[SI-LIST] Re: termination for routing 8 SDRAMs to single Processor
- From: "Dimiter Popoff" <dp@xxxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Tue, 16 Aug 2005 14:23:34 +0300
After this thread has been recurring for a week, I'll timeout my promise to
no longer post on it, as Steve keeps on posting nonsense on it.
So let me see:
- the chip spec explicitly says that unlike the 5V tolerant PCI pins the memory
controller
pins are 3.3V only;
- I explained there were visible diferences in the behaviour of the two pin
groups;
- and I stated, that the trace length is within an inch or so.
And here comes Steve Weir and weighs in with the assumption, that all of the
above may be wrong and that an inch long trace can produce enough overshoot
at 100 MHz to kill parts if I had not been lucky.
Well, I realize selling consulting services may be a priority if that's all one
has to sell,
but after this output as far as it would be up to me the consultant would have
even
more time for posting to the net.
------------------------------------------------------
Dimiter Popoff Transgalactic Instruments
http://www.tgi-sci.com
------------------------------------------------------
-------Original Message-------
> From: steve weir <weirsi@xxxxxxxxxx>
> Subject: [SI-LIST] Re: termination for routing 8 SDRAMs to single
> Processor
> Sent: Aug 16 '05 13:02
>
> Navaneeth, thanks, but the RAMs weren't at issue. The controller
> was. Dimiter has used that particular controller without termination and
> experienced reliable operation for 4 years . We discussed reasons why that
> might be when excessive overshoot can cause damage and premature
> failures. Either there wasn't too much overshoot, less likely, or the
> component tested was tolerant to the amplitude and duration by design or
> good fortune.
> Steve.
>
> At 10:33 AM 8/16/2005 +0530, navaneeth.kumar@xxxxxxxxx wrote:
> >Hi,
> > Manufacturers like micron and samsung specify in their
> > SDRAM(3.3v) datasheet that their inputs can withstand an overshoot
> > voltage of 5.6vmax provided the overshoot width is lesser then 3nsec.
> >
> >regards
> >Navaneeth
> >
> >
> >----------
> >From: si-list-bounce@xxxxxxxxxxxxx on behalf of Dimiter Popoff
> >Sent: Thu 8/11/2005 12:27 PM
> >To: steve weir;
> >Subject: [SI-LIST] Re: termination for routing 8 SDRAMs to single Processor
> >
> >Memory outputs are separately powered. At least with revision A (which
> >was practically unusable) memory outputs would not obey JTAG if
> >the memory clock did not work or something like that (PCI did).
> >
> >It is possible, of course, that the memory inputs have been overdesigned
> >to be the same as the PCI ones, but quite unlikely, 5V tolerance is
> >not that cheap to make. I guess no one except for the actual chip
> >designer can answer that question, so we better cut it here.
> >
> >Dimiter
> >
> >------------------------------------------------------
> >Dimiter Popoff Transgalactic Instruments
> >
> ><http://www.tgi-sci.com>http://www.tgi-sci.com
> >------------------------------------------------------
> >
> >
> >
> >
> >-------Original Message-------
> > > From: steve weir <weirsi@xxxxxxxxxx>
> > > Subject: Re: [SI-LIST] Re: termination for routing 8 SDRAMs to
> > single Processor
> > > Sent: Aug 11 '05 09:37
> > >
> > > Dimiter, I know the memory power rail is spec'd for 3.3V, but that
>really
> > > doesn't tell us about the drivers / receivers.
> > >
> > > Steve.
> > > At 09:30 AM 8/11/2005 +0300, Dimiter Popoff wrote:
> > > >Only the PCI pins are specified to up to 5.5 V input voltage.
> > > >The rest are specified at max. 3.3V. (Memory might be 2.5 V max.,
> > > >separate power, which in my case is 3.3V - cut and "jumper solder"
> > > >selectable to 2.5, but this feature has never been used).
> > > >
> > > >Dimiter
> > > >
> > > >------------------------------------------------------
> > > >Dimiter Popoff Transgalactic Instruments
> > > >
> > > ><http://www.tgi-sci.com>http://www.tgi-sci.com
> > > >------------------------------------------------------
> > > >
> > > >
> > > >-------Original Message-------
> > > > > From: steve weir <weirsi@xxxxxxxxxx>
> > > > > Subject: Re: [SI-LIST] Re: termination for routing 8 SDRAMs to
> > > > single Processor
> > > > > Sent: Aug 11 '05 09:19
> > > > >
> > > > > Dimiter, that part has 5V tolerant PCI I/O. If the memory I/O's
>are
> > > > > similarly tolerant, it is easy to understand why you don't have
> > > > reliability
> > > > > issues.
> > > > >
> > > > > Steve.
> > > > >
> > > > >
> > > > > At 09:07 AM 8/11/2005 +0300, Dimiter Popoff wrote:
> > > > > >Like I mentioned, he controller was an 8240 (MPC8240 of
> > Motorola, now
> > > > > >Freescale).
> > > > > >If keeping connections within about an inch or just somewhat
> > more length
> > > > > >is luck, then I guess I have been lucky.
