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AR# 8522

Virtex/-E JTAG - What voltage level should I apply to VCCO on bank 2 for the TDO pin? (TDO output voltage)


For Virtex and Virtex-E devices, what should the output levels of the TDO pin be?


For Virtex and Virtex-E devices, the JTAG TDO pin is powered by the VCCO in bank 2. The TDO pin will always switch rail-rail between Ground and the voltage level that appears on this pin. For Virtex/-E devices, any voltage level can be placed on VCCO, provided that the level is within the recommended operating conditions specified in the data sheet.

Primary Considerations:

- Noise margin and the input switching levels on the downstream device TDI pin

- Any voltage requirements that other user outputs in bank 2 might have

For most applications, VCCO should be set to 3.3V.

Related Answer Records:

- For information on the switching levels of JTAG input pins, see (Xilinx Answer 7738).

- For information on I/O switching levels during Boundary Scan testing (EXTEST), see (Xilinx Answer 8762).

- For information on IBIS simulations for JTAG pins, see (Xilinx Answer 12085).

AR# 8522
Date Created 08/21/2007
Last Updated 12/15/2012
Status Active
Type General Article