SN74LS138 1-of-8 Decoder/ Demultiplexer
The LSTTL/MSI SN74LS138 is a high speed 1-of-8 Decoder/ Demultiplexer. This device is ideally suited for high speed bipolar memory chip select address decoding. The multiple input enables allow parallel expansion to a 1-of-24 decoder using just three LS138 devices or to a 1-of-32 decoder using four LS138s and one inverter. The LS138 is fabricated with the Schottky barrier diode process for high speed and is completely compatible with all ON Semiconductor TTL families. • Demultiplexing Capability • Multiple Input Enable for Easy Expansion • Typical Power Dissipation of 32 mW • Active Low Mutually Exclusive Outputs • Input Clamp Diodes Limit High Speed Termination Effects
GUARANTEED OPERATING RANGES
Symbol VCC TA IOH IOL Parameter Supply Voltage Operating Ambient Temperature Range Output Current – High Output Current – Low Min 4.75 0 Typ 5.0 25 Max 5.25 70 –0.4 8.0 Unit V °C mA mA
16 1
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LOW POWER SCHOTTKY
16 1
PLASTIC N SUFFIX CASE 648
SOIC D SUFFIX CASE 751B
16 1
SOEIAJ M SUFFIX CASE 966
ORDERING INFORMATION
Device SN74LS138N SN74LS138D SN74LS138DR2 SN74LS138M SN74LS138MEL Package 16 Pin DIP SOIC–16 SOIC–16 SOEIAJ–16 SOEIAJ–16 Shipping 2000 Units/Box 38 Units/Rail 2500/Tape & Reel See Note 1 See Note 1
1. For ordering information on the EIAJ version of the SOIC package, please contact your local ON Semiconductor representative.
© Semiconductor Components Industries, LLC, 2001
1
October, 2001 – Rev. 7
Publication Order Number: SN74LS138/D
SN74LS138
CONNECTION DIAGRAM DIP (TOP VIEW)
VCC 16 O0 15 O1 14 O2 13 O3 12 O4 11 O5 10 O6 9 NOTE: The Flatpak version has the same pinouts (Connection Diagram) as the Dual In Line Package. 1 A0 2 A1 3 A2 4 E1 5 E2 6 E3 7 O7 8 GND
LOADING (Note a) PIN NAMES A0 - A2 E1, E2 E3 O0 - O7 Address Inputs Enable (Active LOW) Inputs Enable (Active HIGH) Input Active LOW Outputs HIGH 0.5 U.L. 0.5 U.L. 0.5 U.L. 10 U.L. LOW 0.25 U.L. 0.25 U.L. 0.25 U.L. 5 U.L.
NOTES: a) 1 TTL Unit Load (U.L.) = 40 mA HIGH/1.6 mA LOW.
LOGIC SYMBOL
123 456 1 23 A0 A1 A2 E
O0 O1 O2 O3 O4 O5 O6 O7
15 14 13 12 11 10 9 7 VCC = PIN 16 GND = PIN 8
LOGIC DIAGRAM
A2
3 2
A1
1
A0
4
E1 E2 E3
5 6
VCC = PIN 16 GND = PIN 8 = Pin Numbers
7
9
10
11
12
13
14
15
O7
O6
O5
O4
O3
O2
O1
O0
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SN74LS138
FUNCTIONAL DESCRIPTION
The LS138 is a high speed 1-of-8 Decoder/Demultiplexer fabricated with the low power Schottky barrier diode process. The decoder accepts three binary weighted inputs (A0, A1, A2) and when enabled provides eight mutually exclusive active LOW Outputs (O0–O7). The LS138 features three Enable inputs, two active LOW (E1, E2) and one active HIGH (E3). All outputs will be HIGH unless E1 and E2 are LOW and E3 is HIGH. This multiple enable
function allows easy parallel expansion of the device to a 1-of-32 (5 lines to 32 lines) decoder with just four LS138s and one inverter. (See Figure a.) The LS138 can be used as an 8-output demultiplexer by using one of the active LOW Enable inputs as the data input and the other Enable inputs as strobes. The Enable inputs which are not used must be permanently tied to their appropriate active HIGH or active LOW state.
TRUTH TABLE
INPUTS E1 H X X L L L L L L L L E2 X H X L L L L L L L L E3 X X L H H H H H H H H A0 X X X L H L H L H L H A1 X X X L L H H L L H H A2 X X X L L L L H H H H O0 H H H L H H H H H H H O1 H H H H L H H H H H H O2 H H H H H L H H H H H OUTPUTS O3 H H H H H H L H H H H O4 H H H H H H H L H H H O5 H H H H H H H H L H H O6 H H H H H H H H H L H O7 H H H H H H H H H H L
H = HIGH Voltage Level L = LOW Voltage Level X = Don’t Care
A0 A1 A2 LS04 A3 A4 H 123 A0 A1 A2 LS138 O0 O1 O2 O3 O4 O5 O6 O7 O0 E A0 A1 A2 LS138 O0 O1 O2 O3 O4 O5 O6 O7 123 E A0 A1 A2 LS138 O0 O1 O2 O3 O4 O5 O6 O7 123 E A0 A1 A2 LS138 O0 O1 O2 O3 O4 O5 O6 O7 O31 123 E
Figure a
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SN74LS138
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified)
Limits Symbol VIH VIL VIK VOH Parameter Input HIGH Voltage Input LOW Voltage Input Clamp Diode Voltage Output HIGH Voltage 2.7 –0.65 3.5 0.25 VOL Output Output LOW Voltage 0.35 Input Input HIGH Current 0.1 Input LOW Current Short Circuit Current (Note 2) –20 –0.4 –100 0.5 20 IIH IIL IOS V µA mA mA mA 0.4 Min 2.0 0.8 –1.5 Typ Max Unit V V V V V Test Conditions Guaranteed Input HIGH Voltage for All Inputs Guaranteed Input LOW Voltage for All Inputs VCC = MIN, IIN = –18 mA VCC = MIN, IOH = MAX, VIN = VIH or VIL per Truth Table IOL = 4.0 mA IOL = 8.0 mA VCC = VCC MIN, VIN = VIL or VIH per Truth Table
VCC = MAX, VIN = 2.7 V VCC = MAX, VIN = 7.0 V VCC = MAX, VIN = 0.4 V VCC = MAX VCC = MAX
ICC Power Supply Current 10 mA 2. Not more than one output should be shorted at a time, nor for more than 1 second.
