TLF6379

June 1989

54LS85DM54LS85DM74LS85

4-Bit Magnitude Comparators

General Description

These 4-bit magnitude comparators perform comparison of

straight binary or BCD codes Three fully-decoded decisions

about two 4-bit words (A B) are made and are externally

available at three outputs These devices are fully expand-

able to any number of bits without external gates Words of

greater length may be compared by connecting compara-

stage handling less-significant bits are connected to the cor-

responding inputs of the next stage handling more-signifi-

cant bits The stage handling the least-significant bits must

cascading path is implemented with only a two-gate-level

delay to reduce overall comparison times for long words

Features

Y

Typical power dissipation 52 mW

Y

Typical delay (4-bit words) 24 ns

Y

Alternate MilitaryAerospace device (54LS85) is avail-

able Contact a National Semiconductor Sales Office

Distributor for specifications

Connection Diagram

Dual-In-Line Package

TLF6379 – 1

Order Number 54LS85DMQB

54LS85FMQB 54LS85LMQB

DM54LS85J DM54LS85W

DM74LS85M or DM74LS85N

See NS Package Number E20A

J16A M16A N16E or W16A

Function 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

L

LHL

LH

X

X

HL

LH

H

H

LL

LL

L

L

LH

HL

C1995 National Semiconductor Corporation

RRD-B30M105Printed in U S A