SI Community, Is it common for the Vih and Vil on a datasheet to be specified under worst-case conditions (70/30% VDD w/ VDD @ min/max conditions), while the IBIS model for the part only specifies Vih and Vil at VDD @ nominal (even thought the model may have min and max VI and VT corners)? I've now found this to be the case on two completely different parts from completely different manufacturers. What it seems to create is a worst-case simulation that appears to behave fine, but a worst-case noise margin calculation (based on the datasheet) that has little to even negative noise margin. Case in point: Driver has spec'd Voh = 2.4V and the receiver has a Vih = 0.7 * VDD = 0.7 * 3.465V = 2.4255V -25.5 mV of noise margin However, the net simulates just fine across all corners (model Vih = 2.31) Is this a common problem? I would think that Vih and Vil in the model should match that in the datasheet, especially if is dependant on the rail voltage of the part. Comments? Regards, Tim Nash __________________________________ Timothy J. Nash, P.E. Honeywell, Inc. Defense & Space Electronic Systems 13350 U.S. Hwy 19 N M/S 105-4 Clearwater, FL 33764-7290 Office : 727-539-2437 Fax : 727-539-2183 Email : tim.j.nash@xxxxxxxxxxxxx -- Binary/unsupported file stripped by Ecartis -- -- Type: application/x-pkcs7-signature -- File: smime.p7s ------------------------------------------------------------------ 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