HD74AC158 Datasheet, PDF (2/9 Pages) Hitachi Semiconductor – Quad 2-Input Multiplexer

HD74AC158
Logic Symbol
E I0a I1a I0b I1b I0c I1c Iod I1d
S
Za
Zb
Zc
Zd
Pin Names
I_0a to I_0d
I_1a to I_1d
E
S
Z_a to Z_d
Source 0 Data Inputs
Source 1 Data Inputs
Enable Input
Select Input
Outputs
Functional Description
The HD74AC158 quad 2-input multiplexer selects four bits of data from two sources under the control of a
common Select input (S) and presents the data in inverted form at the four outputs. The Enable Input (E) is
active-LOW. When E is HIGH, all of the outputs (Z) are forced HIGH regardless of all other inputs. The
HD74AC158 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.
A common use of the HD74AC158 is the moving of data from two groups of registers to four common
output busses. The particular register from which the data comes is determined by the state of the Select
input. A less obvious use is as a function generator. The HD74AC158 can generate four functions of two
variables with one variable common. This is useful for implementing gating functions.
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