SDAS235 − D2661, DECEMBER 1982 − REVISED NOVEMBER 1985
•
SN54AS882A . . . JT PACKAGE
SN74AS882A . . . DW OR NT PACKAGE
Directly Compatible With ’AS181B,
’AS1181, ’AS881B, and ’AS1881 ALUs
Package Options Include Plastic Small
Outline Packages, Both Plastic and
Ceramic Chip Carriers, and Standard
Plastic and Ceramic 300-mil DIPs
Capable of Anticipating the Carry Across a
Group of Eight 4-Bit Binary Adders
Cascadable to Perform Look-Ahead Across
n-Bit Adders
Typical Carry Time, Cn to Any Cn+i, is Less
Than 6 ns
Dependable Texas Instruments Quality and
Reliability
•
•
•
•
•
(TOP VIEW)
Cn
G0
P0
G1
P1
1
24
2
23
3
22
4
21
5
20
Cn + 8
G2
P2
G3
P3
Cn − 16
GND
6
19
7
18
8
17
9
16
10
15
11
14
12
13
VCC
NC
Cn + 32
P7
G7
P6
G6
Cn + 24
P5
G5
P4
G4
description
SN54AS882A . . . FK PACKAGE
SN74AS882A . . . DW OR NT PACKAGE
The ’AS882A is a high-speed look-ahead carry
generator capable of anticipating the carry across
a group of eight 4-bit adders permitting the
designer to implement look-ahead for a 32-bit ALU
with a single package or, by cascading ’AS882As,
full look-ahead is possible across n-bit adders.
P0
G0
Cn
NC
VCC
NC
C n + 32
(TOP VIEW)
The SN54AS882A is characterized for operation
over the full military temperature range of − 55°C
to 125°C. The SN74AS882A is characterized for
operation from 0°C to 70°C.
Cn+8
=
G1 + P1G0+P1P0Cn
Cn+16
=
G3 + P3G2 + P3P2G1 + P3P2P1G0
+ P3P2P1P0Cn
Cn+24
=
G5 + P5G4 + P5P4G3 + P5P4P3G2
+ P5P4P3P2G1 + P5P4P3P2P1G0
+ P5P4P3P2P1P0Cn
Cn+32
=
3 2 1 28 27 26
5
6
24
Cn + 8
NC
G2
P2
G3
7
23
8
22
9
21
10
20
25
11
19
12 13 14 15 16 17 18
P7
G7
P6
NC
G6
Cn + 24
P5
P3
C n + 16
GND
NC
G4
P4
G5
’AS882A LOGIC EQUATIONS
4
G1
P1
NC − No internal connection
G7 + P7G6 + P7P6G5 + P7P6P5G4
+ P7P6P5P4G3 + P7P6P5P4P3G2
+ P7P6P5P4P3P2G1 + P7P6P5P4P3P2P1G0
+ P7P6P5P4P3P2P1P0Cn
Copyright 1985, Texas Instruments Incorporated
!"#$%! & '("")% $& ! *(+,'$%! -$%).
"!-('%& '!!"# %! &*)''$%!& *)" %/) %)"#& ! )0$& &%"(#)%&
&%$-$"- 1$""$%2. "!-('%! *"!')&&3 -!)& !% )')&&$",2 ',(-)
%)&%3 ! $,, *$"$#)%)"&.
•
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•
1
SDAS235 − D2661, DECEMBER 1982 − REVISED NOVEMBER 1985
logic symbol†
CPG
Cn
P0
GO
P1
G1
P2
G2
P3
G3
P4
G4
P5
G5
P6
G6
P7
G7
1
C1
3
CP0
2
CG0
5
CP1
4
8
7
10
9
CG1
CP2
CO1
CG2
CP3
CO3
6
11
Cn+8
Cn+16
CG3
14
13
16
15
19
18
21
20
CP4
CG4
CO5
CP5
CO7
17
22
Cn+24
Cn+32
CG5
CP6
CG6
CP7
CG7
† This symbol is in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
Pin numbers shown are for DW, JT, and NT packages.
