The SN54LVCH244A octal buffer/line driver is designed for 2.7-V to 3.6-V VCC operation, and the SN74LVCH244A octal buffer/line driver is designed for 1.65-V to 3.6-V VCC operation.
These devices are organized as two 4-bit line drivers with separate output-enable (OE) inputs. When OE is low, these devices pass data from the A inputs to the Y outputs. When OE is high, the outputs 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.
Inputs can be driven from either 3.3-V or 5-V devices. This feature allows the use of these devices as translators in a mixed 3.3-V/5-V system environment.
These devices are fully specified for partial-power-down applications using Ioff. The Ioff circuitry disables the outputs, preventing damaging current backflow through the devices when they are 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.