Inductance
1) Introduction
With the development of inductive devices in the direction of low voltage, large DC bias resistance, good temperature stability, miniaturization, thinness, and lightweight, ordinary soft ferrite materials can no longer meet such high requirements, and integrated inductors have taken the stage of history and become an important member of the inductive device family.
2) Development history
The integrated inductor is also called the power inductor, its emergence is due to the development of computer motherboard technology and the development of power supply technology: the CPU frequency is getting higher and higher, so the requirements for stable power supply and filtering are very high, the integrated inductor solves this problem, it can work for a long time under the condition of high current, and can supply stable power to the CPU, of course, the main role of the inductor is filtering, in this regard, the integrated inductor is not inferior. Good material properties and special design make the inductor structure more stable, the impedance is lower, and therefore it has higher efficiency.
3) Structure
The one-piece inductor (molded inductor) is composed of metal powder, electrode and coil, the coil body is embedded in the metal magnetic powder inside the die-casting, the pin is the winding body of the pin, the pins are directly formed on the surface of the seat body, and the inductor is designed for SMD structure, which will not damage the inductor when used, and can improve production efficiency.
4) Main parameters
1. Sensibility:
It can suppress the change of flowing current, and the inductance value is affected by the material, shape, and size of the core, as well as the number of turns and shape of the winding, and the standard unit of inductance is Henry, which is represented by the letter H, and the symbol of the inductance is L.
2. DC Resistance (DCR):
Impedance measured under direct current of the inductor; The smaller the impedance, the better, in ohms. DC resistance is affected by factors such as the wire diameter, number of turns, and other factors of copper wire. The thicker the winding, the smaller the resistance, the lower the temperature, the smaller the resistance, the shorter the winding, the smaller the resistance, and the resistance of different materials is also different; Gold, silver, copper (resistance from small → large).
3. Saturation Current:
After the product passes through the current, the allowable inductance value decreases by 30 (%), and the higher the saturation beam density (Bs), the higher the current resistance.
4. Temperature rise current:
After the product passes through the current, the temperature rise on the surface of the product is affected by the power consumption, and the current defined by the allowable temperature rise (°C) is affected.
5) Summary
The advantages of one-piece inductors are as follows:
1. Magnetic shielding structure, magnetic circuit closure, strong anti-electromagnetic interference, good EMI suppression effect;
2. No lead end, small parasitic inductance;
3. Strong current capacity, continuous long-term work in high-current environment and low power consumption;
4. Small size, low side, saving PCB space;
5. The inductance whine is small (the coil is tightly combined with the magnetic particle to avoid coil vibration in the structure);
6. The DC impedance DCR of the same size is the lowest.