> > > > > >
> > > > > >Dimiter
> > > > > >
> > > > > >------------------------------------------------------
> > > > > >Dimiter Popoff Transgalactic Instruments
> > > > >
> > > > ><http://www.tgi-sci.com>http://www.tgi-sci.com
> > > > > > >------------------------------------------------------
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >-------Original Message-------
> > > > > > > > From: steve weir <weirsi@xxxxxxxxxx>
> > > > > > > > Subject: Re: [SI-LIST] Re: termination for routing 8 SDRAMs
> to
> > > > > > > single Processor
> > > > > > > > Sent: Aug 11 '05 09:03
> > > > > > > >
> > > > > > > > Dimiter, you may have lucked out on that one. Repeated,
> excess
> > > > > overshoot
> > > > > > > > is well demonstrated to shorten the life of components,
> > > > > especially newer
> > > > > > > > low voltage devices. What was the controller?
> > > > > > > >
> > > > > > > > Steve.
> > > > > > > > At 08:55 AM 8/11/2005 +0300, Dimiter Popoff wrote:
> > > > > > > > >Is about 4 years practically continuous operation good
> enough?
> > > > > > > > >The design has demonstrated it.
> > > > > > > > >
> > > > > > > > >Dimiter
> > > > > > > > >
> > > > > > > > >------------------------------------------------------
> > > > > > > > >Dimiter Popoff Transgalactic Instruments
> > > > > > > > >
> > > > > > > > ><http://www.tgi-sci.com>http://www.tgi-sci.com
> > > > > > > > >------------------------------------------------------
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >-------Original Message-------
> > > > > > > > > > From: Kenneth W. Egan <kegan@xxxxxxxxxxxxx>
> > > > > > > > > > Subject: RE: [SI-LIST] Re: termination for routing 8
> SDRAMs
> > > > > to single
> > > > > > > > > Processor
> > > > > > > > > > Sent: Aug 11 '05 05:21
> > > > > > > > > >
> > > > > > > > > > The question might not be one of stability, but one of
> > > > > > > reliability in the
> > > > > > > > > > long term. Sure, you'll probably meet setup and hold
> > > to/from the
> > > > > > > SDRAM.
> > > > > > > > > > However, SDRAM typically has some pretty hot drivers
> (that
> > > > > I've seen,
> > > > > > > > > > simulated and measured in circuit ) and the real issue
> > > is over
> > > > > > > stressing
> > > > > > > > > > The input protection on the receiver, i.e. overshoot
> > > issues.
> > > > > > > > > >
> > > > > > > > > > Failure modes in this case may not occur until much
> > > later in
> > > > > time.
> > > > > > > > > >
> > > > > > > > > > KWE
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > -----Original Message-----
> > > > > > > > > > From: si-list-bounce@xxxxxxxxxxxxx
> > > > > > > > >
> > >
> [<mailto:si-list-bounce@xxxxxxxxxxxxx>mailto:si-list-bounce@xxxxxxxxxxxxx] On
> > > > > > > > > > Behalf Of Dimiter Popoff
> > > > > > > > > > Sent: Wednesday, August 10, 2005 8:00 PM
> > > > > > > > > > To: aavinda12@xxxxxxxxx; si-list@xxxxxxxxxxxxx
> > > > > > > > > > Subject: [SI-LIST] Re: termination for routing 8
> SDRAMs to
> > > > > single
> > > > > > > > > Processor
> > > > > > > > > >
> > > > > > > > > > I have rooted 8 x8 SDRAMs to an 8240 without any
> > > > > terminations and it
> > > > > > > > > worked
> > > > > > > > > > remarkably stable. However, I had 64 data bits rather
> > > than 32.
> > > > > > > > > > I had put 4 SDRAM chips on top and 4 on the bottom of
> > > the board,
> > > > > > > > > practically
> > > > > > > > > > next to the CPU, no connectors between.
> > > > > > > > > >
> > > > > > > > > > Dimiter
> > > > > > > > > >
> > > > > > > > > > ------------------------------------------------------
> > > > > > > > > > Dimiter Popoff Transgalactic Instruments
> > > > > > > > > >
> > > > > > > > > > <http://www.tgi-sci.com>http://www.tgi-sci.com
> > > > > > > > > > ------------------------------------------------------
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > -------Original Message-------
> > > > > > > > > > > From: Aravnda G <aavinda12@xxxxxxxxx>
> > > > > > > > > > > Subject: [SI-LIST] termination for routing 8 SDRAMs
> > > to single
> > > > > > > > > > > Processor
> > > > > > > > > > > Sent: Aug 11 '05 03:29
> > > > > > > > > > >
> > > > > > > > > > > Hi All,
> > > > > > > > > > > I am working with a micro-processor conneted to 8
> > > SDRAM with
> > > > > > > 12 address
> > > > > > > > > > lines to all SDRAMs and 32 data lines each to two sets
> > > of four
> > > > > > > SDRAMs.
