February 1984
Revised February 1999
MM74HCT138
3-t
o
-8
Li
ne Deco
der
© 1999 Fairchild Semiconductor Corporation
DS005362.prf
www.fairchildsemi.com
MM74HCT138
3-to-8 Line Decoder
General Description
The MM74HCT138 decoder utilizes advanced silicon-gate
CMOS technology, and are well suited to memory address
decoding or data routing applications. Both circuits feature
high noise immunity and low power consumption usually
associated with CMOS circuitry, yet have speeds compara-
ble to low power Schottky TTL logic.
The MM74HCT138 have 3 binary select inputs (A, B, and
C). If the device is enabled these inputs determine which
one of the eight normally HIGH outputs will go LOW. Two
active LOW and one active HIGH enables (G1, G2A and
G2B) are provided to ease the cascading decoders.
The decoders' output can drive 10 low power Schottky TTL
equivalent loads and are functionally and pin equivalent to
the 74LS138. All inputs are protected from damage due to
static discharge by diodes to V
CC
and ground.
MM74HCT devices are intended to interface between TTL
and NMOS components and standard CMOS devices.
These parts are also plug-in replacements for LS-TTL
devices and can be used to reduce power consumption in
existing designs.
Features
s
TTL input compatible
s
Typical propagation delay: 20 ns
s
Low quiescent current: 80
µ
A maximum (74HCT Series)
s
Low input current: 1
µ
A maximum
s
Fanout of 10 LS-TTL loads
Ordering Code:
Devices also available in Tape and Reel. Specify by appending the suffix letter "X" to the ordering code.
Connection Diagram
Pin Assignments for DIP, SOIC, SOP and TSSOP
Order Number
Package Number
Package Description
MM74HCT138M
M16A
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150" Narrow
MM74HCT138SJ
M16D
16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
MM74HCT138MTC
MTC16
16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
MM74HCT138N
N16E
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide
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2
MM
74HCT138
Truth Table
H
=
HIGH Level
L
=
LOW Level
X
=
Don't Care
Note 1: G2
=
G2A
+
G2B
Logic Diagram
Inputs
Outputs
Enable
Select
G1
G2
(Note 1)
C
B
A
Y0
Y1
Y2
Y3
Y4
Y5
Y6
Y7
X
H
X
X
X
H
H
H
H
H
H
H
H
L
X
X
X
X
H
H
H
H
H
H
H
H
H
L
L
L
L
L
H
H
H
H
H
H
H
H
L
L
L
H
H
L
H
H
H
H
H
H
H
L
L
H
L
H
H
L
H
H
H
H
H
H
L
L
H
H
H
H
H
L
H
H
H
H
H
L
H
L
L
H
H
H
H
L
H
H
H
H
L
H
L
H
H
H
H
H
H
L
H
H
H
L
H
H
L
H
H
H
H
H
H
L
H
H
L
H
H
H
H
H
H
H
H
H
H
L
3
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MM74HCT138
Absolute Maximum Ratings
(Note 2)
(Note 3)
Recommended Operating
Conditions
Note 2: Absolute Maximum Ratings are those values beyond which dam-
age to the device may occur.
Note 3: Unless otherwise specified all voltages are referenced to ground.
Note 4: Power Dissipation temperature derating -- plastic "N" package:
-
12 mW/
°
C from 65
°
C to 85
°
C.
DC Electrical Characteristics
V
CC
=
5V
±
10% (unless otherwise specified)
Note 5: This is measured per input pin. All other inputs are held at V
CC
or ground.
