The SN74AVCH24T245 is designed so that the control pins (1DIR, 2DIR, 3DIR, 4DIR, 5DIR, 6DIR, 1OE, 2OE, 3OE, 4OE, 5OE, and 6OE) are supplied by VCCA. This device is fully specified for partial-power-down applications using Ioff. The Ioff circuitry disables the outputs, preventing damaging current backflow through the device when it is powered down. The VCC isolation feature ensures that if either VCC input is at GND, then both ports are in the high-impedance state.