How to solve the ripple harmonics and noise interference caused by switching power supply
Ripple
Ripple: It is a clutter signal containing periodic and random components attached to the DC level. The peak value of the AC voltage in the output voltage at the rated output voltage and current. Narrowly defined, ripple voltage refers to the power frequency AC component contained in the output DC voltage.
Noise
Noise: For the nominal noise in electronic circuits, it can be summarized as a general term for all signals other than the target signal. Initially, people referred to the electronic signals that caused noise from audio devices such as radios as noise. However, the consequences of some unintended electronic signals on electronic circuits are not always related to sound, so people gradually expanded the concept of noise. For example, the electronic signals that cause white stripes on the visual screen are also referred to as noise. It can be said that all signals in a circuit, except for the intended signal, regardless of whether they have an impact on the circuit, can be called noise. For example, ripples or self-excited oscillations in the power supply voltage can have adverse effects on the circuit, causing the audio device to produce AC sound or causing circuit malfunctions, but sometimes they may not necessarily lead to the aforementioned consequences. For this type of ripple or oscillation, it should be referred to as a type of noise in the circuit. There is also a radio wave signal of a certain frequency, which is a normal target signal for the receiver that needs to receive this signal, but for another receiver, it is a non target signal, that is, noise. The term interference is often used in electronics, sometimes confused with the concept of noise, but in fact, there is a difference. Noise is an electronic signal, while interference refers to a certain effect, which is an adverse reaction caused by noise on the circuit. There is noise in the circuit, but it does not necessarily mean interference. In digital circuits. Often, it can be observed with an oscilloscope that the presence of small spike pulses mixed with normal pulse signals is not expected, but rather a form of noise. However, due to the characteristics of the circuit, these small spike pulses are not likely to affect the logic of the digital circuit and cause confusion, so it can be considered that there is no interference.
When a noise voltage is large enough to interfere with the circuit, the noise voltage is called interference voltage. The maximum noise voltage applied to a circuit or device when it can still maintain normal operation is called the anti-interference tolerance or anti-interference degree of the circuit or device. Generally speaking, noise is difficult to eliminate, but efforts can be made to reduce the intensity of the noise or improve the circuit's immunity to interference, so that the noise does not form interference.
