HD74AC157

HD74AC157 Quad 2-Input Multiplexer Description The HD74AC157 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 (noninverted) form. The HD74AC157 can also be used as a function generator. Feature Outputs Source/Sink 24 mA Pin Arrangement S 1 I0a 2 I1a 3 Za 4 I0b 5 I1b 6 Zb 7 GND 8 (Top view) 16 VCC 15 E 14 I0c 13 I1c 12 Zc 11 I0d 10 I1d 9 Zd HD74AC157 Logic Symbol E I0a I1a I0b I1b I0c I1c Iod I1d S Za Zb Zc Zd Pin Names I0a to I0d I1a to I1d E S Za to Zd Source 0 Data Inputs Source 1 Data Inputs Enable Input Select Input Outputs Functional Description The HD74AC157 is a quad 2-input multiplexer. It selects four bits of data from two sources under the control of a common Select input (S). The Enable input (E) is active-Low. when E is High, all of the outputs (Z) are forced Low regardless of all other inputs. The HD74AC157 is the logic implementation of a 4-pole, 2-position switch where the position of the switch is determined by the logic levels supplied to the Select input. The logic equations for the outputs are shown below: Za = E(I1aS + I0a S) Zb = E(I1bS + I0bS) Zc = E(I1cS + I0c S) Zd = E(I1dS + I0dS) A common use of the HD74AC157 is the moving of data from two groups of register to four common output busses. The particular register from which the data comes is determined by the state of the Select input. A...