SN54HCT138, SN74HCT138
3-LINE TO 8-LINE DECODERS/DEMULTIPLEXERS
SCLS171C – MARCH 1984 – REVISED MA Y 1997
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
D
Inputs Are TTL-Voltage Compatible
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
Package Options Include Plastic
Small-Outline (D), Thin Shrink
Small-Outline (PW), and Ceramic Flat (W)
Packages, Ceramic Chip Carriers (FK), and
Standard Plastic (N) and Ceramic (J)
300-mil DIPs
description
The ’HCT138 are designed for high-performance
memory-decoding or data-routing applications
requiring very short propagation delay times. In
high-performance memory systems, these
decoders can 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 are usually 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 (G
) and one active-high (G) 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.
The SN54HCT138 is characterized for operation over the full military temperature range of –55°C to 125°C. The
SN74HCT138 is characterized for operation from –40°C to 85°C.
3212019
910111213
4
5
6
7
8
18
17
16
15
14
Y1
Y2
NC
Y3
Y4
C
G
2A
NC
G
2B
G1
BANC
Y6
Y5
V
Y0
Y7
GND
NC
SN54HCT138 ...FK PACKAGE
(TOP VIEW)
CC
NC – No internal connection
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
A
B
C
G
2A
G
2B
G1
Y7
GND
V
CC
Y0
Y1
Y2
Y3
Y4
Y5
Y6
SN54HCT138 ...J OR W PACKAGE
SN74HCT138 . . . D, N, OR PW PACKAGE
(TOP VIEW)
Copyright 1997, Texas Instruments Incorporated
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.
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.
SN54HCT138, SN74HCT138
3-LINE TO 8-LINE DECODERS/DEMULTIPLEXERS
SCLS171C – MARCH 1984 – REVISED MA Y 1997
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
FUNCTION TABLE
INPUTS
ENABLE SELECT
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 XHXXXHHHHHHHH
L XXXXXHHHHHHHH
H LLLLLLHHHHHHH
H LLLLHHLHHHHHH
H LLLHLHHLHHHHH
H LLLHHHHHLHHHH
H LLHLLHHHHLHHH
H LLHLHHHHHHLHH
H LLHHLHHHHHHLH
H L L H H H H H H H H H H L
logic symbols (alternatives)
†
1
1
A
Y0
15
0
2
2
B
4
3
C
Y1
14
1
Y2
13
2
Y3
12
3
Y4
11
4
Y5
10
5
Y6
9
6
Y7
7
7
BIN/OCT
6
4
5
G1
G2A
G
2B
&
EN
0
1
A
Y0
15
0
2
B
2
3
C
Y1
14
1
Y2
13
2
Y3
12
3
Y4
11
4
Y5
10
5
Y6
9
6
Y7
7
7
DMUX
6
4
5
G1
G2A
G
2B
&
G
0
7
†
These symbols are in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
Pin numbers shown are for the D, J, N, PW, and W packages.
SN54HCT138, SN74HCT138
3-LINE TO 8-LINE DECODERS/DEMULTIPLEXERS
SCLS171C – MARCH 1984 – REVISED MA Y 1997
3
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
logic diagram (positive logic)
A
Y0
Y1
Y2
Y3
Y4
Y5
Y6
Y7
B
C
G1
G2A
G2B
Pin numbers shown are for the D, J, N, PW, and W packages.
1
2
3
6
4
5
15
14
13
12
11
10
9
7
absolute maximum ratings over operating free-air temperature range
†
Supply voltage range, VCC –0.5 V to 7 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input clamp current, IIK (VI < 0 or VI > VCC) (see Note 1) ±20 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output clamp current, IOK (VO < 0 or VO > VCC) (see Note 1) ±20 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Continuous output current, IO (VO = 0 to VCC) ±25 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Continuous current through V
CC
or GND ±50 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Package thermal impedance, θ
JA
(see Note 2): D package 113°C/W. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
N package 78°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, except for through-hole packages, which use a trace
length of zero.
