5-1
FACT DATA
8 Bit Identity Comparator
The MC74AC521/74ACT521 is an expandable 8-bit comparator. It
compares two words of up to eight bits each and provides a LOW output when
the two words match bit for bit. The expansion input IA=B also serves as an
active LOW enable input.
Compares Two 8-Bit Words in 6.5 ns Typ
Expandable to Any Word Length
20-Pin Package
Outputs Source/Sink 24 mA
ACT521 has TTL-Compatible Inputs
19
20
18
17
16
15
14
2
1
3
4
5
6
7
VCC
13
8
12
9
11
10
OA=B
B7
A7
B6
A6
B5
A5
B4
A4
IA=B
A0
B0
A1
B1
A2
B2
A3
B3
GND
PIN NAMES
A0A7
Word A Inputs
B0B7
Word B Inputs
IA=B
Expansion or Enable Input
OA=B
Identity Output
TRUTH TABLE
Inputs
Outputs
IA=B
A, B
OA=B
L
A = B*
L
L
A
B
H
H
A = B*
H
H
A
B
H
H = HIGH Voltage Level
L = LOW Voltage Level
*A0=B0, A1=B1, A2=B2, etc.
8-BIT IDENTITY
COMPARATOR
N SUFFIX
CASE 738-03
PLASTIC
DW SUFFIX
CASE 751D-04
PLASTIC
MC74AC521
MC74ACT521
LOGIC SYMBOL
B7 A7 B6 A6 B5 A5 B4 A4 B3 A3 B2 A2 B1 A1 B0 A0
IA=B
OA=B
MC74AC521 MC74ACT521
5-2
FACT DATA
Please note that this diagram is provided only for the understanding of logic
operations and should not be used to estimate propagation delays.
LOGIC DIAGRAM
A0
B0
A1
B1
A2
B2
A3
B3
A4
B4
A5
B5
A6
B6
A7
B7
IA=B
OA=B
MAXIMUM RATINGS*
Symbol
Parameter
Value
Unit
VCC
DC Supply Voltage (Referenced to GND)
0.5 to +7.0
V
Vin
DC Input Voltage (Referenced to GND)
0.5 to VCC +0.5
V
Vout
DC Output Voltage (Referenced to GND)
0.5 to VCC +0.5
V
Iin
DC Input Current, per Pin
20
mA
Iout
DC Output Sink/Source Current, per Pin
50
mA
ICC
DC VCC or GND Current per Output Pin
50
mA
Tstg
Storage Temperature
65 to +150
C
* Maximum Ratings are those values beyond which damage to the device may occur. Functional operation should be restricted to the Recommended
Operating Conditions.
MC74AC521 MC74ACT521
5-3
FACT DATA
RECOMMENDED OPERATING CONDITIONS
Symbol
Parameter
Min
Typ
Max
Unit
VCC
Supply Voltage
AC
2.0
5.0
6.0
V
VCC
Supply Voltage
ACT
4.5
5.0
5.5
V
Vin, Vout
DC Input Voltage, Output Voltage (Ref. to GND)
0
VCC
V
tr, tf
Input Rise and Fall Time (Note 1)
AC Devices except Schmitt Inputs
VCC @ 3.0 V
150
tr, tf
Input Rise and Fall Time (Note 1)
AC Devices except Schmitt Inputs
VCC @ 4.5 V
40
ns/V
r, tf
AC Devices except Schmitt Inputs
VCC @ 5.5 V
25
tr, tf
Input Rise and Fall Time (Note 2)
ACT Devices except Schmitt Inputs
VCC @ 4.5 V
10
ns/V
tr, tf
Input Rise and Fall Time (Note 2)
ACT Devices except Schmitt Inputs
VCC @ 5.5 V
8.0
ns/V
TJ
Junction Temperature (PDIP)
140
C
TA
Operating Ambient Temperature Range
40
25
85
C
IOH
Output Current -- High
24
mA
IOL
Output Current -- Low
24
mA
1. Vin from 30% to 70% VCC; see individual Data Sheets for devices that differ from the typical input rise and fall times.
2. Vin from 0.8 V to 2.0 V; see individual Data Sheets for devices that differ from the typical input rise and fall times.
