Page 21 - EE2449_TTL_Datasheet

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 (C 4 ) outputs.

C 0 + (A 1 +B 1 )+2(A 2 +B 2 )+4(A 3 +B 3 )+8(A 4 +B 4 ) = ∑ 1 +2∑ 2 +4∑ 3 +8∑ 4 +16C 4
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:

C 0 A 1 A 2 A 3 A 4 B 1 B 2 B 3 B 4 ∑ 1 ∑ 2 ∑ 3 ∑ 4 C 4
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 C 0 , A 1 , B 1 , can be arbitrarily assigned to pins 10, 11,
13, etc.

FUNCTIONAL TRUTH TABLE
C (n–1) A n B n ∑ n C n
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
C 1 — C 3 are generated internally
C 0 — is an external input
C 4 — is an output generated internally

GUARANTEED OPERATING RANGES
Symbol Parameter Min Typ Max Unit
V CC Supply Voltage 54 4.5 5.0 5.5 V
74 4.75 5.0 5.25
T A Operating Ambient Temperature Range 54 –55 25 125 °C
74 0 25 70

I OH Output Current — High 54, 74 –0.4 mA
I OL Output Current — Low 54 4.0 mA
74 8.0

FAST AND LS TTL DATA
5-81
www.AirSuplyLab.com
www.AirSuplyLab.com