Hi *,
I'm planning a device with a backup battery. In case of power failure, the FPGA (a Virtex4 in this case) should be shut down to save power, whereas other components on the board need to keep working.
So, since the PWRDWN-pin doesn't do anything what I was planning to do is to simply turn off the regulators for Vccint and Vccaux as soon as the power fails. But I can't turn off Vcco, since it's used as a supply for other components as well (unless I use a separate regulator just for Vcco).
Can I damage the FPGA if the IO-banks are powered but the core isn't? And what will happen to the I/Os once the core supply goes away, but Vcco stays? Will they just start floating?
cu, Sean