Electromagnetic interference is an unavoidable problem in electronic products. How to reduce the solution to electromagnetic compatibility and radiation, we must understand the role and characteristics of the filter. The power supply filter is composed of resistors, capacitors and inductors. Also known as filter circuit. It effectively reduces or even filters the frequency of a specific frequency in the power line or the frequency outside the frequency point to obtain a power signal of a specific frequency, or eliminate the power signal after a specific frequency.
The function of the filter is mainly in the following aspects: improving the anti-interference ability of the disturbed device, avoiding the malfunction of the switching power supply due to the power supply equipment or external interference, thereby improving the anti-interference ability of the switching power supply and suppressing the interference generated by the switching power supply. The impact on other products, reduce the interference of the switching power supply to the outside. Suppress the interference of the switching power supply to the power grid.
In the switching power supply, there are a protection circuit, an input/output level detecting circuit, a driving circuit, a rectifying and filtering circuit, a power conversion circuit, a PWM controller circuit, etc., and these circuits are mainly composed of dedicated or general-purpose power supply integrated circuits to prevent these circuits. An effective method for malfunction due to external noise is to use a noise filter. In the switching power supply input circuit, the incoming interference due to external influences is generated in the internal circuit of the power adapter and the switching power supply, which is a malfunction of the switching power supply. The main factor of the filter is a good solution. It can effectively prevent the switching power supply adapter from being disturbed by the outside world. For the output electromagnetic interference and electromagnetic radiation, the switching power supply adapter itself will be in the switching action and the clock frequency switching action. The terminal noise of the input end of the switching power adapter generates interference radiation. They will interfere with other devices, so the filter is also a powerful solution. The filter also reflects its important value in solving the interference problem of the switching power adapter.