IC 4047 – Monostable/Astable Multivibrator

Overview

The IC 4047 – Monostable/Astable Multivibrator is a versatile CMOS integrated circuit that functions as a monostable or astable multivibrator. This dual-purpose IC is widely used in timing, pulse generation, and oscillator circuits. Its low power consumption, high noise immunity, and wide operating voltage range make it ideal for a variety of applications in both digital and analog circuits.

Features

• Monostable and Astable Operation: The IC can be configured to work in either monostable (one-shot) or astable (free-running oscillator) modes.
• Wide Operating Voltage: Operates from 3V to 15V, allowing compatibility with various power supply systems.
• High Noise Immunity: Designed using CMOS technology, which ensures robustness against noise.
• Low Power Consumption: Consumes minimal power, making it suitable for battery-powered applications.
• Long Time Delays: Capable of generating long time delays in monostable mode, with delay periods determined by external components (resistor and capacitor).
• Complementary Outputs: Provides both Q and ~Q (inverted) outputs, which are useful in various timing and control applications.
• Adjustable Duty Cycle: In astable mode, the duty cycle can be adjusted by selecting appropriate external resistor and capacitor values.
• Package Type: Available in DIP (Dual In-line Package) and SOP (Small Outline Package).

Pin Configuration

• Pin 1: Astable/Monostable selection pin. Connect to Vcc for astable mode, or to GND for monostable mode.
• Pin 2: External resistor connection pin (Rx) for timing control.
• Pin 3: External capacitor connection pin (Cx) for timing control.
• Pin 4: Discharge pin (externally controlled).
• Pin 5: External control voltage pin.
• Pin 6: Trigger input for starting the timing process in monostable mode.
• Pin 7: Ground (GND).
• Pin 8: Trigger input (negative edge trigger).
• Pin 9: Complementary output (~Q).
• Pin 10: Output (Q).
• Pin 11: Retrigger input (monostable mode).
• Pin 12: Vcc (Power Supply).

Applications

• Oscillator Circuits: Used to generate square waves for clock pulses, signal generation, and timing applications.
• Pulse Generation: Generates precise timing pulses in monostable mode, useful in timers, delay circuits, and pulse-width modulation (PWM).
• Frequency Divider: Can be configured to divide the frequency of an input signal, useful in digital clocks and counters.
• Timer Circuits: Ideal for creating time delay circuits in various applications such as alarms, blinkers, and automotive systems.
• Tone Generation: Used in audio applications for tone generation, such as in sirens, alarms, and sound effects.
• Signal Conditioning: Employed in conditioning and shaping signals in communication and control systems.

Working Principle

The IC 4047 operates in two modes: monostable and astable. In monostable mode, a trigger pulse at the input initiates a single output pulse with a duration determined by the external resistor (Rx) and capacitor (Cx). The output pulse remains high for the calculated time period and then returns to low until the next trigger pulse.

In astable mode, the IC generates a continuous square wave output, oscillating between high and low states. The frequency and duty cycle of the output waveform are determined by the values of the external resistor and capacitor connected to the timing pins.

Advantages

• Versatility: Can operate in both monostable and astable modes, making it useful in a wide range of timing and oscillator applications.
• Long Time Delays: Capable of generating long time delays, which are useful in various timing circuits.
• Complementary Outputs: Provides both normal and inverted outputs, offering flexibility in circuit design.
• Low Power Consumption: Efficient power usage, which is crucial for portable and battery-operated devices.
• High Noise Immunity: Robust against electrical noise, ensuring stable operation in noisy environments.

Example Circuit

• Monostable Mode: To use the IC 4047 in monostable mode, connect pin 1 to ground. Apply a trigger pulse to pin 6, and the output at pin 10 will produce a single pulse with a duration determined by the external resistor and capacitor.
• Astable Mode: To use the IC in astable mode, connect pin 1 to Vcc. The IC will generate a continuous square wave at the output, with the frequency determined by the external timing components.

The IC 4047 is an essential component for designers and engineers looking to implement reliable and versatile timing and oscillator circuits in their projects. Whether for generating clock signals, creating time delays, or controlling frequency, this IC offers a robust and flexible solution.

Monostable Multivibrator with IC 555 Timer Circuit