Hi Sudarshan: It is OK and reasonable to increase the resistor to a higher value for two reasons: 1, The buffer is slow, so high speed issues are not really a factor. So Transmission line characteristic impedance modeling should have minimal impact on the simulation. 2, If the Buffer is weak, a large resistor allows you to extract the table over a larger swing to correspond to how the part may operate (in a mostly infinite to small capacitive load. If you have to use 10,000 ohms, then do so, but it would be better to use a smaller value. Perhaps 500 ohms or 1,000 ohms might be better as long as there is a reasonable voltage swing (such as 30 - 50 percent of the Vdd-Gnd rail.) While, for example, on the rising edge, the response to a load to Vdd will remain fast, a smaller resistor load should capture some buffer speed reduction better if it is actually connected with a termination load to Gnd. Bob Sudarshan Honnudike wrote: > > Hello Experts, > > One of my IO buffer is very slow and i need to increase R_fixture to > considerably high value to > make the V-t curves attains steady state. I actually increased to > 10k(10,000). > > Will this have any major effect during SI simulations or is it ok to > have this big load also.? > > > Best Regards, > > Sudarshan HN > NXP Semiconductors/CTO /PLT > C-4, Manyata Tech Park, Nagawara > Bangalore-560 045 , India. > Ph:+91-80-40247073 > Fax: +91-80-4026 7855 > seri:sudarsha@inpsblr > E-mail: sudarshan.honnudike@nxp.com > -- > This message has been scanned for viruses and > dangerous content by MailScanner <http://www.mailscanner.info/>, and is > believed to be clean. -- Bob Ross Teraspeed Consulting Group LLC Teraspeed Labs 121 North River Drive 13610 SW Harness Lane Narragansett, RI 02882 Beaverton, OR 97008 401-284-1827 503-430-1065 http://www.teraspeed.com 503-246-8048 Direct bob@teraspeed.com Teraspeed is a registered service mark of Teraspeed Consulting Group LLC -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. -------------------------------------------------------------------- |For help or to subscribe/unsubscribe, e-mail majordomo@eda-stds.org |with 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 e-mail a request to ibis-request@eda-stds.org. | |IBIS reflector archives exist under: | | http://www.eda-stds.org/pub/ibis/email_archive/ Recent | http://www.eda-stds.org/pub/ibis/users_archive/ Recent | http://www.eda-stds.org/pub/ibis/email/ E-mail since 1993Received on Thu Apr 12 15:19:25 2007
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