For high-frequency electromagnetic interference (EMI), generally three techniques can be used for power supply filtering, which can suppress interference noise. In actual use, two or more of these techniques are often mixed. They are:
1. Add a capacitor between the live and neutral lines of the power supply, that is, the X capacitor. Choose X2 type, the main function is to eliminate common mode interference, the capacity range is 0.01UF --- 0.47UF.
2. Add a capacitor between the power line and the ground line, that is, Y capacitor. The Y2 type is selected to eliminate crosstalk interference, and the capacity range is 2200pF ~ 0.1μF. In order to reduce the leakage current, the electric capacity should not exceed 0.1μF, this circuit board uses 3300PF.
3. Common mode suppression, common mode inductance (suppression coils on the two power lines), when the rated current is large, the wire diameter of the common mode choke should also be increased accordingly, so as to be able to withstand larger currents. In addition, appropriate increase in inductance can improve low-frequency attenuation characteristics, this line uses 10MH.
product description
Introduction of power purifier circuit: The circuit consists of two parts, the first part is a DC component filtering circuit, and the second part is a two-stage composite EMI filter circuit.
1. DC component filtering circuit: The first-stage imitation British DC elimination circuit eliminates the interference of AC components caused by the frequency conversion air conditioners, electronic switching power supplies, refrigerators, chargers, etc. in AC AC220V mains. The DC elimination circuit built with diodes and capacitors eliminates and prevents the DC component in the AC power supply of the commercial power supply to prevent the transformer from having magnetic saturation or an increase in quiescent current due to the DC component.
2. The internal circuit of the two-stage composite EMI filter, because of the two-stage (also known as two-section) filtering, so the effect of filtering noise is better. For some users, the problem of fast transient group pulse interference with a repetition frequency of several kilohertz can be suppressed.
Specifications
Size: 43X107mm, 2mm thicker printed board, 70um thicker copper foil (generally 35um thick)
The shortest design of high-current circuit, short path, can withstand more current and less interference to the outside world.