[SI-LIST] Re: ac drive strength

On Monday 23 July 2001 10:30, you wrote:
> Hello,
> 
> What's the best way to specify the ac drive strength of a buffer? The
> requirement should be testable.
> 
> I was thinking about defining it with a source impedance at typical
> voltage/temp's....any suggestions on how to test this?

Figure out the extrema for launch operating point into the impedances
of interest, and specify the output at those points.  For instance, if
you're going to drive a 50-ohm line with a source-terminated driver
into a receiver with a Vref of 49-51% of Vddq and 310 mV of Vih(ac)
then you should specify Voh(ac) at (310 mV + 0.51Vddq)/2 and
Ioh(ac) as Voh(ac)/50 ohms.  Plus some reasonable margin, of course.

-- 
| The race is not always to the swift, nor the battle to the strong. |
| Because the slow, feeble old codgers like me cheat.                |
+--------------- D. C. Sessions <dcs@xxxxxxxxxxxxxxxx> --------------+
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