DC CHARACTERISTICS
Symbol
Parameter
VCC
(V)
74AC
74AC
Unit
Conditions
Symbol
Parameter
VCC
(V)
TA = +25
C
TA =
40
C to +85
C
Unit
Conditions
Typ
Guaranteed Limits
VIH
Minimum High Level
Input Voltage
3.0
1.5
2.1
2.1
VOUT = 0.1 V
Input Voltage
4.5
2.25
3.15
3.15
V
or VCC 0.1 V
5.5
2.75
3.85
3.85
VIL
Maximum Low Level
Input Voltage
3.0
1.5
0.9
0.9
VOUT = 0.1 V
Input Voltage
4.5
2.25
1.35
1.35
V
or VCC 0.1 V
5.5
2.75
1.65
1.65
VOH
Minimum High Level
Output Voltage
3.0
2.99
2.9
2.9
IOUT = 50
A
Output Voltage
4.5
4.49
4.4
4.4
V
5.5
5.49
5.4
5.4
V
*VIN = VIL or VIH
3.0
2.56
2.46
V
12 mA
4.5
3.86
3.76
V
IOH
24 mA
5.5
4.86
4.76
24 mA
VOL
Maximum Low Level
Output Voltage
3.0
0.002
0.1
0.1
IOUT = 50
A
Output Voltage
4.5
0.001
0.1
0.1
V
5.5
0.001
0.1
0.1
V
*VIN = VIL or VIH
3.0
0.36
0.44
V
12 mA
4.5
0.36
0.44
V
IOL
24 mA
5.5
0.36
0.44
24 mA
IIN
Maximum Input
Leakage Current
5.5
0.1
1.0
A
VI = VCC, GND
Leakage Current
5.5
0.1
1.0
A
VI = VCC, GND
IOLD
Minimum Dynamic
Output Current
5.5
75
mA
VOLD = 1.65 V Max
IOHD
Output Current
5.5
75
mA
VOHD = 3.85 V Min
ICC
Maximum Quiescent
Supply Current
5.5
8.0
80
A
VIN = VCC or GND
Supply Current
5.5
8.0
80
A
VIN = VCC or GND
* All outputs loaded; thresholds on input associated with output under test.
Maximum test duration 2.0 ms, one output loaded at a time.
Note: IIN and ICC @ 3.0 V are guaranteed to be less than or equal to the respective limit @ 5.5 V VCC.
MC74AC521 MC74ACT521
5-4
FACT DATA
AC CHARACTERISTICS (For Figures and Waveforms -- See Section 3)
Symbol
Parameter
VCC*
(V)
74AC
74AC
Unit
Fig.
No.
Symbol
Parameter
VCC*
(V)
TA = +25
C
CL = 50 pF
TA = 40
C
to +85
C
CL = 50 pF
Unit
Fig.
No.
Min
Typ
Max
Min
Max
tPLH
Propagation Delay
3.3
3.5
11
3.0
12
ns
3-6
tPLH
An or Bn to OA=B
5.0
2.5
8.0
2.0
9.0
ns
3-6
tPHL
Propagation Delay
3.3
4.5
11.5
3.5
12.5
ns
3-6
tPHL
An or Bn to OA=B
5.0
3.0
8.5
2.5
9.0
ns
3-6
tPLH
Propagation Delay
3.3
3.0
8.0
2.5
9.0
ns
3-6
tPLH
IA=B to OA=B
5.0
2.5
6.0
2.0
7.0
ns
3-6
tPHL
Propagation Delay
3.3
3.0
8.0
2.5
9.0
ns
3-6
tPHL
IA=B to OA=B
5.0
2.0
6.0
2.0
7.0
ns
3-6
* Voltage Range 3.3 V is 3.3 V
0.3 V.
Voltage Range 5.0 V is 5.0 V
0.5 V.
DC CHARACTERISTICS
Symbol
Parameter
VCC
(V)
74ACT
74ACT
Unit
Conditions
Symbol
Parameter
VCC
(V)
TA = +25
C
TA =
40
C to +85
C
Unit
Conditions
Typ
Guaranteed Limits
VIH
Minimum High Level
Input Voltage
4.5
1.5
2.0
2.0
V
VOUT = 0.1 V
Input Voltage
5.5
1.5
2.0
2.0
V
or VCC 0.1 V
VIL
Maximum Low Level
Input Voltage
4.5
1.5
0.8
0.8
V
VOUT = 0.1 V
Input Voltage
5.5
1.5
0.8
0.8
V
or VCC 0.1 V
VOH
Minimum High Level
Output Voltage
4.5
4.49
4.4
4.4
V
IOUT = 50
A
Output Voltage
5.5
5.49
5.4
5.4
V
*VIN = VIL or VIH
4.5
3.86
3.76
V
IOH
24 mA
5.5
4.86
4.76
IOH
24 mA
VOL
Maximum Low Level
Output Voltage
4.5
0.001
0.1
0.1
V
IOUT = 50
A
Output Voltage
5.5
0.001
0.1
0.1
V
*VIN = VIL or VIH
4.5
0.36
0.44
V
IOL
24 mA
5.5
0.36
0.44
IOL
24 mA
IIN
Maximum Input
Leakage Current
5.5
0.1
1.0
A
VI = VCC, GND
Leakage Current
5.5
0.1
1.0
A
VI = VCC, GND
ICCT
Additional Max. ICC/Input
5.5
0.6
1.5
mA
VI = VCC 2.1 V
IOLD
Minimum Dynamic
Output Current
5.5
75
mA
VOLD = 1.65 V Max
IOHD
Output Current
5.5
75
mA
VOHD = 3.85 V Min
ICC
Maximum Quiescent
Supply Current
5.5
8.0
80
A
VIN = VCC or GND
Supply Current
5.5
8.0
80
A
VIN = VCC or GND
* All outputs loaded; thresholds on input associated with output under test.
