[SI-LIST] Re: DDR1 without VTT termination
- From: Ravinder.Ajmani@xxxxxxxxxxxxxx
- To: "Kathiresan K" <k.kathir@xxxxxxxxx>, si-list@xxxxxxxxxxxxx
- Date: Mon, 31 Mar 2008 08:43:30 -0700
Hi Kathiresan,
I have designed two designs with single 32-bit DDR1 (160 MHz and 200 MHz).
It is possible to realize these designs without VTT termination, if the
trace length is kept small (< 1.5"), and Half-strength drivers are used at
the DRAM. I used series terminations on the DDR side only, as my ASIC
drivers are well behaved. If your processor has impedance matched drivers
and the trace length can be further minimized, then you may even be able
to use the Weak drivers on the DRAM without using any terminations.
The best way to find it out will be by running a simulation.
Regards, Ravinder
Server PCB Development
Hitachi Global Storage Technologies
Email: Ravinder.Ajmani@xxxxxxxxxxxxxx
"Kathiresan K" <k.kathir@xxxxxxxxx>
Sent by: si-list-bounce@xxxxxxxxxxxxx
03/31/2008 07:18 AM
To
si-list@xxxxxxxxxxxxx
cc
Subject
[SI-LIST] DDR1 without VTT termination
Hi,
I need to have a single chip DDR1 (160 MHz, 16-Bit) memory for a
processor.
I don't want to provide VTT terminations. I'll keep the trace length as
minimum as possible. I may provide series termination but I haven't done
pre-layout simulation yet.
Can somebody please clarify whether it can be designed without VTT
termination? If yes, what can be the maximum trace length I go for? If I'm
providing series termination, should I provide at both the ends for
bi-directional signals?
Regards,
Kathir
------------------------------------------------------------------
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 technical documents are available at:
http://www.si-list.net
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
------------------------------------------------------------------
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 technical documents are available at:
http://www.si-list.net
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:
