total etch length does not consider the package or pin delays prop delay does consider the package or pin delay..... _____ From: Andy_Kulik@xxxxxxx [mailto:Andy_Kulik@xxxxxxx] Sent: Monday, March 07, 2005 7:54 AM To: icu-pcb-forum@xxxxxxxxxxxxx Subject: [PCB_FORUM] Re: Constraint Manager - difference between " Austin, For all 2pin nets/xnets use Total_Etch_Length (TEL). The router just loves it. All net/xnets above 2 pins use min/max propdelay rules. Think pinpairs or drivers/receivers for these types of nets. Picture a xnet with one driver and 3 receivers. The length from the driver to each receivers needs to be the same. TEL doesn't get you anywhere here. You need to implement constraints based on the pin pairs of the net.... I wrote a tutorial which was handed out to attendees at the local Cadence users meeting in February in Massachusetts. Contact me directly and I will forward it to you and others who are interested. It covers the basics and explains what to do and what not to do in order to master CM and SigXp and is based on SPB15.2 Best Regards Andy andy_kulik@xxxxxxx andreas_kulik@xxxxxxxxxxx Austin Franklin Sent by: 03/06/2005 11:42 PM Please respond to icu-pcb-forum@xxxxxxxxxxxxx To <icu-pcb-forum@xxxxxxxxxxxxx> cc Subject [PCB_FORUM] Re: Constraint Manager - difference between " Hi Michael, > Propagation Delay is mainly used to verify the length or time between > Pin Pairs on a net where as Total Etch Length is used to control the > length of the entire net by adding up all the segments. Thanks, I think I understand what you are saying the difference is. "Total Etch Length" add up ALL the tracks, including branches. For a two pin net, essentially the two would be the same, but with three or more pins on the same net, then they are different. If my understanding is correct, I'm not sure what design wise (not physically on the PCB, that I believe I understand if what I wrote above is correct, but electrically) a constraint like this would be used for. How do you come up with the value for that rule? Regards, Austin ----------------------------------------------------------- To subscribe/unsubscribe: Send a message to icu-pcb-forum-request@xxxxxxxxxxxxx with a subject of subscribe or unsubscribe To view the archives of this list please login at //www.freelists.org. Our list name is icu-pcb-forum or go to //www.freelists.org/archives/icu-pcb-forum/ Problems or Questions: Send an email to icu-pcb-forum-admins@xxxxxxxxxxxxx Want to post a job listing ? DON'T DO IT HERE! Better yet, join our jobs listing forum. SUBSCRIBE: icu-jobs-forum-subscribe@xxxxxxxxxx POST: icu-jobs-forum@xxxxxxxxxx -----------------------------------------------------------