The optocoupler function of TD1018 TD1019 optocoupler in general switch power supply circuits

The optocouplers TD1018 and TD1019 mainly serve as isolation and feedback switches in the switching power supply. The power supply of the optocoupler in the switching power supply circuit is provided by the secondary voltage of the high-frequency transformer. When the output voltage is lower than the voltage of the voltage regulator, the signal optocoupler is turned on to increase the duty cycle, causing the output voltage to rise; On the contrary, turn off the optocoupler to reduce the duty cycle, resulting in a decrease in output voltage. Once the secondary load of the high-frequency transformer is overloaded or there is a fault in the switch circuit, there will be no optocoupler power supply, and the optocoupler will control the switch circuit to not vibrate, thereby protecting the switch tube from being broken down and burned out.