Common Mode Choke Core

Super common mode choke core for hot sale 

The motherboard inside the computer is mixed with various high-frequency circuits, digital circuits and analog circuits. When they work, they will produce a large number of high-frequency electromagnetic waves that interfere with each other, which is called EMI. EMI may also be emitted outwards through mainboard wiring or external cables, causing electromagnetic radiation pollution and affecting the normal operation of other electronic devices。

Tips: The basic parameters required to design a common mode choke core inductor are input current, impedance, and frequency. The input current determines the size of the winding conductor. Wire diameters are generally calculated at 400 amperes per square centimeter, but other values may be used depending on the temperature rise acceptable to the inductor. In almost all cases, a single conductor is used, as it is not only the cheapest, but the copper loss due to high-frequency skin effects helps to reduce noise.

The impedance of an inductor is usually a minimum at a given frequency. This impedance is in series with the line impedance to achieve desired noise attenuation. It's a pity that most of line impedance is unknown, so designers often use 50 Ω line impedance stabilization network (LISN) filter test. This has become the standard method for testing the performance of filters, but the results may be in line with the actual one-medium = order filter, which increases the attenuation by -6db per octave beyond the turn frequency. The transition frequency is generally low enough to make the inductance a major part of the impedance, so the inductance can be calculated using the following formula Ls=Xs/2πf

After knowing the inductance, the remaining design work is to select the magnetic core and materials, and calculate the number of turns.