Point-to-point is a special case. Check out Micron's site. They have an app note for doing point-to-point to DDR RAM using only a single series termination on the data bus. And on the address/control bus, if you run the trace to a routing via, then route from the via in a 'star' with equal length legs to all the SDRAM, then the address shouldn't need the parallel termination either. There is enough capacitance so that there is no over/undershoot. It all depends on your drivers, memory, and cycle time. So be careful and run simulations if you are doing a new design. -tom -----Original Message----- From: Raj, Shankar [mailto:Shankar.Raj@xxxxxxx]=20 Sent: Thursday, May 01, 2003 9:57 PM To: 'shane.san.miguel@xxxxxxxxx'; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: SDRAM bus termination Hi Shane, I am having point-to-point data interconnections between chipset and stacked DDR's(SSTL2). The length varies from 3 - 5 inches and there is no parallel termination to 1.25V. The signal quality and timings are fine wrt simulation, but I would like to know whether there are any implcations of not using a parallel termination to 1.25V. I read your mail, but couldn't understand clearly. It will be of great help if u can explain the same. Thanks and Regards, Shankar V Force Computers Bangalore -----Original Message----- From: San Miguel, Shane [mailto:shane.san.miguel@xxxxxxxxx] Sent: Wednesday, 30 April 2003 1:34 AM To: ganesancp@xxxxxxxxxxx; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: SDRAM bus termination The SDRAM stuff will work fine in point to point config as long as the = =3D data bus is short. Shouldn't be a concern even though SSTL specs =3D specify a high-z state. I have no knowledge of the FPGA side of your = =3D situation but as long as it doesn't use the DQS preamble/postamble to = =3D set up any data window timings you'll be fine. You can't do the =3D preamble/postamble with point to point. I've seen point to point SDRAM =3D and DDR DRAM on testers using FPGAs and point to point with no = issues. =3D Without termination there WILL BE a charge up time for the data bus, = 1 =3D or two bits worth maybe, depends. You'll see this represented as = the =3D high/low swing gradually rising in DC level over a couple of successive =3D reads (or bits). As long as you know this is happening = it shouldn't be =3D an issue. Shane San Miguel=3D20 Product Engineer=3D20 Platform Memory Operations=3D20 Intel Corporation=3D20 =3D20 =3D20 -----Original Message----- From: ganesancp [mailto:ganesancp@xxxxxxxxxxx] Sent: Tuesday, April 29, 2003 9:33 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] SDRAM bus termination Hello SI experts, I am designing a board with one SDR SDRAM and i want to connect = this=3D20 SDRAM to a Xilinx Virtex-E FPGA in another board. SDRAM interface=3D20 will be working at 120MHz and there is no other component in the = bus=3D20 (point-to-point).=3D20 Any termination suggested for the data bus and any other SI related=3D20 issues expected in this configuration? Regards, Ganesan ------------------------------------------------------------------ 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 archives are viewable at: =3D20 //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages=3D20 Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu =3D20 ------------------------------------------------------------------ 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 archives are viewable at: =20 //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages=20 Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu =20 ------------------------------------------------------------------ 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 archives are viewable at: =20 //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages=20 Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu =20 ------------------------------------------------------------------ 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 archives are viewable at: //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