what comes first reverse protection or EMI filter?

[slloyd]

hi all, for functional reasons i'd like to put the reverse protection circuit ahead of the EMI filter. does this affect how well the EMI filter will work due to the reverse circuit's body diode?

[Gyro]

It certainly puts more components, PCB area, and tracks before the filter. These can all act as antennas, reducing the effectiveness of the filtering - and exposing the active semiconductors to the unfiltered supply.

It's not ideal to have anything before the filter.