LM324 Comparator
The LM324 operational amplifier IC can be worked as a comparator. This IC has 4 independent operational amplifiers on a single chip. This a Low Power Quad Operational Amplifier and it has high stability, bandwidth which was designed to operate from a single power supply over a wide range of voltages. The quad amplifier can operate at supply voltages as low as 3.0 V or as high as 3.2 V with quiescent currents about one fifth of those associated with the MC174.
The common mode input range includes the negative supply, thereby eliminating the necessity for external biasing components in many applications. The output voltage range also includes the negative power supply voltage. please follow the link to know more about different types of comparators and their applications. Different types of comparators and their applications.
What is a Comparator?
The comparator is a circuit and it is used to compare the two output voltages of V1 & V2. If the voltage V1 > V2 then the output voltage is zero. If the V2 > V1 then the output voltage is a positive terminal. The symbol of the comparator is shown below.
Symbol of Comparator
LM324 Comparator
The LM324 comparator circuit consists of sensor voltage, reference voltage, Vcc, ground and output pins. The following circuit shows the LM324 IC circuit and here we are explaining about the each pin of LM324 comparator.
LM324 Comparator
Pin Diagram of LM324 Comparator
The following diagram shows the pin configuration of the LM324 comparator circuit. It consists of 14 pins and the function of each pin is described below.
| Pin No. | Function of the Pin |
| 1 | Output of the first comparator |
| 2 | Inverting input of the first comparator |
| 3 | Non-inverting input of the first comparator |
| 4 | Supply voltage 5V |
| 5 | Non-inverting input of the second comparator |
| 6 | Inverting input of the second comparator |
| 7 | Output of the second comparator |
| 8 | Output of the third comparator |
| 9 | Inverting input of the third comparator |
| 10 | Non-inverting input of the third comparator |
| 11 | Ground |
| 12 | Non-inverting input of the fourth comparator |
| 13 | Inverting input of the fourth comparator |
| 14 | Output of the fourth comparator |
Comparator Circuit Using LM324
The following circuit shows the Voltage comparator, the components required for this circuit is the LM324 comparator and the two resistors with a value of 10K ohms. The two inputs like input A and input B are from the output of the line sensor circuit and the two resistors are used to set the voltage reference to produce the best digital output.
Comparator Circuit Using LM324
From the above circuit, we can observe that Node A & Node B, they are connected to the non-inverting input of left and right comparators. The output of the left comparator is connected to P1.0 of the Microcontroller and output of the right comparator is connected to P1.1 of the Microcontroller. Both the comparators are wired in non-inverting mode.
Working of LM324 Comparator
The working of the LM324 comparator circuit consists of three comparators of LM324 and some other components like resistors, capacitors, and ground. The working of this comparator is explained by using the following circuit by simple steps.
Working of LM324 Comparator
- When the power is applied to the non-inverting terminal which is less than the inverting voltage of the op-amp then the output becomes zero which means there is no current flow. Because we already know that when “+ > – = 1”. Here the ‘+ ‘sign indicates non-inverting terminal and ‘-‘ sign indicates the inverting terminal.
- If the non-inverting voltage is greater than the inverting voltage then the output will be high.
- In this output of LM324 is internally connected to some resistance and it has some arrangement inside the IC, which makes a lot of difference to other comparators.
- It is internally pulled-up, so no need of any resistor connection of the power supply.
Features of LM324 Comparator Circuit
- Internally frequency compensated for unity gain
- Large DC voltage gain 100 dB
- Wide bandwidth 1 MHz
- Wide power supply range: Single supply 3V to 32V
- Essentially independent of supply voltage
- Differential input voltage range equal to the power supply voltage
- Large output voltage swing 0V to V+ − 1.5V
Advantages of LM324 Comparator
- The LM324 is used as both like comparator and op-amp
- LM324 is a high-gain electronic voltage amplifier
Please refer to this link to know about Comparator MCQ
Applications of LM324 Comparator
- The LM324 comparator is generally used in the line following robot
- The applications of conventional op-amp can easily be implemented by using the LM324
- The LM324 is applicable for the oscillators, amplifiers, rectifiers, comparators etc.
In this article we have discussed the LM324 comparator circuits, working and its applications. I hope by reading this article you have gained some basic information on LM324 comparator.
If you have any queries about this article or about the implementation of the Electronics & Electrical projects please don’t hesitate to comment in the below section. Here is the question for you, what is the difference between LM324 and LM339?