Design of Overvoltage Protection Circuit for Linear Adapters

　　The overvoltage protection circuit in a linear adapter is designed to safeguard the connected device from excessive voltage levels. One common approach is to use a voltage comparator - based circuit. The circuit first samples the output voltage of the adapter using a voltage divider network. This sampled voltage is then compared with a reference voltage set by a precision voltage reference.

　　If the sampled voltage exceeds the reference voltage, indicating an overvoltage condition, the comparator outputs a signal. This signal can be used to trigger a switch, such as a metal - oxide - semiconductor field - effect transistor (MOSFET), to disconnect the adapter from the load. Another design may incorporate zener diodes. Zener diodes are connected in parallel with the load. When the voltage exceeds the zener breakdown voltage, the zener diodes conduct, diverting the excess voltage and current away from the load, thus protecting the device.

　　In more advanced designs, microcontroller - based overvoltage protection is employed. The microcontroller continuously monitors the output voltage and can perform more complex operations. For example, it can record the occurrence of overvoltage events, and based on pre - programmed algorithms, it can take different actions such as shutting down the adapter completely or reducing the output voltage gradually.

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