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DM74LS85N

P1-P3P4-P6
© 2000 Fairchild Semiconductor Corporation DS006379 www.fairchildsemi.com
August 1986
Revised March 2000
DM74LS85 4-Bit Magnitude Comparator
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
■ Typical power dissipation 52 mW
■ 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
www.fairchildsemi.com 2
DM74LS85
Function Table
H = HIGH Level, L = LOW Level, X = Don’t Care
Logic Diagram
Comparing Cascading Outputs
Inputs Inputs
A3, B3 A2, B2 A1, B1 A0, B0 A > BA < BA = BA > BA < BA = B
A3 > B3X X X XXXHLL
A3 < B3X X X XXXLHL
A3 = B3 A2 > B2X X XXXHLL
A3 = B3 A2 < B2X X XXXLHL
A3 = B3 A2 = B2 A1 > B1X XXXHLL
A3 = B3 A2 = B2 A1 < B1X XXXLHL
A3 = B3 A2 = B2 A1 = B1 A0 > B0XXXHLL
A3 = B3 A2 = B2 A1 = B1 A0 < B0XXXLHL
A3 = B3 A2 = B2 A1 = B1 A0 = B0 H L L H L L
A3 = B3 A2 = B2 A1 = B1 A0 = B0 L H L L H L
A3 = B3 A2 = B2 A1 = B1 A0 = B0 L L H L L H
A3 = B3 A2 = B2 A1 = B1 A0 = B0 X X H L L H
A3 = B3 A2 = B2 A1 = B1 A0 = B0HHLLLL
A3 = B3 A2 = B2 A1 = B1 A0 = B0LLLHHL
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 < B20
Input Current V
I
= 2.7V A > B20µA
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
P1-P3P4-P6

DM74LS85N

Mfr. #:
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Manufacturer:
ON Semiconductor / Fairchild
Description:
Logic Comparators 4-Bit Magnitude Comp
Lifecycle:
New from this manufacturer.
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