At 05:18 PM 3/6/2002 -0500, Robison Michael R CNIN wrote:
>my problem is that i would like to set a design rule to allow
>a MAXIMUM distance from the pad to a power/ground via, but
>the smd-to-plane constraint is a minimum length.  is there a
>rule (or other method) i can use to constrain the maximum
>trace length to a plane via during autoroute?

I very much doubt that the autorouter is that sophisticated. If the pins in 
question are power pins or are otherwise critical such that you must keep 
the lengths short, then you cannot trust the autorouter to handle them. I'd 
consider all power pins to be critical; I'd consider routing the entire 
power net by hand. I would routinely make the trace lengths *very* short; 
we'd put the vias in the pads if we could.

Remember that it is the enclosed area in the entire power loop that 
matters. (The loop may be considered to be a "complete" circuit including 
the IC and the bypass cap and/or plane capacitance).

>p.s. to mr. lomax.  the suggestion about using the edit/move/
>component and then clicking an empty space to get a parts
>listing was a lifesaver.  as you could tell, i had been doing
>a find and then having to travel back to where i wanted to
>drag it.  thank you.

Been there and done that, for far too long. Now, I don't use the parts 
listing much, I just enter the refdes for the part I need.

Abdulrahman Lomax
Easthampton, Massachusetts USA

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