5 Description (continued)

The SN74AVCH16T245 control pins (1DIR, 2DIR, 1OE, and 2OE) are supplied by V_CCA.

The I_off circuitry disables the outputs, preventing damaging current backflow through the device when it is powered down. This device is fully specified for partial-power-down applications using I_off.

The V_CC isolation feature ensures that if either V_CC input is at GND, then both ports are in the high-impedance state.

Active bus-hold circuitry holds unused or undriven inputs at a valid logic state. Use of pullup or pulldown resistors with the bus-hold circuitry is not recommended.

To ensure the high-impedance state during power up or power down, OE should be tied to V_CC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.

The SN74AVCH16T245 is designed for asynchronous communication between data buses. The device transmits data from the A bus to the B bus or from the B bus to the A bus, depending on the logic level at the direction-control (DIR) input. The output-enable (OE) input can be used to disable the outputs so the buses are effectively isolated.