The network TV converter is a necessary equipment for watching network TV, which is increasingly favored by young people. However, due to the transmission of network signals through coaxial cables and long-distance communication, there are safety issues in applications such as installation wiring errors, short circuits, ESD damage, induced high voltage damage, lightning damage, etc. It is necessary to design overcurrent protection and overvoltage protection, To ensure the service life and reliability of network TV converter equipment.
Among various protection circuits, the protection circuit with the least components, the lowest cost, and the highest reliability is the PTC self recovery fuse element and the circuit that PTC cooperates with varistors or TVS tubes.
PTC self recovery fuse, also known as ten thousand fuse or self reset overcurrent protector, is also known as polymer polymer switch. In general, a PTC overcurrent protector can be combined with a varistor or TVS tube. Connect a PTC in series at the input port of the network TV converter and then connect a varistor or TVS in parallel. In case of a short circuit or high voltage surge, the varistor or TVS tube will conduct, and a large current will pass through the PTC, rapidly increasing the resistance value of the PTC to the current limiting protection varistor or TVS tube, thus protecting the entire system circuit. When the power is cut off or the fault disappears, the PTC will automatically recover and become a normal working state with low resistance, This scheme has been applied and validated for a long time and is currently the best protection scheme
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