HD74HC688
8-bit Magnitude Comparator
Description
The HD74HC688 compares bit for bit two 8-bit words and indicates whether or not they are equal. The
P=Q output indicates equality when it is low.
A single active low enable is provided to facilitate cascading of several packages and enable comparison of
words greater than 8-bits.
This device is useful in memory block decoding applications, where memory block enable signals must be
generated from computer address information.
Features
·
High Speed Operation: t
pd
(P or Q to Output) = 17 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
Input
Data P, Q
Enable
G
P=Q
P=Q
L
L
P>Q
L
H
P<Q
L
H
X
H
H
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