The detailed selection procedure of PTC self - restoring fuse is discussed

FAEWhen developing and designing circuits according to customers' specific functional requirements, electronic engineers will confirm with customers the protection types of products, and recommend them to use in order to prevent overcurrentPTCSelf-restoring fuse. On the one hand can greatly improve the safety and reliability of the product, on the other hand from the cost of the whole item to consider, choosePTCSelf-restoring fuse is the best solution in anti-overcurrent circuit protection devices, only need to be used in the front of the circuit to be protected.

1Determine the following parameters of the circuit:

a Maximum operating environment temperature b Standard working current c Maximum operating voltage (Umax) d Maximum fault current (Imax)

2Select a self-restoring fuse element that can adapt to the maximum ambient temperature and standard operating current of the circuit

Use temperature reduction{Ambient temperature(℃) operating current (A)}Table and select the temperature that best matches the maximum ambient temperature of the circuit.

3The maximum electrical rating of the selected component is compared with the maximum operating voltage and fault current of the circuit

Use the electrical characteristics table to verify that you are in the No2Whether the selected component in the step will use the circuit's maximum operating voltage and fault current. Check the maximum operating voltage and maximum fault current of the device. ensureUmaxandImaxGreater than or equal to the maximum operating voltage and maximum fault current of the circuit.

4Determine the action time

Operation time is the amount of time it takes to switch the component to a high resistance state when the fault current is present throughout the device. In order to provide the desired protection function, it is important to specify the operating time of the self-restoring fuse element. If the component you select acts too quickly, abnormal or harmful actions may occur. If the element acts too slowly, the protected component may become damaged before the element switches to a high resistance state.

use25℃To determine whether the action time of the self-restoring fuse element is too fast or too slow for the circuit. If so, return the no2Step Reselect the spare component.

5Verify the ambient operating temperature

Ensure that the minimum and maximum ambient temperatures for the application are within the operating temperature range of the self-restoring fuse element. Most self-restoring fuse elements operate in the temperature range-40℃to85℃.

6Verify the dimensions of the self-restoring fuse element

Use the contour size table to compare the contour size of your selected self-restoring fuse to the spatial conditions of the application.

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