First, a little background - I'm working on replacing an old (late 1970's) output driver board. The old equipment this came off of has a very dirty and poorly-regulated 5V system. Since I'm using newer pieces and replacing some address decoders with a FPGA, I need to have a more stable 5V on the board.
The 5V coming in can range from 4.75V to 5.5V (or more, if the other boards have bad caps, thermal wear, etc). I was looking at using a 1117 to at least keep the voltage close to 5V when/if possible - to avoid a bad power board destroying the new board.
I haven't used 1117's before (2705's usually in the past), and noticed on the datasheet it says:
Vin: This pin must always be 1.3V higher than Vout in order for the device to regulate properly.
Am I correct in assuming that means that in a case like this, if the inpute voltage was between 4.75V and 6.3V, my FPGA and buffers would get the same as the incoming voltage, and then if say the power board blew up and fed 8V in, it would prevent the 8V from frying everything?