HD74AC182

Rev.2.00, Jul.16.2004, page 3 of 6

C

C

C

G

= G

P = P

Also, the HD74AC182/HD74ACT182 can be used with binary ALUs in an active Low or active High input operand

mode. The connections (Figure a) to and from the ALU to the carry lookahead generator are identical in both cases.

Carries are rippled between lookahead blocks. The critical speed path follows the circled numbers. There are several

possible arrangements for the carry interconnects, but all achieve about the same speed. A 28-bit ALU is formed by

dropping the last HD74AC182/HD74ACT182.

Truth Table

Inputs

Outputs

C

n

G

G

G

G

0

P

PP

P

0

G

G

G

G

1

P

PP

P

1

G

G

G

G

2

P

PP

P

2

G

G

G

G

3

P

PP

P

3

C

n + x

C

n + y

C

n + z

G

G

G

GP

PP

P

XH

H

L

LH

X

L

XL

X

H

HX

L

H

XX

XH

H

L

X

H

HHX

L

LH

X

H

X

L

XX

XL

X

H

XL

XXL

H

HX

L

X

L

H

XX

XXX

H

H

L

XX

XH

H

H

X

L

X

H

HHX

HX

L

LH

X

H

X

H

X

L

XX

XXX

L

X

H

XX

XL

X

XL

H

XL

XXL

XL

H

HX

L

X

L

X

L

H

X

XX

XXH

H

H

X

X

X

HHH

X

H

XH

H

H

X

H

X

H

HH

X

H

X

H

X

H

X

XX

XXL

X

L

XX

X

L

X

X

L

L

XL

X

X

L

X

L

L

LX

L

X

L

X

L

L

H

XXX

H

XH

X

X

H

XX

H

X

H

X

XXH

H

L

LLL

L

H :

High Voltage Level

L

:

Low Voltage Level

X :

Immaterial