CD54AC138, CD74AC138
3-LINE TO 8-LINE DECODERS/DEMULTIPLEXERS
SCHS328A JANUARY 2003 REVISED FEBRUARY 2003
1
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
D
AC Types Feature 1.5-V to 5.5-V Operation
and Balanced Noise Immunity at 30% of the
Supply Voltage
D
Speed of Bipolar F, AS, and S, With
Significantly Reduced Power Consumption
D
Designed Specifically for High-Speed
Memory Decoders and Data-Transmission
Systems
D
Incorporate Three Enable Inputs to Simplify
Cascading and/or Data Reception
D
Balanced Propagation Delays
D
24-mA Output Drive Current
Fanout to 15 F Devices
D
SCR-Latchup-Resistant CMOS Process and
Circuit Design
D
Exceeds 2-kV ESD Protection Per
MIL-STD-883, Method 3015
description/ordering information
The 'AC138 decoders/demultiplexers are designed for high-performance memory-decoding and data-routing
applications that require very short propagation-delay times. In high-performance memory systems, these
decoders can be used to minimize the effects of system decoding. When employed with high-speed memories
utilizing a fast enable circuit, the delay times of these decoders and the enable time of the memory usually are
less than the typical access time of the memory. This means that the effective system delay introduced by the
decoders is negligible.
The conditions at the binary-select inputs and the three enable inputs select one of eight output lines. Two
active-low and one active-high enable inputs reduce the need for external gates or inverters when expanding.
A 24-line decoder can be implemented without external inverters, and a 32-line decoder requires only one
inverter. An enable input can be used as a data input for demultiplexing applications (see Application
Information).
ORDERING INFORMATION
TA
PACKAGE
ORDERABLE
PART NUMBER
TOP-SIDE
MARKING
PDIP E
Tube
CD74AC138E
CD74AC138E
55
C to 125
C
SOIC
M
Tube
CD74AC138M
AC138M
55
C to 125
C
SOIC M
Tape and reel
CD74AC138M96
AC138M
CDIP F
Tube
CD54AC138F3A
CD54AC138F3A
Package drawings, standard packing quantities, thermal data, symbolization, and PCB design guidelines
are available at www.ti.com/sc/package.
On products compliant to MIL-PRF-38535, all parameters are tested
unless otherwise noted. On all other products, production
processing does not necessarily include testing of all parameters.
Copyright
2003, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
A
B
C
G2A
G2B
G1
Y7
GND
V
CC
Y0
Y1
Y2
Y3
Y4
Y5
Y6
CD54AC138 . . . F PACKAGE
CD74AC138 . . . E OR M PACKAGE
(TOP VIEW)
CD54AC138, CD74AC138
3-LINE TO 8-LINE DECODERS/DEMULTIPLEXERS
SCHS328A JANUARY 2003 REVISED FEBRUARY 2003
2
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
FUNCTION TABLE
ENABLE INPUTS
SELECT INPUTS
OUTPUTS
G1
G2A
G2B
C
B
A
Y0
Y1
Y2
Y3
Y4
Y5
Y6
Y7
X
H
X
X
X
X
H
H
H
H
H
H
H
H
X
X
H
X
X
X
H
H
H
H
H
H
H
H
L
X
X
X
X
X
H
H
H
H
H
H
H
H
H
L
L
L
L
L
L
H
H
H
H
H
H
H
H
L
L
L
L
H
H
L
H
H
H
H
H
H
H
L
L
L
H
L
H
H
L
H
H
H
H
H
H
L
L
L
H
H
H
H
H
L
H
H
H
H
H
L
L
H
L
L
H
H
H
H
L
H
H
H
H
L
L
H
L
H
H
H
H
H
H
L
H
H
H
L
L
H
H
L
H
H
H
H
H
H
L
H
H
L
L
H
H
H
H
H
H
H
H
H
H
L
logic diagram (positive logic)
G1
G2B
G2A
C
B
A
Y7
Y6
Y5
Y4
Y3
Y2
Y1
Y0
Data
Outputs
Select
Inputs
Enable
Inputs
1
2
3
4
5
6
15
14
13
12
11
10
9
7
CD54AC138, CD74AC138
3-LINE TO 8-LINE DECODERS/DEMULTIPLEXERS
SCHS328A JANUARY 2003 REVISED FEBRUARY 2003
3
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
Supply voltage range, V
CC
0.5 V to 6 V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input clamp current, I
IK
(V
I
< 0 V or V
I
> V
CC
)
(see Note 1)
20 mA
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output clamp current, I
OK
(V
O
< 0 V or V
O
> V
CC
)
(see Note 1)
50 mA
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Continuous output current, I
O
(V
O
> 0 V or V
O
< V
CC
)
50 mA
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Continuous current through V
CC
or GND
100 mA
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Package thermal impedance,
JA
(see Note 2): E package
67
C/W
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
M package
73
C/W
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature range, T
stg
65
C to 150
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
NOTES:
