Key Points of Inductance Selection

In circuit design, there are three main types of applications for inductors:
Power inductor: mainly used for voltage conversion, commonly used DCDC circuit to use power inductor;

Decoupling inductance, differential mode inductance, common mode inductance: mainly used to filter out the noise on the power line or signal line, EMC engineers should be familiar;

High-frequency inductance: mainly used in RF circuits, to achieve bias, matching, filtering and other circuits.

The correct choice of inductor is a very important step. The following are several points to note when selecting inductors:
1. Inductance value: The inductance value is the ability of the inductor to store magnetic energy and is one of the most important parameters of the inductor. The inductance with appropriate inductance value should be selected according to the actual needs of the circuit. Generally speaking, the larger the inductance value of the inductor, the smaller the current limit, but it will also affect the response speed and impedance of the circuit.
2. Frequency response: The frequency response of the inductor refers to the inductance value and impedance of the inductor at different frequencies. An inductor with a suitable frequency response should be selected according to the actual needs of the circuit. For example, if there is high-frequency signal processing in the circuit, it is necessary to select an inductor with a better frequency response to maintain the quality of the signal.
3. Temperature rise and heat dissipation: Inductors generate heat during operation. Inductors with appropriate temperature rise and heat dissipation capabilities should be selected according to the actual needs of the circuit. For example, if the operating temperature in the circuit is high, it is necessary to select an inductor with better heat dissipation ability to keep the performance of the circuit stable.
Package mode and shape: select the appropriate package mode and shape according to the circuit layout and space requirements. Different packaging methods and shapes have different characteristics and applicable scenarios, and need to be selected according to the actual situation.
5, pay attention to the wire (enameled wire, yarn or bare wire), commonly used enameled wire. To find the most suitable wire diameter.
The basis for selection should be clearly consulted in the inductance specification:
1) Understand the packaging specifications and dimensions of inductors;
2) Understand the basic static electrical parameters and test conditions of the inductor:
A) nominal inductance and error; B) rated current; C) maximum DC resistance value (D.C.R);D) quality factor (q value) and resonant frequency (F0)(for high frequency inductance);E) insulation resistance and withstand voltage requirements.
3) understand the dynamic working performance of inductance: a) inductance vs frequency; B) inductance vs working current; C) inductance vs working environment temperature; D) surface temperature rise vs working current.
4) Understand the conditions and specific requirements of the test definition of the reliability of the inductor (mechanical strength, environmental testing, continuous durability testing, etc.).
5) Understand the definition of inductor process assembly and welding conditions (weldability test, welding heat resistance test).
6) Enquiry of compliance status of environmental protection laws and regulations (EU RoHS, Reach, halogen-free and other requirements).