HD74HCT688
8-bit Magnitude Comparator
Description
The HD74HCT688 compares bit for bit two 8-bit words and indicate 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
LSTTL Output Logic Level Compatibility as well as CMOS Output Compatibility
High Speed Operation: t
pd
(Data to
P=Q) = 18 ns typ (C
L
= 50 pF)
High Output Current: Fanout of 10 LSTTL Loads
Wide Operating Voltage: V
CC
= 4.5 to 5.5 V
Low Input Current: 1 A max
Low Quiescent Supply Current: I
CC
(static) = 4 A max (Ta = 25C)
Function Table
Inputs
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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