Input over-voltage protection circuit of switching power supply based on UC3842

In order to achieve input over-voltage protection function of the UC3842 a switching power supply, which allows a power supply to avoid potential safety problems, the inherent UC3842 chip voltage reference voltage source and the TL431 are used in the design of electrical specifications which meet the requirements of normal use conditions. A relatively low pressure switch is chosen and is designed a simple structure of circuit with low-cost, innovative and practical input over-voltage protection circuit. Case analysis and experimental results show the feasibility of the protection circuit.