[SI-LIST] Re: DDR-2 address Termination Topology

  • From: "Xu, Catherine (ICS)" <xu@xxxxxx>
  • To: Ragesh <rageshmb@xxxxxxxxx>, "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
  • Date: Thu, 11 Mar 2010 16:51:06 +0000

Hi, Ragesh,

It depends on many factors such as the driver strength ( and adjustability of 
strength) of address pads on DRAM controller, the design scheme of your DRAM 
address buses( T vs. pass through), how well are the address/cmd buses match 
the length of clock pair, and if not, do you have ability to adjust delay lines 
in DRAM driver o compensate. And if your design's major challenge is voltage 
margin ( due to challenges of PDN and SSN) or timing margin. 


You could get very good insight by performing simple simulation with a decent 
IBIS model for the driver and DRAM part's receiver pads. And there are lots of 
good tools around for that purpose.

Assume you are doing embedded DRAM design drive two parts, at -533 grade, with 
trace length <2 inch, if you can choose a driver with proper Tr /Tf, there are 
very good chance of not needing any external termination components. 


Catherine Xu
__________________________________
Lead HW Design Engineer, Ph.D
HP ICS  CHIL - San Diego
_________________________________ 


-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On 
Behalf Of Ragesh
Sent: Thursday, March 11, 2010 6:23 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] DDR-2 address Termination Topology

Hi Guru's,
Which is the preferred termination for DDR-2 address lines? the
configuration is 2 devices sharing address lines.

1) One 50E parallel termination to Vtt at the split.
2) Two 100E resistors each at the devices.

The maximum length for any address line is less than 2 inches and the DDR-2
frequency is 533.

Reagrds
RaGZ & AVM


------------------------------------------------------------------
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
 
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
 
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu
  

Other related posts: