2
Functional Diagram
Logic Symbol
TRUTH TABLE
INPUTS OUTPUT
nA nB nC nD nY
LXXXL
XLXXL
XXLXL
XXXLL
HHHHH
H = High Voltage Level, L = Low Voltage Level, X = Irrelevant
1A
1C
2A
2B
2D
1
4
5
9
12
13
6
2Y
1Y
8
1D
GND = 7
V
CC
= 14
NC = 3, 11
2C
1B
2
10
nA
nB
nY
nC
nD
CD54HC21, CD74HC21, CD74HCT21
