74ALS138N - NXP SEMICONDUCTORS

September 1986

Revised February 2000

DM74ALS138 3 to 8 Line Decoder/Demultiplexer

DM74ALS138

3 to 8 Line Decoder/Demultiplexer

General Descript ion

These Schottky-clamped circuits are de signed to be used

in high-performance memory-decoding or data-routing

applicatio ns, requiring very short propagation delay times.

In high-perf ormance me mory systems th ese decoders can

be used to minimize the effects of system de coding. When

used with high-speed memories, the delay times of these

decoders are usually less than the typical access time of

the memory. This means that the effective system delay

introd uced by the dec oder is negligi ble.

The DM74ALS138 decodes one-of-eight lines, based upon

the conditions at the three binary select inputs and the

three enable inputs. Two active-LOW and one active-HIGH

enable inp uts reduce the ne ed for externa l gates or invert-

ers when expanding. A 24-line decoder can be imple-

mented with no external inverters, and 32-line decoder

requires only one inve rter. An enable input can be used as

a data input for demultiplexing applications.

This decoder/demultiplexer features fully buffered inputs,

presenting only one normalized load to its driving circuit. All

inputs ar e cla mp ed wi t h hig h-p er for man ce S ch ottk y diodes

to suppress line-ringing and simplify system design.

Features

■Designed specifically for high speed:

Memory decoders

Data transmission systems

■3- to 8-l in e d ecod er inco rporates 3 e nab l e in put s to sim-

plify cascading and/or data reception

■Low power dissipation…23 mW typ

■Switching specifications guaranteed over full tempera-

ture and VCC range

■Advanced oxide-isolated, ion-implanted Schottky TTL

process

Ordering Code:

Devices also available in Tape and R eel. Speci fy by appending the s uffix let t er “X” to the orderin g c ode.

Connection Diagram Function Table

Note 1: G2 = G2A + G2B

Order Number Package Number Package Description

DM74ALS138M M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow

DM74ALS138SJ M16D 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide

DM74ALS138N N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide

Enable Select Outputs

Inputs Inputs

G1 G2

(Note 1) C B A Y0Y1Y2Y3Y4Y5Y6Y7

X H XXXHHHHHHHH

L X XXXHHHHHHHH

H L LLLLHHHHHHH

H L LLHHLHHHHHH

H L LHLHHLHHHHH

H L LHHHHHLHHHH

H L HLLHHHHLHHH

H L HLHHHHHHLHH

H L HHLHHHHHHLH

H L HHHHHHHHHHL

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DM74ALS138

Logic Diagram

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DM74ALS138

Absolute Maximum Ratings(Note 2)

Note 2: The “A bsol ute M axim um Ratin gs” are those valu es b eyo nd which

the safety of the device cannot be guaranteed. The device should not be

operated at these limits. The parametric values defined in the Electrical

Characteristics tables are not guaranteed at the absolute maximum ratings.

The “Re comm ended Operat ing Co ndition s” table will de fine the cond itions

for actu al device operation.

Recommended Operating Conditions

Electri cal Characteristics

over recommended operating free air temperature range. All typical values are measured at VCC = 5V, TA = 25°C.

Switching Characteristics

over recommended operating free air temperature range.

Supply Voltage 7V

Input Voltage 7V

Operating Free Air Temperature Range 0°C to +70°C

Storage Temperature Range −65°C to +150°C

Typical θJA

N Package 75.5°C/W

M Package 104.0°C/W

Symbol Parameter Min Nom Max Units

VCC Supply Voltage 4.5 5 5.5 V

VIH HIGH Level Input Voltage 2 V

VIL LOW Level Input Voltage 0.8 V

IOH HIGH Level Output Current −0.4 mA

IOL LOW Level Output Current 8 mA

TAFree Air Operating Temperature 0 70 °C

Symbol Parameter Conditions Min Typ Max Units

VIK Input Clamp Voltage VCC = 4.5V, II = −18 mA −1.5 V

VOH HIGH Level IOH = −0.4 mA VCC − 2V

Output Voltage VCC = 4.5V to 5.5V

VOL LOW Level VCC = 4.5V IOL = 8 mA 0.35 0.5 V

Output Voltage

IIInput Current @ Max. VCC = 5.5V, VIH = 7V 0.1 mA

Input V oltag e

IIH HIGH Level Input Current VCC = 5.5V, VIH = 2.7V 20 µA

IIL LOW Level Input Current VCC = 5.5V, VIL = 0.4V −0.1 mA

IOOutput Drive Current VCC = 5.5V VO = 2.25V −30 −112 mA

ICC Supply Current VCC = 5.5V 5 10 mA

Symbol Parameter Conditions From (Input) Min Max Units

To (Output)

tPLH Propagation Delay Time VCC = 4.5V to 5.5V A, B, C 622ns

LOW-to-HIGH Level Output RL = 500Ωto Y

tPHL Propagation Delay Time CL = 50 pF A, B, C 618ns

HIGH-to-LOW Level Output to Y

tPLH Propagation Delay Time Enable 417ns

LOW-to-HIGH Level Output to Y

tPHL Propagation Delay Time Enable 517ns

HIGH-to-LOW Level Output to Y

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DM74ALS138

Physical Dimensions inches (millimeters) unless otherwise noted

16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow

Package Number M16A

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DM74ALS138

Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide

Package Number M16D

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DM74ALS138 3 to 8 Line Decoder/Demultiplexer

Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide

Package Number N16E

Fairchild does no t assume any responsibility for use of any circuitry de scribed, no circuit patent licenses are implied and

Fairchild reserves the right at any time without notice to change said circuitry and specifications.

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FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT

DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD

SEMICONDUCTOR CORPORATION. As used herein:

1. Life suppor t de vices o r systems a re devices or syste ms

which, (a) are intended for surgical implant into the

body, or (b) support or sustain life, and (c) whose failure

to perform when properly used in accordance with

instructions for use provided in the labeling, can be rea-

sonably expected to result in a significant injury to the

user.

2. A critical compon ent i n any compon ent of a life su pport

device or system whose failure to perform can be rea-

sonabl y ex pect ed to ca use the fa i lure of the life su pp ort

device or system, or to affect its safety or effectiveness.