How to Conduct Effective EMC Design for Power Ports at the System Level?

The power port is a primary path for the conduction of internal and external interference, requiring the construction of a multi-stage protection and filtering network. At the AC input or DC power entry point, a TVS diode with high surge current capability, such as the SMDJ series, should first be used to absorb surge and transient overvoltage energy. Subsequently, a π-type or LC filter circuit should be deployed to filter out wideband conducted noise. For internal sensitive analog and digital circuits, separate LDOs should be employed for power isolation and secondary regulation. Additionally, decoupling capacitors should be placed as close as possible to the power pins of each chip, which is crucial for blocking noise propagation through the power network.