Hello, YY Lau, This is a modeling issue. The tolerance allowed on V-t table endpoints is a modeling decision. Large mismatches can lead to simulation problems (hence parser mismatch error/warning messages). If the mismatch is between 2% and 10%, the parser issues a warning. Common causes are too few points in the I-V tables, or not waiting until the V-t transition is fully complete (in which case, V-t data might look OK, but with enough slope to cause this warning). The transistor strength requirement is not evaluated by IBIS. That is a design/application requirement. Best regards, Lynne "IBIS training when you need it, where you need it." Dr. Lynne Green Green Streak Programs http://www.greenstreakprograms.com 425-788-0412 lgreen22@mindspring.com _____ From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of lau yy Sent: Thursday, April 06, 2006 3:23 AM To: ibis-users@eda.org Subject: [IBIS-Users] Warning message for MISMATCH Hi ALL, Below I attach a model for an IO pin. The model pass with warning. I show 1 of the warning message as below: WARNING - Model IO: The [Falling Waveform] with [R_fixture]=50 Ohms and [V_fixture_max]=3.6V has MAX column DC endpoints of 1.98V and 3.53v, but an equivalent load applied to the model's I-V tables yields different voltages ( 1.94V and 3.39V), a difference of 2.36% and 3.96%, respectively. I study the rising and falling datas, can see that the pin is already stable but is just the voltage level can fall to 0 or reach VCC. Is this a design issue or modeling issue? I belive that is the pullup and pulldown transistor not strong enough. Am I right? PLease comment. Thanks rdgs yylau |------------------------------------------------------------------ |For help or to subscribe/unsubscribe, email majordomo@eda.org |with just the appropriate command message(s) in the body: | | help | subscribe ibis <optional e-mail address, if different> | subscribe ibis-users <optional e-mail address, if different> | unsubscribe ibis <optional e-mail address, if different> | unsubscribe ibis-users <optional e-mail address, if different> | |or email a written request to ibis-request@eda.org. | |IBIS reflector archives exist under: | | http://www.eda.org/pub/ibis/email_archive/ Recent | http://www.eda.org/pub/ibis/users_archive/ Recent | http://www.eda.org/pub/ibis/email/ E-mail since 1993Received on Thu Apr 6 09:51:39 2006
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