Power inductor is widely used in electronic products, but how to choose a suitable power inductor? The selection of power inductor mainly depends on the inductance, DC resistance, saturation current, temperature rise current, test frequency, size and other parameters. Next, we will explain in detail how to choose a suitable power inductor according to these parameters
1、 The first is the inductance, which is needless to say. The first thing to choose an inductance is to determine the inductance.
2、 DC resistance is the resistance value of the inductance conductor itself, that is, the resistance measured under DC state. From the ideal state, the smaller the DC resistance of the inductance, the better.
3、 Saturation current is to add a specific amount of DC bias current to the inductor, so that the inductance value of the inductor decreases by 10% - 30% compared with the inductance value without current (generally calculated as 30%). This DC bias current is called the saturation current of the inductor, and the larger the saturation current is, the better.
4、 The temperature rise current is to add a specific amount of DC bias current to the inductor, so that the temperature of the inductor body will not rise more than 40 ℃ compared with the temperature without current (the temperature needs to be stable for more than 30 minutes and will not continue to rise). This DC bias current is called the temperature rise current of the inductor, and the larger the temperature rise current is, the better.
5、 Test frequency refers to a frequency for testing inductance value. Many engineers think that inductance value has nothing to do with frequency, but in fact, inductance values under different frequencies are different. The higher the test frequency of most inductors is, the higher the inductance value will be. Therefore, when selecting power inductors, it is necessary to know the application frequency of the product and the test frequency of inductors. If the difference is too large, it will be difficult It is possible that the actual application and specification of inductance are different.
6、 Size: if there are no special requirements, I suggest engineers choose the inductor whose height is 1 / 2 of the length as far as possible when selecting the inductor size. This kind of inductor structure and technology are the most mature.
Saturation current and temperature rise current should be the focus of power inductor selection in many projects, and many engineers don't know how to select them. Normally, saturation current is larger than temperature rise current, so it's much easier to select saturation current as surge current and temperature rise current as working current.