Maximum test duration 2.0 ms, one output loaded at a time.
MC74AC521 MC74ACT521
5-5
FACT DATA
AC CHARACTERISTICS (For Figures and Waveforms -- See Section 3)
Symbol
Parameter
VCC*
(V)
74ACT
74ACT
Unit
Fig.
No.
Symbol
Parameter
VCC*
(V)
TA = +25
C
CL = 50 pF
TA = 40
C
to +85
C
CL = 50 pF
Unit
Fig.
No.
Min
Typ
Max
Min
Max
tPLH
Propagation Delay
An or Bn to OA=B
5.0
3.0
9.0
2.5
9.5
ns
3-6
tPLH
An or Bn to OA=B
5.0
3.0
9.0
2.5
9.5
ns
3-6
tPHL
Propagation Delay
An or Bn to OA=B
5.0
3.0
10
2.5
11
ns
3-6
tPHL
An or Bn to OA=B
5.0
3.0
10
2.5
11
ns
3-6
tPLH
Propagation Delay
IA=B to OA=B
5.0
2.0
6.5
2.0
7.0
ns
3-6
tPLH
IA=B to OA=B
5.0
2.0
6.5
2.0
7.0
ns
3-6
tPHL
Propagation Delay
IA=B to OA=B
5.0
2.5
7.5
2.0
8.0
ns
3-6
tPHL
IA=B to OA=B
5.0
2.5
7.5
2.0
8.0
ns
3-6
* Voltage Range 5.0 V is 5.0 V
0.5 V.
CAPACITANCE
Symbol
Parameter
Value
Typ
Unit
Test Conditions
CIN
Input Capacitance
4.5
pF
VCC = 5.0 V
CPD
Power Dissipation Capacitance
40
pF
VCC = 5.0 V
........
........
APPLICATIONS
RIPPLE EXPANSION
IA=B
A0 B0
A7 B7
OA=B
ENABLE
LOW
IA=B
A8 B8
A15 B15
OA=B
IA=B
A16 B16
A23 B23
OA=B
PARALLEL EXPANSION
IA=B
A0 B0
A7 B7
OA=B
ENABLE
LOW
IA=B
A8 B8
A15 B15
OA=B
IA=B
A16 B16
A23 B23
OA=B
........
........
........
........
MC74AC521 MC74ACT521
5-6
FACT DATA
OUTLINE DIMENSIONS
N SUFFIX
PLASTIC DIP PACKAGE
CASE 73803
ISSUE E
DW SUFFIX
PLASTIC SOIC PACKAGE
CASE 751D04
ISSUE E
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ANSI Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSIONS A AND B DO NOT INCLUDE
MOLD PROTRUSION.
4. MAXIMUM MOLD PROTRUSION 0.150
(0.006) PER SIDE.
5. DIMENSION D DOES NOT INCLUDE
DAMBAR PROTRUSION. ALLOWABLE
DAMBAR PROTRUSION SHALL BE 0.13
(0.005) TOTAL IN EXCESS OF D
DIMENSION AT MAXIMUM MATERIAL
CONDITION.
A
B
20
1
11
10
S
A
M
0.010 (0.25)
B
S
T
D
20X
M
B
M
0.010 (0.25)
P
10X
J
F
G
18X
K
C
T
SEATING
PLANE
M
R
X 45
_
DIM
MIN
MAX
MIN
MAX
INCHES
MILLIMETERS
A
12.65
12.95
0.499
0.510
B
7.40
7.60
0.292
0.299
C
2.35
2.65
0.093
0.104
D
0.35
0.49
0.014
0.019
F
0.50
0.90
0.020
0.035
G
1.27 BSC
0.050 BSC
J
0.25
0.32
0.010
0.012
K
0.10
0.25
0.004
0.009
M
0
7
0
7
P
10.05
10.55
0.395
0.415
R
0.25
0.75
0.010
0.029
_
_
_
_
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ANSI Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION L TO CENTER OF LEAD WHEN
FORMED PARALLEL.
4. DIMENSION B DOES NOT INCLUDE MOLD
FLASH.
M
L
J
20 PL
M
B
M
0.25 (0.010)
T
DIM
MIN
MAX
MIN
MAX
MILLIMETERS
INCHES
A
25.66
27.17
1.010
1.070
B
6.10
6.60
0.240
0.260
C
3.81
4.57
0.150
0.180
D
0.39
0.55
0.015
0.022
G
2.54 BSC
0.100 BSC
J
0.21
0.38
0.008
0.015
K
2.80
3.55
0.110
0.140
L
7.62 BSC
0.300 BSC
M
0
15
0
15
N
0.51
1.01
0.020
0.040
_
_
_
_
E
1.27
1.77
0.050
0.070
1
11
10
20
A
SEATING
PLANE
K
N
F
G
D
20 PL
T
M
A
M
0.25 (0.010)
T
E
B
C
F
1.27 BSC
0.050 BSC
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MC74AC521/D
*MC74AC521/D*
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