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: logic levels Active HIGH Active LOW C0 A1 A2 A3 A4 B1 B2 B3 B4 ∑1 ∑2 ∑3 ∑4 C4 L LHL HHL LHHH L LH 0010 11001 1 1 0 01 1101 00110 0 0 1 10 (10+9=19) (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. 3 SN74LS283 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...
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