4-Bit Magnitude

Comparator

The SN74LS85 is a 4-Bit Magnitude Camparator which compares

two 4-bit words (A, B), each word having four Parallel Inputs

(A0 –A3, B0 –B3); A3, B3 being the most significant inputs. Operation

is not restricted to binary codes, the device will work with any

monotonic code. Three Outputs are provided: “A greater than B”

(OA>B), “A less than B” (OA<B), “A equal to B” (OA=B). Three

Expander Inputs, IA>B, IA<B, IA=B, allow cascading without external

gates. For proper compare operation, the Expander Inputs to the least

significant position must be connected as follows: IA<B= IA>B = L,

IA=B = H. For serial (ripple) expansion, the OA>B, OA<B and OA=B

Outputs are connected respectively to the IA>B, IA<B, and IA=B

Inputs of the next most significant comparator, as shown in Figure 1.

Refer to Applications section of data sheet for high speed method of

comparing large words.

The Truth Table on the following page describes the operation of the

SN74LS85 under all possible logic conditions. The upper 11 lines

describe the normal operation under all conditions that will occur in a

single device or in a series expansion scheme. The lower five lines

describe the operation under abnormal conditions on the cascading

inputs. These conditions occur when the parallel expansion technique

is used.

• Easily Expandable

• Binary or BCD Comparison

• O

A>B, OA<B, and OA=B Outputs Available

GUARANTEED OPERATING RANGES

Symbol

Parameter

Min

Typ

Max

Unit

VCC

Supply Voltage

4.75

5.0

5.25

V

TA

Operating Ambient

Temperature Range

0

25

70

°C

IOH

Output Current – High

– 0.4

mA

IOL

Output Current – Low

8.0

mA

LOW

POWER

SCHOTTKY

Device

Package

Shipping

ORDERING INFORMATION

SN74LS85N

16 Pin DIP

SN74LS85D

16 Pin

SOIC

D SUFFIX

CASE 751B

PLASTIC

N SUFFIX

CASE 648

16

1

16

1

74LS85

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