In the datasheet it says on page 3:
3V operation with 5V I/O signal tolerance
But in the table with Absolute Maximum ratings:
DC input voltage: -0.5 to 4.6 V
What is the actual maximum voltage for io pins??
I used W5100 in the 5V I/O environment. It was total failure. While chip did not fry, its timing (due to capacitances and overcharging) was inadequate. If you have an option, do not use these chips in 5V I/O environment.
