Notes on selecting patch fuse

时间:2019-03-26 丨 预览:295 人次

With the development of highly integrated electronic products such as digital cameras, notebooks, smart phones, and factories, there is an urgent need to adopt full automation to reduce high labor costs in a market environment. SMD fuses are widely used in overcurrent protection applications. However, due to process differences, they have different advantages over plug-in self-recovery fuses. SMD fuses also have some of their own weaknesses.


Some matters need to be paid attention to when selecting the chip fuse:


Hold current. When selecting the model, you need to determine the normal current of the circuit to select the corresponding type of chip fuse. The holding current needs to be equal to the normal working current of the circuit or similar


Action current. When selecting the protected current, the operating current of the chip fuse should be less than or equal to the current that the protected circuit needs to protect.


Withstand voltage value: when selecting the model, the withstand voltage value needs to be higher than the highest voltage of the protected circuit, otherwise there will be burnout protection components or false protection


Action time: Some protected circuits need to be protected within a certain time under a certain current. At this time, it is necessary to consider whether the protection time of the fuse meets the requirements.


Product size: Since chip fuses are generally used in more highly integrated products, it is usually necessary to pay attention to whether the corresponding package can be properly installed on the protected circuit at the time of selection


certified product. If the product certification needs to be exported, it is necessary to consider whether the product has the corresponding certification requirements. For example, exporting to Germany requires TUV's certified chip fuse selection. As a type of overcurrent protector, the selection considerations will be based on different actual applications There is a difference. The application range of the fuse is very wide, and the selection requirements of the chip fuse will be different according to the requirements of the product and the customer.


Working temperature. Self-recovery fuses in the circuit will be affected by the temperature of the working environment to produce a temperature reduction, of course, chip fuses are no exception. Therefore, it is necessary to reduce the use of chip fuses according to the operating environment temperature for degrading.


Ability to withstand pulses and surge currents. Pulses, surge currents, surge currents, starting currents, etc. in the circuit will have transient values. This is because this transient is worth the time and size. Since the small size of the chip fuse is limited by industry, it is necessary to consider whether it can withstand the surges and pulses that occur in the circuit.


But the above points need to pay attention to at any time in the selection. In short, whether it is the selection of chip fuse pptc or the selection of chip fuse at a time, it is necessary to combine the theory and the actual situation to select the most suitable product.