(PDO = low); pulling PDO low places all the output drivers, except CTL1 and SCDT, into a high-impedance state. The SCDT output, which indicates link-disabled or link-inactive, can be tied directly to the PDO input to disable the output drivers when the link is inactive or when the cable is disconnected. An internal pullup on the PDO pin defaults the TFP401/401A to the normal nonpower-down output drive mode if left unconnected.