Rev.2.00, Mar 30, 2006 page 1 of 7

HD74HC688

8-bit Magnitude Comparator

REJ03D0643–0200

(Previous ADE-205-529)

Rev.2.00

Mar 30, 2006

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

• High Output Current: Fanout of 10 LSTTL Loads

• Wide Operating Voltage: V

• Low Input Current: 1 µA max

• Low Quiescent Supply Current: I

• Ordering Information

Part Name

Package Type

Package Code

(Previous Code)

Package

Abbreviation

Taping Abbreviation

(Quantity)

HD74HC688P

DILP-20 pin (JEDEC)

PRDP0020AC-B

(DP-20NEV)

P

—

HD74HC688FPEL

SOP-20 pin (JEITA)

PRSP0020DD-B

(FP-20DAV)

FP

EL (2,000 pcs/reel)

HD74HC688RPEL

SOP-20 pin (JEDEC)

PRSP0020DC-A

(FP-20DBV)

RP

EL (1,000 pcs/reel)

Function Table

Input

Data P, Q

Enable

G

Output

P=Q

P=Q

L

L

P>Q

L

H

P<Q

L

H

X

H

H

H :

high level

L

:

low level

X :

irrelevant