TECHNICAL DATA
IN74HC138A
1-of-8 Decoder/Demultiplexer
High-Performance Silicon-Gate CMOS
The IN74HC138A is identical in pinout to the LS/ALS138. The
device inputs are compatible with standard CMOS outputs; with pullup
resistors, they are compatible with LS/ALSTTL outputs.
The IN74HC138A decodes a three-bit Address to one-of-eight
active-low outputs. This device features three Chip Select inputs, two
active-low and one active-high to facilitate the demultiplexing,
cascading, and chip-selecting functions. The demultiplexing function is
accomplished by using the Address inputs to select the desired device
output; one of the Chip Selects is used as a data input while the other
Chip Selects are held in their active states.
•
Outputs Directly Interface to CMOS, NMOS, and TTL
•
Operating Voltage Range: 2.0 to 6.0 V
•
Low Input Current: 1.0
µA
•
High Noise Immunity Characteristic of CMOS Devices
ORDERING INFORMATION
IN74HC138AN Plastic
IN74HC138AD SOIC
T
A
= -55° to 125° C for all packages
PIN ASSIGNMENT
LOGIC DIAGRAM
FUNCTION TABLE
Inputs
CS1 CS2 CS3
X X H
X H X
L X X
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
A2 A1 A0
X X X
X X X
X X X
L
L
L
L
H
H
H
H
L
L
H
H
L
L
H
H
L
H
L
H
L
H
L
H
Outputs
Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7
H H H H H H H H
H H H H H H H H
H H H H H H H H
L
H
H
H
H
H
H
H
H
L
H
H
H
H
H
H
H
H
L
H
H
H
H
H
H
H
H
L
H
H
H
H
H
H
H
H
L
H
H
H
H
H
H
H
H
L
H
H
H
H
H
H
H
H
L
H
H
H
H
H
H
H
H
L
PIN 16 =V
CC
PIN 8 = GND
H = high level (steady state)
L = low level (steady state)
X = don’t care
141
IN74HC138A
MAXIMUM RATINGS
*
Symbol
V
CC
V
IN
V
OUT
I
IN
I
OUT
I
CC
P
D
Tstg
T
L
*
Parameter
DC Supply Voltage (Referenced to GND)
DC Input Voltage (Referenced to GND)
DC Output Voltage (Referenced to GND)
DC Input Current, per Pin
DC Output Current, per Pin
DC Supply Current, V
CC
and GND Pins
Power Dissipation in Still Air, Plastic DIP+
SOIC Package+
Storage Temperature
Lead Temperature, 1 mm from Case for 10 Seconds
(Plastic DIP or SOIC Package)
Value
-0.5 to +7.0
-1.5 to V
CC
+1.5
-0.5 to V
CC
+0.5
±20
±25
±50
750
500
-65 to +150
260
Unit
V
V
V
mA
mA
mA
mW
°C
°C
Maximum Ratings are those values beyond which damage to the device may occur.
Functional operation should be restricted to the Recommended Operating Conditions.
+Derating - Plastic DIP: - 10 mW/°C from 65° to 125°C
SOIC Package: : - 7 mW/°C from 65° to 125°C
RECOMMENDED OPERATING CONDITIONS
Symbol
V
CC
V
IN
, V
OUT
T
A
t
r
, t
f
Parameter
DC Supply Voltage (Referenced to GND)
DC Input Voltage, Output Voltage (Referenced to GND)
Operating Temperature, All Package Types
Input Rise and Fall Time
(Figure 2)
V
CC
=2.0 V
V
CC
=4.5 V
V
CC
=6.0 V
Min
2.0
0
-55
0
0
0
Max
6.0
V
CC
+125
1000
500
400
Unit
V
V
°C
ns
This device contains protection circuitry to guard against damage due to high static voltages or electric
fields. However, precautions must be taken to avoid applications of any voltage higher than maximum rated
voltages to this high-impedance circuit. For proper operation, V
IN
and V
OUT
should be constrained to the range
GND≤(V
IN
or V
OUT
)≤V
CC
.