1. The input and output voltage ratings may be exceeded if the input and output current ratings are observed.
2. The package thermal impedance is calculated in accordance with JESD 51-7.
recommended operating conditions (see Note 3)
TA = 25
C
55
C to
125
C
40
C to
85
C
UNIT
MIN
MAX
MIN
MAX
MIN
MAX
VCC
Supply voltage
1.5
5.5
1.5
5.5
1.5
5.5
V
VCC = 1.5 V
1.2
1.2
1.2
VIH
High-level input voltage
VCC = 3 V
2.1
2.1
2.1
V
VCC = 5.5 V
3.85
3.85
3.85
VCC = 1.5 V
0.3
0.3
0.3
VIL
Low-level input voltage
VCC = 3 V
0.9
0.9
0.9
V
VCC = 5.5 V
1.65
1.65
1.65
VI
Input voltage
0
VCC
0
VCC
0
VCC
V
VO
Output voltage
0
VCC
0
VCC
0
VCC
V
IOH
High-level output current
VCC = 4.5 V to 5.5 V
24
24
24
mA
IOL
Low-level output current
VCC = 4.5 V to 5.5 V
24
24
24
mA
t/
v
Input transition rise or fall rate
VCC = 1.5 V to 3 V
50
50
50
ns/V
t/
v
Input transition rise or fall rate
VCC = 3.6 V to 5.5 V
20
20
20
ns/V
NOTE 3: All unused inputs of the device must be held at VCC or GND to ensure proper device operation. Refer to the TI application report,
Implications of Slow or Floating CMOS Inputs, literature number SCBA004.
CD54AC138, CD74AC138
3-LINE TO 8-LINE DECODERS/DEMULTIPLEXERS
SCHS328A JANUARY 2003 REVISED FEBRUARY 2003
4
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
VCC
TA = 25
C
55
C to
125
C
40
C to
85
C
UNIT
CC
MIN
MAX
MIN
MAX
MIN
MAX
1.5 V
1.4
1.4
1.4
IOH = 50
A
3 V
2.9
2.9
2.9
4.5 V
4.4
4.4
4.4
VOH
VI = VIH or VIL
IOH = 4 mA
3 V
2.58
2.4
2.48
V
IOH = 24 mA
4.5 V
3.94
3.7
3.8
IOH = 50 mA
5.5 V
3.85
IOH = 75 mA
5.5 V
3.85
1.5 V
0.1
0.1
0.1
IOL = 50
A
3 V
0.1
0.1
0.1
4.5 V
0.1
0.1
0.1
VOL
VI = VIH or VIL
IOL = 12 mA
3 V
0.36
0.5
0.44
V
IOL = 24 mA
4.5 V
0.36
0.5
0.44
IOL = 50 mA
5.5 V
1.65
IOL = 75 mA
5.5 V
1.65
II
VI = VCC or GND
5.5 V
0.1
1
1
A
ICC
VI = VCC or GND,
IO = 0
5.5 V
8
160
80
A
Ci
10
10
10
pF
Test one output at a time, not exceeding 1-second duration. Measurement is made by forcing indicated current and measuring voltage to minimize
power dissipation. Test verifies a minimum 50-
transmission-line drive capability at 85
C and 75-
transmission-line drive capability at 125
C.
switching characteristics over recommended operating free-air temperature range,
V
CC
= 1.5 V, C
L
= 50 pF (unless otherwise noted) (see Figure 1)
PARAMETER
FROM
(INPUT)
TO
(OUTPUT)
55
C to
125
C
40
C to
85
C
UNIT
(INPUT)
(OUTPUT)
MIN
MAX
MIN
MAX
tPLH
A B C
Any Y
138
125
ns
tPHL
A, B, C
Any Y
138
125
ns
tPLH
G1
Any Y
138
125
ns
tPHL
G1
Any Y
138
125
ns
tPLH
G2A G2B
Any Y
125
114
ns
tPHL
G2A, G2B
Any Y
125
114
ns
CD54AC138, CD74AC138
3-LINE TO 8-LINE DECODERS/DEMULTIPLEXERS
SCHS328A JANUARY 2003 REVISED FEBRUARY 2003
5
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
switching characteristics over recommended operating free-air temperature range,
V
CC
= 3.3 V
0.3 V, C
L
= 50 pF (unless otherwise noted) (see Figure 1)
PARAMETER
FROM
(INPUT)
TO
(OUTPUT)
55
C to
125
C
40
C to
85
C
UNIT
(INPUT)
(OUTPUT)
MIN
MAX
MIN
MAX
tPLH
A B C
Any Y
3.9
15.4
4
14
ns
tPHL
A, B, C
Any Y
3.9
15.4
4
14
ns
tPLH
G1
Any Y
3.9
15.4
4
14
ns
tPHL
G1
Any Y
3.9
15.4
4
14
ns
tPLH
G2A G2B
Any Y
3.5
14
3.6
12.7
ns
tPHL
G2A, G2B
Any Y
3.5
14
3.6
12.7
ns
switching characteristics over recommended operating free-air temperature range,
V
CC
= 5 V
0.5 V, C
L
= 50 pF (unless otherwise noted) (see Figure 1)
PARAMETER
FROM
(INPUT)
TO
(OUTPUT)
55
C to
125
C
40
C to
85
C
UNIT
(INPUT)
(OUTPUT)
MIN
MAX
MIN
MAX
tPLH
A B C
Any Y
2.8
11
2.8
10
ns
tPHL
A, B, C
Any Y
2.8
11
2.8
10
ns
tPLH
G1
Any Y
2.8
11
2.8
10
ns
tPHL
G1
Any Y
2.8
11
2.8
10
ns
tPLH
G2A G2B
Any Y
2.5
10
2.6
9.1
ns
tPHL
G2A, G2B
Any Y
2.5
10
2.6
9.1
ns
operating characteristics, V
CC
= 5 V, T
A
= 25
C
PARAMETER
TYP
UNIT
Cpd
Power dissipation capacitance
110
pF
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