Texas Instruments SN74AHC240

These octal buffers/drivers are designed specifically to improve the performance and density of 3-state memory-address drivers, clock drivers, and bus-oriented receivers and transmitters. The ’AHC240 devices are organized as two 4-bit buffers/line drivers with separate output-enable (OE)\ inputs. When OE\ is low, the device passes data from the A inputs to the Y outputs. When OE\ is high, the outputs are in the high-impedance state. 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.