54AC521
54ACT521
8-Bit Identity Comparator
General Description
The AC/ACT521 is an expandable 8-bit comparator. It com-
pares two words of up to eight bits each and provides a LOW
output when the two words match bit for bit. The expansion
input I
A = B
also serves as an active LOW enable input.
Features
n
I
CC
reduced by 50%
n
Compares two 8-bit words in 6.5 ns typ
n
Expandable to any word length
n
Outputs source/sink 24 mA
n
ACT521 has TTL-compatible inputs
n
Standard microcircuit Drawing (SMD)
54AC521: 5962-90985
54ACT521: 5962-89793
Logic Symbols
Connection Diagram
Pin Descriptions
Pin Names
Description
A
0
A
7
Word A Inputs
B
0
B
7
Word B Inputs
T
A = B
Expansion or Enable Input
O
A = B
Identity Output
FACT
TM
is a trademark of Fairchild Semiconductor Corporation.
DS100291-1
IEEE/IEC
DS100291-4
Pin Assignment
for DIP and CERPACK
DS100291-2
Pin Assignment
for LCC
DS100291-3
September 1998
54AC521
54ACT521
8-Bit
Identity
Comparator
1998 National Semiconductor Corporation
DS100291
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Truth Table
Inputs
Outputs
I
A = B
A, B
O
A = B
L
A = B (Note 1)
L
L
A
B
H
H
A = B (Note 1)
H
H
A
B
H
H = HIGH Voltage Level
L = LOW Voltage Level
Note 1: A
0
= B
0
, A
1
= B
1
, A
2
= B
2
, etc.
Logic Diagram
DS100291-5
Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.
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2
Absolute Maximum Ratings
(Note 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage (V
CC
)
-0.5V to +7.0V
DC Input Diode Current (I
IK
)
V
I
= -0.5V
-20 mA
V
I
= V
CC
+ 0.5V
+20 mA
DC Input Voltage (V
I
)
-0.5V to V
CC
+ 0.5V
DC Output Diode Current (I
OK
)
V
O
= -0.5V
-20 mA
V
O
= V
CC
+ 0.5V
+20 mA
DC Output Voltage (V
O
)
-0.5V to V
CC
+ 0.5V
DC Output Source
or Sink Current (I
O
)
50 mA
DC V
CC
or Ground Current
per Output Pin (I
CC
or I
GND
)
50 mA
Storage Temperature (T
STG
)
-65C to +150C
Junction Temperature (T
J
)
CDIP
175C
Recommended Operating
Conditions
Supply Voltage (V
CC
)
AC
2.0V to 6.0V
ACT
4.5V to 5.5V
Input Voltage (V
I
)
0V to V
CC
Output Voltage (V
O
)
0V to V
CC
Operating Temperature (T
A
)
54AC/ACT
-55C to +125C
Minimum Input Edge Rate (
V/
t)
AC Devices
V
IN
from 30% to 70% of V
CC
V
CC
@
3.3V, 4.5V, 5.5V
125 mV/ns
Minimum Input Edge Rate (
V/
t)
ACT Devices
V
IN
from 0.8V to 2.0V
V
CC
@
4.5V, 5.5V
125 mV/ns
Note 2: Absolute maximum ratings are those values beyond which damage
to the device may occur. The databook specifications should be met, without
exception, to ensure that the system design is reliable over its power supply,
temperature, output/input loading variables. Fairchild does not recommend
operation of FACT
TM
circuits outside databook specifications.
DC Electrical Characteristics for AC
Symbol
Parameter
V
CC
T
A
= -55C to +125C
Units
Conditions
(V)
Guaranteed Limits
V
IH
Minimum High Level
3.0
2.1
V
OUT
= 0.1V
Input Voltage
4.5
3.15
V
or V
CC
- 0.1V
5.5
3.85
V
IL
Maximum Low Level
3.0
0.9
V
OUT
= 0.1V
Input Voltage
4.5
1.35
V
or V
CC
- 0.1V
5.5
1.65
V
OH
Minimum High Level
3.0
2.9
I
OUT
= -50 A
Output Voltage
4.5
4.4
V
5.5
5.4
V
IN
= V
IL
or V
IH
3.0
2.4
I
OH
= -4 mA
4.5
3.7
V
I
OH
= -24 mA
5.5
4.7
I
OH
= -24 mA (Note 3)
V
OL
Maximum Low Level
3.0
0.1
I
OUT
= 50 A
Output Voltage
4.5
0.1
V
5.5
0.1
V
IN
= V
IL
or V
IH
3.0
0.4
I
OL
= 12 mA
4.5
0.5
V
I
OL
= 24 mA
5.5
0.5
I
OL
= 24 mA (Note 3)
I
IN
Maximum Input
5.5
1.0
A
V
I
= V
CC
, GND
(Note 5)
Leakage Current
I
OLD
Minimum Dynamic
Output Current (Note 4)
5.5
50
mA
V
OLD
= 1.65V Max
I
OHD
5.5
-50
mA
V
OHD
= 3.85V Min
I
CC
Maximum Quiescent
5.5
80.0
A
V
IN
= V
CC
(Note 5)
Supply Current
or GND
Note 3: All outputs loaded; thresholds on input associated with output under test.
