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