[SI-LIST] Re: termination for routing 8 SDRAMs to single Processor
- From: steve weir <weirsi@xxxxxxxxxx>
- To: dp@xxxxxxxxxxx, "Kenneth W. Egan" <kegan@xxxxxxxxxxxxx>, "" <aavinda12@xxxxxxxxx>, "" <si-list@xxxxxxxxxxxxx>
- Date: Wed, 10 Aug 2005 23:03:53 -0700
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
>------------------------------------------------------
>
>
>
>
>-------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] 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
> > ------------------------------------------------------
> >
> >
> >
> >
> > -------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.
> > >
> > > ---------------------------------
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