A circuit provides fail safe protection of an input/output (I/O) circuit of a chip. The I/O circuit comprises an I/O pad connected to one or more other chips via an I/O bus. The circuit comprise a supply and failsafe detector component. The supply and failsafe detector component generates an I/O supply output signal. The I/O supply output signal has a low voltage value when the I/O supply voltage of the chip is below a medium voltage level and the I/O supply output signal having a high voltage value when the I/O supply voltage of the chip is above the medium voltage level. The medium voltage is above a threshold voltage of the transistor of the I/O circuit and below the high voltage value. The circuit uses the I/O supply output signal to provide a reference voltage as input to the transistor of the I/O circuit.