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Contributor
Contributor
8,793 Views
Registered: ‎01-02-2015

Net connections for unused GTX transceivers.

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I am designing a carrier card for the PicoZed 7030. The design will not make use of the GTX transceivers at all. From table 5-6 of UG476, I understand that the following connections should be made for the unused transceivers:

MGTAVCC -> GND
MGTAVTT -> GND

MGTVCCAUX -> GND

MGTREFCLKP/MGTREFCLKN -> Open

MGTRXP/MGTRXN -> GND

MGTTXP/MGTTXN -> Open

MGTRREF -> GND

 

Three questions:

Can anyone verify that this is correct?

 

MGTVCCAUX is already connected to 1.8V on the PicoZed. Is there any reason to not leave this connected as is?

 

Is there anything on the PicoZed other than the transceivers that use MGTREFCLKP/N, MGTAVCC, and MGTAVTT? It would be a shame to make these boards and find out that the ethernet controller doesn't work.

 

 

 

 

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Instructor
Instructor
17,059 Views
Registered: ‎08-14-2007

Re: Net connections for unused GTX transceivers.

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If your board already has power to the MGT, then it's best to leave it.  Unused MGTs won't use much power.  The best recommendation is to treat this as a partially unused GTX quad, so just ground the unused MGTRXP/MGTRXN inputs.

-- Gabor
3 Replies
Instructor
Instructor
17,060 Views
Registered: ‎08-14-2007

Re: Net connections for unused GTX transceivers.

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If your board already has power to the MGT, then it's best to leave it.  Unused MGTs won't use much power.  The best recommendation is to treat this as a partially unused GTX quad, so just ground the unused MGTRXP/MGTRXN inputs.

-- Gabor
Moderator
Moderator
8,757 Views
Registered: ‎02-16-2010

Re: Net connections for unused GTX transceivers.

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The guidance mentioned in ug476 is correct

The clock on MGTREFCLKP/N ports can be used for fabric logic by forwarding it using a BUFG. This will be useful even when MGTs are not used in the design.

MGTAVCC, MGTAVTT are only used for transceivers.
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Xilinx Employee
Xilinx Employee
8,753 Views
Registered: ‎08-01-2012

Re: Net connections for unused GTX transceivers.

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Also refer http://www.xilinx.com/support/answers/41451.html

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