Anti - interference magnetic ring and anti - interference core of the working principle and application

Anti-interference core also known as ferrite anti-interference core!

The characteristics of anti-interference core ferrite anti-interference core is developed in recent years, a new low-cost interference suppression device, its role is equivalent to low-pass filter, a better solution to the power line, signal lines and (EMI) is a simple and effective method to suppress the electromagnetic interference (EMI) by ferrite anti-interference core, and it is a simple and effective method to suppress the electromagnetic interference (EMI), which is simple, convenient, effective, Has been widely used in computers and other military or civilian electronic equipment. Ferrite is a kind of high permeability magnetic materials used in the other one or more magnesium, zinc, nickel and other metals in 2000 ℃ from the burning,

In the low frequency band, the ferrite anti-jamming core exhibits a very low inductive impedance value and does not affect the transmission of useful signals on the data lines or signal lines. In the high frequency range, starting from about 10MHz, the impedance increases, the inductance component remains very small, the resistive component is rapidly increasing, when there is high-frequency energy through the magnetic material, the resistive component will convert these energies For the heat energy dissipation. This constitutes a low-pass filter, so that high-frequency noise signal has a large attenuation, and low-frequency useful signal impedance can be ignored, does not affect the circuit's normal work.

EMI absorption ring / beads is made of ferrite components, is a kind of absorption loss type components. Its characteristic is as follows: the absorption of high-frequency signal and the absorption of energy into heat energy dissipation, so as to achieve the purpose of suppressing the transmission of high-frequency interference signals along the wire, the equivalent impedance of the resistance component is a function of frequency, And change. EMI absorption ring / bead effective band for the 2 1000MHz, the best performance band was 5 200MHz, in this band to maintain the impedance to maintain a constant. EMI absorption ring / beads selection should pay attention to: through the current size is proportional to the component volume, the two disorders, easy to cause saturation, reduce component performance, to avoid saturation is an effective way to power the two lines

(Positive, negative or fire, ground) at the same time through an anti-interference ring. Anti-interference magnetic ring in the use of a better way is to let the wire through the magnetic ring repeatedly string a few, one can improve the area through the ring to increase the equivalent absorption length, and second to make full use of anti-interference magnetic The ring has a hysteresis feature that improves low end characteristics.

Its manufacturing process and mechanical properties are similar to ceramics. Its electromagnetic properties and the addition of metal components and sintering process of the time, temperature and gas composition. Separate magnetic ring, as far as possible the use of smaller diameter, longer length of the magnetic ring, at the same time, the magnetic ring must be tightly wrapped around the cable, that is, the inner diameter of the magnetic ring to fit the outer diameter of the cable. Why do I set up an anti-jamming ring?

Computer motherboards, CPU, power, and IDE data lines are working in a very high frequency state, resulting in the chassis there is a lot of space spurious electromagnetic interference signal, and the signal strength is several times the number of chassis ten times! Absorption magnetic ring, also known as ferrite magnetic ring, commonly used in removable detachable magnetic ring, which is commonly used in electronic circuits anti-jamming components, for high-frequency noise has a very good inhibitory effect, the general use of ferrite materials (Mn-Zn). Magnetic ring at different frequencies have different impedance characteristics, generally in the low frequency impedance is very small, when the signal frequency increases the performance of the magnetic ring of the sharp rise in impedance. So that the normal useful signal through a very good, but also a good inhibition of high-frequency interference signal through, and low cost.

Anti-interference core is a cubic lattice structure of ferrous magnetic materials. Anti-interference core material for the iron-magnesium alloy or iron-nickel alloy, its manufacturing process and mechanical properties similar to the ceramic, the color is gray and black. Electromagnetic interference filter is often used in a class of magnetic ferrite material, many manufacturers have provided specifically for electromagnetic interference suppression ferrite materials. This material is characterized by high frequency loss is very large, with a high permeability, he can be the inductance of the coil winding between the high frequency and high resistance in the case of the smallest capacitance. For the suppression of electromagnetic interference with ferrite, the most important performance parameters for the permeability μ and saturation magnetic flux density Bs. The permeability μ can be expressed as a complex number, the real part constitutes the inductance, and the imaginary part represents the loss, which increases as the frequency increases. Therefore, its equivalent circuit is composed of inductor L and resistor R series circuit, L and R are a function of frequency. When the wire through this ferrite core, the composition of the inductance impedance in the form is increased with the frequency increases, but at different frequencies when the mechanism is completely different. Different ferrite suppressor elements have different optimum suppression frequency ranges. Usually the higher the permeability, the lower the frequency of inhibition. In addition, the larger the ferrite volume, the better the inhibitory effect. When the volume is constant, the long and thin shape is better than the short and thick suppression effect, the smaller the inner diameter the better the suppression effect. However, in the case of DC or AC bias current, there is also the problem of ferrite saturation, the greater the cross-section of the component, the less saturated and the greater the allowable bias current.

EMI absorption magnetic ring / magnetic beads to suppress differential mode interference, through its current value is proportional to its volume, the two offset caused by saturation, reducing component performance; inhibition of common mode interference, the power of the two lines (plus or minus) At the same time through a magnetic ring, the effective signal for the differential mode signal, EMI absorption magnetic ring / magnetic beads have no effect on it, and for the common mode signal will show a larger amount of inductance. There is also a better way to use the magnetic ring is to pass through the magnetic ring of the wire several times to increase the amount of inductance. Can be based on its inhibition of electromagnetic interference principle, the rational use of its inhibitory effect.

The anti-jamming core suppression element should be installed near the source of the interference. For the input / output circuit, should be close to the shell into the shell, the exit. Anti-interference magnetic ring and magnetic beads constitute the absorption filter, in addition to the use of high permeability magnetic materials should be used, but also pay attention to its application. They exhibit a resistance of about ten to several hundred Ωs for high-frequency components in the line, so that it does not work in high-impedance circuits. On the contrary, in low-impedance circuits such as power distribution, power or RF circuits Use will be very effective. Conclusion: Since the ferrite can attenuate the higher frequency and allow the lower frequency to pass almost unimpeded, it is widely used in EMI control. The magnetic ring / magnetic beads used for EMI absorption can be made into various shapes and are widely used in various applications. Such as in the PCB board, can be added to the DC / DC module, data lines, power lines, etc.. It absorbs the high frequency interference signal on the line, but it will not produce new zero pole in the system, will not damage the stability of the system.

Anti-interference magnetic ring | Anti-interference core | Magnetic flux