CD74HCT138E

Product Overview

• Category: Integrated Circuit (IC)
• Use: Decoder/Demultiplexer
• Characteristics: High-speed, CMOS logic, 3-to-8 line decoder/demultiplexer
• Package: DIP (Dual In-line Package)
• Essence: Converts a binary input into a corresponding output line
• Packaging/Quantity: Available in tubes of 25 pieces or reels of 2,000 pieces

Specifications

• Supply Voltage Range: 4.5V to 5.5V
• Input Voltage Range: 0V to VCC
• Output Voltage Range: 0V to VCC
• Maximum Operating Frequency: 25 MHz
• Number of Inputs: 3
• Number of Outputs: 8
• Propagation Delay Time: 15 ns (typical)

Detailed Pin Configuration

The CD74HCT138E has a total of 16 pins. The pin configuration is as follows:

1. GND (Ground)
2. A0 (Input A0)
3. A1 (Input A1)
4. A2 (Input A2)
5. E1 (Enable Input 1)
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. E2 (Enable Input 2)
15. VCC (Positive Power Supply)
16. GND (Ground)

Functional Features

• Decodes a 3-bit binary input into one of the eight outputs
• Enables cascading multiple devices for larger decoding applications
• High-speed operation suitable for time-critical applications
• CMOS logic ensures low power consumption and compatibility with other ICs

Advantages and Disadvantages

Advantages: - High-speed operation allows for quick decoding of input signals - Low power consumption due to CMOS technology - Can be easily cascaded for larger decoding requirements

Disadvantages: - Limited to 3-bit binary inputs, not suitable for higher bit decoding - Requires external enable inputs for proper functioning

Working Principles

The CD74HCT138E is a decoder/demultiplexer IC that converts a 3-bit binary input into one of the eight corresponding output lines. The inputs A0, A1, and A2 determine which output line will be active based on the binary value applied. The enable inputs E1 and E2 control the overall operation of the device.

When the enable inputs are active (typically high), the decoder is enabled, and the selected output line becomes active based on the binary input. When the enable inputs are inactive (typically low), all output lines are in a high-impedance state.

Detailed Application Field Plans

The CD74HCT138E can be used in various applications where decoding or demultiplexing of binary inputs is required. Some potential application fields include:

1. Address Decoding: Used in microcontrollers and memory systems to decode address lines and select specific memory locations.
2. Data Routing: Enables selection of specific data paths in multiplexed systems, such as communication switches or data selectors.
3. Display Control: Used in combination with display drivers to control multiple segments or digits in numeric displays.
4. Signal Demultiplexing: Allows routing of different signals based on the input binary code, useful in communication systems and signal processing.

Detailed and Complete Alternative Models

1. SN74LS138N: Similar 3-to-8 line decoder/demultiplexer IC with TTL logic levels.
2. CD74HC238E: 3-to-8 line decoder/demultiplexer IC with high-speed CMOS logic and active-low outputs.
3. 74HC138: Another popular 3-to-8 line decoder/demultiplexer IC with similar specifications.

These alternative models provide similar functionality to the CD74HCT138E and can be used as replacements based on specific requirements.

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