2000 Fairchild Semiconductor Corporation
DS006379
www.fairchildsemi.com
August 1986
Revised March 2000
DM74LS85 4-
B
i
t
Magni
tude Com
p
a
r
at
or
DM74LS85
4-Bit Magnitude Comparator
General Description
These 4-bit magnitude comparators perform comparison of
straight binary or BCD codes. Three fully-decoded deci-
sions about two, 4-bit words (A, B) are made and are exter-
nally available at three outputs. These devices are fully
expandable to any number of bits without external gates.
Words of greater length may be compared by connecting
comparators in cascade. The A
>
B, A
<
B, and A
=
B out-
puts of a stage handling less-significant bits are connected
to the corresponding inputs of the next stage handling
more-significant bits. The stage handling the least-
significant bits must have a high-level voltage applied to
the A
=
B input. The cascading path is implemented with
only a two-gate-level delay to reduce overall comparison
times for long words.
Features
s
Typical power dissipation 52 mW
s
Typical delay (4-bit words) 24 ns
Ordering Code:
Devices also available in Tape and Reel. Specify by appending the suffix letter "X" to the ordering code.
Connection Diagram
Order Number
Package Number
Package Description
DM74LS85M
M16A
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
DM74LS85N
N16E
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
3
www.fairchildsemi.com
DM74LS85
Absolute Maximum Ratings
(Note 1)
Note 1: The "Absolute Maximum Ratings" are those values beyond which
the safety of the device cannot be guaranteed. The device should not be
operated at these limits. The parametric values defined in the Electrical
Characteristics tables are not guaranteed at the absolute maximum ratings.
The "Recommended Operating Conditions" table will define the conditions
for actual device operation.
Recommended Operating Conditions
Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Note 2: All typicals are at V
CC
=
5V, T
A
=
25
C.
Note 3: Not more than one output should be shorted at a time, and the duration should not exceed one second.
Note 4: I
CC
is measured with all outputs OPEN, A
=
B grounded and all other inputs at 4.5V.
Supply Voltage
7V
Input Voltage
7V
Operating Free Air Temperature Range
0
C to
+
70
C
Storage Temperature Range
-
65
C to
+
150
C
Symbol
Parameter
Min
Nom
Max
Units
V
CC
Supply Voltage
4.75
5
5.25
V
V
IH
HIGH Level Input Voltage
2
V
V
IL
LOW Level Input Voltage
0.8
V
I
OH
HIGH Level Output Current
-
0.4
mA
I
OL
LOW Level Output Current
8
mA
T
A
Free Air Operating Temperature
0
70
C
Symbol
Parameter
Conditions
Min
Typ
Max
Units
(Note 2)
V
I
Input Clamp Voltage
V
CC
=
Min, I
I
=
-
18 mA
-
1.5
V
V
OH
HIGH Level
V
CC
=
Min, I
OH
=
Max
2.7
3.4
V
Output Voltage
V
IL
=
Max, V
IH
=
Min
V
OL
LOW
Level V
CC
=
Min, I
OL
=
Max
0.35
0.5
Output Voltage
V
IL
=
Max, V
IH
=
Min
V
I
OL
=
4 mA, V
CC
=
Min
0.25
0.4
I
I
Input Current @ Max
V
CC
=
Max
A
<
B
0.1
Input Voltage
V
I
=
7V
A
>
B
0.1
mA
Others
0.3
I
IH
HIGH Level
V
CC
=
Max
A
<
B
20
Input Current
V
I
=
2.7V
A
>
B
20
A
Others
60
I
IL
LOW
Level V
CC
=
Max
A
<
B
-
0.4
Input Current
V
I
=
0.4V
A
>
B
-
0.4
mA
Others
-
1.2
I
OS
Short Circuit Output Current
V
CC
=
Max (Note 3)
-
20
-
100
mA
I
CC
Supply Current
V
CC
=
Max (Note 4)
10
20
mA
5
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DM74LS85
Physical Dimensions
inches (millimeters) unless otherwise noted
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
Package Number M16A
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