74ALS138

The 74ALS138 decoder accepts three binary weighted inputs (A0, A1, A2) and when enabled, provides eight mutually exclusive, active-Low outputs (Q0 Q7). The device features three Enable inputs; two active-Low (E0, E1) and one active-High (E2). Every output will be High unless E0 and E1 are Low and E2 is High. This multiple enable function allows easy parallel expansion of the 74ALS138 to 1-of-32 (5 lines to 32 lines) decoder with just four 74ALS138s and one inverter. The device 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. Enable inputs not used must be permanently tied to their appropriate active-High or active-Low state.