> > > > > > > > > I was
> > > > > > > > > > wondering if anyone has managed to route this sort of
> > > topology
> > > > > > > without
> > > > > > > > > using
> > > > > > > > > > terminations. If so please send information on
> topology
> > > > > used. The
> > > > > > > IO are
> > > > > > > > > > lvttl compatible at 3.3V. Any input on routing
> > > possibilities is
> > > > > > > welcome.
> > > > > > > > > > >
> > > > > > > > > > > Thanks & Regards,
> > > > > > > > > > > Alex.
> > > > > > > > > > >
> > > > > > > > > > > ---------------------------------
> > > > > > > > > > > Yahoo! Mail
> > > > > > > > > > > Stay connected, organized, and protected. Take the
> tour
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > ------------------------------------------------------------------
> > > > > > > > > > > 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>//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>http://si-list.org/wiki/wiki.pl?Si-List_FAQ
> > > > > > > > > > >
> > > > > > > > > > > List technical documents are available at:
> > > > > > > > > > >
> > > <http://www.si-list.org>http://www.si-list.org
> > > > > > > > > > >
> > > > > > > > > > > List archives are viewable at:
> > > > > > > > > > >
> > >
> <//www.freelists.org/archives/si-list>//www.freelists.org/archives/si-list
> > > > > > > > > > > or at our remote archives:
> > > > > > > > > > >
> > >
> <http://groups.yahoo.com/group/si-list/messages>http://groups.yahoo.com/group/si-list/messages
> > > > > > > > > > > Old (prior to June 6, 2001) list archives are
> > > viewable at:
> > > > > > > > >
> > > <http://www.qsl.net/wb6tpu>http://www.qsl.net/wb6tpu
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > -------Original Message-------
> > > > > > > > > >
> > > > > ------------------------------------------------------------------
> > > > > > > > > > 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>//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>http://si-list.org/wiki/wiki.pl?Si-List_FAQ
> > > > > > > > > >
> > > > > > > > > > List technical documents are available at:
> > > > > > > > > >
> > > <http://www.si-list.org>http://www.si-list.org
> > > > > > > > > >
> > > > > > > > > > List archives are viewable at:
> > > > > > > > > >
> > >
> <//www.freelists.org/archives/si-list>//www.freelists.org/archives/si-list
> > > > > > > > > > or at our remote archives:
> > > > > > > > > >
> > >
> <http://groups.yahoo.com/group/si-list/messages>http://groups.yahoo.com/group/si-list/messages
> > > > > > > > > > Old (prior to June 6, 2001) list archives are
> viewable at:
> > > > > > > > > > <http://www.qsl.net/wb6tpu>http://www.qsl.net/wb6tpu
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >-------Original Message-------
> > > > > > > >
> > > >------------------------------------------------------------------
> > > > > > > > >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>//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>http://si-list.org/wiki/wiki.pl?Si-List_FAQ
> > > > > > > > >
> > > > > > > > >List technical documents are available at:
> > > > > > > > >
> <http://www.si-list.org>http://www.si-list.org
> > > > > > > > >
> > > > > > > > >List archives are viewable at:
> > > > > > > > >
> > >
> <//www.freelists.org/archives/si-list>//www.freelists.org/archives/si-list
> > > > > > > > >or at our remote archives:
> > > > > > > > >
> > >
> <http://groups.yahoo.com/group/si-list/messages>http://groups.yahoo.com/group/si-list/messages
> > > > > > > > >Old (prior to June 6, 2001) list archives are viewable at:
> > > > > > > > >
> > > <http://www.qsl.net/wb6tpu>http://www.qsl.net/wb6tpu
> > > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > >-------Original Message-------
> > > > > >
> > > > > >
> > > > > >
> > > > >-------Original Message-------
> > > >
> > > >
> > > >
> > >-------Original Message-------
> > >------------------------------------------------------------------
> > >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>//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>http://si-list.org/wiki/wiki.pl?Si-List_FAQ
> > >
> > >List technical documents are available at:
> > > <http://www.si-list.org>http://www.si-list.org
> > >
> > >List archives are viewable at:
> > >
>
> > ><//www.freelists.org/archives/si-list>//www.freelists.org/archives/si-list
> > >or at our remote archives:
> > >
>
> > ><http://groups.yahoo.com/group/si-list/messages>http://groups.yahoo.com/group/si-list/messages
> > >Old (prior to June 6, 2001) list archives are viewable at:
> > > <http://www.qsl.net/wb6tpu>http://www.qsl.net/wb6tpu
> > >
> > >
> > >
> > >
> > >Confidentiality Notice
> > >
> > >The information contained in this electronic message and any attachments
> > >to this message are intended
> > >for the exclusive use of the addressee(s) and may contain confidential or
> > >privileged information. If
> > >you are not the intended recipient, please notify the sender at Wipro or
> > >Mailadmin@xxxxxxxxx immediately
> > >and destroy all copies of this message and any attachments.
> >
> >
> > ------------------------------------------------------------------
> > 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
> >
> >
> >
> -------Original Message-------
>
-------Original Message-------
------------------------------------------------------------------
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:
