Inductors are common, two-terminal electrical devices that store energy in a magnetic field. They're typically made from a simple coil of wire, wound around either a metal or air core. They are commonly used in filters, transformers, tuning circuits, energy storage, impedance matching, sensors, and more.
The most important step when selecting an inductor is to understand and consider your specific application. From there, you'll want to consider parameters such as inductance, tolerance, and DC resistance to ensure the maximal performance and efficiency of your design.
In this blog, we will explore the main parameters of inductors, their definitions, and tips to help you choose the right one!
1) Quality Factor (Q)
The Quality Factor is the ratio of the reactance of the inductor to its resistance. Inductors are not purely inductive, and their resistance causes energy loss which can limit their performance. Hence, the higher the Q factor, the lower the rate of energy loss.
2) Self-Resonant Frequency or SRF
The low distributed capacitance between inductor terminals causes inductors to have a self-resonant frequency (SRF). The SRF is the frequency at which an inductor stops working as an inductor. Designers should select an inductor with an SRF that is higher than the operating frequency.
3) Saturation Current
The saturation current is the current value at which the conductor can not take in any more magnetic flux. At this point, the inductance will drop at a specified value. Like the SRF, the saturation current must be significantly higher than the maximum current that will pass through the inductor.
4) DC Resistance
The DC resistance (DCR) is the resistance component of the coil. A high DCR will cause high losses, so it is always better to select an inductor with a low DCR value. It is important to consider the acceptable DCR of the inductor according to your application.
Tolerance indicates how much the inductance can vary from the nominal value. This information is usually found in the component's datasheet. Tolerances in general are not desired but are inversely proportional to cost. Therefore, this parameter should be ultimately selected based on your application.
We hope that this blog helped you to understand some of the basic parameters to consider when selecting an inductor to use in your next PCB project! If you have any comments or questions, feel free to contact us now!