降低LED驱动噪音的解决方案

噪音来源

LED驱动的噪音来自哪里?

噪声来源来自一些磁性元件(如变压器,电感器…)和多层陶瓷电容器(MLCC)。

为什么会产生噪音?

磁组件产生噪音主要有以下几个方面：

Percussion - The face of core pieces can scrape together when the magnetic flux is varied；
Collision of movable elements (bobbin, core , wire ..etc.)；
Magnetostriction- The dimension of coil material is changed；
Coil self Motion-The ripple current pass through coil produces attractive and repulsive force that to move the wires.

多层陶瓷电容器也会产生噪音，原因在于：

Piezoelectric effect – Substrate vibrate with Voltage amplitude, and when the time amplitude cycle come to the bandwidth of auditory are, Harmony is recognized as a noise. Capacitor distortion transferred to the PCB acting as an amplifier。

降低噪音的方法

虽然目前我们没有方法来消除噪音，但是我们可以降低噪音水平。具体方案就是降低磁性元件的噪音水平：

Reducing peak flux of magnetic as low as possible；
Potting the PCBA；
Vacuum Varnish for magnetic parts. Method to reduce noise level for MLCCic parts；
Reduce capacitance value in a capacitor；
Add a soft material to absolved the mechanical vibration；
Replace the MLCC with a plastic film (Polypropyleneor, Polyester…etc)；
Potting : Pot the PCBA.