HD74ACT283 Datasheet | Hitachi Semiconductor

Description The HD74AC283/HD74ACT283 high-speed 4-bit binary full adder with internal carry lookahead accepts two 4-bit binary works (A0 - A3, B0 - B 3) and a Carry input (C0). It generates the binary Sum outputs (S0 - S 3) and the Carry output (C4) from the most significant bit. The HD74AC283/HD74ACT283 will operate with either active High or active Low operands (positive or negative logic). Features - Outputs Source/Sink 24 m A - HD74ACT283 has TTL-Cmpatible Inputs Pin Arrangement S1 1 B1 2 A1 3 S0 4 A0 5 B0 6 C0 7 GND 8 (Top view) 16 VCC 15 B2 14 A2 13 S2 12 A3 11 B3 10 S3 9 C4 HD74AC283/HD74ACT283 Logic Symbol A0 B0 A1 B1 A2 B2 A3 B3 C0 C4 S0 S1 S2 S3 Pin Names A0 - A3 B0 - B3 C0 S0 - S3 C4 A Operand Inputs B Operand Inputs Carry Input Sum Outputs Carry Output Functional Description The HD74AC283/HD74ACT283 adds two 4-bit binary words (A plus B) plus the ining Carry (C0). The binary sum appears on the Sum (S0 - S3) and outgoing carry (C4) outputs. The binary weight of the various inputs and outputs is indicated by the subscript numbers, representing powers of two. 20 (A0 + B0 + C0) + 21 (A1 + B1) + 22 (A2 + B2) + 23 (A3 + B3) = S0 + 2S1 + 4S2 + 8S3 + 16C4 Where (+) = plus Interchanging inputs of equal weight does not affect the operation. Thus C0, A0, B0 can be arbitrarily assigned to pins 5, 6 and 7 for DIPS. Due to the symmetry of the binary add function, the HD74AC283/HD74ACT283 can be used either with all inputs and outputs active High (positive logic) or with all inputs and outputs active Low (negative logic). See Figure a. Note that if C0 is not used it must be tied Low for active High logic or tied High for active Low logic. Due to pin limitations, the intermediate carries of the HD74AC283/HD74ACT283 are not brought out for use as inputs or outputs. However, other means can be used to effectively insert a carry into, or bring a carry out from, an intermediate stage. Figure b shows how to make a 3-bit adder. Tying the operand inputs of the...