Many manufacturers often encounter some minor problems when choosing smd inductor beads. Here is the basic knowledge for the older sister to answer for your reference.
1. The parameter of a magnetic bead is 100R@100MHz, please explain the meaning of the parameter.
The impedance value at 100MHz frequency is 100 ohms.
2. Please explain the difference between filter bead and filter inductor.
The magnetic beads are composed of wires passing through ferrite, the DC resistance is very small, the impedance is also very small at low frequencies, and it has almost no effect on the DC signal. At high frequencies (above tens of megahertz), the impedance of the magnetic beads is relatively large, and the high-frequency electromagnetic field generates eddy currents on the ferrite material, so that high-frequency interference signals are converted into heat and consumed. Magnetic beads are often used for power supply filtering and high-frequency signal loop filtering of high-frequency circuit modules to suppress EMI interference. The inductance is composed of a coil and a magnetic core, the DC resistance is small, and the inductance is large. Inductor are mostly used in the filtering of medium and low frequency circuits, focusing on suppressing conductive interference, and their application frequency is below tens of MHz.
3. What is the role of common mode inductor?
Suppress common mode interference.
4. What parameters should be paid attention to when selecting inductor?
Inductance (including measurement frequency), accuracy, maximum withstand current, packaging.
5. What parameters should be paid attention to when selecting magnetic beads?
Impedance value (including measurement frequency), accuracy, maximum withstand current, DC resistance (converted to the maximum DC voltage drop), packaging.