What is the function of magnetic ring inductance?

Speaking of the magnetic ring inductance, let's start with the magnetic ring. The magnetic ring and the connecting cable form an inductor. It is a common anti-interference element in electronic circuits and has a good shielding effect on high-frequency noise, so it is called the absorption magnetic ring. Because it is usually made of ferrite materials, it is also called the ferrite magnetic ring (magnetic ring for short).

We know that magnetic rings have different impedance characteristics at different frequencies. At low frequencies, the impedance is very small. When the signal frequency increases, the impedance of the magnetic ring increases rapidly. As we all know, the higher the signal frequency is, the easier it is to radiate out, and the general signal lines have no shielding layer. These signal lines become a good antenna to receive all kinds of messy high-frequency signals in the surrounding environment, and these signals superimposed on the original transmission signal will even change the original transmission of useful signals, seriously interfering with the normal operation of electronic equipment.

Therefore, it is very necessary to reduce the electromagnetic interference (EM) of electronic equipment. Under the action of the magnetic ring, it can not only make the normal and useful signal pass smoothly, but also can weaken the high-frequency interference signal. Not only that, but also the low cost is another advantage of it.

What does an inductor do? We say that it is easy to understand that the AC signal can be isolated, filtered or combined with capacitors and resistors to form a resonant circuit. In addition, inductance also plays an important role in filtering signal, filtering noise, stabilizing current and weakening electromagnetic interference.

The LC tuning circuit can be composed of inductance coil and capacitor in parallel. That is, if the natural oscillation frequency f0 of the circuit is equal to the frequency f of the non AC signal, the inductive reactance and capacitive reactance of the circuit are also equal, so the electromagnetic energy oscillates back and forth between the inductance and capacitance, which is the resonance phenomenon of the LC circuit.

During resonance, the inductive reactance and capacitive reactance of the circuit are equivalent and reverse, so the inductive reactance of the total circuit current is the minimum and the current amount is the maximum (referring to the AC signal with f=f0). Therefore, the LC resonant circuit has the function of selecting frequency, and can select the AC signal with a certain frequency f.

What are the test items of magnetic ring inductance?

1. Test the package size: first test the package size. Because the space reserved for inductance on the customer's circuit board has been determined, the package size must meet the requirements before it can be correctly installed on the circuit board. The inspection of package size is very simple, just use vernier caliper to measure;

2. Magnetic ring inductance performance test: after the package size is tested, the magnetic ring inductance performance parameters need to be tested. Generally, the performance parameters to be measured include: the resistance and inductance of the magnetic ring inductance. The performance parameters must be tested with professional testing instruments;

3. Other tests: Other tests mainly focus on specific requirements for magnetic ring inductance, such as requirements for pin length. If the length of the pin exceeds the requirement, the angle must be cut. The length of the pin does not affect the inductance performance of the magnetic ring inductor, but if the pin is too long, it may be necessary to cut corners when installing in the circuit.