LM393M Integrated Circuits (ICs)

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LM393M is a low-power differential comparator with offset voltage adjustable, normally used for industrial, commercial and educational testing. It is usually used for switching, amplifier, timer circuits and motor control applications. This application note describes the working principle of the LM393M, as well as its application field.

The Working Principle of LM393M

The LM393M has two pins on the same row and two opposite pins on the row below it. The two pins on the same row are the Non-inverting (+) and Inverting (-) logic pin, and the bottom row pins named Offset Voltage Adjustable. By adjusting the resistance between these four pins, the gain or offset of the LM393M can be adjusted.

The LM393M chip contains two high-speed comparators inside, which monitor two reference voltages. When the Non-inverting input voltage is higher than the Inverting voltage, the output is high and will be relatively low when the non-inverting input is below the Inverting input. The output will change to the opposite state when either the Inverting or non-inverting input voltage increases to a higher voltage than the other one. Furthermore, the output state will not change until the voltage difference between both inputs is larger than the hysteresis level.

Application Field of LM393M

One of the main application fields of the LM393M is internal comparator applications. The chip can be used in amplifier design as a controllable gain element, allowing for wide adjustment. It can also be used for switching, for instance between different levels of amplifier gain. Another example for internal application would be a timer circuit, where the chip can be used to control the speed of the cycle.

External applications are aiding industries in motor control applications and process control. The internal comparator enables amplifiers that can be used in relay driving, inverter controls and pulse width modulation (PWM). The LM393M can detect spikes or over current conditions in 24V industrial circuits and provide a feedback control signal to a microcontroller. Another application can be used in conjunction with an analog to digital converter, where the chip is used to compare the analog input voltage with a reference voltage and determine the Digital Value.

The IC is also used in educational and hobby machines. It is often used as a parking sensor or vibration and shock detector in energy saving automatic doors, lighting and motors. Its adjustable gain and hysteresis makes it suitable for wide variety of applications.

Conclusion

The LM393M is low-power and low-cost differential comparator, capable of providing adjustable gain and Hysteresis. It is especially useful for industrial, commercial and educational testing, providing integrated functions and wide error detection. The output will change states when either of the two inputs surpasses a threshold and will remain steady as long as the voltage difference is in the set hysteresis region.

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