SN74LS138DR

Product Overview

Category

SN74LS138DR belongs to the category of integrated circuits (ICs).

Use

It is commonly used as a decoder/demultiplexer in digital electronic systems.

Characteristics

• Low-power Schottky (LS) technology
• 3-to-8 line decoding capability
• Active low outputs
• High fan-out (ability to drive multiple inputs)
• Wide operating voltage range: 2V to 6V

Package

SN74LS138DR is available in a small-outline integrated circuit (SOIC) package.

Essence

The essence of SN74LS138DR lies in its ability to decode and demultiplex multiple input signals into separate output lines, enabling efficient data routing in digital systems.

Packaging/Quantity

SN74LS138DR is typically packaged in reels or tubes, with each reel/tube containing a specific quantity of ICs. The exact packaging and quantity may vary depending on the supplier.

Specifications

• Supply Voltage: 2V to 6V
• Input Voltage: 0V to Vcc
• Output Voltage: 0V to Vcc
• Operating Temperature Range: -40°C to +85°C
• Maximum Propagation Delay: 35 ns
• Maximum Power Dissipation: 500 mW

Detailed Pin Configuration

SN74LS138DR has a total of 16 pins, which are assigned specific functions:

1. G1 (Enable Input 1)
2. G2A (Enable Input 2)
3. G2B (Enable Input 3)
4. A (Input A)
5. B (Input B)
6. C (Input C)
7. Y0 (Output 0)
8. Y1 (Output 1)
9. Y2 (Output 2)
10. Y3 (Output 3)
11. Y4 (Output 4)
12. Y5 (Output 5)
13. Y6 (Output 6)
14. Y7 (Output 7)
15. Vcc (Positive Power Supply)
16. GND (Ground)

Functional Features

SN74LS138DR offers the following functional features:

• Decodes three binary inputs (A, B, C) into eight mutually exclusive outputs (Y0-Y7).
• The enable inputs (G1, G2A, G2B) control the operation of the decoder.
• Active low outputs allow easy interfacing with other digital components.

Advantages and Disadvantages

Advantages

• Low-power consumption due to LS technology.
• Wide operating voltage range allows compatibility with various systems.
• High fan-out capability enables driving multiple inputs.
• Compact SOIC package facilitates space-saving designs.

Disadvantages

• Relatively slower propagation delay compared to newer decoder ICs.
• Limited to 3-to-8 line decoding, may not be suitable for more complex applications.

Working Principles

SN74LS138DR operates based on the principle of combinational logic. It uses a combination of AND and NOT gates to decode the input signals and generate the corresponding output signals. The enable inputs control the activation of the decoder, allowing selective routing of data to specific output lines.

Detailed Application Field Plans

SN74LS138DR finds extensive application in various digital systems, including but not limited to: - Address decoding in microprocessors and microcontrollers - Memory selection and expansion - Data multiplexing and demultiplexing - Programmable logic devices - Control circuitry in industrial automation

Detailed and Complete Alternative Models

Some alternative models that offer similar functionality to SN74LS138DR include: - 74HC138: High-speed CMOS version - CD74HC138: High-speed CMOS version with improved noise immunity - 74HCT138: CMOS version with TTL-compatible inputs

These alternative models can be considered based on specific requirements such as speed, power consumption, and compatibility.

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