The main benefit of external is that you get to choose the common mode choke, and it will have a lot more iron (read attenuation) than the puny :-) little thing inside the RJ-45. When I worked for a telecom manufacturer we always used external. However, the small footprint boards we make here require the integrated jacks, and we have made them work. As noted below, you need to be extra careful keeping your signal clean into the transformer .... 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 Chris Padilla (cpad) Sent: Tuesday, February 28, 2006 12:11 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Integrated vs. discrete magnetics for Ethernet Prakash, Most of my experience is with Broadcom and Marvell Phys. They both are wonderfully robust parts but a side effect of that robustness (which comes from their DSP), is higher harmonic noise: Namely the 125 MHz harmonics all the way to 1 GHz can be troublesome. I have mostly dealt with 2x6 (6 over 6) and 2x8 (8 over 8) IntMags to the tune of 48 ports as we are always trying to maximize port density. That is a lot of DSPs pumping away through the fairly (electrically) large cavities within the shielded jacks. Trying to pass Class A can be difficult! How many ports did you have, Charles? :o) There is no way I can compress 6 years of experience on these parts into a simple reply here. As has been repeated ad naseum on this list, it depends on so many factors: stack-up, board routing, part selection, chassis design, etc. In my experience, I don't think it matters much if you go discrete or integrated. Board real estate is often a very precious commodity HOWEVER: With discrete, you have a great deal of "access" to play with and tune parts. With integrated, you must rely on the manufacturer of the part (Pulse, Bel, etc.) to tune things for you. Make no bones about it, going discrete or integrated, without a good deal of forethought and experienced leadership, it could be difficult in the chamber passing a great number of ports. All that said, integrated magnetic RJ45s are a relatively mature product for the big boys like Pulse and Bel and so they have a good deal of experience to help you with the design of the board: use them! Find out how much support you can expect from them. Personally, I would lean towards Bel but Pulse is good as well. Good Luck! Chris Padilla Cisco Systems San Jose, CA=3D20 -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Grasso, Charles Sent: Tuesday, February 28, 2006 7:58 AM To: jswarrier@xxxxxxxxx; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Integrated vs. discrete magnetics for Ethernet Well I suppose this is another case where "it depends". We have a system with an Ethernet integrated magnetics that passed with >10dB of margin to ClassB with the ENet running at full bore. Now - we only use one connector...anyone from Cisco and involved in EMC on this list care to comment?? Best Regards Charles Grasso Senior Compliance Engineer Echostar Communications Corp. Tel: 303-706-5467 Fax: 303-799-6222 Cell: 303-204-2974 Pager/Short Message: 3032042974@xxxxxxxx Email: charles.grasso@xxxxxxxxxxxx; Email Alternate: chasgrasso@xxxxxxxx -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Jai Shanker Sent: Monday, February 27, 2006 10:34 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Integrated vs. discrete magnetics for Ethernet Its probably LXT PHYs from Level One that Intel has used in its previous chips and not Marvell. I think the jacks come in different versions with 1:1.25 or 1:1 ratios as required for different PHYs. We used the integrated jack in a prototype but didnt go for any EMC compliance tests so I have no further info on this. regards, Jai --- "Chauhan, Prakash" <pchauhan@xxxxxxxxxxx> wrote: > This is an Intel PCI Express based Gigabit Ethernet Controller. =20 >The=3D20 Phy is integrated. I think Intel had integrated Marvell's = Phy >on=3D20 some chips in the past, but I don't know whether this device = is=20 >=3D20 different. =3D3D3D20 =3D3D20 Thanks, Prakash.=3D3D3D20 =3D3D20 = >-----Original =3D >Message----- > From: Chris Padilla (cpad) > [mailto:cpad@xxxxxxxxx]=3D3D3D20 > Sent: Monday, February 27, 2006 1:20 PM > To: Chauhan, Prakash; si-list@xxxxxxxxxxxxx > Subject: RE: [SI-LIST] Integrated vs. discrete magnetics for Ethernet >=3D3D20 Tell us what Phy vendor you are planning to use: Marvell or=20 >Broadcom or ??? >=3D3D20 > Chris Padilla > Cisco Systems > San Jose, CA=3D3D3D20 >=3D3D20 > -----Original Message----- > From: si-list-bounce@xxxxxxxxxxxxx > [mailto:si-list-bounce@xxxxxxxxxxxxx] > On Behalf Of Chauhan, Prakash > Sent: Monday, February 27, 2006 10:00 AM > To: si-list@xxxxxxxxxxxxx > Subject: [SI-LIST] Integrated vs. discrete magnetics for Ethernet =3D =3D3D20 >Hi All, > I was wondering if anyone has comments regarding the use of =3D20 >integrated magnetics (In the RJ-45) versus a discrete implementation=20 >=3D20 (for 10/100/1000 Base-T). I have been advised that = integrated=3D20=20 >magnetics have poorer shielding (between diff pairs) and can be=3D20=20 >problematic from an EMC compliance standpoint. I would much prefer=20 >=3D20 to use integrated Magnetics for space conservation and to have=20 >less =3D20 component count and simplify layout. If anyone has had=20 >problems with >the Integrated Magnetics I would love to hear about it. (I am =3D20=20 >planning on using Belfuse Magjack family part: 0826-1X1T-23-F). =20 >Any=3D20 appnotes that can help implement this from a compliance=20 >standpoint=3D20 would be greatly appreciated. =3D3D20 > Thanks, > Prakash. > ------------------------------------------------------------------ > To unsubscribe from si-list: > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field >=3D3D20 or to administer your membership from a web page, go > to: > //www.freelists.org/webpage/si-list >=3D3D20 > For help: > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field = =3D3D20 >=3D >List FAQ wiki page is located at: > =3D3D20 http://si-list.org/wiki/wiki.pl?Si-List_FAQ >=3D3D20 > List technical documents are available at: > http://www.si-list.org =3D3D20 > List archives are viewable at: =3D3D3D20 > //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 > =3D3D3D20 > ------------------------------------------------------------------ > To unsubscribe from si-list: > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field >=3D3D20 or to administer your membership from a web page, go > to: > //www.freelists.org/webpage/si-list >=3D3D20 > For help: > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field = =3D3D20 >=3D >List FAQ wiki page is located at: > =3D3D20 http://si-list.org/wiki/wiki.pl?Si-List_FAQ >=3D3D20 > List technical documents are available at: > http://www.si-list.org =3D3D20 > List archives are viewable at: =3D3D20 > //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 > =3D3D20 >=3D3D20 >=3D3D20 __________________________________________________ Do You Yahoo!? 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