January 1988
MM54HC181/MM74HC181
Arithmetic Logic Units/Function Generators
General Description
These arithmetic logic units (ALU)/function generators uti-
lize advanced silicon-gate CMOS technology. They possess
the high noise immunity and low power consumption of
standard CMOS integrated circuits, as well as the ability to
drive 10 LS-TTL loads.
If high speed is not of importance, a ripple-carry input (C )
n
a
and a ripple-carry output (C
4) are available. However,
n
the ripple-carry delay has also been minimized so that arith-
metic manipulations for small word lengths can be per-
formed without external circuitry.
The MM54HC181/MM74HC181 are arithmetic logic unit
(ALU)/function generators that have a complexity of 75
equivalent gates on a monolithic chip. These circuits per-
form 16 binary arithmetic operations on two 4-bit words as
shown in Tables 1 and 2. These operations are selected by
the four function-select lines (S0, S1, S2, S3) and include
addition, subtraction, decrement, and straight transfer.
When performing arithmetic manipulations, the internal car-
ries must be enabled by applying a low-level voltage to the
mode control input (M). A full carry look-ahead scheme is
made available in these devices for fast, simultaneous carry
generation by means of two cascade-outputs (pins 15 and
17) for the four bits in the package. When used in conjunc-
tion with the MM54HC182 or MM74HC182, full carry look-
ahead circuits, high-speed arithmetic operations can be per-
formed. The method of cascading HC182 circuits with these
ALU’s to provide multi-level full carry look-ahead is illustrat-
ed under typical applications data for the MM54HC182/
MM74HC182.
Features
Y
Full look-ahead for high-speed operations on
long words
Y
Arithmetic operating modes:
Addition
Subtraction
Shift operand a one position magnitude comparison
Plus twelve other arithmetic operations
Y
Logic function modes:
Exclusive-OR
Comparator
AND, NAND, OR, NOR
Plus ten other logic operations
Y
Wide operating voltage range: 2V–6V
Y
Low input current: 1 mA maximum
Y
Low quiescent current: 80 mA maximum
Connection Diagram
Pin Designations
Dual-In-Line Package
Designation
A3, A2, A1, A0
B3, B2, B1, B0
Pin Nos.
Function
19, 21, 23, 2
18, 20, 22, 1
Word A Inputs
Word B Inputs
Function-Select
Inputs
S3, S2, S1, S0
3, 4, 5, 6
C
7
8
Inv. Carry Input
n
Mode Control
Input
M
F3, F2, F1, F0
13, 11, 10, 9
14
Function Outputs
e
A
B
Comparator Outputs
Carry Propagate
Output
P
15
16
17
a
C
4
Inv. Carry Output
n
Carry Generate
Output
G
V
24
12
Supply Voltage
Ground
TL/F/5320–1
CC
Top View
GND
Order Number MM54HC181 or MM74HC181
C
1995 National Semiconductor Corporation
TL/F/5320
RRD-B30M105/Printed in U. S. A.