Discussion on Materials for Common Mode Inductors 2

Inconvenient installation and high failure rate - Sharing from audiophiles: "Generally, the performance is the same, but the magnetic ring with the same wire diameter has higher sensitivity than UF10.5, which is easy to implement. When testing conduction, it is better to encounter UF10.5 with the same sensitivity, with a difference of about 5 DBs! If the magnetic ring looks like an age picture, it is relatively cheap, but it is difficult to plug in and has a higher risk of failure. If a base is added, it won't be cheap, it's more expensive than UF10.5

Application:

Due to cost factors, magnetic rings are mostly used in high-power power supplies. Enthusiasts describe it as' using magnetic rings for low-power applications is too high-end ', which makes sense.

Of course, due to its small size, low-power power supplies with volume requirements are also a good choice to use magnetic rings.  diode

Compared to UF series, it has better overall performance. If there is not much cost pressure on the project, magnetic rings can be considered. I actually tested and found that the margin for using magnetic rings is much lower. And the sensitivity is also smaller than UF's.

Let's talk about the common mode of UF/UU series!

Material: Basically ferrite, of course, this ferrite also has differences, generally MXO manganese zinc and NXO nickel zinc. The main advantage of nickel zinc materials is that they have a low initial magnetic permeability (less than 1000u), but can operate at relatively high frequencies (greater than 100MHZ. html "target=" -blank "title=" 100MHz ">100MHz) while maintaining the same magnetic permeability. Very strong and great.

NXO has a higher resistivity than MXO. The use of ferrite's damping effect on high-frequency clutter releases it as thermal energy, which explains the temperature issue of common mode inductors.

Baidu explains the principle of common mode inductance more clearly than I do: two coils are wound on the same iron core, with the same number of turns and phase (wound in the opposite direction). In this way, when the normal current in the circuit flows through the common mode inductor, the current generates a reverse magnetic field in the inductor coils wound in the same phase and cancels each other out. At this time, the normal signal current is mainly affected by the coil resistance (and a small amount of damping caused by leakage inductance); When a current with common mode interference flows through the coil, a magnetic field in the same direction is generated inside the coil, which increases the inductance of the coil and makes it exhibit high impedance, producing a strong damping effect to attenuate the common mode current and achieve the purpose of filtering.diode