3-to-8 line decoder/demultiplexer; inverting

The 74LVC138A decodes three binary weighted address inputs (A0, A1 and A2) to eight mutually exclusive outputs (Y0 to Y7). The 74LVC138A features three enable inputs (E1, E2 and E3). Every output will be HIGH unless E1 and E2 are LOW and E3 is HIGH. This multiple enable function allows easy parallel expansion of the 74LVC138A to a 1-of-32 (5 to 32 lines) decoder with just four 74LVC138A ICs and one inverter. The 74LVC138A can be used as an eight output demultiplexer by using one of the active LOW enable inputs as the data input and the remaining enable inputs as strobes. Inputs can be driven from either 3.3 V or 5 V devices. This feature allows the use of these devices as translators in mixed 3.3 V and 5 V environments.

Schmitt-trigger action at all inputs makes the circuit tolerant of slower input rise and fall times.