I realized that there were a few discussions last week on separation of analog and digital powers. I may have missed those but this is the question: For a 4 layer BGA and the following power and grounds.. digital core power digital IO power digital ground analog power analog ground? Would you split the power and ground planes and assign a part of them to analog sections or you would bring the analog powers separately?.if you bring them separately, then does it impact the impedance of the analog supply? Kami Note: forwarded message attached. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com -- Attached file included as plaintext by Ecartis -- X-Apparently-To: azizi_kamran@xxxxxxxxx via 66.163.178.154; Wed, 07 Jun 2006 21:27:02 -0700 X-Originating-IP: [206.53.239.180] Authentication-Results: mta342.mail.mud.yahoo.com from=conexant.com; domainkeys=neutral (no sig) Received: from 206.53.239.180 (EHLO turing.freelists.org) (206.53.239.180) by mta342.mail.mud.yahoo.com with SMTP; Wed, 07 Jun 2006 21:27:01 -0700 Received: from localhost (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 0E94834DF2B; Thu, 8 Jun 2006 00:26:59 -0400 (EDT) Received: from turing.freelists.org ([127.0.0.1]) by localhost (turing [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 26811-09; Thu, 8 Jun 2006 00:26:58 -0400 (EDT) Received: from turing (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id DF7B634DDE6; Thu, 8 Jun 2006 00:26:56 -0400 (EDT) Received: with ECARTIS (v1.0.0; list si-list); Thu, 08 Jun 2006 00:26:03 -0400 (EDT) X-Original-To: si-list@xxxxxxxxxxxxx Delivered-To: si-list@xxxxxxxxxxxxx Received: from localhost (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id C52B434D9AE for <si-list@xxxxxxxxxxxxx>; Thu, 8 Jun 2006 00:26:02 -0400 (EDT) Received: from turing.freelists.org ([127.0.0.1]) by localhost (turing [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 26445-08 for <si-list@xxxxxxxxxxxxx>; Thu, 8 Jun 2006 00:26:02 -0400 (EDT) Received: from dellaware1.bbnet.ad (cnxtsmtp5.conexant.com [198.62.9.40]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 6D60834D702 for <si-list@xxxxxxxxxxxxx>; Thu, 8 Jun 2006 00:26:02 -0400 (EDT) Received: Conexant Mail Received: Conexant Mail Received: Conexant Mail Received: Conexant Mail Content-class: urn:content-classes:message MIME-Version: 1.0 Content-type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit Subject: [SI-LIST] Re: SDRAM Termination Date: Thu, 8 Jun 2006 09:55:54 +0530 X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [SI-LIST] Re: SDRAM Termination Thread-Index: AcaKO4Jhbs58IkarTgq+RU8K2um0SQAdyvag From: "Dharmendra Gowra" <dharmendra.gowra@xxxxxxxxxxxx> To: <signalintegrity@xxxxxxxxxxx>, <saril_k@xxxxxxxxx>, <si-list@xxxxxxxxxxxxx> X-OriginalArrivalTime: 08 Jun 2006 04:26:00.0640 (UTC) FILETIME=[A5762400:01C68AB3] X-Virus-Scanned: by amavisd-new-20030616-p10 (Debian) at avenirtech.net X-archive-position: 18856 X-ecartis-version: Ecartis v1.0.0 Sender: si-list-bounce@xxxxxxxxxxxxx Errors-to: si-list-bounce@xxxxxxxxxxxxx X-original-sender: dharmendra.gowra@xxxxxxxxxxxx Precedence: normal Reply-to: dharmendra.gowra@xxxxxxxxxxxx X-list: si-list X-Virus-Scanned: by amavisd-new-20030616-p10 (Debian) at avenirtech.net Content-Length: 2043 Hi Saril and All, If a 50E termination has to be put at the flash, I would recommend to put the RC termination (to have less current assumption) where R will be 50E and the 'c' value to be decided by your data rate or speed. Also it should be taken care of rise time of the signals(RC time constant) which may lead to setup and hold timing violation. Please correct me if I am wrong. Thanks Dharmendra.G -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Stephen Zinck Sent: Wednesday, June 07, 2006 7:36 PM To: saril_k@xxxxxxxxx; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: SDRAM Termination Hi Saril, In my experience, I would put the SDRAM at the end of the line so incident=20 wave switching occurs for this faster part (if you must daisy chain the=20 interface). The FLASH, because it is slower from a timing point of view, can=20 easily handle the knee that will result (due to the fact that it is in the=20 middle of the bus)... But I wouldn't forgo simulation. You still need to understand if you have any signal integrity issues (no way to guess if you=20 have a good termination methodology or not). You also need to find the=20 flight times associated with the paths to understand the resulting setup and=20 hold margins. Signal integrity is important. But having the interface work=20 in the lab/field from a timing point of view should always be highest on the=20 triage list... You just can't do the timing analysis without simulation. Best, Steve Stephen P. Zinck Interconnect Engineering Inc. P.O. Box 577 South Berwick, ME 03908 Phone - (207) 384-8280 Fax - (207) 676-8676 Email - szinck@xxxxxxxxxxxxxxxxxxxxxxxxxxx Web - www.interconnectengineering.com ----- Original Message -----=20 From: "Saril" <saril_k@xxxxxxxxx> To: <si-list@xxxxxxxxxxxxx> Sent: Wednesday, June 07, 2006 4:28 AM Subject: [SI-LIST] SDRAM Termination > Hi, > > We have an External Memory Interface Bus, which is shared by Boot FLASH=20 > and SDRAM memories. This triggers a Daisy chain topology, we decided to=20 > use a 33 ohm series termination resistor near to the CPU bga balls and > route to SDRAM first, then take it to the FLASH. But there is one more > suggestion, put a 50ohm parallel termination ( trace impedance is 50 ohm)=20 > to ground at the end of the trace near to FLASH, but it will consume more=20 > current. > > Can anybody please give a good termination strategy for this Daisy chain=20 > topology? > > Thanks and regards > Saril Kaiprath > Design Engineer > FDL > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam protection around > http://mail.yahoo.com > > ------------------------------------------------------------------ > 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 > > >=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 ********************** Legal Disclaimer **************************** "This email may contain confidential and privileged material for the sole u= se of the intended recipient. 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