HD74ACT138P - Hitachi Semiconductor

HD74AC138/HD74ACT138

1-of-8 Decoder/Demultiplexer

ADE-205-368 (Z)

1st. Edition

Sep. 2000

Description

The HD74AC138/HD74ACT138 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 HD74AC138/HD74ACT138 devices or a 1-of-32

decoder using four HD74AC138/HD74ACT138 devices and one inverter.

Features

• Demultiplexing Capability

• Multiple Input Enable for Easy Expansion

• Active LOW Mutually Exclusive Outputs

• Outputs Source/Sink 24 mA

• HD74ACT138 has TTL-Compatible Inputs

HD74AC138/HD74ACT138

Pin Arrangement

GND

VCC

(Top view)

Logic Symbol

A0A1A2E1

O0O1O2O3O4O5O6O7

E2E3

Pin Names

A0 to A2Address Inputs

E1 to E 2 Enable Inputs

E 3 Enable Input

O0 to O 7 Outputs

HD74AC138/HD74ACT138

Functional Description

The HD74AC138/HD74ACT138 high-speed 1-of-8 decoder/demultiplexer accepts three binary weighted

inputs (A0, A1, A2) and, when enabled, provides eight mutually exclusive active-LOW outputs (O0 to O7).

The HD74AC138/HD74ACT138 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 enabled function

allows easy parallel expansion of the device to a 1-of-32 (5 lines to 32 lines) decoder with just four

HD74AC138/HD74ACT138 devices and one inverter (See Figure a). The HD74AC138/HD74ACT138

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 Enables inputs which are not used must be permanently tied to

their appropriate active-High or active-Low state.

Truth Table

Inputs Outputs

E1E 2 E3A0A1A2O0O 1 O 2 O 3 O 4 O 5 O 6 O 7

HXXXXXHHHHHHHH

XHXXXXHHHHHHHH

XXLXXXHHHHHHHH

LLHLLLLHHHHHHH

LLHHLLHLHHHHHH

LLHLHLHHLHHHHH

LLHHHLHHHLHHHH

LLHLLHHHHHLHHH

LLHHLHHHHHHLHH

LLHLHHHHHHHHLH

LLHHHHHHHHHHHL

H : High Voltage Level

L : Low Voltage Level

X : Immaterial

HD74AC138/HD74ACT138

Logic Diagram

A2A1A0E1

O0O1O2O3O4O5O6O7

E2E3

Please note that this diagram is provided only for the understanding of logic operations and should not be

used to estimate propagation delays.

Figure a: Expansion of 1-of-32 Decoding

O0O31

123

O0O1O2O3O4O5O6O7

123

A0A1A2

O0O1O2O3O4O5O6O7

A0A1A2

O0O1O2O3O4O5O6O7

A0A1A2

O0O1O2O3O4O5O6O7

A0A1A2E

123

’04

HD74AC138/HD74ACT138

DC Characteristics (unless otherwise specified)

