In the power circuit of electronic equipment, how to choose a suitable fuse resistor to protect the circuit from short circuit and overload?
Publish Time: 2024-12-11
In the power circuit of electronic equipment, fuse resistor plays a vital role, and its reasonable selection is the key to ensure the safe and stable operation of the circuit.First, the rated voltage and current parameters of the circuit should be fully considered. The rated voltage of the fuse resistor must be greater than or equal to the working voltage of the power circuit, otherwise it may be broken down and damaged during normal operation. The rated current should be determined based on the maximum current of the circuit during normal operation. Generally, a fuse resistor with a rated current slightly greater than the normal working current is selected. For example, if the normal working current is 1A, a product with a rated current of about 1.2A can be selected. This can not only ensure the normal power supply of the circuit under normal circumstances, but also prevent the circuit from being accidentally blown when the current fluctuates slightly.Secondly, pay attention to the fusing characteristics of the fuse resistor. For some circuits that are more sensitive to instantaneous current shocks, such as electronic devices containing precision chips, a fast-blow fuse resistor should be selected to quickly cut off the circuit at the moment of short circuit to prevent excessive current from causing irreversible damage to components such as chips. For some circuits with large starting current but short duration, such as motor starting circuits, slow-blow fuse resistors are suitable. They can withstand the large current impact when the motor starts and will not malfunction due to the starting current. They will only blow when the overload lasts for a certain period of time and the current exceeds the fuse threshold, thereby effectively protecting the circuit from long-term overload.Furthermore, the accuracy and stability of the resistance value cannot be ignored. In some power supply circuits with high requirements for voltage and current sampling accuracy, such as the feedback circuit of the switching power supply, it is necessary to select a fuse resistor with high resistance value accuracy and small temperature coefficient. High-precision resistance value can ensure the accuracy of sampling and keep the power supply output voltage stable within the set range; small temperature coefficient ensures that when the circuit operating temperature changes, the resistance value will not have a large deviation, thereby affecting the normal operation and protection function of the circuit.In addition, the size and packaging form of the fuse resistor must also be considered. For small electronic devices with limited space, such as smartphones and smart watches, small-size SMD fuse resistors should be selected to meet their compact circuit board layout requirements. At the same time, the package should also have good heat dissipation performance to avoid premature failure or malfunction of the resistor due to excessive temperature during normal operation or overload due to poor heat dissipation.In summary, only by comprehensively considering the above factors can we select a suitable fuse resistor in the power circuit of an electronic device to provide reliable short-circuit and overload protection for the circuit, extend the service life of the electronic device and ensure its stable operation.