Unused inputs must always be tied to an appropriate logic voltage level (e.g., either GND or V
CC
).
Unused outputs must be left open.
142
IN74HC138A
DC ELECTRICAL CHARACTERISTICS
(Voltages Referenced to GND)
V
CC
Symbol
Parameter
Test Conditions
V
Guaranteed Limit
25
°C
to
-55°C
1.5
3.15
4.2
0.5
1.35
1.8
1.9
4.4
5.9
3.98
5.48
0.1
0.1
0.1
0.26
0.26
±0.1
4.0
≤85
°C
1.5
3.15
4.2
0.5
1.35
1.8
1.9
4.4
5.9
3.84
5.34
0.1
0.1
0.1
0.33
0.33
±1.0
40
≤125
°C
1.5
3.15
4.2
0.5
1.35
1.8
1.9
4.4
5.9
3.7
5.2
0.1
0.1
0.1
0.4
0.4
±1.0
160
µA
µA
V
Unit
V
IH
Minimum High-Level
Input Voltage
Maximum Low -
Level Input Voltage
Minimum High-Level
Output Voltage
V
OUT
=0.1 V or V
CC
-0.1 V
I
OUT
≤
20
µA
V
OUT
=0.1 V or V
CC
-0.1 V
I
OUT
≤
20
µA
V
IN
=V
IH
or V
IL
I
OUT
≤
20
µA
V
IN
=V
IH
or V
IL
I
OUT
≤
4.0 mA
I
OUT
≤
5.2 mA
2.0
4.5
6.0
2.0
4.5
6.0
2.0
4.5
6.0
4.5
6.0
2.0
4.5
6.0
4.5
6.0
6.0
6.0
V
V
IL
V
V
OH
V
V
OL
Maximum Low-Level
Output Voltage
V
IN
=V
IH
or V
IL
I
OUT
≤
20
µA
V
IN
=V
IH
or V
IL
I
OUT
≤
4.0 mA
I
OUT
≤
5.2 mA
I
IN
I
CC
Maximum Input
Leakage Current
Maximum Quiescent
Supply Current
(per Package)
V
IN
=V
CC
or GND
V
IN
=V
CC
or GND
I
OUT
=0µA
143
IN74HC138A
AC ELECTRICAL CHARACTERISTICS
(C
L
=50pF,Input t
r
=t
f
=6.0 ns)
V
CC
Symbol
Parameter
V
Guaranteed Limit
25
°C
to
-55°C
135
27
23
110
22
19
120
24
20
75
15
13
10
≤85°C
≤125°C
Unit
t
PLH
, t
PHL
Maximum Propagation Delay, Input A to
Output Y (Figures 1 and 4)
Maximum Propagation Delay , CS1 to
Output Y (Figures 2 and 4)
Maximum Propagation Delay , CS2 or CS3 to
Output Y (Figures 3 and 4)
Maximum Output Transition Time, Any Output
(Figures 2 and 4)
Maximum Input Capacitance
Power Dissipation Capacitance (Per Package)
2.0
4.5
6.0
2.0
4.5
6.0
2.0
4.5
6.0
2.0
4.5
6.0
-
170
34
29
140
28
24
150
30
26
95
19
16
10
205
41
35
165
33
28
180
36
31
110
22
19
10
ns
t
PLH
, t
PHL
ns
t
PLH
, t
PHL
ns
t
TLH
, t
THL
ns
C
IN
pF
Typical @25°C,V
CC
=5.0 V
55
pF
C
PD
Used to determine the no-load dynamic power
consumption:
P
D
=C
PD
V
CC2
f+I
CC
V
CC
Figure 1. Switching Waveforms
Figure 2. Switching Waveforms
144
IN74HC138A
Figure 3. Switching Waveforms
Figure 4. Test Circuit
EXPANDED LOGIC DIAGRAM
145
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