Encyclopedia Entry: 74ACT138SCX

Product Overview

Category

The 74ACT138SCX belongs to the category of integrated circuits (ICs).

Use

This IC is commonly used in digital electronics for decoding applications.

Characteristics

• The 74ACT138SCX is a 3-to-8 line decoder/demultiplexer.
• It operates on a supply voltage range of 2.0V to 6.0V.
• This IC has high-speed performance with a propagation delay of 5ns.
• It offers low power consumption and high noise immunity.
• The 74ACT138SCX is compatible with TTL input and CMOS output levels.

Package

The 74ACT138SCX is available in a small outline package (SOIC) with 16 pins.

Essence

The essence of the 74ACT138SCX lies in its ability to decode three binary inputs into eight mutually exclusive outputs.

Packaging/Quantity

This IC is typically sold in reels or tubes, with a quantity of 250 units per reel/tube.

Specifications

• Supply Voltage Range: 2.0V to 6.0V
• Input Voltage Range: 0V to VCC
• Output Voltage Range: 0V to VCC
• Operating Temperature Range: -40°C to +85°C
• Propagation Delay: 5ns (typical)
• Output Current: ±24mA

Detailed Pin Configuration

The 74ACT138SCX has 16 pins, each serving a specific purpose:

1. GND: Ground (0V reference)
2. A0: Binary input A0
3. A1: Binary input A1
4. A2: Binary input A2
5. /G1: Enable input (active low)
6. Y0: Output Y0
7. Y1: Output Y1
8. Y2: Output Y2
9. Y3: Output Y3
10. Y4: Output Y4
11. Y5: Output Y5
12. Y6: Output Y6
13. Y7: Output Y7
14. VCC: Positive supply voltage
15. /G2A: Enable input (active low)
16. /G2B: Enable input (active low)

Functional Features

The 74ACT138SCX offers the following functional features:

• Decodes three binary inputs (A0, A1, A2) into eight mutually exclusive outputs (Y0-Y7).
• The enable inputs (/G1, /G2A, /G2B) control the operation of the decoder/demultiplexer.
• When the enable inputs are active low, the corresponding output is enabled.

Advantages and Disadvantages

Advantages

• High-speed performance with a propagation delay of 5ns.
• Low power consumption.
• High noise immunity.
• Compatibility with TTL input and CMOS output levels.

Disadvantages

• Limited to 3-to-8 line decoding applications.
• Requires additional external components for more complex decoding tasks.

Working Principles

The 74ACT138SCX operates based on the principle of combinational logic. It uses the binary inputs (A0, A1, A2) to select one of the eight outputs (Y0-Y7). The enable inputs (/G1, /G2A, /G2B) control the activation of the decoder/demultiplexer. When an enable input is active low, the corresponding output is enabled, allowing the selected output to reflect the input combination.

Detailed Application Field Plans

The 74ACT138SCX finds application in various fields, including:

1. Address decoding in microprocessors and microcontrollers.
2. Memory selection in digital systems.
3. Data routing and multiplexing in communication systems.
4. Control signal generation in industrial automation.
5. Display panel control in consumer electronics.

Detailed and Complete Alternative Models

Some alternative models to the 74ACT138SCX include:

1. 74HC138: A similar 3-to-8 line decoder/demultiplexer with CMOS technology.
2. CD74AC138: A compatible IC with advanced characteristics and improved performance.
3. SN74LS138: A TTL-compatible decoder/demultiplexer with different voltage requirements.

These alternative models offer similar functionality but may vary in terms of specific characteristics, package types, or voltage ranges.

In conclusion, the 74ACT138SCX is a versatile integrated circuit used for decoding applications. Its high-speed performance, low power consumption, and compatibility with various input/output levels make it suitable for a wide range of digital electronic systems.