SMD fuses are new varieties with relatively high technical content in the small fuse industry. SMD fuses can be divided into SMD current fuses and SMD self-recovery fuses. Due to the differences in product technology, the focus of their selection is also slightly different. So how to choose the right chip fuse? Hurry up and find out with the editor!
The selection of chip fuses involves the following factors:
(1) The normal working current of the circuit. The operating current through the fuse should not exceed 75% of the rated current of the fuse.
(2) Pulse, surge current, surge current, starting current and circuit transient value. SMD fuses pay particular attention to this point. Due to the process reasons brought by the small size, the impact resistance of SMD fuses is much smaller than that of glass tube fuses or other larger fuses with the same rated current.
(3) The magnitude of the overload current of the circuit and the shortest and longest time that the overload current exists. Usually need to use the combination of oscilloscope test and theoretical calculation to determine the magnitude of overload current. The basic requirement of the fuse is that it should not be broken when it should not be broken (such as when an inrush current occurs), and it must be broken within an appropriate time (such as when an overload current needs to be cut off).
(4) Resistance. The resistance of the chip fuse has a certain effect on some circuits: if a fuse with an excessively large internal resistance is installed in some circuits, it will affect the system parameters of the circuit, making the circuit not work properly.
(5) The ambient temperature of the fuse. When SMD fuses are used in portable equipment, the temperature rise of the fuse should be properly considered, that is, the reduction of the fuse‘s rated current. The ambient temperature when the fuse is working should be within the specified operating temperature range. When the ambient temperature around the fuse exceeds 25 ° C, the temperature reduction curve should be used to degrade it.
(6) The applied voltage applied to the fuse. Generally, SMD fuses are used in portable equipment, and the circuit operating voltage is generally not high. As long as the rated voltage of the SMD fuse is higher than the circuit operating voltage, you can safely choose it.
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