Re: Vmeas

Hi,
Thanks for your answer.
The data sheet takes the worst case between rising and falling, or
specifies falling (for strobes). The measurments were done from
clock=2.0v (active gigh) to either signal=2.0v (rising) or signal = 0.8v
(falling). These measurments are done so that the signal is active
(wither high or low), and not just mid way through the device voltage.
Thanks

D. C. Sessions wrote:
>
> "Amir Shavit (r56010)" wrote:
> >
> > Hi,
> > I'm cuurrently working on an ibis model. I'v encountered some problem
> > with this parameter since it is different for rising and falling time. I
> > don't know what it should be equal to, since there are 2 different
> > values.
> > Thanks for your answers
> > Amir Shavit
> > Motorola Semiconductors Israel
>
> Shalom Amir.
>
> I'm a bit puzzled about the "different rising and falling" cases.
> Are the defined timing points for the device you're working with
> actually specified differently for the two directions? The reason
> I ask is because it's very hard to have a setup time, for instance,
> which is different for rising and falling edges.
>
> Vmeas _should_ be the point at which the characterized ("data sheet")
> timing is defined. This is usually 1.5v for LVCMOS, but is sometimes
> 50% of supply (a better way), 40% of supply (PCI and AGP), or an
> external threshold (SSTL, HSTL, GTL, Rambus, etc.)
>
> --
> D. C. Sessions
> dc.sessions@vlsi.com
Received on Tue Oct 5 23:22:26 1999