PPTC resettable fuse is a positive temperature coefficient polymer thermistor. It is used for overcurrent protection and can replace current fuse. When the circuit is working normally, its resistance value is very small (the voltage drop is very small). When the circuit overcurrent causes its temperature to rise, the resistance value increases sharply by several orders of magnitude, so that the current in the circuit decreases below the safe value. As a result, the circuit behind is protected, and it automatically recovers to a low resistance value after the overcurrent disappears. The effect is similar to the switching element, but the response speed is slower. So what are the applications of PPTC resettable fuses in automobiles?
PPTC self-recovery fuse protects car cigarette lighter circuit:
Car cigarette lighters usually need to adapt to more demanding application environments, so they are also prone to various abnormal conditions, such as overcurrent and other problems. When the cigarette lighter circuit is used as a charging power source for a mobile phone, improper use (such as excessive load, reverse electrode connection, load short circuit, etc.) may damage the cigarette lighter circuit or damage the charging circuit. Use a one-time fuse for protection. The fuse needs to be replaced after a failure. This is difficult for ordinary users. If you use SOCAY PPTC fuse for overcurrent protection, you can implement protection when a failure occurs, and at the same time, the failure Automatic recovery after elimination, has the advantage of not requiring frequent replacement.
PPTC resettable fuse to protect the power supply system of automobile windows:
The power supply system of the car window needs to bear a large current, so it needs a thicker wire, otherwise there will be a risk of the wire overheating or even burning. Inserting the PPTC fuse of SOCAY in the line can reduce the diameter of the wire and ensure the safety of the line. The increase in line resistance will not affect the speed of the window switch and the pressure of the window. This can greatly reduce the cost of the power supply system of the window.
When a circuit designer selects a self-recovery fuse for an overcurrent device, it should be considered from two aspects: static and dynamic. Static refers to voltage, current, ambient temperature, size, failure current, etc .; dynamic refers to fusing time, melting heat energy value, etc. These are the key points in the selection and design of fuse products. Secondly, after the theoretical calculation of the fuse, it is necessary to combine the field test and verification, and finally reach the ideal design plan with the help of reliability analysis. Shuokai Electronics EMC Lab supports automotive electronics ISO7637 5a / 5b load dump impact test.