Chip inductors, also known as power inductors, high-current inductors and surface-mounted high-power inductors.It features miniaturization, high quality, high energy storage and low resistance.
Power SMT inductance is divided into two types, with and without a magnetic mask, mainly composed of magnetic core and copper wire.It mainly ACTS as filter and oscillation in the circuit.The main parameters of SMT inductor are inductance, allowable deviation, distributed capacitance, rated current and quality factor.
1. The inductance
No-load measurements (theoretical values) and measurements in actual circuits (actual values).Because inductance USES actual circuit too much, hard to class.Only measurements without load are explained.
The amount of inductance, mainly depends on the number of turns (turns) of the inductance coil, winding method, whether there is a core and core material.In general, the more winding, the denser the coil, the greater the inductance.A coil with a core has more inductance than one without.
The higher the core permeability, the greater the inductance.So the amount of inductance is a number of factors that determine its size.The basic unit of inductance is Henry, denoted by the letter H.Other commonly used units are the milliheng (mH) and the micheng (muh).Mh 1 = 1000 mu H
2. Allow deviation
A unit of inductance is followed by an English letter to indicate its allowable deviation. The allowable deviation represented by each letter is shown in the table below.For example, 560uHK represents that the nominal inductance is 560uH, the allowable deviation is 10%, and the text symbol is the normal text symbol method, which is to combine the nominal value and allowable deviation value of the inductor with the number and text symbol according to the law.
These are usually small power inductors, usually in nH or pH, with N or R for the decimal point.For example, 4N7 means the inductance is 4.7nH and 4R7 represent inductance of 4.7 uh;47N means the inductance is 47nH, and 6R8 means the inductance is 6.8 uh.
The allowable error between the labeled sensitivity and the actual sensitivity.Generally used in oscillating or filtering lines, SMT inductance requires high precision, and the allowable deviation is ±0.2%~±0.5%.However, the accuracy required for coupling or high frequency choke is not high, and the allowable deviation is ±10%~15%.
3. Distributed capacitance
Capacitance between turns of the coil and between the coil and the core.The smaller the distributed capacitance, the better its stability.
Usually the analog and digital circuits are reasonably separated, and the power cord and ground cord are drawn separately, and the power supply is collected to a point.If be in the family again when integrated wiring, want to meet 220V power supply line line telephone line, network line and audio, video line to wait for separate wiring, and the requirement does not want parallel lay as far as possible.
4. Rated current
The rated current refers to the current of the product equipment when it is running at the rated voltage and at the rated power.Maximum current allowed when SMT inductor is working normally.If the working current exceeds the rated current, it will burn out.
5. Quality factor
Quality factor, also known as Q value or excellent value, is the main parameter to measure the quality of the inductor.It refers to the ratio of inductance of SMD inductance to its equivalent loss resistance when working at an ac voltage of a certain frequency.The higher the Q value, the smaller the loss and the higher the efficiency.
Post time: Oct-30-2019