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74138 Datasheet Download - Fairchild Semiconductor

Номер произв 74138
Описание Decoder/Demultiplexer
Производители Fairchild Semiconductor
логотип Fairchild Semiconductor логотип 

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74138 Даташит, Описание, Даташиты
August 1986
Revised March 2000
DM74LS138 • DM74LS139
Decoder/Demultiplexer
General Description
These Schottky-clamped circuits are designed to be used
in high-performance memory-decoding or data-routing
applications, requiring very short propagation delay times.
In high-performance memory systems these decoders can
be used to minimize the effects of system decoding. When
used with high-speed memories, the delay times of these
decoders are usually less than the typical access time of
the memory. This means that the effective system delay
introduced by the decoder is negligible.
The DM74LS138 decodes one-of-eight lines, based upon
the conditions at the three binary select inputs and the
three enable inputs. Two active-low and one active-high
enable inputs reduce the need for external gates or invert-
ers when expanding. A 24-line decoder can be imple-
mented with no external inverters, and a 32-line decoder
requires only one inverter. An enable input can be used as
a data input for demultiplexing applications.
The DM74LS139 comprises two separate two-line-to-four-
line decoders in a single package. The active-low enable
input can be used as a data line in demultiplexing applica-
tions.
All of these decoders/demultiplexers feature fully buffered
inputs, presenting only one normalized load to its driving
circuit. All inputs are clamped with high-performance
Schottky diodes to suppress line-ringing and simplify sys-
tem design.
Features
s Designed specifically for high speed:
Memory decoders
Data transmission systems
s DM74LS138 3-to-8-line decoders incorporates 3 enable
inputs to simplify cascading and/or data reception
s DM74LS139 contains two fully independent 2-to-4-line
decoders/demultiplexers
s Schottky clamped for high performance
s Typical propagation delay (3 levels of logic)
DM74LS138 21 ns
DM74LS139 21 ns
s Typical power dissipation
DM74LS138 32 mW
DM74LS139 34 mW
Ordering Code:
Order Number Package Number
Package Description
DM74LS138M
M16A
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
DM74LS138SJ
M16D
16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
DM74LS138N
N16E
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
DM74LS139M
M16A
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
DM74LS139SJ
M16D
16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
DM74LS139N
N16E
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.
© 2000 Fairchild Semiconductor Corporation DS006391
www.fairchildsemi.com







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74138 Даташит, Описание, Даташиты
Connection Diagrams
DM74LS138
DM74LS139
Function Tables
DM74LS138
DM74LS139
Inputs
Enable
Select
Outputs
Inputs
Enable
Select
Outputs
G1 G2 (Note 1) C B A YO Y1 Y2 Y3 Y4 Y5 Y6 Y7
G B A Y0 Y1 Y2
X H XXX H H H H H H H H
H
XX
H
H
H
L X XXX H H H H H H H H
L
LL
L
H
H
H L LLL L H H H H H H H
L
LH
H
L
H
H L LLH H L H H H H H H
L
HL
H
H
L
H L LHL H H L H H H H H
L
HH
H
H
H
H L LHH H H H L H H H H
H L HLL H H H H L H H H
H L H L H H H H H H L H H H = HIGH Level
H
L
HH L H
HHHHH L H
L = LOW Level
X = Don’t Care
H L HHH H H H H H H H L
Note 1: G2 = G2A + G2B
Y3
H
H
H
H
L
Logic Diagrams
DM74LS138
DM74LS139
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74138 Даташит, Описание, Даташиты
Absolute Maximum Ratings(Note 2)
Supply Voltage
7V
Input Voltage
7V
Operating Free Air Temperature Range 0°C to +70°C
Storage Temperature Range
65°C to +150°C
Note 2: 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.
DM74LS138 Recommended Operating Conditions
Symbol
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
4.75
2
0
Nom
5
Max
5.25
0.8
0.4
8
70
Units
V
V
V
mA
mA
°C
DM74LS138 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol
Parameter
Conditions
Min
VI Input Clamp Voltage
VCC = Min, II = −18 mA
VOH HIGH Level Output Voltage
VCC = Min, IOH = Max, VIL = Max, VIH = Min
2.7
VOL LOW Level
VCC = Min, IOL = Max, VIL = Max, VIH = Min
Output Voltage
IOL = 4 mA, VCC = Min
II Input Current @ Max Input Voltage VCC = Max, VI = 7V
IIH HIGH Level Input Current
VCC = Max, VI = 2.7V
IIL LOW Level Input Current
VCC = Max, VI = 0.4V
IOS Short Circuit Output Current VCC = Max (Note 4)
20
ICC Supply Current
VCC = Max (Note 5)
Note 3: All typicals are at VCC = 5V, TA = 25°C.
Note 4: Not more than one output should be shorted at a time, and the duration should not exceed one second.
Note 5: ICC is measured with all outputs enabled and OPEN.
Typ
(Note 3)
3.4
0.35
0.25
6.3
Max
1.5
0.5
0.4
0.1
20
0.36
100
10
Units
V
V
V
mA
µA
mA
mA
mA
DM74LS138 Switching Characteristics
at VCC = 5V and TA = 25°C
From (Input)
Levels
Symbol
Parameter
To (Output)
of Delay
tPLH
Propagation Delay Time
Select to Output
LOW-to-HIGH Level Output
tPHL
Propagation Delay Time
Select to Output
HIGH-to-LOW Level Output
tPLH
Propagation Delay Time
Select to Output
LOW-to-HIGH Level Output
tPHL
Propagation Delay Time
Select to Output
HIGH-to-LOW Level Output
tPLH
Propagation Delay Time
Enable to Output
LOW-to-HIGH Level Output
tPHL
Propagation Delay Time
Enable to Output
HIGH-to-LOW Level Output
tPLH
Propagation Delay Time
Enable to Output
LOW-to-HIGH Level Output
tPHL
Propagation Delay Time
Enable to Output
HIGH-to-LOW Level Output
2
2
3
3
2
2
3
3
RL = 2 k
CL = 15 pF
CL = 50 pF
Min Max Min Max
18 27
27 40
18 27
27 40
18 27
24 40
18 27
28 40
Units
ns
ns
ns
ns
ns
ns
ns
ns
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