5-82

FAST AND LS TTL DATA

SN54/74LS83A

FUNCTIONAL DESCRIPTION

The LS83A adds two 4-bit binary words (A plus B) plus the incoming carry. The binary sum appears on the sum outputs (

∑1–∑4)

and outgoing carry (C4) outputs.

C0 + (A1+B1)+2(A2+B2)+4(A3+B3)+8(A4+B4) = ∑1+2∑2+4∑3+8∑4+16C4

Where: (+) = plus

Due to the symmetry of the binary add function the LS83A can be used with either all inputs and outputs active HIGH (positive

logic) or with all inputs and outputs active LOW (negative logic). Note that with active HIGH Inputs, Carry Input can not be left open,

but must be held LOW when no carry in is intended.

Example:

C0

A1

A2

A3

A4

B1

B2

B3

B4

∑1 ∑2 ∑3 ∑4

C4

Logic Levels

L

L

H

L

H

H

L

L

H

H

H

L

L

H

Active HIGH

0

0

1

0

1

1

0

0

1

1

1

0

0

1

(10+9 = 19)

Active LOW

1

1

0

1

0

0

1

1

0

0

0

1

1

0

(carry+5+6 = 12)

Interchanging inputs of equal weight does not affect the operation, thus C0, A1, B1, can be arbitrarily assigned to pins 10, 11,

13, etc.

FUNCTIONAL TRUTH TABLE

C (n–1)

An

Bn

∑n

Cn

L

L

L

L

L

L

L

H

H

L

L

H

L

H

L

L

H

H

L

H

H

L

L

H

L

H

L

H

L

H

H

H

L

L

H

H

H

H

H

H

C1 — C3 are generated internally

C0 — is an external input

C4 — is an output generated internally

GUARANTEED OPERATING RANGES

Symbol

Parameter

Min

Typ

Max

Unit

VCC

Supply Voltage

54

74

4.5

4.75

5.0

5.0

5.5

5.25

V

TA

Operating Ambient Temperature Range

54

74

– 55

0

25

25

125

70

°C

IOH

Output Current — High

54, 74

– 0.4

mA

IOL

Output Current — Low

54

74

4.0

8.0

mA