SN74LS221D

Product Overview

• Category: Integrated Circuit (IC)
• Use: Dual Monostable Multivibrator
• Characteristics:
  • TTL (Transistor-Transistor Logic) technology
  • Low power consumption
  • High-speed operation
  • Wide operating voltage range
• Package: DIP (Dual In-line Package)
• Essence: Reliable and versatile IC for timing applications
• Packaging/Quantity: Available in tubes of 25 or reels of 2000 units

Specifications

• Supply Voltage Range: 4.75V to 5.25V
• Operating Temperature Range: 0°C to 70°C
• Propagation Delay Time: 15 ns (typical)
• Trigger Pulse Width: 30 ns (minimum)
• Reset Pulse Width: 20 ns (minimum)
• Output Current: ±8 mA
• Power Dissipation: 500 mW (maximum)

Detailed Pin Configuration

The SN74LS221D has a total of 16 pins, which are assigned as follows:

1. CLR (Clear)
2. A (Trigger Input A)
3. B (Trigger Input B)
4. REXT (External Resistor)
5. CEXT (External Capacitor)
6. VCC (Positive Power Supply)
7. Q (Output)
8. GND (Ground)
9. Q (Complementary Output)
10. Q (Complementary Output)
11. Q (Complementary Output)
12. Q (Complementary Output)
13. Q (Complementary Output)
14. Q (Complementary Output)
15. Q (Complementary Output)
16. Q (Complementary Output)

Functional Features

• Dual monostable multivibrator with independent trigger inputs
• Produces a pulse at the output upon receiving a trigger signal
• Adjustable pulse width using external resistor and capacitor
• Non-retriggerable operation ensures a single output pulse per trigger event
• Schmitt-trigger inputs provide noise immunity

Advantages and Disadvantages

Advantages: - TTL technology offers high-speed operation - Wide operating voltage range allows compatibility with various systems - Low power consumption makes it suitable for battery-powered devices - Reliable performance and long lifespan - Versatile timing applications

Disadvantages: - Limited number of complementary outputs - Not suitable for applications requiring precise timing control

Working Principles

The SN74LS221D operates as a dual monostable multivibrator. When a trigger signal is applied to either input A or B, the corresponding output Q produces a pulse of adjustable width. The pulse width is determined by the values of the external resistor (REXT) and capacitor (CEXT) connected to the IC. The output pulse remains active for a duration determined by the RC time constant.

Detailed Application Field Plans

The SN74LS221D finds applications in various fields, including:

1. Timing circuits: Used to generate precise time delays in digital systems.
2. Pulse shaping: Converts irregular input pulses into well-defined output pulses.
3. Frequency division: Utilized in frequency divider circuits to divide the input frequency by a specific factor.
4. Control systems: Provides timing signals for controlling sequential operations.
5. Communication systems: Used in data transmission and reception circuits for synchronization purposes.

Detailed and Complete Alternative Models

1. CD74HC221E: High-Speed CMOS Logic Dual Monostable Multivibrator
2. MC14528B: Dual Monostable Multivibrator with Schmitt-Trigger Inputs
3. 74HCT123D: Dual Retriggerable Monostable Multivibrator

These alternative models offer similar functionality and can be used as substitutes for the SN74LS221D in various applications.

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