Page 33 - EE2449_TTL_Datasheet

SN54/74LS151

LOGIC DIAGRAM
I 0 I 1 I 2 I 3 I 4 I 5 I 6 I 7
9 4 3 2 1 15 14 13 12
S 2
10
S 1
11
S 0
7
E

V CC = PIN 16
GND = PIN 8 6 5
= PIN NUMBERS
Z Z

FUNCTIONAL DESCRIPTION
The LS151 is a logical implementation of a single pole, Z = E ⋅ (I 0 ⋅ S 0 ⋅ S 1 ⋅ S 2 + ⋅ I 1 ⋅ S 0 ⋅ S 1 ⋅ S 2 + I 2 ⋅ S 0 ⋅ S 1 ⋅ S 2
8-position switch with the switch position controlled by the + I 3 ⋅ S 0 ⋅ S 1 ⋅ S 2 + I 4 ⋅ S 0 ⋅ S 1 ⋅ S 2 + I 5 ⋅ S 0 ⋅ S 1 ⋅ S 2 + I 6 ⋅ S 0
state of three Select inputs, S 0 , S 1 , S 2 . Both assertion and ⋅ S 1 ⋅ S 2 + I 7 ⋅ S 0 ⋅ S 1 ⋅ S 2 ).
negation outputs are provided. The Enable input (E) is active The LS151 provides the ability, in one package, to select
LOW. When it is not activated, the negation output is HIGH from eight sources of data or control information. By proper
and the assertion output is LOW regardless of all other inputs. manipulation of the inputs, the LS151 can provide any logic
The logic function provided at the output is: function of four variables and its negation.

TRUTH TABLE
E S 2 S 1 S 0 I 0 I 1 I 2 I 3 I 4 I 5 I 6 I 7 Z Z
H X X X X X X X X X X X H L
L L L L L X X X X X X X H L
L L L L H X X X X X X X L H
L L L H X L X X X X X X H L
L L L H X H X X X X X X L H
L L H L X X L X X X X X H L
L L H L X X H X X X X X L H
L L H H X X X L X X X X H L
L L H H X X X H X X X X L H
L H L L X X X X L X X X H L
L H L L X X X X H X X X L H
L H L H X X X X X L X X H L
L H L H X X X X X H X X L H
L H H L X X X X X X L X H L
L H H L X X X X X X H X L H
L H H H X X X X X X X L H L
L H H H X X X X X X X H L H
H = HIGH Voltage Level
L = LOW Voltage Level
X = Don’t Care

FAST AND LS TTL DATA
5-145
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