HD74HC147
10-to-4-line Priority Encoder
Description
The HD74HC147 features priority encoding of the inputs to ensure that only the highest order data line is
encoded. Nine input lines are encoded to a four line BCD output. The implied decimal zero codition
requires no input condition as zero is encoded when all nine data lines are at a high logic level. All data
inputs and outputs are active at the low logic level.
Features
·
High Speed Operation: t
pd
= 14.5 ns typ (C
L
= 50 pF)
·
High Output Current: Fanout of 10 LSTTL Loads
·
Wide Operating Voltage: V
CC
= 2 to 6 V
·
Low Input Current: 1 µA max
·
Low Quiescent Supply Current: I
CC
(static) = 4 µA max (Ta = 25°C)
Function Table
Inputs
Outputs
1
2
3
4
5
6
7
8
9
D
C
B
A
H
H
H
H
H
H
H
H
H
H
H
H
H
X
X
X
X
X
X
X
X
L
L
H
H
L
X
X
X
X
X
X
X
L
H
L
H
H
H
X
X
X
X
X
X
L
H
H
H
L
L
L
X
X
X
X
X
L
H
H
H
H
L
L
H
X
X
X
X
L
H
H
H
H
H
L
H
L
X
X
X
L
H
H
H
H
H
H
L
H
H
X
X
L
H
H
H
H
H
H
H
H
L
L
X
L
H
H
H
H
H
H
H
H
H
L
H
L
H
H
H
H
H
H
H
H
H
H
H
L
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