The ’AC245 octal bus transceivers are designed for asynchronous two-way communication between data buses. The control-function implementation minimizes external timing requirements.
When the output-enable OE is low, the device passes noninverted 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. A high on OE disables the device so that the buses are effectively isolated.
To ensure the high-impedance state during power up or power down, OE should be tied to VCC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.