The four major protection functions of power adapters

Overvoltage protection: When the output voltage exceeds the set value, the power adapter will automatically cut off the output to prevent excessive voltage from damaging the connected electronic device. Overvoltage protection is usually implemented by a circuit composed of components such as comparators and voltage regulator tubes. For example, when the output voltage of the power adapter rises to 15V for some reason and the set overvoltage protection threshold is 12V, the protection circuit will act quickly to cut off the output and protect the safety of the device.

Overcurrent protection: When the output current exceeds the rated value, the power adapter will limit the output current or cut off the output to prevent excessive current from damaging the internal circuit or the connected device. Overcurrent protection can be implemented by means of fuses, current-limiting resistors, current detection chips, and other methods. For example, when a device short-circuits or is overloaded, the output current increases sharply and exceeds the rated current of the power adapter. At this time, the overcurrent protection circuit will start quickly to limit the output current within a safe range or cut off the output.

Overtemperature protection: The power adapter will generate heat during operation. If the temperature is too high, internal components may be damaged. The overheat protection function can detect the temperature of the power adapter through a temperature sensor. When the temperature exceeds the set value, the output power will be automatically reduced or the output will be cut off to prevent overheating damage. For example, some power adapters are integrated with thermistors. When the temperature rises to a certain extent, the resistance value of the thermistor will change and trigger the protection circuit to act.
Short-circuit protection: When a short circuit occurs at the output end, the power adapter will immediately cut off the output to prevent excessive current from damaging the internal circuit. Short-circuit protection is usually implemented by components such as fast fuses and electronic switches. For example, when the output line is accidentally short-circuited, the short-circuit protection circuit will respond within a few microseconds and cut off the output to protect the power adapter and the connected device.