SN74ALS280, SN74AS280
9 BIT PARITY GENERATORS/CHECKERS
SDAS038C − DECEMBER 1982 − REVISED DECEMBER 1994
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•
•
•
Generate Either Odd or Even Parity for Nine
Data Lines
Cascadable for n-Bit Parity
Can Be Used to Upgrade Existing Systems
Using MSI Parity Circuits
Package Options Include Plastic
Small-Outline (D) Packages and Standard
Plastic (N) 300-mil DIPs
D OR N PACKAGE
(TOP VIEW)
description
G
H
NC
I
Σ
EVEN
Σ
ODD
GND
1
2
3
4
5
6
7
14
13
12
11
10
9
8
V
CC
F
E
D
C
B
A
NC − No internal connection
These universal 9-bit parity generators/checkers
utilize advanced Schottky high-performance
circuitry and feature odd (Σ ODD) and even (Σ EVEN) outputs to facilitate operation of either odd- or even-parity
applications. The word-length capability is easily expanded by cascading.
These devices can be used to upgrade the performance of most systems utilizing the SN74ALS180 and
SN74AS180 parity generators/checkers. Although the SN74ALS280 and SN74AS280 are implemented without
expander inputs, the corresponding function is provided by the availability of an input (I) at terminal 4 and the
absence of any internal connection at terminal 3. This permits the SN74ALS280 and SN74AS280 to be
substituted for the SN74ALS180 and SN74AS180 in existing designs to produce an identical function even if
the devices are mixed with existing SN74ALS180 and SN74AS180 devices.
All SN74AS280 inputs are buffered to lower the drive requirements.
The SN74ALS280 and SN74AS280 are characterized for operation from 0°C to 70°C.
FUNCTION TABLE
NO. OF INPUTS
A −I
THAT ARE HIGH
0, 2, 4, 6, 8
1, 3, 5, 7, 9
OUTPUTS
Σ
EVEN
H
L
Σ
ODD
L
H
logic symbol
†
8
9
10
11
12
13
1
2
4
6
Σ
ODD
5
Σ
EVEN
2k
A
B
C
D
E
F
G
H
I
† This symbol is in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
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.
Copyright
1994, Texas Instruments Incorporated
POST OFFICE BOX 655303
POST OFFICE BOX 1443
•
HOUSTON, TEXAS 77251−1443
•
DALLAS, TEXAS 75265
1
SN74ALS280, SN74AS280
9 BIT PARITY GENERATORS/CHECKERS
SDAS038C − DECEMBER 1982 − REVISED DECEMBER 1994
logic diagram (positive logic)
A
B
8
9
C
10
5
Σ
EVEN
D
E
11
12
F
13
6
Σ
ODD
G
H
1
2
I
4
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
†
Supply voltage, V
CC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
Input voltage, V
I
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
Operating free-air temperature range, T
A
: SN74ALS280 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C
Storage temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −65°C to 150°C
† Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
2
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
POST OFFICE BOX 1443 HOUSTON, TEXAS 77251−1443
•
•
SN74ALS280, SN74AS280
9 BIT PARITY GENERATORS/CHECKERS
SDAS038C − DECEMBER 1982 − REVISED DECEMBER 1994
recommended operating conditions
SN74ALS280
MIN
VCC
VIH
VIL
IOH
IOL
TA
Supply voltage
High-level input voltage
Low-level input voltage
High-level output current
Low-level output current
Operating free-air temperature
0
4.5
2
0.8
−2.6
24
70
NOM
5
MAX
5.5
UNIT
V
V
V
mA
mA
°C
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
PARAMETER
VIK
VOH
VOL
II
IIH
IIL
IO‡
TEST CONDITIONS
VCC = 4.5 V,
VCC = 4.5 V to 5.5 V,
VCC = 4.5 V,
VCC = 4.5 V
VCC = 5.5 V,
VCC = 5.5 V,
VCC = 5.5 V,
VCC = 5.5 V,
II = − 18 mA
IOH = − 0.4 mA
IOH = − 2.6 mA
IOL = 12 mA
IOL = 24 mA
VI = 7 V
VI = 2.7 V
VI = 0.4 V
VO = 2.25 V
−30
SN74ALS280
MIN TYP†
MAX
−1.5
VCC − 2
2.4
3.3
0.25
0.35
0.4
0.5
0.1
20
−0.1
−112
V
mA
µA
mA
mA
UNIT
V
V
ICC
VCC = 5.5 V
10
16
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.
switching characteristics (see Figure 1)
VCC = 4.5 V to 5.5 V,
CL = 50 pF,
RL = 500
Ω
,
TA = MIN to MAX§
SN74ALS280
MIN
tPLH
tPHL
tPLH
tPHL
Any
Any
Σ
EVEN
Σ
ODD
3
3
3
4
MAX
20
20
20
22
ns
ns
PARAMETER
FROM
(INPUT)
TO
(OUTPUT)
UNIT
§ For conditions shown as MIN or MAX, use the appropriate value specified under recommended operating conditions.
