JM38510/30702BFA - National Semiconductor

TL/F/6391

54LS138/DM54LS138/DM74LS138,

54LS139/DM54LS139/DM74LS139 Decoders/Demultiplexers

June 1989

54LS138/DM54LS138/DM74LS138,

54LS139/DM54LS139/DM74LS139

Decoders/Demultiplexers

General Description

These Schottky-clamped circuits are designed to be used in

high-performance memory-decoding or data-routing appli-

cations, requiring very short propagation delay times. In

high-performance memory systems these decoders can be

used to minimize the effects of system decoding. 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 intro-

duced by the decoder is negligible.

The LS138 decodes one-of-eight lines, based upon the con-

ditions at the three binary select inputs and the three enable

inputs. Two active-low and one active-high enable inputs

reduce the need for external gates or inverters when ex-

panding. A 24-line decoder can be implemented with no ex-

ternal inverters, and a 32-line decoder requires only one

inverter. An enable input can be used as a data input for

demultiplexing applications.

The LS139 comprises two separate two-line-to-four-line de-

coders in a single package. The active-low enable input can

be used as a data line in demultiplexing applications.

All of these decoders/demultiplexers feature fully buffered

inputs, presenting only one normalized load to its driving

circuit. All inputs are clamped with high-performance

Schottky diodes to suppress line-ringing and simplify system

design.

Features

YDesigned specifically for high speed:

Memory decoders

Data transmission systems

YLS138 3-to-8-line decoders incorporates 3 enable in-

puts to simplify cascading and/or data reception

YLS139 contains two fully independent 2-to-4-line decod-

ers/demultiplexers

YSchottky clamped for high performance

YTypical propagation delay (3 levels of logic)

LS138 21 ns

LS139 21 ns

YTypical power dissipation

LS138 32 mW

LS139 34 mW

YAlternate Military/Aerospace devices (54LS138,

54LS139) are available. Contact a National Semicon-

ductor Sales Office/Distributor for specifications.

Connection Diagrams

Dual-in-Line Package

TL/F/6391–1

Order Number 54LS138DMQB, 54LS138FMQB,

54LS138LMQB, DM54LS138J, DM54LS138W,

DM74LS138M or DM74LS138N

See NS Package Number E20A, J16A,

M16A, N16E or W16A

Dual-in-Line Package

TL/F/6391–2

Order Number 54LS139DMQB, 54LS139FMQB,

54LS139LMQB, DM54LS139J, DM54LS139W,

DM74LS139M or DM74LS139N

See NS Package Number E20A, J16A,

M16A, N16E or W16A

C1995 National Semiconductor Corporation RRD-B30M105/Printed in U. S. A.

Absolute Maximum Ratings (Note)

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales

Office/Distributors for availability and specifications.

Supply Voltage 7V

Input Voltage 7V

Operating Free Air Temperature Range

DM54LS and 54LS b55§Ctoa

125§C

DM74LS 0§Ctoa

70§C

Storage Temperature Range b65§Ctoa

150§C

Note:

The ‘‘Absolute Maximum Ratings’’ are those values

beyond which the safety of the device cannot be guaran-

teed. The device should not be operated at these limits. The

parametric values defined in the ‘‘Electrical Characteristics’’

table are not guaranteed at the absolute maximum ratings.

The ‘‘Recommended Operating Conditions’’ table will define

the conditions for actual device operation.

Recommended Operating Conditions

Symbol Parameter DM54LS138 DM74LS138 Units

Min Nom Max Min Nom Max

VCC Supply Voltage 4.5 5 5.5 4.75 5 5.25 V

VIH High Level Input Voltage 2 2 V

VIL Low Level Input Voltage 0.7 0.8 V

IOH High Level Output Current b0.4 b0.4 mA

IOL Low Level Output Current 4 8 mA

TAFree Air Operating Temperature b55 125 0 70 §C

’LS138 Electrical Characteristics

over recommended operating free air temperature range (unless otherwise noted)

Symbol Parameter Conditions Min Typ Max Units

(Note 1)

VIInput Clamp Voltage VCC eMin, IIeb

18 mA b1.5 V

VOH High Level Output VCC eMin, IOH eMax, DM54 2.5 3.4 V

Voltage VIL eMax, VIH eMin DM74 2.7 3.4

VOL Low Level Output VCC eMin, IOL eMax, DM54 0.25 0.4

Voltage VIL eMax, VIH eMin DM74 0.35 0.5 V

IOL e4 mA, VCC eMin DM74 0.25 0.4

IIInput Current @Max VCC eMax, VIe7V 0.1 mA

Input Voltage

IIH High Level Input Current VCC eMax, VIe2.7V 20 mA

IIL Low Level Input Current VCC eMax, VIe0.4V b0.36 mA

IOS Short Circuit VCC eMax DM54 b20 b100 mA

Output Current (Note 2) DM74 b20 b100

ICC Supply Current VCC eMax (Note 3) 6.3 10 mA

Note 1: All typicals are at VCC e5V, TAe25§C.

Note 2: Not more than one output should be shorted at a time, and the duration should not exceed one second.

Note 3: ICC is measured with all outputs enabled and open.

