Xuefeng, You are raising an excellent question. The IBIS spec may not be totally clear on this, but the enable signal should have no effect on the operation of the bus hold portion of a model. The bus-hold buffer's purpose in life is to keep the bus from floating and/or to terminate it to reduce reflections. You can think of it as a buffer that drives the pad based on a signal level that is sees on the pad (instead of a stimulus coming from an internal logic output). You can also think of it as an active terminator which changes states as the signal is changing on the pad. Based on this description it would not make sense to disable such a buffer. Of course, I could imagine cases when the bus hold is turned off while the driver is driving, or when special conditions require that, but those cases could be taken care of with making separate models and using the [Model Selector] keyword. I hope this answered your question. Arpad Muranyi Intel Corporation ------------------------------------------------------ -----Original Message----- From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of Xuefeng Chen Sent: Tuesday, February 28, 2006 12:48 AM To: ibis-users@eda.org; ibis@eda.org Subject: [IBIS-Users] Bush Hold and Enable node Hi expert, Is there any relation between the transition of Bush Hold submodel and the shift of enable->disable of top model? I failed to find the relation in IBIS4.1. I think the transition of Bush Hold is only related to Vdie, disregarding whether or not top buffer is disable. Is it right? Many thanks Xuefeng |------------------------------------------------------------------ |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 1993 |------------------------------------------------------------------ |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 Wed Mar 1 10:49:44 2006
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