74F381 Datasheet, PDF (1/7 Pages) NXP Semiconductors – Arithmetic Logic Unit

Philips Semiconductors
Arithmetic Logic Unit
Product specification
74F381
FEATURES
• Low-input loading minimizes drive requirements
• Performs six arithmetic and logic functions
• Selectable Low (clear) and High (preset) functions
• Carry Generate and Propagate outputs for use with Carry
look-ahead generator
DESCRIPTION
The 74F381 performs three arithmetic and three logic operations on
two 4-bit words, A and B. Three additional Select (S0–S2) input
codes force the Function outputs Low or High. Carry Propagate (P)
and Generate (G) ouputs are provided for use with the 74F182
Carry Look Ahead Generator for high-speed expansion to longer
word lengths. For ripple expansion, refer to the 74F382 ALU data
sheet.
Signals applied to the Select inputs (S0–S2) determine the mode of
operation, as indicated in the Function Select Table. An extensive
listing of input and output function levels is shown in the Function
Table. The circuit performs the arithmetic functions for either
active-HIgh or active-Low operands, with output levels in the same
convention. In the subtract operating modes, it is necessary to force
a Carry (High for active-HIgh operands, Low for active-Low
operands) into the Cn input of the least significant package. The
Carry Generate (G) and Carry Propagate (P) outputs supply input
signals to the 74F182 Carry look-ahead generator for expansion to
longer word length, as shown in Figure 1. Note that a 74F382 ALU is
used for the most significant package. Typical delays for Figure 1
are given in Table 1.
PIN CONFIGURATION
A1 1
B1 2
A0 3
B0 4
S0 5
S1 6
S2 7
F0 8
F1 9
GND 10
20 _VCC
19 _A2
18 _B2
17 _A3
16 _B3
15 Cn
14 P
13 G
12 F3
11 F2
SF00921
TYPE
74F381
TYPICAL
PROPAGATION
DELAY
6.5ns
TYPICAL SUPPLY
CURRENT (TOTAL)
59mA
ORDERING INFORMATION
DESCRIPTION
20-pin plastic DIP
COMMERCIAL RANGE
V_CC = 5V ±10%, T_amb = 0°C to +70°C
N74F381N
20-pin plastic SO
N74F381D
INPUT AND OUTPUT LOADING AND FAN OUT TABLE
PINS
DESCRIPTION
A0 – A3
A operand inputs
B0 – B3
A operand inputs
S0 – S2
Function select inputs
Cn
Carry input
P
Carry Propagate ouptut (active-Low)
G
Carry Generate ouptut (active-Low)
F0–F3
Outputs
NOTE:
One (1.0) FAST unit load is defined as 20µA in the High state and 0.6mA in the Low state.
74F (U.L.)
HIGH/LOW
1.0/4.0
1.0/4.0
1.0/1.0
1.0/4.0
50/33
50/33
50/33
LOAD VALUE
HIGH/LOW
20µA/2.4mA
20µA/2.4mA
20µA/0.6mA
20µA/2.4mA
1.0mA/20mA
1.0mA/20mA
1.0mA/20mA
1989 Mar 01
1
853–0418 95907