Item Symbol Max Unit Condition

Maximum quiescent supply current ICC 80 µAV

IN = VCC or ground, VCC = 5.5 V,

Ta = Worst case

Maximum quiescent supply current ICC 8.0 µAV

IN = VCC or ground, VCC = 5.5 V,

Ta = 25°C

Maximum ICC/input (HD74ACT138) ICCT 1.5 mA VIN = VCC – 2.1 V, VCC = 5.5 V

Ta = Worst case

AC Characteristics: HD74AC138

Ta = +25°C

CL = 50 pF Ta = –40°C to +85°C

CL = 50 pF

Item Symbol VCC (V)*1Min Typ Max Min Max Unit

Propagation delay tPLH 3.3 1.0 8.5 13.0 1.0 15.0 ns

An to On5.0 1.0 6.5 9.5 1.0 10.5

Propagation delay tPHL 3.3 1.0 8.0 12.5 1.0 14.0 ns

An to On5.0 1.0 6.0 9.0 1.0 10.5

Propagation delay tPLH 3.3 1.0 11.0 15.0 1.0 16.0 ns

E1 or E 2 to On5.0 1.0 8.0 11.0 1.0 12.0

Propagation delay tPHL 3.3 1.0 9.5 13.5 1.0 15.0 ns

E1 or E 2 to On5.0 1.0 7.0 9.5 1.0 10.5

Propagation delay tPLH 3.3 1.0 11.0 15.5 1.0 16.5 ns

E3 to On5.0 1.0 8.0 11.0 1.0 12.5

Propagation delay tPHL 3.3 1.0 8.5 13.0 1.0 14.0 ns

E3 to On5.0 1.0 6.0 8.0 1.0 9.5

Note: 1. Voltage Range 3.3 is 3.3 V ± 0.3 V

Voltage Range 5.0 is 5.0 V ± 0.5 V

HD74AC138/HD74ACT138

AC Characteristics: HD74ACT138

Ta = +25°C

CL = 50 pF Ta = –40°C to +85°C

CL = 50 pF

Item Symbol VCC (V)*1Min Typ Max Min Max Unit

Propagation delay

An to On

tPLH 5.0 1.0 7.0 10.5 1.0 11.5 ns

Propagation delay

An to On

tPHL 5.0 1.0 6.5 10.5 1.0 11.5 ns

Propagation delay

E1 or E 2 to On

tPLH 5.0 1.0 8.0 11.5 1.0 12.5 ns

Propagation delay

E1 or E 2 to On

tPHL 5.0 1.0 7.5 11.5 1.0 12.5 ns

Propagation delay

E3 to On

tPLH 5.0 1.0 8.0 12.0 1.0 13.0 ns

Propagation delay

E3 to On

tPHL 5.0 1.0 6.5 10.5 1.0 11.5 ns

Note: 1. Voltage Range 5.0 is 5.0 V ± 0.5 V

Capacitance

Item Symbol Typ Unit Condition

Input capacitance CIN 4.5 pF VCC = 5.5 V

Power dissipation capacitance CPD 60.0 pF VCC = 5.0 V

HD74AC138/HD74ACT138

Package Dimensions

Hitachi Code

JEDEC

EIAJ

Mass

(reference value)

DP-16

Conforms

1.07 g

Unit: mm

6.30

19.20

16 9

81 1.3

20.00 Max

7.40 Max

7.62

0.25

+ 0.13

– 0.05

2.54 ± 0.25 0.48 ± 0.10

0.51 Min

2.54 Min 5.06 Max

0° – 15°

1.11 Max

Hitachi Code

JEDEC

EIAJ

Mass

(reference value)

FP-16DA

—

Conforms

0.24 g

Unit: mm

*Dimension including the plating thickness

Base material dimension

*0.22 ± 0.05

*0.42 ± 0.08

0.12

0.15

2.20 Max 5.5

10.06

0.80 Max

16 9

10.5 Max

+ 0.20

– 0.30

7.80

0.70 ± 0.20

0° – 8°

0.10 ± 0.10

1.15

1.27

0.40 ± 0.06

0.20 ± 0.04

HD74AC138/HD74ACT138

Hitachi Code

JEDEC

EIAJ

Mass

(reference value)

FP-16DN

Conforms

0.15 g

Unit: mm

*Dimension including the plating thickness

Base material dimension

1.27

16 9

0.15

0.25

1.75 Max 3.95

*0.22 ± 0.03

9.9

0° – 8°

10.3 Max

+ 0.10

– 0.30

6.10

+ 0.67

– 0.20

0.60

+ 0.11

– 0.04

0.14

*0.42 ± 0.08

0.635 Max

0.40 ± 0.06

0.20 ± 0.03

1.08

Hitachi Code

JEDEC

EIAJ

Mass

(reference value)

TTP-16DA

—

0.05 g

Unit: mm

*Dimension including the plating thickness

Base material dimension

0.50 ± 0.10

0° – 8°

*0.17 ± 0.05

6.40 ± 0.20

0.10

1.10 Max

0.13 M

0.65

16 9

4.40

5.00

5.30 Max

0.07

+0.03

–0.04

0.65 Max

1.0

0.20 ± 0.06

+ 0.08

– 0.07

*0.22

0.15 ± 0.04

HD74AC138/HD74ACT138

Cautions

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intellectual property rights, in connection with use of the information contained in this document.

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received the latest product standards or specifications before final design, purchase or use.

3. Hitachi makes every attempt to ensure that its products are of high quality and reliability. However,

contact Hitachi’s sales office before using the product in an application that demands especially high

quality and reliability or where its failure or malfunction may directly threaten human life or cause risk

of bodily injury, such as aerospace, aeronautics, nuclear power, combustion control, transportation,

traffic, safety equipment or medical equipment for life support.

4. Design your application so that the product is used within the ranges guaranteed by Hitachi particularly

for maximum rating, operating supply voltage range, heat radiation characteristics, installation

conditions and other characteristics. Hitachi bears no responsibility for failure or damage when used

beyond the guaranteed ranges. Even within the guaranteed ranges, consider normally foreseeable

failure rates or failure modes in semiconductor devices and employ systemic measures such as fail-

safes, so that the equipment incorporating Hitachi product does not cause bodily injury, fire or other

consequential damage due to operation of the Hitachi product.

5. This product is not designed to be radiation resistant.

6. No one is permitted to reproduce or duplicate, in any form, the whole or part of this document without

written approval from Hitachi.

7. Contact Hitachi’s sales office for any questions regarding this document or Hitachi semiconductor

products.

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