TECHNICAL DATA
IN74HCT138A
1-of-8 Decoder/Demultiplexer
High-Performance Silicon-Gate CMOS
The IN74HCT138A is identical in pinout to the LS/ALS138. The
IN74HCT138A may be used as a level converter for interfacing TTL or
NMOS outputs to High Speed CMOS inputs.
The IN74HCT138A decodes a three-bit Address to one-of-eight
active-lot 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.
•
TTL/NMOS Compatible Input Levels
•
Outputs Directly Interface to CMOS, NMOS, and TTL
•
Operating Voltage Range: 4.5 to 5.5 V
•
Low Input Current: 1.0
µA
ORDERING INFORMATION
IN74HCT138AN Plastic
IN74HCT138AD 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
PIN 16 =V
CC
PIN 8 = GND
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
H = high level (steady state)
L = low level (steady state)
X = don’t care
Rev. 00
IN74HCT138A
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)
Min
4.5
0
-55
0
Max
5.5
V
CC
+125
500
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.
Rev. 00
IN74HCT138A
DC ELECTRICAL CHARACTERISTICS
(Voltages Referenced to GND)
V
CC
Symbol
Parameter
Test Conditions
V
Guaranteed Limit
25
°C
to
-55°C
2.0
2.0
0.8
0.8
4.4
5.4
3.98
0.1
0.1
0.26
±0.1
4.0
≤85
°C
2.0
2.0
0.8
0.8
4.4
5.4
3.84
0.1
0.1
0.33
±1.0
40
≤125
°C
2.0
2.0
0.8
0.8
4.4
5.4
3.7
0.1
0.1
0.4
±1.0
160
µA
µA
V
Unit
V
IH
V
IL
V
OH
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
4.5
5.5
4.5
5.5
4.5
5.5
4.5
4.5
5.5
4.5
5.5
5.5
V
V
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
IN
I
CC
Maximum Input
Leakage Current
Maximum Quiescent
Supply Current
(per Package)
Additional Quiescent
Supply Current
V
IN
=V
CC
or GND
V
IN
=V
CC
or GND
I
OUT
=0µA
V
IN
= 2.4 V, Any One Input
V
IN
=V
CC
or GND, Other
Inputs
I
OUT
=0µA
∆I
CC
≥-55°C
25°C to
125°C
2.4
mA
5.5
2.9
Rev. 00
IN74HCT138A
AC ELECTRICAL CHARACTERISTICS
(V
CC
=5.0 V, C
L
=50pF,Input t
r
=t
f
=6.0 ns)
Guaranteed Limit
Symbol
Parameter
25
°C
to
-55°C
30
27
30
15
10
≤85°C
≤125°C
Unit
t
PLH
, t
PHL
t
PLH
, t
PHL
t
PLH
, t
PHL
t
TLH
, t
THL
C
IN
Maximum Propagation Delay, Input A to
Output Y (Figures 1 and 4)
Maximum Propagation Delay , CS1 to
Output Y (Figures 2 and 4)
Maximum Output Transition Time , 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 Enabled
Output)
38
34
38
19
10
45
41
45
22
10
ns
ns
ns
ns
pF
Typical @25°C,V
CC
=5.0 V
51
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
Rev. 00
IN74HCT138A
Figure 3. Switching Waveforms
Figure 4. Test Circuit
EXPANDED LOGIC DIAGRAM
Rev. 00
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