
thing for Telco approvals. I am mystified about what I am hearing on this site.
----- Original Message -----
From: Curt McNamara
To: Joel Brown;leeritchey@xxxxxxxxxxxxx
Cc: Chandupcb; si-list@xxxxxxxxxxxxx
Sent: 6/9/2006 10:25:09 AM
Subject: RE: [SI-LIST] Re: RJ-45 Connector
IF safety approvals are not a concern (i.e. this is not a CE marked product or
is exempted from the standards) then this is fine advice, and will keep you
away from ESD issues as well.
I have designed and gotten CE approval for products (ISDN) where this coupling
on the output side was critical. There are also Ethernet devices that need to
pass Class B for the US where the common mode coupling can be an issue as well.
It all depends on your system.
Curt
Curt McNamara. P.E.
Senior Electrical Engineer
Logic Product Development
411 Washington Ave. N Suite 101
Minneapolis, MN 55401
Tel 612-436-5178
Fax 612-672-0443
curtm@xxxxxxxxxxx
www.logicpd.com
This message (including any attachments) contains confidential information
intended for a specific individual and purpose, and is protected by law. If you
are not the intended recipient, you should delete this message and are hereby
notified that any disclosure, copying, or distribution of this message, or the
taking of any action based on it, is strictly prohibited.
-----Original Message-----
From: Joel Brown [mailto:joel@xxxxxxxxxx]
Sent: Friday, June 09, 2006 11:45 AM
To: leeritchey@xxxxxxxxxxxxx
Cc: Curt McNamara; Chandupcb; si-list@xxxxxxxxxxxxx
Subject: Re: [SI-LIST] Re: RJ-45 Connector
My understanding from a question I previously posted was that the board ground
should not go past the Ethernet magnetics for fear that common mode noise would
couple from the board ground to the RJ45 side of the magnetics and radiate out
on the Ethernet cable.
It was suggested that the area under the RJ45 should be connected to chassis
ground with a split between chassis ground and board ground. This was
recommended in an Intel app note, but our EMI consultant said it was wrong and
recommended we run the board ground under the RJ45 with no plane split and also
to connect the RJ45 shield to chassis ground.
Joel
Lee Ritchey wrote:
Curt,
The creepage distance is on the surface, not internally. The internal
spec is 1700 VDC withstanding and that is achieved with only 2 mils of
FR-4. So, there is no need to clear planes that are internal to the PCB.
Why do engineers globally apply specs, when they don't apply?
Yes, there is one regulator person in Australia who does not understand
this and insists that planes need to be cleared. He is out to lunch! We
solved the problem by just not shipping to Australia! The whole market in
Australia is less than half of Californina, so it wasn't much of a
sacrifice.
[Original Message]
From: Curt McNamara <CurtM@xxxxxxxxxxx>
To: <leeritchey@xxxxxxxxxxxxx>; Chandupcb <chandupcb@xxxxxxxxx>;
<si-list@xxxxxxxxxxxxx>
Date: 6/9/2006 9:10:42 AM
Subject: [SI-LIST] Re: RJ-45 Connector
From a safety standpoint the "line side" of the RJ45 can be TNV
(tele-communications network voltages). These wires can go through
wiring cabinets where a single fault could short them to AC (Ethernet),
or could go on poles outside the building (DSL or modem). As a result
approval bodies require a transformer for isolation between TNV and
SELV. To ensure the isolation, you need to keep minimum distances
(called creepage and clearance) between these line side signals and
anything on the SELV (safety extra low voltage) side. In practice this
requires there be no planes under the output side, since the distance
between the planes and the output traces or pins would violate the
standard. You should check with your approvals body to ensure that the
correct standard is being applied.
Curt
Curt McNamara. P.E.=20
Senior Electrical Engineer=20
Logic Product Development=20
411 Washington Ave. N Suite 101=20
Minneapolis, MN 55401=20
Tel 612-436-5178=20
Fax 612-672-0443=20
curtm@xxxxxxxxxxx=20
www.logicpd.com=20
This message (including any attachments) contains confidential
information intended for a specific individual and purpose, and is
protected by law. If you are not the intended recipient, you should
delete this message and are hereby notified that any disclosure,
copying, or distribution of this message, or the taking of any action
based on it, is strictly prohibited.
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Lee Ritchey
Sent: Friday, June 09, 2006 11:00 AM
To: Chandupcb; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: RJ-45 Connector
Chandu,
There is no valid reason to do this. Rules like this are often called
elephant repellant.
[Original Message]
From: Chandupcb <chandupcb@xxxxxxxxx>
To: <si-list@xxxxxxxxxxxxx>
Date: 6/9/2006 3:46:00 AM
Subject: [SI-LIST] RJ-45 Connector
Hi Gurus,
May I know why will we remove the Plane under the RJ-45=20
connector.Some
times only chasis gnd is Allowed under the connector.
Why?
Regards
Chandu
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:=20
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at: =20
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
=20
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at: =20
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
=20
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
