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Re: XAUI IO specs

Mark Kerestes wrote:
> Rich, Ali
>  On slide 22 of the XAUI/XGXS Proposal from Albuquerque was listed :
> Vo Dif(max) 800mV
> Vo Dif(min) 500mV
> Vin Dif(max)  1000mV
> Vin Dif(min) 175mV
> I assume these are truely Vdif and NOT Vdif peak to peak? I have some
> confusion from looking back at the
> Nov 5 1999 "HARI the Electrical Interface" which seems to have a table
> that mixes Vdif and Vdif peak to peak
> showing PECL vs LVDS vs HARI side by side.

For both PECL and LVDS the min and max values are the differences
between the two lines.  For instance, in a nominal PECL case with
Vcm=-1.32v, Vo(difmax)=800 mV would appear as Vo+ = -0.92 v and
Vo- = -1.72 v  Since the differential limits are symmetrical this
also applies to Vo+ = -1.72 v and Vo- = -0.92 v

For LVDS, with a positive offset, the Vo Dif(min) would appear as
Vo+ = 1.50 v and Vo- = 1.0 v

The input range is of course wider than the output range to allow
for both attenuation and noise.

D. C. Sessions