I didn't post this to the group earlier. My apologies. I found that the clocks and signals were not the main culprits; switching noise from the cards was worse. It causes all signal lines to be perturbed, and as many cards have outside interfaces, this provides not only a fairly high current source, but a good radiating wire as well. Remember, PC slot termination is often a poor ground.
Cortland ====================== Original Message Follows ==================== >> Date: 19-Sep-00 10:44:16 MsgID: 1072-50909 ToID: 72146,373 From: "Fleury, Bill" >INTERNET:[email protected] Subj: RE: compactPCI bus Chrg: $0.00 Imp: Norm Sens: Std Receipt: No Parts: 1 From: "Fleury, Bill" <[email protected]> Subject: RE: compactPCI bus List-Post: [email protected] Date: Tue, 19 Sep 2000 12:44:11 -0500 Thanks Cortland, I was thinking that I was going to have to somehow terminate or filter the PCI clock lines on the unused backplane slots but the PCI spec is pretty picky about trace lengths, pulse shape and, in general, what you can do to the clocks and still be compliant with the spec. That was the main reason why I was asking the question. Thanks for your response. Bill Fleury -----Original Message----- From: Cortland Richmond [mailto:[email protected]] Sent: Tuesday, September 19, 2000 9:30 AM To: Fleury, Bill Subject: Re: compactPCI bus Some time ago, at a previous employer, we had to modify riser cards with PC buss slots on them. We had to add bypassing for each slot in order to reduce emissions caused by PS impedance and poor card design. Cortland ====================== Original Message Follows ==================== >> Date: 19-Sep-00 06:02:16 MsgID: 1072-50820 ToID: 72146,373 From: "Fleury, Bill" >INTERNET:[email protected] Subj: compactPCI bus Chrg: $0.00 Imp: Norm Sens: Std Receipt: No Parts: 2 ------ OzWin: Content #1, Text ------ Sender: [email protected] Received: from ruebert.ieee.org (ruebert.ieee.org [199.172.136.3]) by spdmgaac.compuserve.com (8.9.3/8.9.3/SUN-1.9) with ESMTP id JAA05048; Tue, 19 Sep 2000 09:02:13 -0400 (EDT) Received: by ruebert.ieee.org (8.9.3/8.9.3) id JAA13778; Tue, 19 Sep 2000 09:00:28 -0400 (EDT) Message-ID: <[email protected]> From: "Fleury, Bill" <[email protected]> To: [email protected] Subject: compactPCI bus List-Post: [email protected] Date: Tue, 19 Sep 2000 08:00:17 -0500 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2650.21) Content-Type: multipart/mixed; boundary="----_=_NextPart_000_01C02239.92AA701C" Sender: [email protected] Precedence: bulk Reply-To: "Fleury, Bill" <[email protected]> X-Resent-To: Multiple Recipients <[email protected]> X-Listname: emc-pstc X-Info: Help requests to [email protected] X-Info: [Un]Subscribe requests to [email protected] X-Moderator-Address: [email protected] Judging from the number of responses (0) I got to my question about EMI problems from compactPCI backplanes I am assumiong that either no one uses cPCI backplanes or I'm the only one that has experienced problems when testing in this environment. I didn't think that ever happened in this group. I'll repost this just in case some of you didn't get the last one. This is a question regarding systems which use CompactPCI bus architecture. On a cPCI backplane the PCI clock is routed to every slot on the backplane with up to 7 peripheral slots possible on a normal backplane. My question is this: With the cPCI specification calling out specific trace lengths for clock traces on both the backplane itself and on peripheral cards, have other people experienced any unique EMI problems in trying to meet the design constraints associated with this synchronous bus; especially where there are unpopulated slots on the backplane? Please feel free to respond privately if the question is unclear. I wasn't sure if it was worded properly. Thanks, Bill Fleury ***************Artesyn Communication Products, LLC****************** ******************************************************************** Bill Fleury Email: [email protected] Compliance Engineer Phone: 608-831-5500 8310 Excelsior Drive Fax: 608-831-8844 Madison, WI 53717 ******************************************************************** "The difficult can be done immediately, the impossible takes a little longer" (Army Corp of Engineers) ******************* Visit us at www.artesyn.com/cp ****************** <<Bill Fleury (E-mail).vcf>> ------ OzWin: Content #2, Binary File ------ Filename: C:\OZWIN2\MAIL\BILL FLEURY (E-MAIL).VCF Size: 462 bytes ** File transfer OK ** ====================== End of Original Message ===================== ====================== End of Original Message ===================== ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected]
