[SI-LIST] Re: DDR Timing Relation
- From: Hermann Ruckerbauer <hermann.ruckerbauer@xxxxxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx, karthiyen@xxxxxxxxx
- Date: Tue, 31 May 2011 09:17:45 +0200
Hello Karthi,
maybe a first start could be the video DDR3 Setup/Hold tutorial on
http://www.eyeknowhow.de/index.php/downloads/5-movies
Often you find a quite good explanation from your Controller vendor, or
you get even some excel tables that are checking routing requirements.
I think there have been also some DDRx timing budgeting questions on the
SI-List, so a search in the archive might also answer already some of
your questions.
Here some quick information (but I did not check the official parameter
names as they might be slightly different for different memory generations:
The most important databus related timing is DQ to DQS setup/hold timing
On DDR2 there is an important timing relation between CLK and DQS
On the CA bus clock to Control and CLK to Command/Address Setup/Hold
must be fulfilled for all DRAMs (important on the DDR3 FlyBy bus).
In addition you need to consider the derating if you have slow slew
rates on big systems to figure out the required Setup/Hold time for your
system
===> But all this is not just a length matching, but a Signal Integrity
question as well.
I think it is to complex to start the explanation on Length matching for
DDRx (especially without more detailed information on your system) in an
e-mail.
More specific questions can be answered on an e-mail basis, but to
explain a complete timing budget might be difficult.
Best regards (and good luck)
Hermann
EKH - EyeKnowHow
Hermann Ruckerbauer
www.EyeKnowHow.de
Hermann.Ruckerbauer@xxxxxxxxxxxxx
Veilchenstrasse 1
94554 Moos
Tel.: +49 (0)9938 / 902 083
Mobile: +49 (0)176 / 787 787 77
Fax: +49 (0)3212 / 121 9008
schrieb karthi keyan:
> Hi Experts,
> can anybody working in DDR & its timing budgets help me to
> understand the DDR timing relations, In Micron data sheet i found a
>
> number of AC characteristics which shows the relationship between Data ,
> Data strobe , CLK & Address/CMD . From that which
>
> Particular AC characteristics relation i need to follow for Length matching.
>
>
> Thanks,
> Karthi.
>
>
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