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AR# 45598

7 Series FPGA GTX/GTH Transceivers - Quad usage priority information / RCAL master

Description

This answer record discusses quad usage priority for 7 series GTX/GTH transceivers.

Solution

In Virtex-6 GTX transceivers, the quad usage priority requires that GTX0 in Quad MGT 115 be instantiated if any of the GTX transceivers are used in the application.

This is because this quad contains the RCAL circuit that is required for the internal termination resistors for all of the transceivers.

Unlike Virtex-6 GTX, users do not have to follow any quad usage priority with the 7 series.

For 7 series, the RCAL values are distributed at configuration whether the RCAL master is instantiated or not.

However, the RCAL master must be powered.

Special care should be taken when using packages with multiple GT power planes because the RCAL master is present only in one of the power planes.

The GT power plane which has the RCAL master should always be powered.

In previous families there was only one GT which could be the RCAL master (MGT115).

This changes for some devices in 7 series as you can have different columns of GTs or several SLRs.

Each will have its own RCAL master which has to be powered as explained above.

Unlike the user guides of previous families, ug476 v1.4 does not yet explicitly state which GT is a RCAL master in the chapter for calibration.

To find the RCAL master(s) for a specific device, you currently have to search for MGTAVTTRCAL pins in the package placement diagrams.

This information should be added in v1.5.

Linked Answer Records

Associated Answer Records

Answer Number Answer Title Version Found Version Resolved
41613 7 Series FPGAs GTX/GTH Transceivers - Known Issues and Answer Record List N/A N/A
AR# 45598
Date Created 01/17/2012
Last Updated 06/18/2014
Status Active
Type General Article
Devices
  • Kintex-7
  • Virtex-7