Why Set Up Anti-interference Magnetic Ring
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Why set up anti-interference magnetic ring?
The main board, CPU, power supply and IDE data line in the computer cabinet all work at very high frequency, so there are a lot of spatial stray EMI signals in the cabinet, and the signal intensity is several to tens of times as much as that outside the cabinet! Absorbing magnetic ring, also known as ferrite magnetic ring, is often used in detachable separating magnetic ring. It is a common anti-interference element in electronic circuits. It has a good suppression effect on high-frequency noise. It is usually made of ferrite material (Mn-Zn). Magnetic rings have different impedance characteristics at different frequencies. Generally, the impedance is very small at low frequencies. When the signal frequency increases, the impedance of magnetic rings increases sharply. It makes the normal and useful signals pass well, and can suppress the passage of high frequency interference signals well, and the cost is low.
Ferrite is a ferromagnetic material with cubic lattice structure. Ferrite material is ferro-magnesium alloy or ferro-nickel alloy. Its manufacturing process and mechanical properties are similar to those of ceramics, and its color is gray-black. Ferrite is a kind of core commonly used in EMI filters. Many manufacturers provide ferrite materials specially for EMI suppression. This material is characterized by high frequency loss and high permeability. It can produce the smallest capacitance between coil windings of inductors at high frequency and high resistance. For the ferrite used to suppress electromagnetic interference, the most important performance parameters are permeability and saturated flux density Bs. Permeability mu can be expressed as complex number, real number part constitutes inductance, imaginary number part represents loss, and increases with the increase of frequency. Therefore, its equivalent circuit is a series circuit consisting of inductance L and resistance R, both of which are functions of frequency. When the conductor passes through the ferrite core, the inductance impedance increases formally with the increase of frequency, but the mechanism is completely different at different frequencies.
Different ferrite restraining elements have different optimal restraining frequency range. Usually the higher the permeability, the lower the suppression frequency. In addition, the larger the volume of ferrite, the better the inhibition effect. When the volume is fixed, the inhibition effect of long and thin shape is better than that of short and thick shape, and the smaller the inner diameter, the better the inhibition effect. However, in the case of DC or AC bias current, there is also the problem of ferrite saturation. The larger the cross section of the restraining element, the less saturated it is, the greater the bearable bias current is.
When EMI absorbs the magnetic ring/bead to suppress the differential mode interference, its current value is proportional to its volume, the misalignment of the two leads causes saturation and reduces the performance of the components; when common mode interference is suppressed, two lines (positive and negative) of the power supply pass through a magnetic ring at the same time, the effective signal is the differential mode signal, and EMI absorbs the magnetic ring/bead has no effect on it. For common-mode signals, the inductance is larger. A better way to use magnetic rings is to make the wires passing through the magnetic rings twist several times to increase the inductance. According to its suppression principle of electromagnetic interference, it can be used reasonably to restrain electromagnetic interference.
Ferrite suppression elements should be installed near the source of interference. For the input/output circuit, it should be as close as possible to the inlet and outlet of the shielding case. For the absorption filter composed of ferrite magnetic rings and beads, besides the high permeability lossy material, attention should be paid to its application occasion. Their resistance to high frequency components in the circuit is about 10 to several hundred_, so their role in high impedance circuits is not obvious, on the contrary, they will be very effective in low impedance circuits (such as power distribution, power supply or radio frequency circuits).
The Gold-Stone factory can also customize the products according to customer requirements.
Also we can producce EE/EI/EF/ER/EFD/EFT/EP/EPC/POT/PQ/RM/SMD/POT Type High frequency transformer
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