Abstract

As a switching supply, a power adapter generates electromagnetic interference affecting nearby electronics. The power adapter lowers conducted and radiated noise through EMI filter circuits. This power adapter covers conducted emission, radiated emission and filter component parameters, helping meet FCC and CE-EMC standards for stable wireless communication.

1. EMI Source and Frequency Band

EMI of the power adapter comes from high-frequency switching. Conducted emission of the power adapter covers 150kHz-30MHz. Radiated emission of the power adapter covers 30MHz-1GHz.

2. Input EMI Filter Circuit

The input stage of the power adapter sets X/Y capacitors and common-mode inductors. Two-stage filtering of the power adapter suppresses differential and common-mode noise. Filter parameters of the power adapter match the power rating.

3. Radiated Suppression Design

Switching nodes of the power adapter add RC snubbers to suppress spikes. Shielding and grounding of the power adapter reduce radiated noise. PCB layout of the power adapter shortens high-frequency loops.

4. EMC Test and Margin Parameters

Conducted and radiated emission of the power adapter must meet EN55032 Class B. Design of the power adapter reserves over 6dB margin. The unit must pass at full, half and no-load states.

5. Value of EMC Compliance

EMC compliance of the power adapter is the market-access threshold for EU and US. Good EMC design of the power adapter ensures wireless performance and lowers certification failure risk.

Conclusion

Mature EMI filter design of the power adapter meets global EMC regulations. For power adapter EMC pre-test reports, contact Simsukian for support.

References

1. IEC 62368-1 Audio/video, information and communication technology equipment safety standard

2. DOE Level VI External Power Supply Standard (US)

3. IEC 63002 Interoperability specifications for external power supplies