Hi Austin,
Thanks for your reply, that's cleared up my question!
Cheers, Syms.
"Austin Lesea" <austin@xilinx.com> wrote in message
news:e90o4d$bt8@xco-news.xilinx.com...
> Symon,
>
> The LVDS input buffer is a full CMOS differential comparator. You may
> go within ~ 0.6 volts of either ground, or Vccaux, and it will still
> meet speed spec.
>
> You may go all the way to the rails (and even a bit beyond -- see abs
> max pin V specs), but then you take the diff stage out of its linear
> region, and it gets a bit slower.
>
> Austin
>
> Symon wrote:
>> Hi All,
>> So, it looks like it's OK for me to use an unterminated LVDS input on an
>> I/O
>> bank with Vcco = 3.3V. I even checked that the tools don't complain! Does
>> anyone know of any data for Vicm (the common mode range) for these
>> inputs?
>> If the receivers are powered by Vccaux, I assume the spec is the same as
>> for
>> LVDS_25, otherwise maybe the spec scales with Vcco.
>> TIA, Syms.
>>
>>
Reply by Austin Lesea●July 11, 20062006-07-11
Symon,
The LVDS input buffer is a full CMOS differential comparator. You may
go within ~ 0.6 volts of either ground, or Vccaux, and it will still
meet speed spec.
You may go all the way to the rails (and even a bit beyond -- see abs
max pin V specs), but then you take the diff stage out of its linear
region, and it gets a bit slower.
Austin
Symon wrote:
> Hi All,
> So, it looks like it's OK for me to use an unterminated LVDS input on an I/O
> bank with Vcco = 3.3V. I even checked that the tools don't complain! Does
> anyone know of any data for Vicm (the common mode range) for these inputs?
> If the receivers are powered by Vccaux, I assume the spec is the same as for
> LVDS_25, otherwise maybe the spec scales with Vcco.
> TIA, Syms.
>
>
Reply by Symon●July 11, 20062006-07-11
Hi All,
So, it looks like it's OK for me to use an unterminated LVDS input on an I/O
bank with Vcco = 3.3V. I even checked that the tools don't complain! Does
anyone know of any data for Vicm (the common mode range) for these inputs?
If the receivers are powered by Vccaux, I assume the spec is the same as for
LVDS_25, otherwise maybe the spec scales with Vcco.
TIA, Syms.