buenos
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Yes, you'll find an optimal resistor value which achieves maximum oscillation dampening, which is related to the characteristic impedance of the unwanted resonant cicruit.is the resistor necessary?
I think, filtering is always reasonable. According to the said commutation loop structure, interferences will mostly spread through the Vin node and the ground plane rather than the output node, which is already filtered by the output LC circuit. Radiated emission can be a problem, but not from the core components of a physical small converter. Observing radiated emissions is another word for the first filter level has been already cut out.Filtering at the output of the converter often doesn't do much for this kind of "noise," since it is radiated everywhere and can bypass even a well designed filter.
I've made switching supplies where the transient spikes would show up on practically every node in the circuit, even those that do not share a ground or supply. I could just probe the ground of the circuit and pick it up clearly. Short of shielding, there's no way to eliminate that sort of signal except by eliminating it at the source. This is generally with relatively high power converters though (10KW 400V boost operating at 50KHz), so it's an extreme case.I think, filtering is always reasonable. According to the said commutation loop structure, interferences will mostly spread through the Vin node and the ground plane rather than the output node, which is already filtered by the output LC circuit. Radiated emission can be a problem, but not from the core components of a physical small converter. Observing radiated emissions is another word for the first filter level has been already cut out.
Reduce, yes. Unlikely eliminate, significantly reduce, possibly. You have to try.so, would the RC snubber always eliminate/significantly-reduce this noise?
R equal to characteristic impedance of the unwanted resonant circuit as a first estimation, Zc >= R. The latter is a compromise between effective snubber action and losses. As said, you need to identify the resonant circuit. If you have no clue about it, just try the RC values.what is the R, C values, and how to calcualte the effect?
Zc <= R. resonant circuit C is about 1 nF, I would try a snubber C of 1.5 to 4.7 nFWhat should be the capacitor value?
I suggest the previously described current loop. The calculation results in a rather small L of about 4nH, I believe that the "layout is not so bad".I have no clue about the resonant circuit.
Yes. Or split across the high and low side switch. Even a snubber across the input capacitors can have some effect (an the advantage of not causing switching losses).The question is still there: is it a series RC between the switching node and the ground?
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