DM74LS85 [FAIRCHILD]
4-Bit Magnitude Comparator; 4位数值比较器
| 型号： | DM74LS85 |
| 厂家： | 
FAIRCHILD SEMICONDUCTOR |
| 描述： | 4-Bit Magnitude Comparator |
| 文件： | 总6页 (文件大小：62K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
August 1986
Revised March 2000
DM74LS85
4-Bit Magnitude Comparator
General Description
Features
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.
■ Typical power dissipation 52 mW
■ Typical delay (4-bit words) 24 ns
Ordering Code:
Order Number Package Number
Package Description
DM74LS85M
DM74LS85N
M16A
N16E
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.
Connection Diagram
© 2000 Fairchild Semiconductor Corporation
DS006379
www.fairchildsemi.com
Function Table
Comparing
Inputs
Cascading
Outputs
Inputs
A3, B3
A3 > B3
A3 < B3
A2, B2
A1, B1
A0, B0
A > B
X
A < B
X
A = B
X
A > B
H
L
A < B
L
A = B
X
X
X
X
X
X
X
X
X
X
X
X
L
L
L
L
L
L
L
L
L
L
H
H
L
L
X
X
X
H
L
A3 = B3 A2 > B2
A3 = B3 A2 < B2
X
X
X
H
L
X
X
X
H
L
A3 = B3 A2 = B2 A1 > B1
A3 = B3 A2 = B2 A1 < B1
X
X
X
H
L
X
X
X
H
L
A3 = B3 A2 = B2 A1 = B1 A0 > B0
A3 = B3 A2 = B2 A1 = B1 A0 < B0
A3 = B3 A2 = B2 A1 = B1 A0 = B0
A3 = B3 A2 = B2 A1 = B1 A0 = B0
A3 = B3 A2 = B2 A1 = B1 A0 = B0
A3 = B3 A2 = B2 A1 = B1 A0 = B0
A3 = B3 A2 = B2 A1 = B1 A0 = B0
A3 = B3 A2 = B2 A1 = B1 A0 = B0
X
X
X
H
L
X
X
X
H
L
H
L
L
L
H
L
H
L
L
H
L
L
H
H
L
L
X
X
L
L
H
L
H
L
L
L
L
H
H
H = HIGH Level, L = LOW Level, X = Don’t Care
Logic Diagram
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2
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.
Supply Voltage
Input Voltage
7V
7V
Operating Free Air Temperature Range
Storage Temperature Range
0°C to +70°C
−65°C to +150°C
Recommended Operating Conditions
Symbol
Parameter
Min
4.75
2
Nom
Max
Units
V
VCC
VIH
VIL
IOH
IOL
TA
Supply Voltage
5
5.25
HIGH Level Input Voltage
LOW Level Input Voltage
HIGH Level Output Current
LOW Level Output Current
Free Air Operating Temperature
V
0.8
−0.4
8
V
mA
mA
°C
0
70
Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Typ
Symbol
Parameter
Conditions
= Min, I = −18 mA
Min
Max
Units
(Note 2)
V
V
Input Clamp Voltage
HIGH Level
V
V
V
V
V
−1.5
V
V
I
CC
CC
I
= Min, I = Max
OH
OH
2.7
3.4
Output Voltage
LOW Level
= Max, V = Min
IH
IL
V
= Min, I = Max
OL
OL
CC
0.35
0.25
0.5
Output Voltage
= Max, V = Min
V
IL
IH
I
= 4 mA, V = Min
0.4
0.1
OL
CC
I
I
I
Input Current @ Max
Input Voltage
V
V
= Max
A < B
A > B
Others
A < B
A > B
Others
A < B
A > B
Others
I
CC
= 7V
0.1
mA
µA
mA
I
0.3
HIGH Level
V
= Max
20
IH
IL
CC
Input Current
V = 2.7V
20
I
60
LOW Level
V
= Max
−0.4
−0.4
−1.2
−100
20
CC
Input Current
V = 0.4V
I
I
I
Short Circuit Output Current
Supply Current
V
V
= Max (Note 3)
= Max (Note 4)
−20
mA
mA
OS
CC
CC
CC
10
Note 2: All typicals are at V = 5V, T = 25°C.
CC
A
Note 3: Not more than one output should be shorted at a time, and the duration should not exceed one second.
Note 4: I is measured with all outputs OPEN, A = B grounded and all other inputs at 4.5V.
CC
3
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Switching Characteristics
at VCC = 5V and T = 25°C
A
R
= 2 kΩ
From
Input
To
Number of
L
Symbol
Parameter
Output Gate Levels
C
= 15 pF
C
= 50 pF
Units
L
L
Min
Max
36
Min
Max
t
t
Propagation Delay Time
Any A or B
Data Input
A < B,
3
PLH
42
40
40
40
26
LOW-to-HIGH Level Output
A > B
ns
ns
A = B
A < B,
A > B
A = B
4
3
4
1
40
Propagation Delay Time
Any A or B
Data Input
PHL
30
HIGH-to-LOW Level Output
30
t
t
t
t
t
t
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
PLH
PHL
PLH
PHL
PLH
PHL
A < B or A = B
A < B or A = B
A = B
A > B
A > B
A = B
A = B
A < B
A < B
22
ns
ns
ns
ns
ns
ns
1
2
2
1
1
17
20
17
22
17
26
25
26
26
26
A = B
A > B or A = B
A > B or A = B
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4
Physical Dimensions inches (millimeters) unless otherwise noted
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
Package Number M16A
5
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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Package Number N16E
Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and
Fairchild reserves the right at any time without notice to change said circuitry and specifications.
LIFE SUPPORT POLICY
FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD
SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the
body, or (b) support or sustain life, and (c) whose failure
to perform when properly used in accordance with
instructions for use provided in the labeling, can be rea-
sonably expected to result in a significant injury to the
user.
2. A critical component in any component of a life support
device or system whose failure to perform can be rea-
sonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
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6
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