Mo-han
The derating tables are a composite of two functions. Baseline derating is a
function which increases
as slew rate decreases. This derating is only positive at slew rates of less
than 1V/ns, and is zero
everywhere else. The second function is calculated from a normalization formula
which
normalizes the setup and hold specs at the AC/DC threshold, for slew rates
other than 1V/ns,
which is the default used in establishing the setup and hold specs. In this
case higher slew rate
results in larger derating. When you combine the two functions you get a
composite curve which
is always zero at 1V/ns, and can be somewhat irregular below 1V/ns, but above
1V/ns it always
increases with slew rate. Granted it does seem non-intuitive to penalize
margins due to higher slew
rates, but this is the technically correct result of the derating theory. To
some degree it does
relate to charge accumulation effects, as someone state earlier, but the actual
formula is
a simple equation. I forwarded a power-point document which explains derating
in more detail.
Brian Moran
Intel Corporation
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Hermann Ruckerbauer
Sent: Monday, April 13, 2015 12:25 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Derating values for DDR3-800/1066/1333/1600 tDS/tDH
Hello,
Yes, it sounds strange that setup/hold times are getting smaller with slower
slew rates and it is somehow difficult to describe this by e-mail I'm just
doing the Black Box of Memory Seminar (what is the reason for the big Latency I
have on answering this question ;-), and setup/hold times with derating is 1
hour of explanation with quite some help of power point animations.
So here the short version (which is for free ;-) ):
Setup/Hold times are defined at AC/DC level. If you have slower slew rates the
setuptime based on VREF and the engergy provided to the receiver for switching
is increased.
So AC/DC based you need less setup time for slower slew rate in order to
provide the same amount of energy to the receiver to ensure it is switching.
It would be great if this short paragraph could replace 1 hour of
talking, as I can use this time for other topics ;-)
Hermann
Our next Events:
Seminar "Open the Black Box of Memory"
(13.-14.04.2015 and 15.-16.04.2015) in Stockholm Sweden
EKH - EyeKnowHow
Hermann Ruckerbauer
www.EyeKnowHow.de
Hermann.Ruckerbauer@xxxxxxxxxxxxx
Itzlinger Strasse 21a
94469 Deggendorf
Tel.: +49 (0)991 / 29 69 29 05
Mobile: +49 (0)176 / 787 787 77
Fax: +49 (0)3212 / 121 9008
Am 13.04.2015 um 17:16 schrieb Paul Callahan:
Is there any better reference than the February 2010 SI-LIST discussions by:------------------------------------------------------------------
Brian Moran, Hermann Ruckerbauer, Perry Qu, el. Al.?
Paul Callahan
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Boris Bakshan
Sent: Monday, April 13, 2015 3:38 AM
To: hanmoggq@xxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Derating values for DDR3-800/1066/1333/1600
tDS/tDH
Hello Mo han,
With faster edges, larger timing budget is imperative. Think of it
this
way: If the edges are slow enough, there would be enough charge
accumulating at the gates of receivers to trigger the receiving stage.
If you make it faster, it should be comprehended with larger setup
times to allow enough charge accumulation.
This might help:
[image: Inline image 1]
On Mon, Apr 13, 2015 at 9:42 AM, mo han <hanmoggq@xxxxxxxxx> wrote:
HI experts:
why dose the dq slew rate increase,the tDS and tDH increases at the
same time?
Best Regards!
Peter
[image: 内嵌图片 1]
------------------------------------------------------------------
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 forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
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 forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
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 forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
