For the xc2v1000-5, the equation

tcko + tnet + tif5x + tdxck = 493 + tnet + 826 (worst case) + 322
= tnet + 1641 ps

This allows 135 ps for routing to meet the 563 MHz which - although small -
may be very reasonable for (nearly) adjacent slices in the -5 speed grade.
Also, the "worst case" number for tif5x may not be needed for a simple 4:1
mux.

If you try to compile your own registered 4:1 mux, you should be able to see
these numbers broken down to the timing elements like I've shown above in
the Timing Analyzer, at least when the appropriate "View" options are
selected.

I got the numbers from the "speedprint" utility that's command-line
accessible on our Solaris platform.


"Adam" <unreal@rpi.edu> wrote in message
news:qIQVb.50404$n62.1146@twister.nyroc.rr.com...
> On the bottom of page 7 of the Virtex II DC and Switching Characteristics
> datasheet, a table shows that register-to-register performance of a 4:1
mux
> can reach 563 MHz.  I'm just curious exactly how this was measured.
>
> Thanks,
>
> Adam
>
>
>

On the bottom of page 7 of the Virtex II DC and Switching Characteristics
datasheet, a table shows that register-to-register performance of a 4:1 mux
can reach 563 MHz.  I'm just curious exactly how this was measured.

Thanks,

Adam