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SSM3302 Output filtering

Question asked by aerskine on Apr 23, 2014
Latest reply on Apr 29, 2014 by aerskine

Dear Colleagues


I have some customer questions regarding the SSM3302 output circuit, as shown in the UG-360 Eval Board documentation. 


Common-mode output choke component selection (L1 and L2)

On page 4 of UG-360, the selection of a common mode output choke for EMI filtering is discussed, and two component recommendations are given.


The common-mode choke in combination with shunt capacitors on the "secondary side" filter out switching noise, which would otherwise be present on the speaker connections, and could cause EM radiation if the cables are too long.


- What are the technical requirements for this common-mode choke (in case another component or an alternative manufacturer needs to be chosen)?

- Are there any known alternatives from another manufacturer?

- In what frequency range does the switching noise occur?
(The datasheet refers to proprietary modulation and spread-spectrum techniques, but it would be useful to have specific information about the nature of the noise signal that needs to be filtered out)


Thanks and best regards