’LS138 Switching Characteristics

at VCC e5V and TAe25§C (See Section 1 for Test Waveforms and Output Load)

From (Input) Levels RLe2kX

Symbol Parameter To (Output) of Delay CLe15 pF CLe50 pF Units

Min Max Min Max

tPLH Propagation Delay Time Select to 21827ns

Low to High Level Output Output

tPHL Propagation Delay Time Select to 22740ns

High to Low Level Output Output

tPLH Propagation Delay Time Select to 31827ns

Low to High Level Output Output

tPHL Propagation Delay Time Select to 32740ns

High to Low Level Output Output

tPLH Propagation Delay Time Enable to 21827ns

Low to High Level Output Output

tPHL Propagation Delay Time Enable to 22440ns

High to Low Level Output Output

tPLH Propagation Delay Time Enable to 31827ns

Low to High Level Output Output

tPHL Propagation Delay Time Enable to 32840ns

High to Low Level Output Output

Recommended Operating Conditions

Symbol Parameter DM54LS139 DM74LS139 Units

Min Nom Max Min Nom Max

VCC Supply Voltage 4.5 5 5.5 4.75 5 5.25 V

VIH High Level Input Voltage 2 2 V

VIL Low Level Input Voltage 0.7 0.8 V

IOH High Level Output Current b0.4 b0.4 mA

IOL Low Level Output Current 4 8 mA

TAFree Air Operating Temperature b55 125 0 70 §C

’LS139 Electrical Characteristics

over recommended operating free air temperature range (unless otherwise noted)

Symbol Parameter Conditions Min Typ Max Units

(Note 1)

VIInput Clamp Voltage VCC eMin, IIeb

18 mA b1.5 V

VOH High Level Output VCC eMin, IOH eMax, DM54 2.5 3.4 V

Voltage VIL eMax, VIH eMin DM74 2.7 3.4

VOL Low Level Output VCC eMin, IOL eMax DM54 0.25 0.4

Voltage VIL eMax, VIH eMin DM74 0.35 0.5 V

IOL e4 mA, VCC eMin DM74 0.25 0.4

IIInput Current @Max VCC eMax, VIe7V 0.1 mA

Input Voltage

IIH High Level Input Current VCC eMax, VIe2.7V 20 mA

IIL Low Level Input Current VCC eMax, VIe0.4V b0.36 mA

IOS Short Circuit VCC eMax DM54 b20 b100 mA

Output Current (Note 2) DM74 b20 b100

ICC Supply Current VCC eMax (Note 3) 6.8 11 mA

Note 1: All typicals are at VCC e5V, TAe25§C.

Note 2: Not more than one output should be shorted at a time, and the duration should not exceed one second.

Note 3: ICC is measured with all outputs enabled and open.

’LS139 Switching Characteristics

at VCC e5V and TAe25§C (See Section 1 for Test Waveforms and Output Load)

From (Input) RLe2kX

Symbol Parameter To (Output) CLe15 pF CLe50 pF Units

Min Max Min Max

tPLH Propagation Delay Time Select to 18 27 ns

Low to High Level Output Output

tPHL Propagation Delay Time Select to 27 40 ns

High to Low Level Output Output

tPLH Propagation Delay Time Enable to 18 27 ns

Low to High Level Output Output

tPHL Propagation Delay Time Enable to 24 40 ns

High to Low Level Output Output

Function Tables

LS138

Inputs Outputs

Enable Select

G1 G2*CBAYOY1Y2Y3Y4Y5Y6Y7

X HXXXHHHHHHHH

L X XXXH HHHHHHH

H L LLLL HHHHHHH

H L LLHH LHHHHHH

H L LHLH HLHHHHH

H L LHHHHHLHHHH

H L HLLH HHHL HHH

H L HLHH HHHHLHH

H L HHLH HHHHHLH

H L HHHH HHHHHHL

*G2 eG2A aG2B

HeHigh Level, L eLow Level, X eDon’t Care

LS139

Inputs Outputs

Enable Select

G BAY0Y1Y2Y3

H XXHHHH

L LLLHHH

L LHHLHH

L HLHHLH

L HHHHHL

High Level, L eLow Level, X eDon’t Care

Logic Diagrams

LS138

TL/F/6391–3

LS139

TL/F/6391–4

Physical Dimensions inches (millimeters)

Ceramic Leadless Chip Carrier Package (E)

Order Number 54LS138LMQB or 54LS139LMQB

NS Package Number E20A

16-Lead Ceramic Dual-In-Line Package (J)

Order Number 54LS138DMQB, 54LS139DMQB, DM54LS138J or DM54LS139J

NS Package Number J16A

Physical Dimensions inches (millimeters) (Continued)

16-Lead Small Outline Molded Package (M)

Order Number DM74LS138M or DM74LS139M

NS Packge Number M16A

16-Lead Molded Dual-In-Line Package (N)

Order Number DM74LS138N or DM74LS139N

NS Package Number N16E

54LS138/DM54LS138/DM74LS138,

54LS139/DM54LS139/DM74LS139 Decoders/Demultiplexers

Physical Dimensions inches (millimeters) (Continued)

16-Lead Ceramic Flat Package (W)

Order Number 54LS138FMQB, 54LS139FMQB, DM54LS138W or DM54LS139W

NS Package Number W16A

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