What types of output overvoltage protection circuits are there for switching power supplies?

Switch Mode Power Supply (SMPS), also known as switching power supply and switching converter, is a high-frequency power conversion device and a type of power supply. Its function is to convert a level of voltage into the voltage or current required by the user through different forms of architecture. The following is an introduction to two output overvoltage protection circuits of switching power supplies.

Output overvoltage protection circuit 1

1. Overview (circuit category, description of main functions implemented):

Output overvoltage protection circuit. This circuit will clamp the output voltage at the set value when an external voltage higher than the normal output voltage range is applied to the output terminal or a fault in the circuit itself (open loop or other) causes the output voltage to be higher than the regulated value.

2. Circuit composition (schematic diagram):

3. Working principle analysis (main functions, performance indicators and implementation principles):

When the output is overvoltage, when the voltage applied to VD3 is greater than its regulated value, VD3 is turned on, the output voltage is clamped, and at the same time it is fed back to the primary side through IC4.

Output overvoltage protection circuit 2

1. Overview (circuit category, description of main functions implemented):

Output overvoltage protection circuit. This circuit will stabilize the output voltage at the set value when an external voltage higher than the normal output voltage range is applied to the output terminal or a fault in the circuit itself (open loop or other) causes the output voltage to be higher than the normal value.

2. Circuit composition (schematic diagram):