TLF5205

November 1995

MM54HC85MM74HC85

4-Bit Magnitude Comparator

General Description

The MM54HC85MM74HC85 is a 4-bit magnitude compara-

tor that utilizes advanced silicon-gate CMOS technology It

is designed for high speed comparison of two four bit words

This circuit has eight comparison inputs 4 for each word

is indicated by a high level on one of the decision outputs

Thus it may be determined whether one word is ‘‘greater

than’’ ‘‘less than’’ or ‘‘equal to’’ the other word By con-

necting the outputs of the least significant stage to the cas-

cade inputs of the next stage words of greater than four bits

can be compared In addition the least significant stage

The comparator’s outputs can drive 10 low power Schottky

TTL (LS-TTL) equivalent loads and is functionally and pin

equivalent to the 54LS8574LS85 All inputs are protected

ground

Features

Y

Typical propagation delay 27 ns

Y

Wide operating voltage range 2 – 6V

Y

Low input current 1 mA maximum

Y

Low quiescent current 80 mA maximum (74HC Series)

Y

Output drive capability 10 LS-TTL loads

Connection Diagram

Dual-In-Line Package

TLF5205 – 1

Order Number MM54HC85 or MM74HC85

Truth Table

Comparing

Cascading

Outputs

Inputs

Inputs

A3 B3

A2 B2

A1 B1

A0 B0

X

X

X

X

X

X

H

L

L

X

X

X

X

X

X

L

H

L

X

X

X

X

X

H

L

L

X

X

X

X

X

L

H

L

X

X

X

X

H

L

L

X

X

X

X

L

H

L

X

X

X

H

L

L

X

X

X

L

H

L

H

L

L

H

L

L

L

H

L

L

H

L

X

X

HL

LH

H

H

LL

LL

L

L

LH

HL

C1995 National Semiconductor Corporation

RRD-B30M115Printed in U S A