FEATURES

· High-speed 4-bit binary addition

· Cascadable in 4-bit increments

· Fast internal look-ahead carry

· Output capability: standard

· ICC category: MSI

GENERAL DESCRIPTION

The 74HC/HCT283 are high-speed Si-gate CMOS devices

and are pin compatible with low power Schottky TTL

(LSTTL). They are specified in compliance with JEDEC

standard no. 7A.

The 74HC/HCT283 add two 4-bit binary words (An plus Bn)

plus the incoming carry. The binary sum appears on the

sum outputs (?1 to ?4) and the out-going carry (COUT)

according to the equation:

CIN + (A1 + B1) + 2(A2 + B2) + +4(A3 + B3) + 8(A4 + B4) =

= ?1 + 2?2 + 4?3 + 8?4 + 16COUT

Where (+) = plus.

Due to the symmetry of the binary add function, the “283”

can be used with either all active HIGH operands (positive

logic) or all active LOW operands (negative logic); see

function table. In case of all active LOW operands the

results ?1 to ?4 and COUT should be interpreted also as

active LOW. With active HIGH inputs, CIN must be held

LOW when no “carry in” is intended. Interchanging inputs

of equal weight does not affect the operation, thus CIN, A1,

B1 can be assigned arbitrarily to pins 5, 6, 7, etc.

See the “583” for the BCD version.