The output-enable input (OE) is used to disable the outputs so the buses are effectively isolated. The output-enable pin of the TXU0x04 has V_CC(MIN) circuitry, which allows the OE pin to operate with the lower supply voltage. The Over-Voltage Tolerant Inputs feature allows the OE pin to operate with the higher supply voltage. This combination means that the enable pin can be referenced to either V_CCA or V_CCB supply. Multiple permutations of each device are possible since the controller can be placed on either the A or B port and can still control the enable pin.