Re: XAUI Driver Spec
HI
The receiver max amplitude need to be higher than transmitter to allow
some
margin and protection. Very likely in Tampa the max transmit amplitude
will
be raised, where 1.6 V max will become more logical. The 1.6 volts is
p-p
diff. so each wire only drives 800 mV.
Thanks,
Ali
Broadcom
Robbie Shergill wrote:
>
> Hello all,
>
> Last week in Austin the XAUI group decided to change Max Diff. Amplitude to
> 1.6 volts. As I understood it, the rationale for increasing the max amplitude
> was to achieve commonality with the Infiniband spec. Although I agree with
> the spirit of this rationale, I checked the Infiniband spec and found
> that they are trying to drive a cable as well as a backplane with one
> electrical specification; thus the reason for the 1.6v spec. In this
> case, I'm not sure if it is worth matching the Infiniband spec in this
> one area. My feeling is that a driver circuit can be made to drive
> up to either 1.0 volt or 1.6 volt relatively easily; but it would be
> much more troublesome for a (XAUI) receiver to tolerate 1.6 volts
> *needlessley*.
>
> So, if the above reasoning is agreed to by others, I would propose that we
> stay with 1.0 volt max. diff. amplitude that is in the current draft 1.0
> (page 119, line 22).
>
> -Robbie Shergill
> National Semiconductor