The following schematic diagram of the lack of EMI filter Cd, how much impact. Are there any acceptance criteria?
The LM26420 module in the following figure selects a filter inductance of 0.15uH.When should Lf choose 0.1~1uH？
Hi Jian,
For acceptance criteria of Cd,pls refer to below description as below:
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For Lf selection, it depend on how much corner frequency of EMI filter you want to select. The higher Lf , the smaller of corner frequency and the more reduction of EMI noise, but the cost and solution size will become large as well, so it is a trade off.
Thanks
Colin
Hi Colin
Select a small Lf, as long as the cap value can be increased to get the filtering effect. Shouldn't the smaller Lf be preferred？
Can reduce energy consumption and layout space.
Hi Jian，
If your reduce Lf, the Cf must be big, And you should take parasitic elements into account, the real capacitor model is as below shown:
We can see the capacitance is bigger, the resonance frequency is smaller, so real capacitance is smaller at same frequency.
Parasitic elements can impact EMI filter performance at higher frequency,
Thanks
Colin
Hi Colin
I would like to know the selection of LC filter parts for the power front end.
