Hi! I have to redesign a TTL based design of discere components into an FPGA. I have selected spartan 2 xc2s150. I have a few queries regarding the board design.1) I want my Inputs to be 5V tolerant..which input standard should i use...LVTTL or PCI_5V ? How to select any of these standards as both require VCCO=3.3V and No Vref or VTT...?
2)If any of my xc2s150 ouput pin is an open collector, can i pull it up externally by 5V through a resistor?3)I am intending to use a Level shifter IC(3.3V to 5V) at some FPGA outputs..is it OK to do so?
4)I dont have a global set/reset in the design, can it create problems at startup?5)What should i do of un-used pins of FPGA...can i keep them unconnected?
Thanks for everyone's support.