MC74AC157N ON Semiconductor

MC74AC157, MC74ACT157 Quad 2-Input Multiplexer The MC74AC157/74ACT157 is a high-speed quad 2-input multiplexer. Four bits of data from two sources can be selected using the common Select and Enable inputs. The four outputs present the selected data in the true (non-inverted) form. The MC74AC157/74ACT157 can also be used as a function MC74AC157, MC74ACT157 EI I I I I I I I 0a 1a 0b 1b 0c 1c 0d 1d S Z Z Z Z a b c d Figure 2. Logic Symbol FUNCTIONAL DESCRIPTION Z = E(I S+I S) a 1a 0a Z = E(I S+I S) b 1b 0b The MC74AC157/74ACT157 is a quad 2-input Z = E(I S+I S) c 1c 0c multiplexer. It selects four bits of data from two sources Z = E(I S+I S) d 1d 0d under the control of a common Select input (S). The Enable A common use of the MC74AC157/74ACT157 is the input (E) is active-LOW. When E is HIGH, all of the outputs moving of data from two groups of registers to four common (Z) are forced LOW regardless of all other inputs. The output busses. The particular register from which the data MC74AC157/74ACT157 is the logic implementation of a comes is determined by the state of the Select input. A less 4-pole, 2-position switch where the position of the switch obvious use is as a function generator. The is determined by the logic levels supplied to the Select input. MC74AC157/74ACT157 can generate any four of the The logic equations for the outputs are shown below: sixteen different functions of two variables with one variable common. This is useful for implementing gating functions. I I I I I I I I E S 0a 1a 0b 1b 0c 1c 0d 1d Z Z Z Z a b c d NOTE: This diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays. Figure 3. Logic Diagram