What is a magnetic ring? How to use the magnetic ring?

Categories: Industry news

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2022-04-01

Magnetic ring: As the name suggests, it is a ring-shaped magnet. Magnetic ring is a commonly used anti-jamming component in electronic circuits, which has a good suppression effect on high-frequency noise.

1. What is a magnetic ring

Absorption magnetic ring, also known as ferrite magnetic ring, referred to as magnetic ring. It is a commonly used anti-interference component in electronic circuits, which has a good suppression effect on high-frequency noise. It is generally made of ferrite material (Mn-Zn). The magnetic ring has different impedance characteristics at different frequencies. Generally, the impedance is small at low frequencies. When the signal frequency increases, the impedance of the magnetic ring increases sharply. We all know that the higher the signal frequency, the easier it is to radiate out (it is also necessary to buy a high-quality computer case to reduce electromagnetic leakage), and the general signal lines are not shielded, so these signal lines become good antennas , receive various messy high-frequency signals in the surrounding environment, and these signals are superimposed on the originally transmitted signal, and even change the original transmitted useful signal. Then, under the action of the magnetic ring, normal and useful signals can pass well, and the passage of high-frequency interference signals can be well suppressed, and the cost is low. So it is not surprising that everyone sees the plastic bump-shaped one-piece magnetic ring on the monitor signal line, USB connection line, and even high-end keyboards and mice.

2. The role of the magnetic ring

Magnetic ring is a commonly used anti-interference component in electronic circuits. It has a good suppression effect on high-frequency noise. Generally, ferromagnetic rings have different impedance characteristics at different frequencies. Generally, the impedance is very small at low frequencies. We all know that the higher the frequency of the signal, the easier it is to radiate out (it is also necessary to buy a high-quality computer case to reduce electromagnetic leakage), and the general signal lines do not have a shielding layer, so these signal lines become A very good antenna to receive all kinds of messy high-frequency signals in the surrounding environment, and these power inductors - magnetic ring coils - color ring inductors - chip inductors - magnetic bead inductors - transformers - laminated inductors - electronic news signals are superimposed on the original. The transmitted signal will even change the original transmitted useful signal. Then, under the action of the magnetic ring, the normal and useful signal can pass well, and the passage of high-frequency interference signal can be well suppressed.

3. How to use the magnetic ring

The magnetic ring has different impedance characteristics at different frequencies. Generally, the impedance is small at low frequencies, and the impedance rises sharply at high frequencies. The higher the signal frequency, the easier the magnetic field will be radiated. Generally, the signal lines are not shielded. For example, the CAN bus I use now, these signal lines become a perfect antenna. This antenna constantly receives the surrounding high-frequency signals. These The superposition of the signals changes the actual signal to be transmitted. The magnetic ring can pass useful signals well, while suppressing high-frequency interference signals. In the high frequency band (greater than 10MHz), the inductive reactance is still small, and the impedance is very large, so that when the energy of the high frequency signal passes through the magnetic material, it is converted into heat and dissipated, which prevents the passage of the high frequency signal and inhibits the high frequency signal. interference from frequency signals. Usually the optimal suppression frequency range is related to the ferrite suppression element. Usually, the higher the magnetic permeability, the lower the suppression frequency. The larger the volume of the ferrite, the better the suppression effect. The coarse inhibition effect is good, and the inner strength is smaller, the inhibition effect is better. When suppressing common-mode signal interference, you can pass the signal (with a differential signal line) or power line (positive and negative lines) through the magnetic ring at the same time. Enhances the absorption effect of common mode signals, but has no effect on differential mode signals. Components should be installed close to the source of interference. For input and output circuits, it should be as close as possible to the inlet and outlet of the shielding box.