Hello Timothy,=20 let's start with over-undershoot: IBIS-Definition: | The static overshoot subparameters provide the DC = voltage | values for which the model is no longer guaranteed to = function | correctly. Typically these are voltages that would = cause the | physical component to be destroyed. | | | The dynamic overshoot values provide a time window = during | which the overshoot may exceed the static overshoot = limits | but be below the dynamic overshoot limits. = D_overshoot_time | is required for dynamic overshoot testing. In = addition, if | D_overshoot_high is specified, then S_overshoot_high is | necessary for testing beyond the static limit. = Similarly, if | D_overshoot_low is specified, then S_overshoot_low is | necessary for testing beyond the static limit. The tools are using these parameters to give the desingn engineer = information, whether something in his layout is not okay. e.g. when = there is a to big undershoot he might use a series resistor to avoid = this undershoot. Reference for power-clamp and gnd-clamp -there exists input/outputs, where the protection diode is using = another suply voltage than the IO. e.g. the IO is working with 3p3V, = but the power-diode is connected to a vcc of 5V. so in this case the = pullup-reference will be 3.3v , but the power-clamp-reference is 5v. And I don't understand your first question. Are you just asking for the pinning ( PIN-keyword ) or for the pin = mapping ( which tells you, which IOs or IO groups do belong to a common = gnd or vcc pin) ? Regards Eckhard Eckhard Lenski Siemens AG ICN WN OP TDC TC3 Phone : 0049 89 722 27776 Fax : 0049 89 722 44692 Email : eckhard.lenski@xxxxxxxxxxx -----Urspr=FCngliche Nachricht----- Von: Timothy Coyle [mailto:Timothy.Coyle@xxxxxxx] Gesendet: Mittwoch, 16. Oktober 2002 21:35 An: si-list@xxxxxxxxxxxxx Betreff: [SI-LIST] Question Regarding Some IBIS Parameters Hi, I am trying to find some information on how I should define my pin = mapping in my IBIS file. Do I just declare an arbitrarily named ground and = power buses for my pins? If the pulldown_ref and pullup_ref are for the ground and power, what are the gnd_clamp_ref and power_clamp_ref for? Also, what are the benefits of including static and dynamic overshoot values for Model Spec? How do simulators such as XTK and SpecctraQuest = use these values? Regards, Tim ------------------------------------------------------------------ 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