As a professional distributor of circuit protection components for 18 years, FAE on-site electronic engineers are most exposed to the application of electronic components and circuit design technical solutions, and have a good command of the types, uses, selection and precautions of electronic components. However, for new electronic engineers or purchasers, there must be a hard and time-consuming learning process. Resettable fuse, one of the common circuit protection components, looks strange and professional. But in daily life, you can find the beautiful image of resettable fuses, such as the protection of battery charger, main control IC, input/output interface protection, audio circuit protection, CPU protection, etc.
How much do you know about resettable fuses? Recently, it has been found that more buyers are coming to Richpower technology consulting than ever before. Most of them come to seek help with various questions and technical problems. Jingruipu technology, for the majority of buyers' questions and problems, summarized the next, hope to help you in the confusion!
What is the difference between resettable fuse PTC and common fuse, ceramic Resettable fuse and other overcurrent protection devices?
The biggest difference between PPTC and ordinary fuse lies in its resettable characteristic, both of which can provide over-current protection. Once the common fuse is blown, it must be replaced to ensure the line's normal operation. At the same time, PPTC has the self resettable feature, which can provide many times of over-current protection. Both PPTC and PTC fuse belong to the resettable type. The main difference lies in their initial resistance, reaction time and size. In which case, PPTC, ordinary fuse, or ceramic PTC self resettable fuse should be considered according to the actual circuit protection solution and customer demand point.
Is the resettable fuse aging?
A procurement and R & D Engineer asked the FAE electronic engineer of Richpower Technology: "will the self resettable fuse age? When the number of over-current protection reaches a certain number, will its function degrade? Under what conditions will failure occur? "
PPTC material itself is not easy to aging. The resettalbe fuse device's aging phenomenon is closely related to the junction between metal electrodes at both ends of the device and PPTC material. Brand DTE of Shenzhen Richpower Technology Technology Co., Ltd PPTC R & D team has been engaged in famous brand B in the United States for 20 years. The polymer chemical formula, experiment, packaging, testing, production, and sales strictly follow the world's highest standards for production and manufacturing. It has a strict quality control system to ensure that the function of PPTC will not deteriorate under the harsh environment of 85 ℃ and 85% relative humidity. However, the resistance value of PPTC will be higher than the initial resistance when it experiences multiple actions. When the resistance value is greater than the maximum action resistance, failure mode, function degradation, or short circuit will occur. The failure of PPTC is related to many operation times; the voltage exceeds the rated working voltage, the fault current exceeds the rated action current, and lasts for a long time.
How to select the type of resettable fuse?
In the face of a wide variety of models of self resettable fuse, which is the best choice? Resettable fuse, selection has always been one of the classic topics in the electronic industry. On the way of PPTC selection, the six steps of Richpower Technology are accompanied, and there is always a suitable model for you.
1) Determined parameters: standard working current, maximum working voltage, maximum fault current, and maximum working environment temperature;
2) With the help of the temperature reduction table, the PPTC which can adapt to the maximum working environment temperature and standard working current is determined;
3) Verify the maximum electrical rating of the resettable fuse selected in step 2 using the electrical characteristic table, and compare it with the maximum working voltage and fault current of the circuit;
4) Determine the action time: to provide a better protection effect for the circuit, it is essential to define the working time of PPTC;
5) Verify the ambient working temperature; ensure that the minimum and the maximum ambient temperature of the application is within the working temperature range of PPTC;
6) Determine the overall dimensions of PPTC: compare the overall dimensions of PPTC with the application space with the outline dimension table's help.