AC CHARACTERISTICS (TA = 25°C)
Symbol tPLH tPHL tPLH tPHL tPLH tPHL tPLH tPHL Parameter Propagation Delay Address to Output Propagation Delay Address to Output Propagation Delay E1 or E2 Enable to Output Propagation Delay E3 Enable to Output Levels of of Delay 2 2 3 3 2 2 3 3 Limits Min Typ 13 27 18 26 12 21 17 25 Max 20 41 27 39 18 32 26 38 Unit ns ns ns ns VCC = 5.0 V .0 CL = 15 pF Test Conditions
AC WAVEFORMS
VIN tPLH 1.3 V VOUT
VIN
1.3 V tPHL
1.3 V
1.3 V tPHL 1.3 V tPLH
1.3 V
VOUT
1.3 V
1.3 V
Figure 1.
Figure 2.
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SN74LS138
PACKAGE DIMENSIONS
N SUFFIX PLASTIC PACKAGE CASE 648–08 ISSUE R
–A–
16 9 NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 3. DIMENSION L TO CENTER OF LEADS WHEN FORMED PARALLEL. 4. DIMENSION B DOES NOT INCLUDE MOLD FLASH. 5. ROUNDED CORNERS OPTIONAL. DIM A B C D F G H J K L M S INCHES MIN MAX 0.740 0.770 0.250 0.270 0.145 0.175 0.015 0.021 0.040 0.70 0.100 BSC 0.050 BSC 0.008 0.015 0.110 0.130 0.295 0.305 0_ 10 _ 0.020 0.040 MILLIMETERS MIN MAX 18.80 19.55 6.35 6.85 3.69 4.44 0.39 0.53 1.02 1.77 2.54 BSC 1.27 BSC 0.21 0.38 2.80 3.30 7.50 7.74 0_ 10 _ 0.51 1.01
B
1 8
F S
C
L
–T– H G D
16 PL
SEATING PLANE
K
J TA
M
M
0.25 (0.010)
M
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SN74LS138
PACKAGE DIMENSIONS
D SUFFIX PLASTIC SOIC PACKAGE CASE 751B–05 ISSUE J
–A–
16 9 NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSIONS A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER SIDE. 5. DIMENSION D DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.127 (0.005) TOTAL IN EXCESS OF THE D DIMENSION AT MAXIMUM MATERIAL CONDITION. DIM A B C D F G J K M P R MILLIMETERS MIN MAX 9.80 10.00 3.80 4.00 1.35 1.75 0.35 0.49 0.40 1.25 1.27 BSC 0.19 0.25 0.10 0.25 0_ 7_ 5.80 6.20 0.25 0.50 INCHES MIN MAX 0.386 0.393 0.150 0.157 0.054 0.068 0.014 0.019 0.016 0.049 0.050 BSC 0.008 0.009 0.004 0.009 0_ 7_ 0.229 0.244 0.010 0.019
–B–
1 8
P
8 PL
0.25 (0.010)
M
B
S
G F
K C –T–
SEATING PLANE
R
X 45 _
M D
16 PL M
J
0.25 (0.010)
TB
S
A
S
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SN74LS138
PACKAGE DIMENSIONS
M SUFFIX SOEIAJ PACKAGE CASE 966–01 ISSUE O
NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSIONS D AND E DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS AND ARE MEASURED AT THE PARTING LINE. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.15 (0.006) PER SIDE. 4. TERMINAL NUMBERS ARE SHOWN FOR REFERENCE ONLY. 5. THE LEAD WIDTH DIMENSION (b) DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.08 (0.003) TOTAL IN EXCESS OF THE LEAD WIDTH DIMENSION AT MAXIMUM MATERIAL CONDITION. DAMBAR CANNOT BE LOCATED ON THE LOWER RADIUS OR THE FOOT. MINIMUM SPACE BETWEEN PROTRUSIONS AND ADJACENT LEAD TO BE 0.46 ( 0.018).
16
9
LE Q1 E HE M_ L DETAIL P
1
8
Z D e A VIEW P
c
b 0.13 (0.005)
M
A1 0.10 (0.004)
DIM A A1 b c D E e HE L LE M Q1 Z
MILLIMETERS MIN MAX --2.05 0.05 0.20 0.35 0.50 0.18 0.27 9.90 10.50 5.10 5.45 1.27 BSC 7.40 8.20 0.50 0.85 1.10 1.50 10 _ 0_ 0.70 0.90 --0.78
INCHES MIN MAX --0.081 0.002 0.008 0.014 0.020 0.007 0.011 0.390 0.413 0.201 0.215 0.050 BSC 0.291 0.323 0.020 0.033 0.043 0.059 10 _ 0_ 0.028 0.035 --0.031
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SN74LS138
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PUBLICATION ORDERING INFORMATION
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SN74LS138/D