The essence of sound is noise, which is caused by vibration. Noise can be divided into structural noise and cavity noise, and finally it is structural vibration which forms compressed air and cavity noise. The frequency heard by human ears is between 20hz and 20khz. So why does the inductor of the patch produce "howling"? And what is the solution? And so on. So today, Xiaobian will give you a detailed introduction.
First, the cause of the "howling" of the patch inductance
When the chip inductor works in the circuit, it will be excited by pulsating current. If there is a switch in the frequency range of 20Hz-20KHz, when the current passes through the coil, the current between the turns of the coil will be slightly offset by repulsion in the same direction. When the current disappears, the position of the coil will return to its original state. If the coil wire is not fixed, the induction coil vibrates and compresses air, which will form cavity noise and cause howling. The hysteresis expansion of magnetic core materials will also cause similar problems. Even if the switching frequency is far away from this frequency band, it will cause howling. Due to the unstable load, in the self-regulation of switching power supply, there are frequency components overlapping with this frequency band in the adjustment of duty ratio.
Second, the "howling" solution of the patch inductor
If the inductance coil is not replaced, inductance immersion is the best choice, and there is no howling. Of course, you can also replace the inductor, or replace the high-power DC-DC, or reduce the load current.
