Reference Standard 1 for Power Inductor Selection: Frequency
Analysis: Because there will be parasitic capacitance between coils, which will resonate in parallel with its inductance, there will be a natural frequency (SRF), which is related to EPC, so the smaller EPC, the better, and the wider frequency range of inductance can be guaranteed. SRF requires at least 10 times more transformers and 10 times more transformers. For example, the switching frequency is 1.RF requires at least 1 time of transformer and 1 time of transformer. Therefore, it should be hollowed out under the inductor, and there should be no metal, so as to avoid generating extra EPC and reducing the frequency range of the inductor.
Reference Standard 2 for Power Inductor Selection: Inductance Value
Analysis: Theoretically, the difference between the maximum value and the inimum value of the output current, that is, the so-called ripple, certainly hopes that the smaller the better, that is, the more stable the output current is. This can have higher conversion efficiency and lower EMI interference. At the same time, the larger the inductance, the smaller the wave. However, if the inductance value is too large, the instantaneous response of the load terminal will slow down, and the output current will not change synchronously with the exchange cycle in real time. Therefore, it is necessary to select an appropriate inductance value instead of blindly increasing it.
Reference Standard 3 for Power Inductor Selection: Rated Current
Analysis: When the flowing current is too large, the inductance value will drop, and the inductance value will drop by 30%. We define it as saturation current. At this time, it can also be called that the power inductor is saturated. It is equivalent to a wire, which has little effect of stabilizing current, and the wave becomes very large, so the saturation current is a pointer to judge the linearity of power inductance. Of course, the bigger the better, it usually needs to flow at least 1.3 times of the current.
Reference Standard 4 for Selection of Power Inductors: Resistors and Shields
Analysis: Every object will have its internal resistance DCR, and inductance is no exception. According to P= I*I*R, a lot of current will be consumed (all converted into heat energy), resulting in a decrease in conversion efficiency, so the smaller DCR, the better. However, if the inductance value is too large, not only the instantaneous response of the load side will slow down, but also the number of windings will increase and the DCR will increase, so it is necessary to select an appropriate resistance value. With the inductance of shield, the number of DCR is small, which can avoid bonding with adjacent metals while preventing bonding with adjacent metals.
