SN74AS882ADW [TI]
32-BIT LOOK-AHEAD CARRY GENERATORS; 32位先行进位发生器
| 型号： | SN74AS882ADW |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 32-BIT LOOK-AHEAD CARRY GENERATORS |
| 文件： | 总9页 (文件大小：142K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
SN54AS882A, SN74AS882A
32-BIT LOOK-AHEAD CARRY GENERATORS
SDAS235 – D2661, DECEMBER 1982 – REVISED NOVEMBER 1985
SN54AS882A . . . JT PACKAGE
SN74AS882A . . . DW OR NT PACKAGE
• Directly Compatible With ’AS181B,
’AS1181, ’AS881B, and ’AS1881 ALUs
(TOP VIEW)
• Package Options Include Plastic Small
Outline Packages, Both Plastic and
Ceramic Chip Carriers, and Standard
Plastic and Ceramic 300-mil DIPs
C
V
CC
NC
1
24
23
22
21
20
19
18
17
16
15
14
13
n
G0
P0
G1
P1
2
C
3
n + 32
• Capable of Anticipating the Carry Across a
P7
G7
P6
G6
C
4
Group of Eight 4-Bit Binary Adders
5
C
• Cascadable to Perform Look-Ahead Across
6
n + 8
G2
P2
G3
P3
n-Bit Adders
7
8
n + 24
• Typical Carry Time, C to Any C , is Less
n
n+i
P5
G5
P4
G4
9
Than 6 ns
10
11
12
• Dependable Texas Instruments Quality and
C
n – 16
GND
Reliability
description
SN54AS882A . . . FK 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
designertoimplementlook-aheadfora32-bitALU
with a single package or, by cascading ’AS882As,
full look-ahead is possible across n-bit adders.
SN74AS882A . . . DW OR NT PACKAGE
(TOP VIEW)
4
3
2 1 28 27 26
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.
5
G1
P1
25 P7
G7
23 P6
6
24
C
7
n + 8
NC
NC
22
8
G2
P2
G3
G6
C
P5
9
21
20
19
’AS882A LOGIC EQUATIONS
10
n + 24
11
C
C
=
=
G1 + P1G0+P1P0C
n
n+8
12 13 14 15 16 17 18
G3 + P3G2 + P3P2G1 + P3P2P1G0
+ P3P2P1P0C
n+16
n
C
=
=
G5 + P5G4 + P5P4G3 + P5P4P3G2
+ P5P4P3P2G1 + P5P4P3P2P1G0
n+24
n+32
NC – No internal connection
+ P5P4P3P2P1P0C
n
C
G7 + P7G6 + P7P6G5 + P7P6P5G4
+ P7P6P5P4G3 + P7P6P5P4P3G2
+ P7P6P5P4P3P2G1 + P7P6P5P4P3P2P1G0
+ P7P6P5P4P3P2P1P0C
n
Copyright 1985, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
SN54AS882A, SN74AS882A
32-BIT LOOK-AHEAD CARRY GENERATORS
SDAS235 – D2661, DECEMBER 1982 – REVISED NOVEMBER 1985
†
logic symbol
CPG
1
3
2
5
C
C1
n
P0
GO
P1
CP0
CG0
CP1
4
8
G1
P2
CG1
CP2
6
CO1
CO3
C
C
n+8
7
G2
P3
CG2
CP3
10
11
n+16
9
G3
CG3
14
13
17
22
P4
G4
CP4
CG4
CO5
CO7
C
C
n+24
n+32
16
15
19
18
21
20
P5
G5
P6
G6
P7
G7
CP5
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
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
SN54AS882A, SN74AS882A
32-BIT LOOK-AHEAD CARRY GENERATORS
SDAS235 – D2661, DECEMBER 1982 – REVISED NOVEMBER 1985
FUNCTION TABLE
FOR C OUTPUT
n + 32
INPUTS
G7 G6 G5 G4 G3 G2 G1 G0 P7 P6 P5 P4 P3 P2 P1 P0
OUTPUT
C
C
n + 32
n
L
X
X
X
X
X
X
X
X
X
L
X
X
L
X
X
X
L
X
X
X
X
L
X
X
X
X
X
L
X
X
X
X
X
X
L
X
X
X
X
X
X
X
L
X
L
L
L
L
L
L
L
L
X
X
L
L
L
L
L
L
L
X
X
X
L
L
L
L
L
L
X
X
X
X
L
L
L
L
L
X
X
X
X
X
L
X
X
X
X
X
X
L
X
X
X
X
X
X
X
L
X
X
X
X
X
X
X
X
L
X
H
X
X
X
X
X
X
X
H
H
H
H
H
H
H
H
H
L
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