Supply Voltage (V
CC
)
-
0.5 to
+
7.0V
DC Input Voltage (V
IN
)
-
1.5 to V
CC
+
1.5V
DC Output Voltage (V
OUT
)
-
0.5 to V
CC
+
0.5V
Clamp Diode Current (I
IK
, I
OK
)
±
20 mA
DC Output Current, per pin (I
OUT
)
±
25 mA
DC V
CC
or GND Current, per pin (I
CC
)
±
50 mA
Storage Temperature Range (T
STG
)
-
65
°
C to
+
150
°
C
Power Dissipation (P
D
)
(Note 4)
600 mW
S.O. Package only
500 mW
Lead Temperature (T
L
)
(Soldering 10 seconds)
260
°
C
Min
Max
Units
Supply Voltage (V
CC
)
4.5
5.5
V
DC Input or Output Voltage
(V
IN
, V
OUT
)
0
V
CC
V
Operating Temperature Range (T
A
)
-
40
+
85
°
C
Input Rise or Fall Times
(t
r
, t
f
)
500
ns
Symbol
Parameter
Conditions
T
A
=
25
°
C
T
A
=
-
40 to 85
°
C T
A
=
-
55 to 125
°
C
Units
Typ
Guaranteed Limits
V
IH
Minimum HIGH Level
2.0
2.0
2.0
V
Input Voltage
V
IL
Maximum LOW Level
0.8
0.8
0.8
V
Input Voltage
V
OH
Minimum HIGH Level
V
IN
=
V
IH
or V
IL
Output Voltage
|I
OUT
|
=
20
µ
A
V
CC
V
CC
-
0.1
V
CC
-
0.1
V
CC
-
0.1
V
|I
OUT
|
=
4.0 mA, V
CC
=
4.5V
4.2
3.98
3.84
3.7
V
|I
OUT
|
=
4.8 mA, V
CC
=
5.5V
5.2
4.98
4.84
4.7
V
V
OL
Maximum LOW Level
V
IN
=
V
IH
or V
IL
Voltage
|I
OUT
|
=
20
µ
A
0
0.1
0.1
0.1
V
|I
OUT
|
=
4.0 mA, V
CC
=
4.5V
0.2
0.26
0.33
0.4
V
|I
OUT
|
=
4.8 mA, V
CC
=
5.5V
0.2
0.26
0.33
0.4
V
I
IN
Maximum Input
V
IN
=
V
CC
or GND,
±
0.1
±
1.0
±
1.0
µ
A
Current
V
IH
or V
IL
I
CC
Maximum Quiescent
V
IN
=
V
CC
or GND
8.0
80
160
µ
A
Supply Current
I
OUT
=
0
µ
A
V
IN
=
2.4V or 0.5V (Note 5)
0.3
0.4
0.5
mA
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4
MM
74HCT138
AC Electrical Characteristics
T
A
=
25
°
C, V
CC
=
5.0V, t
r
=
t
f
=
6 ns, C
L
=
15 pF (unless otherwise specified)
AC Electrical Characteristics
V
CC
=
5V
±
10%, C
L
=
50 pF, t
r
=
t
f
=
6 ns (unless otherwise specified)
Note 6: C
PD
determines the no load dynamic power consumption, P
D
=
C
PD
V
CC
2
f
+
I
CC
V
CC
, and the no load dynamic current consumption,
I
S
=
C
PD
V
CC
f
+
I
CC
.
Symbol
Parameter
Conditions
Typ
Guaranteed
Units
Limit
t
PHL
Maximum Propagation Delay, A, B, or C to Output
20
35
ns
t
PLH
Maximum Propagation Delay, A, B, or C to Output
13
25
ns
t
PHL
Maximum Propagation Delay, G1 to Y Output
14
25
ns
t
PLH
Maximum Propagation Delay, G1 to Y Output
13
25
ns
t
PHL
Maximum Propagation Delay, G2A or G2B to Y Output
17
30
ns
t
PLH
Maximum Propagation Delay, G2A or G2B to Y Output
13
25
ns
Symbol
Parameter
Conditions
T
A
=
25
°
C
T
A
=
-
40 to 85
°
C T
A
=
-
55 to 125
°
C
Units
Typ
Guaranteed Limits
t
PHL
Maximum Propagation Delay
24
40
50
60
ns
A, B, or C to Output
t
PLH
Maximum Propagation Delay
18
30
38
45
ns
A, B, or C to Output
t
PHL
Maximum Propagation Delay
17
30
38
45
ns
G1 to Y Output
t
PLH
Maximum Propagation Delay
20
30
38
45
ns
G1 to Y Output
t
PHL
Maximum Propagation Delay
23
35
43
52
ns
G2A or G2B to Y Output
t
PLH
Maximum Propagation Delay
18
30
38
45
ns
G2A or G2B to Y Output
t
THL
, t
TLH
Maximum Output
15
19
22
ns
Rise and Fall Time
C
IN
Input Capacitance
5
10
10
pF
C
PD
Power Dissipation
55
pF
Capacitance
(Note 6)
5
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MM74HCT138
Physical Dimensions
inches (millimeters) unless otherwise noted
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150" Narrow
Package Number M16A
16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
Package Number M16D
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