hello Jonathan -=20 Do you want to estimate the amount of current rushing in or out of the Altera part, or do you want to analyze the impact of this current surge? If it's the amount of I, then it is straight forward - but don't use the old "hang a capacitor on the buffer" approach. Think transmission line and represent the t-line with a resistor equal to Zo and another resistor for Zs (source impedance) and then tie them to rails (note : there might be other resistors in the path depending on your HSTL term scheme). Solving for I (E/Rtotal) seems to line up very well with SI simulators that can measure the in-rush current (if you have one you can just simulate to get the answer). then take this answer and multiply times the # of outputs switching at the same time for total surge current. If it's the second question (what does this current surge do to my Altera's internal PDS?), then I can't help as much (sorry). There is a technique that's sometimes called the "portal method", that is used to look inside the device. Attach a scope to a quiet buffer driving high. Switch all the outputs from a 0 to a 1 and note the noise spike on the scope (the buffer is driving 1 so you are looking at the Vdd rail). Then have the quiet buffer drive a logic 0 (Vss rail) and switch all of the outputs from a logic 1 to 0 and note the noise spike. I've used this method on large devices and it seems to work ok, but it needs a fast scope.=20 The missing part of this is when will the part fail. This is usually defined as when a quiet buffer toggles because of all the noise...I'd try to get Altera to help you with this. Hope this helps. Jim Honeywell -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Fasig, Jonathan L. Sent: Thursday, August 03, 2006 9:45 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] SSN analysis? We are working on SSN analysis for an application that will have 600 HSTL I/O's on an Altera Stratix-II GX130. Is there anyone in this community who has done (or is currently doing) similar work? jf ------------------------------------------------------------------- Jonathan Fasig Email: fasig.jonathan@xxxxxxxx=09 Mayo Foundation 4001 41st Street NW=20 MSC Sn 2-132 Phone: (507) 538-5464 Rochester, MN 55901 Fax: (507) 284-9171 ------------------------------------------------------------------ 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 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: =20 //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 =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 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: //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