SN74LS138D - ON Semiconductor

 Semiconductor Components Industries, LLC, 1999

December, 1999 – Rev. 6 1Publication Order Number:

SN74LS138/D

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 Ef fects

GUARANTEED OPERATING RANGES

Symbol Parameter Min Typ Max Unit

VCC Supply Voltage 4.75 5.0 5.25 V

TAOperating Ambient

Temperature Range 0 25 70 °C

IOH Output Current – High –0.4 mA

IOL Output Current – Low 8.0 mA

LOW

POWER

SCHOTTKY

Device Package Shipping

ORDERING INFORMATION

SN74LS138N 16 Pin DIP 2000 Units/Box

SN74LS138D 16 Pin

SOIC

D SUFFIX

CASE 751B

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2500/Tape & Reel

PLASTIC

N SUFFIX

CASE 648

SN74LS138

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CONNECTION DIAGRAM DIP (TOP VIEW)

Address Inputs

Enable (Active LOW) Inputs

Enable (Active HIGH) Input

Active LOW Outputs

A0 – A2

E1, E2

O0 – O7

0.5 U.L.

10 U.L.

0.25 U.L.

5 U.L.

NOTES:

a) 1 TTL Unit Load (U.L.) = 40

A HIGH/1.6 mA LOW.

HIGH LOW

(Note a)LOADING

PIN NAMES

NOTE:

The Flatpak version has the same

pinouts (Connection Diagram) as

the Dual In-Line Package.

14 13 12 11 10 9

1234567

16 15

VCC O0

GND

O1O2O3O4O5O6

A0E1E2E3O7

A1A2

LOGIC SYMBOL

VCC = PIN 16

GND = PIN 8

15 14 13 12 11 10 9

123 456

123

A0A1A2E

O0O1O2O3O4O5O6O7

SN74LS138

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LOGIC DIAGRAM

A2A1A0E1E2E3

O7O6O5O4O3O2O1O0

VCC = PIN 16

GND = PIN 8

= Pin Numbers

3 2 1 4 5 6

791514

1312

1110

SN74LS138

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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 OUTPUTS

E1E2E3A0A1A2O0O1O2O3O4O5O6O7

H X X X X X H H H H H H H H

XHXXXXHHHHHHH H

XXLXXXHHHHHHH H

LLHLLLLHHHHHH H

LLHHLLHLHHHHH H

LLHLHLHHLHHHH H

LLHHHLHHHLHHH H

LLHLLHHHHHLHH H

LLHHLHHHHHHLH H

LLHLHHHHHHHHL H

L L H H H H H H H H H H H L

H = HIGH Voltage Level

L = LOW Voltage Level

X = Don’t Care

O0O31

A4H

LS04

A0A1A2E

LS138

O0O1O2O3O4O5O6O7

LS138

123 123 123 123

Figure a

LS138 LS138

A0A1A2E

O0O1O2O3O4O5O6O7

A0A1A2E

O0O1O2O3O4O5O6O7

A0A1A2E

O0O1O2O3O4O5O6O7

SN74LS138

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DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified)

Limits

Symbol Parameter Min Typ Max Unit Test Conditions

VIH Input HIGH Voltage 2.0 VGuaranteed Input HIGH Voltage for

All Inputs

VIL Input LOW Voltage 0.8 VGuaranteed Input LOW Voltage for

All Inputs

VIK Input Clamp Diode Voltage –0.65 –1.5 V VCC = MIN, IIN = –18 mA

VOH Output HIGH Voltage 2.7 3.5 V VCC = MIN, IOH = MAX, VIN = VIH

or VIL per T ruth Table

Out

ut LOW Voltage

0.25 0.4 V IOL = 4.0 mA VCC = VCC MIN,

VIN =V

IL or VIH

LOW

Voltage

0.35 0.5 V IOL = 8.0 mA

IN =

per T ruth Table

ut HIGH Current

20 µA VCC = MAX, VIN = 2.7 V

Inp

HIGH

rrent

0.1 mA VCC = MAX, VIN = 7.0 V

IIL Input LOW Current –0.4 mA VCC = MAX, VIN = 0.4 V

IOS Short Circuit Current (Note 1) –20 –100 mA VCC = MAX

ICC Power Supply Current 10 mA VCC = MAX

Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.

AC CHARACTERISTICS (TA = 25°C)

Levels of Limits

Symbol Parameter

Levels

Delay Min Typ Max Unit Test Conditions

tPLH

tPHL Propagation Delay

Address to Output 2

213

27 20

41 ns

tPLH

tPHL Propagation Delay

Address to Output 3

318

26 27

39 ns VCC = 5.0 V

tPLH

tPHL Propagation Delay E1 or E2

Enable to Output 2

212

21 18

32 ns

CL = 15 pF

tPLH

tPHL Propagation Delay E3

Enable to Output 3

317

25 26

38 ns

AC WAVEFORMS

Figure 1. Figure 2.

VIN

VOUT

1.3 V

tPHL

1.3 V

tPLH

VIN

VOUT

1.3 V

tPHL

1.3 V

tPLH

1.3 V

SN74LS138

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PACKAGE DIMENSIONS

N SUFFIX

PLASTIC PACKAGE

CASE 648–08

ISSUE R

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.

–A–

HGD

16 PL

SEATING

916

PLANE

–T–

0.25 (0.010) T

DIM MIN MAX MIN MAX

MILLIMETERSINCHES

A0.740 0.770 18.80 19.55

B0.250 0.270 6.35 6.85

C0.145 0.175 3.69 4.44

D0.015 0.021 0.39 0.53

F0.040 0.70 1.02 1.77

G0.100 BSC 2.54 BSC

H0.050 BSC 1.27 BSC

J0.008 0.015 0.21 0.38

K0.110 0.130 2.80 3.30

L0.295 0.305 7.50 7.74

M0 10 0 10

S0.020 0.040 0.51 1.01

____

SN74LS138

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PACKAGE DIMENSIONS

D SUFFIX

PLASTIC SOIC PACKAGE

CASE 751B–05

ISSUE J

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.

16 9

SEATING

PLANE

RX 45

8 PLP

–B–

–A–

0.25 (0.010) B S

–T–

16 PL

0.25 (0.010) A S

DIM MIN MAX MIN MAX

INCHESMILLIMETERS

A9.80 10.00 0.386 0.393

B3.80 4.00 0.150 0.157

C1.35 1.75 0.054 0.068

D0.35 0.49 0.014 0.019

F0.40 1.25 0.016 0.049

G1.27 BSC 0.050 BSC

J0.19 0.25 0.008 0.009

K0.10 0.25 0.004 0.009

M0 7 0 7

P5.80 6.20 0.229 0.244

R0.25 0.50 0.010 0.019

____

SN74LS138

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SN74LS138/D

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