Inductor coil related parameters

Inductor coil related parameters：

1. Inductance: The inductance L indicates the inherent characteristics of the coil itself, regardless of the current magnitude. Except for the special inductor (color code inductor), the inductance is generally not marked on the coil, but is marked with a specific name.

2, inductive reactance: the size of the inductance coil against the alternating current is called anti-XL, the unit is ohm. Its relationship with inductance L and AC frequency f is XL=2πfL

3. Quality factor: The quality factor Q is a physical quantity indicating the quality of the coil, and Q is the ratio of the inductive reactance XL to its equivalent resistance, ie: Q=XL/R. 
The higher the Q value of the coil, the smaller the loss of the loop. The Q value of the coil is related to the DC resistance of the wire, the dielectric loss of the skeleton, the loss caused by the shield or the iron core, and the influence of the high frequency skin effect. The Q value of the coil is usually from several tens to several hundreds.

4. Distributed capacitance: The capacitance between the turns and turns of the coil, between the coil and the shield, and between the coil and the bottom plate is called distributed capacitance. The presence of the distributed capacitance reduces the Q value of the coil and the stability is deteriorated, so that the distributed capacitance of the coil is as small as possible.

Various uses of coils：

 

1. Use of SMD Coils: Widely used in common mode filters, multi-frequency transformers, impedance transformers, balanced and unbalanced conversion transformers, suppression of electronic equipment EMI noise, USB lines for personal computers and peripherals, LCD panels, low voltage Differential signals, car remote control keys, etc.

2. Fixed inductors include: ring coil, choke coil, common mode coil, ferrite bead, power inductor, chip type and pin type. Widely used in networks, telecommunications, computers, AC power supplies and peripherals.

3. Closed magnetic circuit high current surface mount power inductor features and uses: ideal DC-DC conversion inductor, high power, high saturation inductor, small DC resistance, suitable for high current, with or with reel packaging for automatic Surface mount, used in video recorder power supply, video recorder power supply, LCD TV, laptop, office automation equipment, mobile communication equipment, DC / DC converter.