In the process of electromagnetic compatibility drawing digital circuits, we often use magnetic beads, the principle of magnetic bead filters and how to use them?

Ferritic magnesium alloy iron or iron-nickel alloy, with high permeability material, it can be considered as the minimum limit of inductance coil capacitance between high frequency and high impedance. Ferrite materials are usually used in high frequency applications, due to their primary characteristic method of inductance at low frequencies, a small loss of line. At high frequencies, this is the primary reactance versus frequency characteristic. Practical application of ferrite materials as high frequency attenuation in RF circuits. In fact, ferrite is equal to the resistance and inductance of the circuit, the parallel resistance is short, the impedance of the high frequency inductance is not high enough, and the low frequency inductance is not high enough, and everything currently goes through the resistance. Ferrite equipment consumes, high frequency thermal energy on top is determined by function.

The ferrite bead inductors have high frequency filtering characteristics compared to normal, the resistance layer ferrite is marked at high frequency, the quality of the equivalent inductance is very low, they can get a high impedance in a wider Frequency scale, i.e. high frequency power supply filtering. Impedance at low frequency, the inductive reactance of the reactor, R is very small, at low frequency, during which, high permeability, the center of inductance plays an important role, considering the suppression of electromagnetic interference, and this time the The loss of the magnetic field lower iron, the whole device and the action of the low loss high Q value inductor, may have low frequency resonance, sometimes disrupt the progress of using ferrite bead inductors. In the high frequency impedance resistive element composition, when the frequency increases, the permeability of the heart rate reduces the composition inductance inductance, but if it is the central component of the increase, the loss of the total impedance increases against the increase, the high frequency signal is The disturbance is absorbed by the electromagnetic ferrite and converted into heat energy.

Ferrite restraint components are widely used in printed circuit boards, power lines and data lines. Combined with ferrite suppression components, such as network connection headers, you can filter out high-frequency noise. Ferrite beads or beads manipulate signal lines, power lines, and introduce dedicated high-frequency distortions, which also have the ability to absorb electrostatic discharge pulses.