I am a little confused with the sentence "5 volt tolerant Open Drain 16mA drivers".These gpios operate at 3.3vLVTTL.So what does 5v tolerant mean exactly.Does it refer to input operation or output operation or both.
It means, that the pins allow to be driven to 5V logic level without damage or sinking current through clamp diodes. Obviously, it's only possible for input, tri-stated output or open drain.
Hi,
This means that your pin can properly function with 5v connected to it (input or output configuration[eg. pulled up to 5v]) without being damaged. However, it does not necessarily mean that the chip can operate at 5v. Example: PIC24F has 5v tolerant IOs, but the PIC itself can not be run at 5v.