App-Notes » Circuit Design » CD4047 Pinout, Astable and Monostable Multivibrator Circuits Explained

CD4047 Pinout, Astable and Monostable Multivibrator Circuits Explained

circuit design oscillator component multivibrator application

The CD4047 is a versatile monostable/astable multivibrator integrated circuit commonly used in timing and oscillator applications. It offers low power consumption, high noise immunity, and operates in two primary modes: monostable (one-shot pulse generator) and astable (free-running oscillator).

Features of CD4047

  • Operating Voltage: Wide voltage range, typically 3V to 15V.
  • Low Power Consumption: CMOS technology ensures low power consumption.
  • Modes: Can be configured as either a monostable or an astable multivibrator.
  • Stable Operation: Highly stable frequency and pulse width due to external resistor-capacitor (RC) timing network.
  • Output Signals: Provides two complementary outputs, Q and Q’ (Q-bar).
  • Frequency Adjustment: The output frequency in astable mode and pulse width in monostable mode can be easily controlled with external resistors and capacitors.

CD4047 Pinout Diagram

The figure-1 depicts CD4047 pinout diagram.

CD4047 pin diagram

As shown, the CD4047 IC is a 14-pin IC with the pin configuration mentioned in the table.

Pin numberDescription
1External R
2External C
3RC common
4Astable Low
5Astable High
6Trigger-
7Vss
8Trigger+
9Ext Reset
10Q (High)
11Q’ (Low)
12Retrigger
13OSC OUT
14VDD

CD4047 Multivibrator Circuit

  • In astable mode, the CD4047 acts as an oscillator, continuously switching between high and low states at a frequency determined by an external resistor (R) and capacitor (C). It generates a continuous square wave without any external trigger.

  • In monostable mode, the CD4047 generates a single pulse of a specific duration when triggered. The pulse width depends on the external RC components and lasts for a time (T) after the trigger, then returns to the inactive state until retriggered.

Application: LED Flasher in Astable Mode

  • Description: The CD4047 can be set up as an astable multivibrator to flash an LED at a specific frequency.

  • Configuration: Connect the Astable pin high, choose appropriate values for R and C, and connect the LED to the Q output pin.

  • Outcome: The LED blinks at the frequency set by the RC network, creating a simple visual signal that can be used in indicators or decorative lights.

Conclusion

The CD4047 is highly suitable for both timing and pulse generation applications due to its flexible multivibrator functionality and stable performance across a wide voltage range.