2
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•
SDAS235 − D2661, DECEMBER 1982 − REVISED NOVEMBER 1985
FUNCTION TABLE
FOR Cn + 32 OUTPUT
OUTPUT
INPUTS
G7
G6
G5
G4
G3
G2
G1
G0
P7
P6
P5
P4
P3
P2
P1
P0
Cn
L
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Cn + 32
H
X
L
X
X
X
X
X
X
L
X
X
X
X
X
X
X
X
H
X
X
L
X
X
X
X
X
L
L
X
X
X
X
X
X
X
H
X
X
X
L
X
X
X
X
L
L
L
X
X
X
X
X
X
H
X
X
X
X
L
X
X
X
L
L
L
L
X
X
X
X
X
H
X
X
X
X
X
L
X
X
L
L
L
L
L
X
X
X
X
H
X
X
X
X
X
X
L
X
L
L
L
L
L
L
X
X
X
H
X
X
X
X
X
X
X
L
L
L
L
L
L
L
L
X
X
H
X
X
X
X
X
X
X
X
L
L
L
L
L
L
L
L
H
H
All other combinations
L
FUNCTION TABLE
FOR Cn+24 OUTPUT
INPUTS
G5
G4
G3
G2
G1
G0
P5
OUTPUT
P4
P3
P2
P1
P0
Cn
Cn + 24
L
X
X
X
X
X
X
X
X
X
X
X
X
H
X
L
X
X
X
X
L
X
X
X
X
X
X
H
X
X
L
X
X
X
L
L
X
X
X
X
X
H
X
X
X
L
X
X
L
L
L
X
X
X
X
H
X
X
X
X
L
X
L
L
L
L
X
X
X
H
X
X
X
X
X
L
L
L
L
L
L
X
X
H
X
X
X
X
X
X
L
L
L
L
L
L
H
H
All other combinations
L
Function Tables
FOR Cn + 16 OUTPUT
INPUTS
G3 G2 G1 G0 P3 P2 P1 P0 Cn
L
X
X
X
X
X
L
X
X
X
X
X
L
X
X
X
X
X
L
X
X
L
L
L
L
X
X
L
L
L
X
X
X
L
L
X
X
X
X
L
X
X
X
X
H
FOR Cn + 8 OUTPUT
INPUTS
OUTPUT
Cn + 16
G1 G0 P1 P0 Cn
H
H
H
H
H
L
L
X
X
X
L
X
X
L
L
X
X
L
X
X
H
OUTPUT
Cn + 16
H
H
H
L
All other combinations
All other combinations
Any inputs not shown in a given table are irrelevant with respect to that output.
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•
3
SDAS235 − D2661, DECEMBER 1982 − REVISED NOVEMBER 1985
logic diagram (positive logic)
P7
P6
P5
P4
21
19
16
14
22
P3
P2
P1
P0
G7
G6
G5
G4
G3
G2
G1
G0
10
8
5
3
20
18
15
13
17
9
4
2
6
1
Pin numbers shown are for DW, JT, and NT packages.
4
Cn + 24
7
11
Cn
Cn + 32
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•
Cn + 16
Cn + 8
SDAS235 − D2661, DECEMBER 1982 − REVISED NOVEMBER 1985
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
Supply voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
Input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
Operating free-air temperature range: SN54AS882A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −55°C to 125°C
SN74AS882A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C
Storage temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −65°C to 150°C
recommended operating conditions
SN54AS882A
SN74AS882A
MIN
NOM
MAX
MIN
NOM
MAX
4.5
5
5.5
4.5
5
5.5
UNIT
VCC
VIH
Supply voltage
VIL
IOH
Low-level input voltage
0.8
0.8
V
High-level output current
−2
−2
mA
IOL
TA
Low-level output current
20
mA
70
°C
High-level input voltage
2
2
20
Operating free-air temperature
−55
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•
125
0
V
V
5
SDAS235 − D2661, DECEMBER 1982 − REVISED NOVEMBER 1985
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
PARAMETER
SN54AS882A
TYP†
MAX
TEST CONDITIONS
VIK
VOH
VCC = 4.5 V,
VCC = 4.5 V to 5.5 V,
II = − 18 mA
IOH = − 2 mA
VOL
VCC = 4.5 V,
IOL = 20 mA
MIN
−1.2
VCC −2
IIH
0.3
0.5
0.5
0.4
0.4
G0, G6
0.8
0.8
1.2
1.2
1.5
1.5
G7
0.9
0.9
P2, P3
0.3
0.3
P4, P5
0.2
0.2
P6, P7
0.1
0.1
Cn, P 0, P1
80
80
G0, G6
160
160
G1, G2, G4
240
240
300
300
180
180
P2, P3
60
60
P4, P5
40
40
P6, P7
20
20
Cn, P 0, P1
−2
−2
G0, G6
−4
−4
G1, G2, G4
−6
−6
G3, G5
G3, G5
VCC = 5.5 V,
VCC = 5.5 V,
VI = 7 V
VI = 2.7 V
G3, G5
VCC = 5.5 V,
VI = 0.4 V
UNIT
V
V
0.3
Cn, P 0, P1
G7
IIL
−1.2
VCC −2
G1, G2, G4
II
SN74AS882A
TYP†
MAX
MIN
−7.5
−7.5
G7
−4.5
−4.5
P2, P3
−1.5
−1.5
P4, P5
−1
−1
P6, P7
−0.5
−0.5
V
mA
µA
mA
IO‡
VCC = 5.5 V,
VO = 2.25 V
−30
−130
−30
−30
mA
ICC
VCC = 5.5 V
44
70
44
70
mA
† All typical values are at VCC = 5 V, TA = 25°C.
