MGT pin details(Xilinx Virtex 2 PRO)

[prav]

Hi all,

I am using Xilinx viretx 2 pro device (1152)package which has 8 MGT's.
for each of the MGT there are 9 dedicated pins which are TXP, TXN,
RXP, RXN,
AVCCAUXTX, AVCCAUXRX, VTTX, VTRX, and GNDA.

In my design i am not using any of the MGT's.
The data sheet suggests that VTRX is the Input Receive termination
supply for the RocketIO multi-gigabit transceiver (1.8V - 2.8V).
Since i am not using the MGT's i wanted to know wether i should keep
these pins open OR tie it to 2.5 V.

Thanks in advance.

Rgds,
prav

 

[Allan Herriman]

On 16 Jun 2004 02:06:37 -0700, praveenkn123@yahoo.com (prav) wrote:

Hi all,

I am using Xilinx viretx 2 pro device (1152)package which has 8 MGT's.
for each of the MGT there are 9 dedicated pins which are TXP, TXN,
RXP, RXN,
AVCCAUXTX, AVCCAUXRX, VTTX, VTRX, and GNDA.

In my design i am not using any of the MGT's.
The data sheet suggests that VTRX is the Input Receive termination
supply for the RocketIO multi-gigabit transceiver (1.8V - 2.8V).
Since i am not using the MGT's i wanted to know wether i should keep
these pins open OR tie it to 2.5 V.

On a recent design, I tied VCCAUXTX, VCCAUXRX, VTRX to +2.5V and left
the TxP, TxN, RxP, RxN pins open.

The RocketIO™ Transceiver User Guide
http://www.xilinx.com/bvdocs/userguides/ug024.pdf
doesn't appear to say anything about the VTRX pins when the
transceiver is unused.

Note that the pinout of the BGA package is such that the VCCAUXTX,
VCCAUXRX and VTRX are all in a row. It's easier to tie the VTRX pins
to +2.5V than to leave them open.

Regards,
Allan.

 

[Andrew Dyer]

On Wed, 16 Jun 2004 19:32:31 +1000, Allan Herriman wrote:

On a recent design, I tied VCCAUXTX, VCCAUXRX, VTRX to +2.5V and left
the TxP, TxN, RxP, RxN pins open.

The RocketIO™ Transceiver User Guide
http://www.xilinx.com/bvdocs/userguides/ug024.pdf
doesn't appear to say anything about the VTRX pins when the
transceiver is unused.

Note that the pinout of the BGA package is such that the VCCAUXTX,
VCCAUXRX and VTRX are all in a row. It's easier to tie the VTRX pins
to +2.5V than to leave them open.

Somewhere in the v2pro datasheet or user guide there is a recommendation
on what to do with unused MGT pins. On our board we have the same setup
as Allan, and I know we followed the recommendations.