LM393 is a commonly used op amp chip, the most important purpose is to be used as a voltage comparator.
What is a voltage comparator, is to compare the voltage of two inputs is the same. This feature is very useful, almost no electrical appliances around us do not use this function. For example, the charger, now the charger is a smart charger, what is smart, one is full of electricity, it automatically breaks off, no longer charged. Second, people can automatically carry out trickle charging, charging to a certain extent automatically stop. So you don't have to worry about the charge blowing up. There is a temperature protection device, many chips or electronic modules now have a temperature protection module, there is a temperature sensor in the module, the temperature sensor will change the temperature into a voltage change, when the voltage exceeds the given voltage, it will automatically cut off the circuit.