5-2

FAST AND LS TTL DATA

SN54/74LS283

LOGIC DIAGRAM

C0

A1

B1

A2

B2

A3

B3

A4

B4

C4

VCC = PIN 16

GND = PIN 8

= PIN NUMBERS

C1

C2

C3

14

1

2

6

7

3

4

5

9

11

12

10

13

15

FUNCTIONAL DESCRIPTION

The LS283 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 LS283

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 7, 5 or 3.