Common mode choke, also known as common mode choke, is often used in computer switching power supply to filter common mode electromagnetic interference signals. The common-mode inductor is essentially a bidirectional filter: on the one hand, it needs to filter out the common-mode electromagnetic interference on the signal line, and on the other hand, it needs to suppress its own transmitted electromagnetic interference, so as not to affect the normal working electromagnetic environment of other electronic equipment in the same area. In short, the common mode inductor should meet the following requirements: the wire wound on the coil core should be insulated from each other to ensure no breakdown and short circuit between the coil turns under the action of instantaneous overvoltage.

Common mode choke, also known as common mode choke, is often used in computer switching power supply to filter common mode electromagnetic interference signals. In the design of the circuit board, the common mode inductor also plays the role of EMI filter, which is used to suppress the electromagnetic wave radiated by the high-speed signal line.

A common-mode inductor is essentially a bidirectional filter: on the one hand, it needs to filter out the common-mode electromagnetic interference on the signal line, and on the other hand, it needs to suppress its own transmitted electromagnetic interference, so as not to affect the normal working electromagnetic environment of other electronic equipment in the same area.

In short, the common mode inductor should meet the following requirements:

(1) the wire wound on the coil core should be mutually insulated to ensure that no breakdown and short circuit will occur between the turns of the coil under the action of instantaneous overvoltage;

(2) When the coil flows through the instantaneous high current, the magnetic core should not be saturated;

(3) the magnetic core in the coil should be insulated from the coil to prevent breakdown between the two under instantaneous overvoltage;

(4) The coil should be wound in a single layer as far as possible to reduce the parasitic capacitance of the coil and improve the ability of the coil to withstand the instantaneous overvoltage.

What are the requirements for common mode inductors? In general, pay attention to the selection of the required frequency band, the greater the common mode impedance, the better. Therefore, when selecting the common mode inductor, it is necessary to check the device information, mainly based on the impedance frequency curve. In addition, attention should be paid to the influence of differential mode impedance on the signal, especially for high-speed ports.