Howling countermeasure of power inductor smd

When notebook computers, tablet computers, smart phones, televisions and on-board electronic devices are running, sometimes "creaking" noise can be heard. This phenomenon is called "howling".

The cause of "howling" may be passive components such as capacitors and inductors.


The principle of capacitor and inductor howling is different, especially the reason of inductor howling is various and complex.

This paper will introduce the cause of howling of power inductor smd, which is the main component of power circuit such as DC-DC converter, and the effective countermeasures.

Cause of power inductor howling

[1]. Intermittent operation, variable frequency mode, load variation, etc. may cause audible frequency vibration of human ear

Sound waves are elastic waves propagating in the air, and human hearing can hear "sound" in the frequency range of about 20-20KHz. In the power inductor of the DC-DC converter, when the alternating current and pulse wave of the frequency within the audible range of the human ear flow, the main body of the inductor vibrates. This phenomenon is called "coil noise", and sometimes it is also heard as a howling phenomenon (Fig. 1).