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TIDA-010046: Coupling Earth and PE

Part Number: TIDA-010046

in this reference design GND and EARTH is coupled with a 1M and a 4700 pF capacitor near the magnetic.
Could you please explain the reason why?

The documentation says: 'Additional capacitors are required to interconnect chassis ground and signal ground. The suggested technique is to use plane coupling capacitor values (for example, from 1000 pF to 4700 pF).
Depending on available board space, place one set of capacitors on each side of the Ethernet magnetic"

It's unclear to me why this coupling is necessary.

Best regards

  • Hello Holger,

                                Thank you for looking into our reference design - TIDA-010046. The components between GND and EARTH helps to meet EMC requirements. High value resistor provides DC Isolation and low capacitance shorts any high frequency noises. These help in passing EFT and emission tests. The value of these components are very subjective and can be tuned during testing.