
Philips Semiconductors
Product specification
74F182
Look-ahead carry generator
2
1991 Apr 15
853–1161 02162
FEATURES
Provides carry look-ahead across a group of four ALUs
Multi-level look-ahead for high speed arithmetic operation over
long word lengths
DESCRIPTION
The 74F182 is a high speed carry look-ahead generator. It accepts
up to four pairs of active-Low Carry Propagate (P0, P1, P2, P3) and
Carry Generate (G0, G1, G2, G3) signals and an active-High Carry
input (Cn) and provides anticipated active-High carries (Cn+x, Cn+y,
Cn+z) across four groups of binary adders. The 74F182 also has
active-Low Carry Propagate (P) Carry Generate (G) outputs which
may be used for further levels of look-ahead.
The logic equations provided at the outputs are:
Cn+x = G0+P0Cn
Cn+y = G1+P1G0+P1P0Cn
Cn+z = G2+P2G1+P2P1G0+P2P1P0Cn
G = G3+P3G2+P3P2G1+P3P2P1G0
P = P3P2P1P0
The 74F182 can also be used with binary ALUs in an active-Low or
active-High input operand mode. The connections to and from the
ALU to the carry look-ahead generator are identical in both cases.
PIN CONFIGURATION
16
15
14
13
12
11
10
7
6
5
4
3
2
1
P
V
CC
Cn+x
Cn+y
G
Cn
P2
G2
G1
P1
P3
G0
P0
G3
9
8
GND
Cn+z
SF00725
TYPE
TYPICAL
PROPAGATION
DELAY
TYPICAL
SUPPLY CURRENT
(TOTAL)
74F182
5.0ns
21mA
ORDERING INFORMATION
DESCRIPTION
ORDER CODE
COMMERCIAL RANGE
V
CC
= 5V
±
10%, T
amb
= 0
°
C to +70
°
C
N74F182N
16-pin plastic DIP
16-pin plastic SO
N74F182D
INPUT AND OUTPUT LOADING AND FAN-OUT TABLE
PINS
DESCRIPTION
74FAST (U.L.) HIGH/LOW
LOAD VALUE HIGH/LOW
Cn
Carry input
2.5/2.0
50
μ
A/1.2mA
50
μ
A/8.4mA
50
μ
A/9.6mA
50
μ
A/4.8mA
50
μ
A/4.8mA
50
μ
A/3.6mA
50
μ
A/2.4mA
G0, G2
Carry generate inputs (active-Low)
2.5/14.0
G1
Carry generate input (active-Low)
2.5/16.0
G3
Carry generate input (active-Low)
2.5/8.0
P0, P1
Carry propagate inputs (active-Low)
2.5/8.0
P2
Carry propagate input (active-Low)
2.5/6.0
P3
Carry propagate input (active-Low)
2.5/4.0
Cn+x–Cn+z
Carry outputs
50/33
1.0mA/20mA
G
Carry generate output (active-Low)
50/33
1.0mA/20mA
P
Carry propagate output (active-Low)
50/33
1.0mA/20mA
NOTE:
One (1.0) FAST unit load is defined as: 20
μ
A in the High state and 0.6mA in the Low state.