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AR# 29766

Virtex-5 RocketIO GTP - Grounding the GTP power supplies causes BSCAN testing to fail


Keywords: GTP_DUAL, Rocket, GTP, Boundary, scan, chain, length, test, fail, BSDL

Many customers use Boundary Scan tools like EXTEST to verify board connectivity in a manufacturing environment. These tools typically start by validating the BSDL file including a Boundary Scan length test. This is implemented inside the FPGA as a shift chain of I/O registers. The GTP column is a part of this shift chain. If the GTP power supplies (MGTAVCC, MGTAVCCPLL, MGTAVTTRX, MGTAVTTTX, and MGTAVTTRXC) are all grounded, the register chain is broken and Boundary Scan validation of the I/O connectivity fails.


If you plan to use Boundary Scan as part of your product verification, you must power the MGTAVCC supply for each GTP_DUAL in the column. The other GTP supplies (MGTAVCCPLL, MGTAVTTRX, MGTAVTTTX, and MGTAVTTRXC) can either be grounded or powered. Of course, grounding them saves you some quiescent power.

It should also be noted that this does not affect JTAG configuration of the FPGA. If all the GTP power supplies are grounded, JTAG configuration still works.
AR# 29766
Date 05/16/2008
Status Active
Type General Article