Different ferrite materials have different optimal suppression frequency ranges, which are related to magnetic permeability. The higher the magnetic permeability of the material, the lower the optimal attenuation frequency; On the contrary, the lower the magnetic permeability of the material, the higher the attenuation frequency. Therefore, manganese zinc ferrite is more suitable for low frequencies, such as 30MHz and below. Nickel zinc ferrite is more suitable for high frequencies, such as 30MHz to 200MHz or higher.

1. Applications on PCB circuit boards

The interference on PCB circuit boards mainly comes from digital circuits, where high-frequency switching currents cause strong interference between power and ground lines. Power and signal lines will emit high-frequency noise generated by digital circuit switches in the form of conduction or radiation. The commonly used method to suppress interference is to add decoupling capacitors between the power supply and ground to short-circuit high-frequency noise. However, using decoupling capacitors alone can sometimes cause high-frequency resonance and generate new interference. Adding ferrite interference suppression magnetic beads at the entrance of PCB circuit board routing can effectively attenuate high-frequency noise.

2. Application on power lines

Power lines can transmit external power grid interference and switch power supply noise to the equipment's wiring. Designing ferrite interference suppression cores at the power outlet and power inlet of PCB circuit boards can not only suppress the transmission of high-frequency interference between the power supply and the PCB circuit board, but also suppress the mutual interference of high-frequency noise between PCB circuit boards.

3. Application on signal lines

Ferrite anti-interference magnetic cores can also be used on signal lines to suppress noise transmission between components or equipment. But the impedance of the signal line is generally greater than that of the power line, so the suppression effect on interference is not as obvious as that of the power line.

Due to the different composition and application purposes of ferrite materials, there are generally different requirements for ferrite core materials as follows:

(1) Application in low-level signals. Require ferrite materials to have low loss, good stability, and minimal changes over time and temperature. The main applications include high-Q inductors, common mode inductors, broadband matched pulse transformers, wireless transmission antennas, etc.

(2) Power application. Require ferrite materials to have high magnetic flux density and low losses at operating frequency and temperature. The main applications include switching power supplies, magnetic amplifiers, DC-DC converters, power line filters, trigger coils, and battery charging transformers.

(3) Application in RF interference suppression. Ferrite materials require high impedance. They are mainly used to suppress parasitic oscillations in the transmission line and attenuate unwanted signals in the transmission line.