What Is The Difference Between LM324 And LM393? 4 Characteristics Compared

The LM324 is an operational amplifier used for amplification and analog signal processing. On the other hand, the LM393 is a voltage comparator used for comparing two input voltages and providing a digital output. 

In this article, we will see the detailed description of various differences between LM324 and LM393.

Differences Between LM324 And LM393

Here are the key differences between LM324 and LM393:

1. LM324 And LM393 Pinouts With Op-amp Blocks

The LM324 is a widely used quad operational amplifier (op-amp) integrated circuit (IC) that performs mathematical operations like addition, subtraction, multiplication, and division on input signals. The LM324 contains four separate op-amps within a single package. 

The LM324 op-amp is known for its low cost, simplicity, and general-purpose functionality. It is often used in a variety of applications such as amplification, signal conditioning, filtering, voltage comparison, and more. Each op-amp inside the LM324 has its inputs (inverting and non-inverting), an output, and power supply pins.

Figure: Pinout of LM324.

The LM393 is an integrated circuit (IC) known as a voltage comparator. It’s designed to compare two input voltages and provide a digital output based on their relationship. When one input voltage is higher than the other, the output is typically high; otherwise, it’s low. 

This makes it useful in applications like level detection, zero-crossing detectors, and digital control based on voltage thresholds. The LM393 often includes features like hysteresis to reduce noise and operates over a wide range of supply voltages. It’s commonly used in electronic circuits for decision-making tasks.

Figure: Pinout of LM393.

2. Internal Circuitry Differences Between LM324 And LM393

• The LM324 is primarily composed of four operational amplifiers (op-amps) within a single package. But the LM393 is fundamentally a voltage comparator, not an op-amp.
• Each op-amp of LM324 consists of multiple transistors, resistors, and other components that create a circuit designed for analog signal amplification and processing. LM393 consists of comparators, not amplifiers. These comparators are designed for binary voltage comparisons, not continuous amplification.
• The internal circuitry of the LM393’s comparators includes transistors and other components optimized for comparing two input voltages and providing a digital output. Whereas op-amps like those in the LM324 require biasing and compensation circuitry to ensure stable and linear operation.
• Compensation circuitry typically includes components like capacitors and resistors to optimize the op-amp’s bandwidth and stability in LM324. LM393 has hysteresis built-in to prevent rapid oscillation near the voltage threshold.
• Op-amps in the LM324 typically have differential input stages that allow for precise voltage amplification and signal processing. Unlike op-amps that provide analog output voltages, the LM393’s comparators generate digital output states (HIGH or LOW) based on the comparison result.

3. Input Bias Current Vs Power Supply Voltage Of LM324 and LM393

For the LM324 operational amplifier, IIB is relatively independent of Vcc within the specified voltage range. Over a wide range of Vcc values, the IIB remains relatively constant. This means that the input bias current of the LM324 is not significantly affected by changes in the supply voltage.

Figure: Input Bias Current vs Power Supply Voltage of LM324.

Similar to the LM324, the input bias current (IIB) of the LM393 voltage comparator is relatively constant over its specified voltage range. Changes in Vcc typically do not significantly impact the IIB of the LM393.

Figure: Input Bias Current vs Power Supply Voltage of LM393.

4. Power Supply Current Vs Power Supply Voltage Of LM324 and LM393

The Icc of the LM324 operational amplifier tends to increase with increasing Vcc, although the rate of increase may not be linear. As Vcc increases, the internal transistors and other components may draw more current to maintain their operation and drive the output to the desired levels.

Figure: Power Supply Current vs Power Supply Voltage of LM324.

Similar to the LM324, the Icc of the LM393 voltage comparator also tends to increase with increasing Vcc. The relationship between Icc and Vcc for the LM393 depends on the specific operation of its comparators and other internal circuitry.

Figure: Power Supply Current vs Power Supply Voltage of LM393.

FAQs – Frequently Asked Questions and Answers

What is the maximum voltage for LM393?

The maximum supply voltage (Vcc) for the LM393 dual comparator is typically around 36 volts. However, this can vary depending on the specific variant and manufacturer.

Is the LM393 analog or digital?

The LM393 is an analog integrated circuit. Specifically, it is a dual voltage comparator. Comparators are analog devices used to compare two input voltages and produce a digital output based on the comparison result.

Is LM324 good for audio?

It has very noisy crossover distortion which can be visible at 60 Hz. So, the LM324 is not a good choice for audio applications.

Conclusion

The main difference between LM324 and LM393 lies in their functionality and use cases. Their distinct characteristics make them suitable for different types of electronic circuits and applications. The LM324 is more suitable for analog signal processing and the LM393 for digital voltage comparisons.