SN74LS21N

Product Overview

• Category: Integrated Circuit (IC)
• Use: Logic Gate
• Characteristics: Dual 4-input Positive-AND Gate
• Package: DIP-14 (Dual In-line Package with 14 pins)
• Essence: The SN74LS21N is a logic gate IC that performs the AND operation on four input signals.
• Packaging/Quantity: Available in tubes or reels, typically containing 25 pieces per package.

Specifications

• Supply Voltage Range: 4.75V to 5.25V
• Input Voltage Range: 0V to VCC
• Operating Temperature Range: -55°C to 125°C
• Propagation Delay Time: 9 ns (typical)
• Output Current: ±8 mA
• Power Dissipation: 500 mW

Detailed Pin Configuration

The SN74LS21N has a total of 14 pins arranged as follows:

+---+--+---+ A1 -|1 +--+ 14|- VCC B1 -|2 13|- C1 A2 -|3 12|- B2 B2 -|4 74LS21N 11|- A3 C2 -|5 10|- B3 GND -|6 9|- C3 C4 -|7 8|- D3 +----------+

Functional Features

• Dual 4-input positive-AND gate functionality.
• High-speed operation with low power consumption.
• TTL (Transistor-Transistor Logic) compatible inputs and outputs.
• Schottky-clamped circuitry for improved noise immunity.
• Open-collector outputs for wired-OR applications.

Advantages and Disadvantages

Advantages: - Versatile logic gate suitable for various digital circuit designs. - High-speed operation allows for efficient data processing. - Low power consumption helps in reducing overall system energy requirements.

Disadvantages: - Limited number of inputs (4) may restrict complex logic operations. - Propagation delay time may affect timing-sensitive applications.

Working Principles

The SN74LS21N operates based on the positive-AND gate principle. It takes four input signals and performs a logical AND operation on them. The output is high only when all four inputs are high; otherwise, the output remains low. The IC utilizes TTL technology, ensuring compatibility with other TTL devices.

Detailed Application Field Plans

The SN74LS21N finds applications in various digital systems, including but not limited to: - Arithmetic circuits - Data processing units - Control systems - Communication devices - Industrial automation

Detailed and Complete Alternative Models

Some alternative models that provide similar functionality to the SN74LS21N include: - 74HC21: Dual 4-input Positive-AND Gate (CMOS technology) - CD4082: Dual 4-input AND Gate (CMOS technology) - MC14081B: Quad 2-input AND Gate (TTL technology)

These alternatives can be considered based on specific project requirements and compatibility with existing circuitry.

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