L
X
X
L
L
X
L
L
L
All other combinations
FUNCTION TABLE
FOR C OUTPUT
n+24
INPUTS
OUTPUT
G5
L
G4
X
G3
G2
X
G1
X
G0
X
P5
X
L
P4
X
X
L
P3
X
X
X
L
P2
X
X
X
X
L
P1
P0
X
X
X
X
X
X
L
C
C
n + 24
n
X
X
L
X
X
X
X
X
L
X
H
X
L
X
X
X
X
X
X
X
X
H
H
H
H
H
H
H
L
X
X
X
X
X
L
X
X
X
X
X
X
L
X
X
L
L
X
X
X
L
X
L
L
L
X
X
X
X
L
L
L
L
L
X
X
X
X
X
L
L
L
L
L
All other combinations
Function Tables
FOR C
OUTPUT
FOR C
OUTPUT
n + 8
n + 16
INPUTS
G3 G2 G1 G0 P3 P2 P1 P0 C
INPUTS
G1 G0 P1 P0 C
n
OUTPUT
OUTPUT
C
C
n + 16
n
n + 16
H
L
X
L
X
X
X
X
X
L
X
X
X
X
X
L
X
L
L
L
L
X
X
L
L
L
X
X
X
L
X
X
X
X
L
X
H
L
X
X
X
L
X
L
L
X
X
L
X
H
H
L
X
X
X
X
X
X
X
H
H
H
H
H
L
X
H
X
All other combinations
X
L
All other combinations
Any inputs not shown in a given table are irrelevant with respect to that output.
3
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
SN54AS882A, SN74AS882A
32-BIT LOOK-AHEAD CARRY GENERATORS
SDAS235 – D2661, DECEMBER 1982 – REVISED NOVEMBER 1985
logic diagram (positive logic)
21
P7
19
P6
16
P5
14
P4
22
C
n + 32
10
P3
8
P2
5
P1
3
P0
20
G7
18
G6
15
G5
13
G4
17
C
n + 24
9
G3
7
G2
4
G1
2
G0
11
C
n + 16
6
C
n + 8
1
Cn
Pin numbers shown are for DW, JT, and NT packages.
4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
SN54AS882A, SN74AS882A
32-BIT LOOK-AHEAD CARRY GENERATORS
SDAS235 – D2661, DECEMBER 1982 – REVISED NOVEMBER 1985
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
Supply voltage, V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
CC
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
MIN NOM MAX
SN74AS882A
MIN NOM MAX
UNIT
V
V
V
Supply voltage
4.5
2
5
5.5
4.5
2
5
5.5
V
V
CC
IH
High-level input voltage
Low-level input voltage
High-level output current
Low-level output current
Operating free-air temperature
0.8
–2
0.8
–2
20
70
V
IL
I
I
mA
mA
°C
OH
OL
20
T
A
–55
125
0
5
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
SN54AS882A, SN74AS882A
32-BIT LOOK-AHEAD CARRY GENERATORS
SDAS235 – D2661, DECEMBER 1982 – REVISED NOVEMBER 1985
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
SN54AS882A
SN74AS882A
PARAMETER
TEST CONDITIONS
UNIT
†
†
MIN TYP
MAX
MIN TYP
MAX
V
V
V
V
V
V
= 4.5 V,
I = –18 mA
–1.2
–1.2
V
V
V
IK
CC
CC
CC
I
= 4.5 V to 5.5 V,
= 4.5 V,
I
I
= –2 mA
= 20 mA
V
CC
–2
V
CC
–2
OH
OL
OH
OL
0.3
0.5
0.4
0.8
1.2
1.5
0.9
0.3
0.2
0.1
80
0.3
0.5
0.4
0.8
1.2
1.5
0.9
0.3
0.2
0.1
80
C , P 0, P1
n
G0, G6
G1, G2, G4
G3, G5
G7
I
I
I
V
CC
V
CC
V
CC
= 5.5 V,
= 5.5 V,
= 5.5 V,
V = 7 V
I
mA
I
P2, P3
P4, P5
P6, P7
C , P 0, P1
n
G0, G6
G1, G2, G4
G3, G5
G7
160
240
300
180
60
160
240
300
180
60
V = 2.7 V
I
µA
IH
P2, P3
P4, P5
P6, P7
40
40
20
20
C , P 0, P1
n
–2
–2
G0, G6
G1, G2, G4
G3, G5
G7
–4
–4
–6
–6
V = 0.4 V
I
–7.5
–4.5
–1.5
–1
–7.5
–4.5
–1.5
–1
mA
IL
P2, P3
P4, P5
P6, P7
–0.5
–130
70
–0.5
–30
70
‡
I
I
V
V
= 5.5 V,
= 5.5 V
V = 2.25 V
O
–30
–30
mA
mA
O
CC
44
44
CC
CC
†
‡
All typical values are at V
= 5 V, T = 25°C.