‡ The output conditions have been chosen to produce a current that closely approximates one half of the true short-circuit output current, IOS.
6
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•
SDAS235 − D2661, DECEMBER 1982 − REVISED NOVEMBER 1985
switching characteristics (see Note 1)
PARAMETER
FROM
(INPUT)
TO
(OUTPUT)
tPLH
tPHL
Cn
Any output
tPLH
tPHL
P or G
Cn + 8
tPLH
tPHL
P or G
Cn + 16
tPLH
tPHL
P or G
Cn + 24
tPLH
tPHL
P or G
Cn + 32
VCC = 4.5 V to 5.5 V,
CL = 50 pF,
RL = 500 Ω,
TA = MIN to MAX
SN54AS882A
UNIT
SN74AS882A
MIN
MAX
MIN
2
10
2
MAX
9
3
15
3
14
2
8
2
7
2
8
2
7
2
8
2
7
2
8
2
7
2
8
2
7
2
11
2
10
1.5
9
2
8
2
13
2
12
ns
NOTE 1: Load circuits and voltage waveforms are shown in Section 1.
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7
SDAS235 − D2661, DECEMBER 1982 − REVISED NOVEMBER 1985
TYPICAL APPLICATION DATA
The application given in Figure 1 illustrates how the ’AS882A can implement look-ahead carry for a 32-bit ALU
(in this case, the popular ’AS881A) with a single package. Typical carry times shown are derived using the
standard Advanced Schottky load circuit.
A
B
A
B
A
B
A
B
A
B
A
B
A
B
A
B
LSB
MSB
’AS881A
’AS881A
6 ns
Cn
6 ns
Cn−4
Cn
Cn−4
Cn
6 ns
’AS881A
F
Cn
’AS881A
G0
6 ns
Cn−4
Cn
Cn
Cn−4
6 ns
6 ns
F
F
F
G1 Cn + 8
P1
6 ns
Cn−4
Cn
’AS881A
F
F
P0
Cn−4
’AS881A
P2 G2
G3 Cn+16
P3
’AS882A
Cn
P4 G4
P5 G5
6 ns
Cn−4
Cn
Cn−4
’AS881A
’AS881A
F
F
Cn + 24
P6 G6
P7 G7
6 ns
Cn + 32
7 ns
Figure 1
Likewise, Figure 2 illustrates the same 32-bit ALU using two ’AS882s. This shows the worst-case delay from
LSB to MSB to be 19 ns as opposed to 25 ns in Figure 1.
LSB
A
B
4
A
4
B
4
B
A
4
4
B
A
4
4
A
B
4
4
6 ns
’AS881A
Cn
Cn
6 ns
F
F
P0
Cn
G0
A
4
Cn
P2 G2
’AS881A
Cn
Cn
Cn
6 ns
F
F
P3
G3
6 ns
F
F
Cn + 16 P4 G4
P5 G5
F
Cn + 24 P6 G6
6 ns
H
P0 G0
Cn
P1 G1 Cn + 8
P2 G2
P3 G3 Cn + 16
P4 G4
P5
6 ns
’AS882A
7 ns
Cn
Figure 2
8
P7 G7
Cn + 32
’AS882A
L
B MSB
4
’AS881A
’AS881A
F
P1 G1
B
4
’AS881A
Cn
’AS881A
A
4
’AS881A
’AS881A
6 ns
B
A
4
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•
G5 Cn + 24
P6 G6
P7 G7
Cn + 32
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