AR# 13428: Virtex-6/-5/-4/-II Pro/-II - Will driving the I/Os of an unpowered bank cause damage to the part?
Virtex-6/-5/-4/-II Pro/-II - Will driving the I/Os of an unpowered bank cause damage to the part?
Will driving the I/Os of an unpowered bank cause damage to the part? How much current can the clamp diodes sink?
Driving Virtex-II/-II Pro and Virtex-4/-5/-6 FPGA I/Os while VCCO is not present does not cause any damage. The outside High driver pulls the pin High, and VCCO is pulled to a level one diode drop below the driving voltage. It is important to keep I/Os from reverse powering the VCCO to levels outside the FPGA's valid voltage range (see data sheet).
However, if VCCO is grounded or there is a strong path to GND, the per-pin current must remain below 10 mA to prevent damage to the device. In this case, numerous pins sinking >100 mA for long periods of time could lead to device failure.
The Iin parameter was added to the Virtex-4 FPGA and newer data sheets.
For more information on hot-swapping issues, please see (Xilinx XAPP251): "Hot-Swapping Virtex-II Devices".