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Application notes for power supply filters?
Sep 07, 2017



Application notes for power supply filters?


It is well known that the purpose of the filter is to filter out excess AC signals in the switching power supply and to eliminate noise in the automatic equipment. To understand the structural principle of the power filter, you first need to understand the characteristics of electromagnetic noise. Any high-frequency transmission to the disturbance signal on the power line can be described as differential interference using differential mode and common mode interference signals; common mode interference is transmitted between the transmission line and ground (ground, grounded chassis), which is non- Symmetrical interference. Therefore, the power filter needs to start from the differential mode and the common mode. The noise to be suppressed by the line filter can be divided into the following two types:

1. Common mode: The noise of the same power line in two (or more) lines can be regarded as the noise of the power line to ground.

2. Differential mode: Noise between the power line and the power line.

The same power supply filter will have different suppression capabilities for common mode noise and differential mode noise, and will generally be described by the spectrum of the frequency corresponding suppression.


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