The JTAG signals are split across two IO
power domains on the device. Timings parameters defined in this table only apply when the
two IO power domains are operating at the same voltage. Values for these timing parameters
are not defined when operating the two IO power domains at different voltages since
propagation delay through the device IO buffers differ when some are operating at 1.8V
while others are operating at 3.3V. This effectively reduces timing margin beyond the
values defined in this table. The JTAG interface is still expected to function when the
two IO power domains are operated at different voltages, assuming the system designer has
implemented appropriate level shifters and the operating frequency is reduced to
accommodate additional delay inserted by the level-shifters and IO buffers operating at
different voltages.
Figure 7-109 JTAG Timing Requirements and Switching
Characteristics