Note 4: Maximum test duration 2.0 ms, one output loaded at a time.
Note 5: I
IN
and I
CC
@
3.0V are guaranteed to be less than or equal to the respective limit
@
5.5V V
CC
.
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3
DC Electical Characteristics for ACT
Symbol
Parameter
V
CC
T
A
= -55C to +125C
Units
Conditions
(V)
Guaranteed Limits
V
IH
Minimum High Level
4.5
2.0
V
V
OUT
= 0.1V
Input Voltage
5.5
2.0
or V
CC
- 0.1V
V
IL
Maximum Low Level
4.5
0.8
V
V
OUT
= 0.1V
Input Voltage
5.5
0.8
or V
CC
- 0.1V
V
OH
Minimum High Level
4.5
4.4
V
I
OUT
= -50 A
Output Voltage
5.5
5.4
V
IN
= V
IL
or V
IH
4.5
3.7
V
I
OH
= -24 mA
5.5
4.7
I
OH
= -24 mA (Note 6)
V
OL
Maximum Low Level
4.5
0.1
V
I
OUT
= 50 A
Output Voltage
5.5
0.1
V
IN
= V
IL
or V
IH
4.5
0.5
V
I
OL
= 24 mA
5.5
0.5
I
OL
= 24 mA (Note 6)
I
IN
Maximum Input
5.5
1.0
A
V
I
= V
CC
, GND
Leakage Current
I
CCT
Maximum
5.5
1.5
mA
V
I
= V
CC
- 2.1V
I
CC
/Input
I
OLD
Minimum Dynamic
Output Current (Note 7)
5.5
50
mA
V
OLD
= 1.65V Max
I
OHD
5.5
-50
mA
V
OHD
= 3.85V Min
I
CC
Maximum Quiescent
5.5
80.0
A
V
IN
= V
CC
Supply Current
or GND
Note 6: All outputs loaded; thresholds on input associated with output under test.
Note 7: Maximum test duration 2.0 ms, one output loaded at a time.
AC Electrical Characteristics for AC
Symbol
Parameter
V
CC
T
A
= -55C to +125C
Units
(V)
C
L
= 50 pF
(Note 8)
Min
Max
t
PLH
Propagation Delay
3.3
1.0
15.0
ns
A
n
or B
n
to O
A = B
5.0
1.0
11.0
t
PHL
Propagation Delay
3.3
1.0
10.5
ns
A
n
or B
n
to O
A = B
5.0
1.0
8.0
t
PLH
Propagation Delay
3.3
1.0
15.0
ns
I
A = B
to O
A = B
5.0
1.0
11.0
t
PHL
Propagation Delay
3.3
1.0
10.5
ns
I
A = B
to O
A = B
5.0
1.0
8.0
Note 8: Voltage Range 3.3 is 3.3V
0.3V
Voltage Range 5.0 is 5.0V
0.5V
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AC Electrical Characteristics for ACT
Symbol
Parameter
V
CC
T
A
= -55C to +125C
Units
(V)
C
L
= 50 pF
(Note 9)
Min
Max
t
PLH
Propagation Delay
5.0
1.5
11.0
ns
A
n
or B
n
to O
A = B
t
PHL
Propagation Delay
5.0
1.5
12.0
ns
A
n
or B
n
to O
A = B
t
PLH
Propagation Delay
5.0
1.5
7.5
ns
I
A = B
to O
A = B
t
PHL
Propagation Delay
5.0
1.5
8.5
ns
I
A = B
to O
A = B
Note 9: Voltage Range 5.0 is 5.0V
0.5V
Capacitance
Symbol
Parameter
Typ
Units
Conditions
C
IN
Input Capacitance
4.5
pF
V
CC
= OPEN
C
PD
Power Dissipation Capacitance
40
pF
V
CC
= 5.0V
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