Description

The 74147 10-Line to 4-Line Priority Encoder is a versatile TTL logic IC designed for encoding multiple inputs into a smaller set of outputs based on priority. This IC accepts 10 active LOW inputs (0–9) and encodes them into 4-bit binary output, ensuring that the highest-priority active input is represented at the output. Housed in a 16-pin Dual Inline Package (DIP), the 74147 is widely used in digital keyboards, keypad scanning, microcontroller interfaces, and priority-based signal processing systems.

Priority encoders are crucial in digital electronics where simultaneous input signals may occur, but only the highest-priority signal needs to be transmitted. The 74147 simplifies circuit design by reducing multiple input lines into fewer outputs, minimizing wiring complexity while maintaining accurate encoding for digital systems.

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⚙️ Key Features:

• Function: 10-Line to 4-Line Priority Encoder (active LOW inputs)

• Logic Family: TTL

• Inputs: 10 active LOW inputs (0–9)

• Outputs: 4-bit binary outputs (A, B, C, D) representing highest-priority input

• Active Low Inputs: Each input is LOW to be considered active

• Priority Function: Highest-numbered active input is encoded

• Operating Voltage: 4.75V – 5.25V (TTL standard)

• Low Power Consumption: Efficient for digital systems

• Standard 16-Pin DIP Package: Easy breadboarding and PCB integration

• Carry Out/Enable: Can be used for cascading additional encoders

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🧩 Pin Configuration (16-Pin DIP):

This configuration allows efficient encoding of up to 10 input lines into a compact 4-bit output, with priority handling ensuring reliable output when multiple inputs are active.

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⚡ Electrical Characteristics:

• Supply Voltage (VCC): 5V TTL standard

• Input High Voltage (VIH): ≥ 2V

• Input Low Voltage (VIL): ≤ 0.8V

• Output High Voltage (VOH): ≥ 2.4V

• Output Low Voltage (VOL): ≤ 0.4V

• Propagation Delay: ~25 ns typical

• Power Dissipation: ~50 mW

The TTL design ensures fast, reliable encoding suitable for digital keypad interfaces, microcontroller inputs, and sequential logic systems.

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🧠 How It Works:

The 74147 IC encodes up to 10 active LOW inputs into a 4-bit binary output, with priority handling as follows:

• Highest-Numbered Active Input: The IC outputs the binary code corresponding to the highest-priority input

• Active LOW Inputs: Input is considered active when LOW, making it compatible with many push-button and switch circuits

• Carry Output / Enable: Can be used to cascade additional 74147 ICs for larger input systems

• Outputs (A–D): Represent the encoded value of the highest-priority input in binary form

This design simplifies multi-input systems and ensures deterministic behavior when multiple keys or signals are pressed simultaneously.

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🛠️ Applications:

• Keypad and Keyboard Encoding – Convert multiple button presses into 4-bit binary codes

• Microcontroller Interfaces – Reduce required input pins by encoding multiple signals

• Digital Priority Systems – Encode highest-priority input in decision-making circuits

• Signal Multiplexing – Combine multiple inputs into compact outputs for digital systems

• Counters and Data Acquisition – Encode signals from sensors or switches efficiently

• Educational Electronics Kits – Demonstrate priority encoding and digital logic

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💡 Advantages:

• Encodes 10 inputs into 4-bit output efficiently

• Priority handling ensures reliable output when multiple inputs are active

• TTL design for fast switching and easy integration

• Reduce component count and wiring complexity

• Supports cascading for larger input systems

• Standard 16-pin DIP for breadboard and PCB use

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📦 Package Includes:

• 1 × 74147 10-Line to 4-Line Priority Encoder IC (DIP-16)

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📘 Conclusion:

The 74147 DIP 10-Line to 4-Line Priority Encoder is a high-speed, reliable IC for encoding multiple active-low inputs into a 4-bit binary output with priority handling. Ideal for keypad interfaces, microcontroller systems, digital logic, and educational applications, it provides a compact, efficient, and versatile solution for modern TTL-based electronics.