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STKNX, 100 µF capacitor CVDDHV: Can I use multiple MLCC in parallel instead of one electrolytic capacitor or are there certain characteristics of the electrolytic capacitor that are needed in the circuit? Datasheet "DS12399 - Rev 3 - May 2021", Table 1

SBart.5
Associate
 
1 ACCEPTED SOLUTION

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Peter BENSCH
ST Employee

Welcome, @SBart.5​, to the community!

Electrolytic capacitors are usually preferred at this point for price reasons. Using MLCC instead should not be a problem, but MLCC, especially when connected in parallel, usually have a much lower ESR than electrolytic capacitors, which can lead to large peak currents when switching on and possibly exceed the KNX limits. If necessary, this can be achieved by adding a series resistor.

Does it answer your question?

Regards,

/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

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3 REPLIES 3
Peter BENSCH
ST Employee

Welcome, @SBart.5​, to the community!

Electrolytic capacitors are usually preferred at this point for price reasons. Using MLCC instead should not be a problem, but MLCC, especially when connected in parallel, usually have a much lower ESR than electrolytic capacitors, which can lead to large peak currents when switching on and possibly exceed the KNX limits. If necessary, this can be achieved by adding a series resistor.

Does it answer your question?

Regards,

/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.
SBart.5
Associate

Thank you for your quick reply, that answers my question.

In our case we do not have enough space in the height for an electrolytic capacitor, so we need an alternative.

Regards, Sebastian

Peter BENSCH
ST Employee

Great!

If the problem is solved, please mark this thread as answered by selecting Select as best, as also explained here. This will help other users find that answer faster.

Good luck!

/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.