An integrated circuit (IC) includes a first I/O cell, a logic cell, a trigger signal generation circuit, and a second I/O cell having a voltage selection pin. I/O interfaces of the first I/O cell receive first and second supply voltages, respectively, and I/O interfaces of the second I/O cell receive third and fourth supply voltages, respectively. The first I/O cell generates a first trigger signal when the first supply voltage reaches a first predetermined voltage. The logic cell receives the first trigger signal and generates a safe-state signal. The trigger signal generation circuit generates a second trigger signal when the third supply voltage reaches a second predetermined voltage. The voltage selection pin receives the safe-state signal and the second trigger signal and sets the second I/O cell in a safe-state mode, which protects the second I/O cell from over voltage damage.