7485 Comparators Datasheet

7485 Datasheet PDF, Equivalent


Part Number

7485

Description

4-Bit Magnitude Comparators

Manufacture

National Semiconductor

Total Page 8 Pages
PDF Download
Download 7485 Datasheet PDF


7485
June 1989
54LS85 DM54LS85 DM74LS85
4-Bit Magnitude Comparators
General Description
www.DataSheet4U.com
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 Typical power dissipation 52 mW
Y Typical delay (4-bit words) 24 ns
Y 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
Function Table
Comparing
Inputs
A3 B3
A2 B2
A1 B1
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
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
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
H e High Level L e Low Level X e Don’t Care
C1995 National Semiconductor Corporation TL F 6379
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
TL F 6379 – 1
Cascading
Inputs
AlB AkB AeB
XXX
XXX
XXX
XXX
XXX
XXX
XXX
XXX
HL L
LHL
LLH
XXH
HH L
LLL
Outputs
AlB
H
L
H
L
H
L
H
L
H
L
L
L
L
H
AkB
L
H
L
H
L
H
L
H
L
H
L
L
L
H
AeB
L
L
L
L
L
L
L
L
L
L
H
H
L
L
RRD-B30M105 Printed in U S A

7485
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
7V
Input Voltage
7V
Operating Free Air Temperature Range
DM54LS and 54LS
b55 C to a125 C
DM74LS
0 C to a70 C
Storage Temperature Range
b65 C to a150 C
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
Recommended Operating Conditions
Symbol
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VCC
VIH
VIL
IOH
IOL
TA
Parameter
Supply Voltage
High Level Input Voltage
Low Level Input Voltage
High Level Output Current
Low Level Output Current
Free Air Operating Temperature
Min
45
2
b55
DM54LS85
Nom
5
Max
55
07
b0 4
4
125
Min
4 75
2
0
DM74LS85
Nom
5
Max
5 25
08
b0 4
8
70
Units
V
V
V
mA
mA
C
Electrical Characteristics over recommended operating free air temperature range (unless otherwise noted)
Symbol
Parameter
Conditions
Min
VI
VOH
Input Clamp Voltage
High Level Output
Voltage
VCC e Min II e b18 mA
VCC e Min IOH e Max
VIL e Max VIH e Min
DM54
DM74
25
27
VOL
Low Level Output
VCC e Min IOL e Max
DM54
Voltage
VIL e Max VIH e Min
DM74
IOL e 4 mA VCC e Min
DM74
II
Input Current Max
VCC e Max
Input Voltage
VI e 7V
AkB
AlB
Others
IIH
High Level Input
VCC e Max
Current
VI e 2 7V
AkB
AlB
Others
IIL
Low Level Input
VCC e Max
Current
VI e 0 4V
AkB
AlB
Others
IOS Short Circuit
Output Current
VCC e Max
(Note 2)
DM54
DM74
b20
b20
ICC Supply Current
VCC e Max (Note 3)
Note 1 All typicals are at VCC e 5V TA 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 ICC is measured with all outputs open A e B grounded and all other inputs at 4 5V
Typ
(Note 1)
34
34
0 25
0 35
0 25
10
Max
b1 5
04
05
04
01
01
03
20
20
60
b0 4
b0 4
b1 2
b100
b100
20
Units
V
V
V
mA
mA
mA
mA
mA
2


Features 54LS85 DM54LS85 DM74LS85 4-Bit Magnitude Comparators June 1989 54LS85 DM54LS8 5 DM74LS85 4-Bit Magnitude Comparators General Description These 4-bit magnitu de comparators perform comparison of st raight binary or BCD codes Three fully- decoded decisions about two 4-bit words (A B) are made and are externally avai lable at three outputs These devices ar e fully expandable to any number of bit s without external gates Words of great er length may be compared by connecting comparators in cascade The A l B A k B and A e B outputs of a www.DataSheet4U .com stage handling less-significant bi ts are connected to the corresponding i nputs of the next stage handling more-s ignificant bits The stage handling the least-significant bits must have a high -level voltage applied to the A e B inp ut The cascading path is implemented wi th only a two-gate-level delay to reduc e overall comparison times for long wor ds Features Y Y Y Typical power dissi pation 52 mW Typical delay (4-bit words) 24 ns Alternate Milita.
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