A
CC
The output conditions have been chosen to produce a current that closely approximates one half of the true short-circuit output current, I
.
OS
6
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
SN54AS882A, SN74AS882A
32-BIT LOOK-AHEAD CARRY GENERATORS
SDAS235 – D2661, DECEMBER 1982 – REVISED NOVEMBER 1985
switching characteristics (see Note 1)
V
C
= 4.5 V to 5.5 V,
= 50 pF,
CC
L
R
T
= 500 Ω,
= MIN to MAX
L
A
FROM
(INPUT)
TO
(OUTPUT)
PARAMETER
UNIT
SN54AS882A
SN74AS882A
MIN
2
MAX
10
15
8
MIN
2
MAX
9
t
t
t
t
t
t
t
t
t
t
PLH
PHL
PLH
PHL
PLH
PHL
PLH
PHL
PLH
PHL
C
Any output
n
3
3
14
7
2
2
P or G
P or G
P or G
P or G
C
+ 8
n
2
8
2
7
2
8
2
7
ns
C
+ 16
+ 24
+ 32
n
2
8
2
7
2
8
2
7
C
C
n
n
2
11
9
2
10
8
1.5
2
2
13
2
12
NOTE 1: Load circuits and voltage waveforms are shown in Section 1.
7
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
SN54AS882A, SN74AS882A
32-BIT LOOK-AHEAD CARRY GENERATORS
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
6 ns
’AS881A
’AS881A
6 ns
C
6 ns
6 ns
6 ns
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
n
n–4
n
n–4
n
n–4
n
n–4
n
n–4
n
n–4
n
n–4
n
n–4
6 ns
6 ns
6 ns
’AS881A
’AS881A
’AS881A
’AS881A
’AS881A
F
F
F
F
F
F
F
F
P0 G0
P1 G1
C
P2 G2
’AS882A
P3
G3 C
P4 G4
P5 G5
C
n + 24
P6 G6
P7 G7
n + 8
n+16
6 ns
C
n
C
n + 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
A
B
A
B
A
B
A
B
A
B
A
B
A
B MSB
4
4
4
4
4
4
4
4
4
4
4
4
4
4
’AS881A
’AS881A
’AS881A
’AS881A
n
’AS881A
n
’AS881A
n
6 ns
6 ns
C
C
C
C
C
C
C
n
6 ns
n
n
n
6 ns
6 ns
’AS881A
’AS881A
F
F
F
F
F
F
F
F
P0
G0
P1 G1
6 ns
P2 G2
P3
G3
C
P4 G4
P5 G5
C
n + 24
P6 G6
P7 G7
n + 16
C
C
n + 32
n
’AS882A
L
H
P0 G0
P1 G1 C
P2 G2
P3 G3
C
P4 G4
P5
G5 C
n + 24
P6 G6
P7 G7
n + 8
n + 16
6 ns
C
’AS882A
7 ns
C
n + 32
n
C
n
Figure 2
8
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
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accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
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Copyright 1998, Texas Instruments Incorporated
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