The SN74LVC257A quadruple 2-line to 1-line data selector/multiplexer is designed for 2.7-V to 3.6-V VCC operation.
The device is designed for high-performance memory-decoding or data-routing applications requiring very short
propagation delay times. In high-performance memory systems, this decoder minimizes the effects of system
decoding. When employed with high-speed memories utilizing a fast enable circuit, delay times of this decoder
and the enable time of the memory usually are less than the typical access time of the memory. This means that
the effective system delay introduced by the decoder is negligible.
The conditions at the binary-select inputs and the three enable inputs select one of eight output lines. Two
active-low enable inputs and one active-high enable input reduce the need for external gates or inverters when
expanding. A 24-line decoder can be implemented without external inverters, and a 32-line decoder requires only
one inverter. An enable input can be used as a data input for demultiplexing applications.
Inputs can be driven from either 3.3-V or 5-V devices. This feature allows the use of this device as a translator in a mixed 3.3-V/5-V system environment.