These octal buffers and line drivers are designed specifically to improve both the performance and density of 3-state memory address drivers, clock drivers, and bus-oriented receivers and transmitters. Together with the SN54ABT241, SN74ABT241A, SN54ABT244, and SN74ABT244A, these devices provide the choice of selected combinations of inverting and noninverting outputs, symmetrical active-low output-enable (OE)\ inputs, and complementary OE and OE\ inputs.
The SN54ABT240 and SN74ABT240A are organized as two 4-bit buffers/line drivers with separate OE\ inputs. When OE\ is low, the devices pass inverted data from the A inputs to the Y outputs. When OE\ is high, the outputs are in the high-impedance state.
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.
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.