Thermosetting SB578F/AU4V110X series lead solenoid valve coil

Not to be neglected parasitic inductance, inductance coil, electromagnetic coil

1. It is introduced that the parasitic inductance that cannot be neglected is half of the parasitic inductance that should be considered in PCB via planning.

In the planning of high-speed digital circuits, the damage caused by parasitic inductance of vias is usually greater than that caused by parasitic capacitance. Its parasitic series inductance will weaken the contribution of bypass capacitor and the filtering effect of the whole power supply system.

2. We can use the following formula to calculate the approximate parasitic inductance of a via:

L=5.08h[In(4h/d)+1] where l refers to the inductance of the via, h is the length of the via, and d is the diameter of the middle hole. It can be seen from the formula that the diameter of the via hole has little influence on the inductance, but the length of the via hole has the greatest influence on the inductance. Still using the above example, the inductance of the hole can be calculated as: l = 5.08 x 0.050 [in (4x0.050/0.010)+1] = 1.015 NH. If the rise time of the signal is 1nS, the equivalent impedance is XL=TL/T10-90=3.190. This kind of impedance can't be ignored when there is high-frequency current. It is especially important to note that the bypass capacitor needs to pass through two vias when connecting the power layer and the stratum, so the parasitic inductance of the vias will increase exponentially.

Causes of inductance heating

Introduce and explain the cause of inductance heating.

1. The wire is too thin, which will cause the resistance of the inductor to be very large. Under the condition that the effective value of the current is certain, it is normal for the pole to heat up.

2, the inductance is full, and this kind of fever is also very widespread.

3. There is a large vibration voltage at both ends of the inductor, so the core is changed to be larger, which can reduce the number of turns and shorten the line length. Forward conversion, small ripple current, small magnetic loss, mainly resistance heat.