What is the POWERDOWN (PWRDWN_B) pin? Can I leave this pin floating when it is not in use?
The PWRDWN_B pin was provided to set a Virtex-II device into power-down mode--a low-power, inactive state.
This sequence was initiated by pulling the PWRDWN_B pin Low.
However, this feature is no longer supported in Virtex-II FPGA. Therefore, the PWRDWN_B pin MUST ALWAYS BE deactivated (pulled up).
The PWRDWN_B pin can be set as a pull-up/pull-none in BitGen using the -g PowerdownPin option. The default value is pull-up. To set it as inactive, the PWRDWN_B should be left at its default value, which is pulled up (PWRDWN_B does not require an external pull-up or pull-down).
The PWRDWN_B pin should not be actively driven or pulled Low, as this will affect device operation and configuration.