SN54HCT138, SN74HCT138
3-LINE TO 8-LINE DECODERS/DEMULTIPLEXERS
SCLS171C – MARCH 1984 – REVISED MA Y 1997
4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
recommended operating conditions
SN54HCT138 SN74HCT138
MIN NOM MAX MIN NOM MAX
UNIT
V
CC
Supply voltage 4.5 5 5.5 4.5 5 5.5 V
V
IH
High-level input voltage VCC = 4.5 V to 5.5 V 2 2 V
V
IL
Low-level input voltage VCC = 4.5 V to 5.5 V 0 0.8 0 0.8 V
V
I
Input voltage 0 V
CC
0 V
CC
V
V
O
Output voltage 0 V
CC
0 V
CC
V
t
t
Input transition (rise and fall) time 0 500 0 500 ns
T
A
Operating free-air temperature –55 125 –40 85 °C
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
TA = 25°C SN54HCT138 SN74HCT138
PARAMETER
TEST CONDITIONS
V
CC
MIN TYP MAX MIN MAX MIN MAX
UNIT
IOH = –20 µA
4.4 4.499 4.4 4.4
V
OH
V
I
=
V
IH
or V
IL
IOH = –4 mA
4.5 V
3.98 4.3 3.7 3.84
V
IOL = 20 µA
0.001 0.1 0.1 0.1
V
OL
V
I
=
V
IH
or
V
IL
IOL = 4 mA
4.5 V
0.17 0.26 0.4 0.33
V
I
I
VI = VCC or 0 5.5 V ±0.1 ±100 ±1000 ±1000 nA
I
CC
VI = VCC or 0, IO = 0 5.5 V 8 160 80 µA
∆I
CC
†
One input at 0.5 V or 2.4 V ,
Other inputs at 0 or V
CC
5.5 V 1.4 2.4 3 2.9 mA
C
i
4.5 V
to 5.5 V
3 10 10 10 pF
†
This is the increase in supply current for each input that is at one of the specified TTL voltage levels rather than 0 V or VCC.
switching characteristics over recommended operating free-air temperature range, CL = 50 pF
(unless otherwise noted) (see Figure 1)
FROM TO
TA = 25°C SN54HCT138 SN74HCT138
PARAMETER
(INPUT) (OUTPUT)
V
CC
MIN TYP MAX MIN MAX MIN MAX
UNIT
4.5 V 23 36 54 45
A, B, or C
Any Y
5.5 V 17 32 49 34
t
pd
4.5 V 22 33 50 42
ns
Enable
Any Y
5.5 V 18 30 45 38
4.5 V 12 15 22 19
ttY
5.5 V 11 14 20 17
ns
operating characteristics, TA = 25°C
PARAMETER TEST CONDITIONS TYP UNIT
C
pd
Power dissipation capacitance No load 85 pF
SN54HCT138, SN74HCT138
3-LINE TO 8-LINE DECODERS/DEMULTIPLEXERS
SCLS171C – MARCH 1984 – REVISED MA Y 1997
5
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
PARAMETER MEASUREMENT INFORMATION
VOLTAGE WAVEFORM
INPUT RISE AND FALL TIMES
1.3 V1.3 V
0.3 V0.3 V
2.7 V 2.7 V
3 V
0 V
t
r
t
f
Input
VOLTAGE WAVEFORMS
PROPAGATION DELAY AND OUTPUT RISE AND FALL TIMES
1.3 V
1.3 V1.3 V
10%10%
90% 90%
3 V
V
OH
V
OL
0 V
t
r
t
f
Input
In-Phase
Output
1.3 V
t
PLH
t
PHL
1.3 V 1.3 V
10% 10%
90%90%
V
OH
V
OL
t
r
t
f
t
PHL
t
PLH
Out-of-Phase
Output
Test
Point
From Output
Under Test
LOAD CIRCUIT
NOTES: A. CL includes probe and test-fixture capacitance.
B. Phase relationships between waveforms were chosen arbitrarily. All input pulses are supplied by generators having the following
characteristics: PRR ≤ 1 MHz, ZO = 50 Ω, tr = 6 ns, tf = 6 ns.
C. The outputs are measured one at a time with one input transition per measurement.
D. t
PLH
and t
PHL
are the same as tpd.
CL = 50 pF
(see Note A)
Figure 1. Load Circuit and Voltage Waveforms
IMPORTANT NOTICE
T exas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue
any product or service without notice, and advise customers to obtain the latest version of relevant information
to verify, before placing orders, that information being relied on is current and complete. All products are sold
subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those
pertaining to warranty, patent infringement, and limitation of liability.
TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily
performed, except those mandated by government requirements.
CERT AIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF
DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL
APPLICATIONS”). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR
WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER
CRITICAL APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICA TIONS IS UNDERSTOOD T O
BE FULLY AT THE CUSTOMER’S RISK.
In order to minimize risks associated with the customer’s applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.
TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent
that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other
intellectual property right of TI covering or relating to any combination, machine, or process in which such
semiconductor products or services might be or are used. TI’s publication of information regarding any third
party’s products or services does not constitute TI’s approval, warranty or endorsement thereof.
Copyright 1998, Texas Instruments Incorporated
Loading...