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
POST OFFICE BOX 1443 HOUSTON, TEXAS 77251−1443
•
•
3
SN74ALS280, SN74AS280
9 BIT PARITY GENERATORS/CHECKERS
SDAS038C − DECEMBER 1982 − REVISED DECEMBER 1994
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
†
Supply voltage, V
CC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
Input voltage, V
I
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
Operating free-air temperature range, T
A
: SN74AS280 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C
Storage temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −65°C to 150°C
† Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
recommended operating conditions
SN74AS280
MIN
VCC
VIH
VIL
IOH
IOL
TA
Supply voltage
High-level input voltage
Low-level input voltage
High-level output current
Low-level output current
Operating free-air temperature
0
4.5
2
0.8
−2
20
70
NOM
5
MAX
5.5
UNIT
V
V
V
mA
mA
°C
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
PARAMETER
VIK
VOH
VOL
II
IIH
IIL
IO§
TEST CONDITIONS
VCC = 4.5 V,
VCC = 4.5 V to 5.5 V,
VCC = 4.5 V,
VCC = 5.5 V,
VCC = 5.5 V,
VCC = 5.5 V,
VCC = 5.5 V,
VCC = 5.5 V
II = − 18 mA
IOH = − 2 mA
IOL = 20 mA
VI = 7 V
VI = 2.7 V
VI = 0.4 V
VO = 2.25 V
−30
SN74AS280
MIN TYP‡
MAX
−1.5
VCC − 2
0.35
0.5
0.1
20
−0.5
−112
UNIT
V
V
V
mA
µA
mA
mA
ICC
25
35
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.
switching characteristics (see Figure 1)
VCC = 4.5 V to 5.5 V,
CL = 50 pF,
RL = 500
Ω
,
TA = MIN to MAX¶
SN74AS280
MIN
tPLH
tPHL
tPLH
tPHL
Any
Any
Σ
EVEN
Σ
ODD
3
3
3
3
MAX
12
11
12
11.5
ns
ns
PARAMETER
FROM
(INPUT)
TO
(OUTPUT)
UNIT
¶ For conditions shown as MIN or MAX, use the appropriate value specified under recommended operating conditions.
4
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
POST OFFICE BOX 1443 HOUSTON, TEXAS 77251−1443
•
•
SN74ALS280, SN74AS280
9 BIT PARITY GENERATORS/CHECKERS
SDAS038C − DECEMBER 1982 − REVISED DECEMBER 1994
APPLICATION INFORMATION
25-LINE
PARITY GENERATOR/CHECKER
A
B
C
D
E
F
G
H
I
Σ
ODD
Σ
EVEN
A
B
C
D
E
F
G
H
I
Σ
ODD
81-LINE
PARITY GENERATOR/CHECKER
A
B
C
D
E
F
G
H
I
Σ
ODD
H - Odd
L = Even
Σ
EVEN
H - Even
L = Odd
A
B
C
D
E
F
G
H
I
Σ
ODD
A
B
C
D
E
F
G
H
I
Σ
ODD
H - Odd
L = Even
Σ
EVEN
H - Even
L = Odd
A
B
C
D
E
F
G
H
I
Three SN74ALS280/SN74AS280 devices can be
used to implement a 25-line parity generator/
checker.
As an alternative, the
Σ
ODD outputs of two or three
parity generators/checkers can be decoded with a
2-input (′AS86A or
′ALS86)
exclusive-OR gate for
18- or 27-line parity applications.
Σ
ODD
Σ
EVEN
A
B
C
D
E
F
G
H
I
To Other
SN74AS280s
Σ
ODD
Longer word lengths can be implemented by cascading SN74ALS280/SN74AS280
devices. Parity can be generated for word lengths up to 81 bits.
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
POST OFFICE BOX 1443 HOUSTON, TEXAS 77251−1443
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•
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