What is EMI Anti-jamming?
That is, electromagnetic interference, which is generated by the action of voltage and current and can be conducted along the circuit or air and other media, is an electromagnetic phenomenon that has adverse effects on the surrounding electronic equipment and electronic system. This kind of electromagnetic interference, one is the external interference introduced from the output terminal line of the power supply, the other is generated by electronic equipment through the power line conduction.
Electromagnetic interference can be divided into common mode interference, differential mode interference two kinds, differential mode interference; Is the interference noise between two power lines (called line to line), common mode interference: is the interference noise between two power lines to the earth (called line to ground). In order to solve this problem, EMI anti-interference circuit is introduced, which mainly uses the characteristics of inductance and capacitance components to filter the EMI generated between the signals generated by the power or electronic system — signals, power supplies, power supplies, signals — power supplies, to ensure that the whole power or electronic system can work stably, but also does not send out harmful electromagnetic interference. It also prevents the introduction of external interference.
The following is based on the specific circuit to analyze the EMI circuit working process:
1. All interference clutter returned from the live line (L) of the power line and through the neutral line (N) of the power line is called differential mode interference (FIG. 1).
(FIG. 1)
Differential mode interference goes in the opposite direction, one in, one out. When the dry anti-clutter enters the circuit, it will pass the X capacitors C1 and C2 to the neutral line to filter out the interference clutter.
Common-mode inductance has no effect on the differential mode interference signal, because when the interference signal enters, it will produce left positive and right negative induced electromotive force, and when it comes out, it will produce right positive and left negative induced electromotive force. The magnetic field is opposite, so they cancel each other, so it has no effect on the differential mode signal.
2. All the interference clutter returned by the live line (L) or the neutral line (N) of the power line but through the line (GND) is called common mode interference. (FIG. 2)
(FIG. 2)
When common-mode interference clutter enters the circuit, common-mode inductor L1 and common-mode capacitors C3 and C4 jointly filter the interference clutter. Because the current direction is the same, the induced electromotive force above and below the inductor L1 has the same direction of positive left and negative right. The two coils generate magnetic fields in the same direction and increase the inductance impedance of the coil, making the coil behave as
High inductance resistance, in order to attenuate the working mode interference current, to achieve the purpose of filtering interference clutter, while the live line (L) and neutral line (N) not filtered clean interference current through the capacitor C3.C4 through PE(connected to the shell and earth) filter out.
The power adapters produced by JPTPOWER can meet EMI requirements. When used with your terminal products, you do not have to worry about too much noise to interfere with the product, to ensure the stability of the product. If you encounter such problems, please consult our technical team.
