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54LS85 DM54LS85 DM74LS85 4-Bit Magnitude Comparators
June 1989
54LS85 DM54LS85 DM74LS85
4-Bit Magnitude Comparators
General Description
These 4-bit magnitude comparators perform comparison of
straight binary or BCD codes Three fully-decoded decisions
about two 4-bit words (A B) are made and are externally
available at three outputs These devices are fully expand-
able to any number of bits without external gates Words of
greater length may be compared by connecting compara-
tors in cascade The A
l
B A
k
B and A
e
B outputs of a
stage handling less-significant bits are connected to the cor-
responding inputs of the next stage handling more-signifi-
cant bits The stage handling the least-significant bits must
have a high-level voltage applied to the A
e
B input The
cascading path is implemented with only a two-gate-level
delay to reduce overall comparison times for long words
Features
Y
Y
Y
Typical power dissipation 52 mW
Typical delay (4-bit words) 24 ns
Alternate Military Aerospace device (54LS85) is avail-
able Contact a National Semiconductor Sales Office
Distributor for specifications
Connection Diagram
Dual-In-Line Package
Order Number 54LS85DMQB
54LS85FMQB 54LS85LMQB
DM54LS85J DM54LS85W
DM74LS85M or DM74LS85N
See NS Package Number E20A
J16A M16A N16E or W16A
TL F 6379 – 1
Function Table
Comparing
Inputs
A3 B3
A3
l
B3
A3
k
B3
A3
e
B3
A3
e
B3
A3
e
B3
A3
e
B3
A3
e
B3
A3
e
B3
A3
e
B3
A3
e
B3
A3
e
B3
A3
e
B3
A3
e
B3
A3
e
B3
A2 B2
X
X
A2
l
B2
A2
k
B2
A2
e
B2
A2
e
B2
A2
e
B2
A2
e
B2
A2
e
B2
A2
e
B2
A2
e
B2
A2
e
B2
A2
e
B2
A2
e
B2
A1 B1
X
X
X
X
A1
l
B1
A1
k
B1
A1
e
B1
A1
e
B1
A1
e
B1
A1
e
B1
A1
e
B1
A1
e
B1
A1
e
B1
A1
e
B1
A0 B0
X
X
X
X
X
X
A0
l
B0
A0
k
B0
A0
e
B0
A0
e
B0
A0
e
B0
A0
e
B0
A0
e
B0
A0
e
B0
A
l
B
X
X
X
X
X
X
X
X
H
L
L
X
H
L
Cascading
Inputs
A
k
B
X
X
X
X
X
X
X
X
L
H
L
X
H
L
A
e
B
X
X
X
X
X
X
X
X
L
L
H
H
L
L
A
l
B
H
L
H
L
H
L
H
L
H
L
L
L
L
H
Outputs
A
k
B
L
H
L
H
L
H
L
H
L
H
L
L
L
H
A
e
B
L
L
L
L
L
L
L
L
L
L
H
H
L
L
H
e
High Level L
e
Low Level X
e
Don’t Care
C
1995 National Semiconductor Corporation
TL F 6379
RRD-B30M105 Printed in U S A
Absolute Maximum Ratings
(Note)
If Military Aerospace specified devices are required
please contact the National Semiconductor Sales
Office Distributors for availability and specifications
Supply Voltage
Input Voltage
7V
7V
Note
The ‘‘Absolute Maximum Ratings’’ are those values
beyond which the safety of the device cannot be guaran-
teed The device should not be operated at these limits The
parametric values defined in the ‘‘Electrical Characteristics’’
table are not guaranteed at the absolute maximum ratings
The ‘‘Recommended Operating Conditions’’ table will define
the conditions for actual device operation
Operating Free Air Temperature Range
b
55 C to
a
125 C
DM54LS and 54LS
DM74LS
0 C to
a
70 C
Storage Temperature Range
b
65 C to
a
150 C
Recommended Operating Conditions
Symbol
V
CC
V
IH
V
IL
I
OH
I
OL
T
A
Parameter
Min
Supply Voltage
High Level Input Voltage
Low Level Input Voltage
High Level Output Current
Low Level Output Current
Free Air Operating Temperature
b
55
DM54LS85
Nom
5
Max
55
Min
4 75
2
07
b
0 4
DM74LS85
Nom
5
Max
5 25
Units
V
V
08
b
0 4
45
2
V
mA
mA
C
4
125
0
8
70
Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol
V
I
V
OH
Parameter
Input Clamp Voltage
High Level Output
Voltage
Low Level Output
Voltage
Conditions
V
CC
e
Min I
I
e b
18 mA
V
CC
e
Min I
OH
e
Max
V
IL
e
Max V
IH
e
Min
V
CC
e
Min I
OL
e
Max
V
IL
e
Max V
IH
e
Min
I
OL
e
4 mA V
CC
e
Min
I
I
Input Current
Input Voltage
Max
V
CC
e
Max
V
I
e
7V
DM54
DM74
DM54
DM74
DM74
A
k
B
A
l
B
Others
I
IH
High Level Input
Current
V
CC
e
Max
V
I
e
2 7V
A
k
B
A
l
B
Others
I
IL
Low Level Input
Current
V
CC
e
Max
V
I
e
0 4V
A
k
B
A
l
B
Others
I
OS
Short Circuit
Output Current
Supply Current
V
CC
e
Max
(Note 2)
V
CC
e
Max (Note 3)
DM54
DM74
b
20
b
20
Min
Typ
(Note 1)
Max
b
1 5
Units
V
V
25
27
34
34
0 25
0 35
0 25
04
05
04
01
01
03
20
20
60
b
0 4
b
0 4
b
1 2
b
100
b
100
V
OL
V
mA
mA
mA
mA
mA
I
CC
10
20
Note 1
All typicals are at V
CC
e
5V T
A
e
25 C
Note 2
Not more than one output should be shorted at a time and the duration should not exceed one second
Note 3
I
CC
is measured with all outputs open A
e
B grounded and all other inputs at 4 5V
2
Switching Characteristics
at V
CC
e
5V and T
A
e
25 C (See Section 1 for Test Waveforms and Output Load)
Symbol
Parameter
From
Input
To
Output
Number of
Gate Levels
R
L
e
2 kX
C
L
e
15 pF
Min
t
PLH
Propagation Delay Time
Low-to-High Level Output
Any A or B
Data Input
A
k
B
A
l
B
A
e
B
t
PHL
Propagation Delay Time
High-to-Low Level Output
Any A or B
Data Input
A
k
B
A
l
B
A
e
B
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
Propagation Delay Time
Low-to-High Level Output
Propagation Delay Time
High-to-Low Level Output
Propagation Delay Time
Low-to-High Level Output
Propagation Delay Time
High-to-Low Level Output
Propagation Delay Time
Low-to-High Level Output
Propagation Delay Time
High-to-Low Level Output
A
k
B
or A
e
B
A
k
B
or A
e
B
A
e
B
A
e
B
A
l
B
or A
e
B
A
l
B
or A
e
B
A
l
B
A
l
B
A
e
B
A
e
B
A
k
B
A
k
B
3
4
3
4
1
1
2
2
1
1
Max
36
40
30
30
22
17
20
17
22
17
C
L
e
50 pF
Min
Max
42
40
40
40
26
26
25
26
26
26
ns
ns
ns
ns
ns
ns
ns
ns
Units
3
Logic Diagram
TL F 6379 – 2
4
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