Matching the lengths of the data lines within +/- 50 mils would add unnecessary work for the PCB designer. In my opinion, +/- 100 mil would be enough. /dan --- Dimiter Popoff <dp@xxxxxxxxxxx> wrote: > Hi everyone, > I found a number of appnotes on DDR-1 which state > that data signals (and the related, dqs and > dqm) must be length matched within +/- 50 mils. Now > I read the spec of a DDR chip I would > use, and it says something like 0.4-0.5 nS max. skew > between these signals. At, say, 160 pS/inch, > 50 mils means 8 pS .... Am I overlooking something > or are those recommendations I found > just nonsense? (I am talking the slowest, 133 MHz > clock DDR, with up to 200 MHz in > mind but unnecessary for this particular design). > > Thanks, > > Dimiter > > > ------------------------------------------------------ > Dimiter Popoff Transgalactic > Instruments > > http://www.tgi-sci.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: > http://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: > http://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 > > > __________________________________ Yahoo! Mail - PC Magazine Editors' Choice 2005 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: http://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: http://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