How to filter and shield industrial servo EtherCAT cables?

As a high-speed industrial Ethernet interface, the EtherCAT interface requires careful EMC design to address high-frequency noise suppression and signal integrity. The Eternity Electronics filtering and shielding solution includes:

1) Transformer-integrated common-mode choke: Using an Ethernet transformer with a built-in common-mode choke (e.g., with CMZ characteristics) to suppress common-mode noise during differential signal input and output.

2) Port protection: Before the transformer, a low-capacitance TVS array (e.g., ESDLC3V3D3B, capacitance <3pF) is used between the wires and ground for ESD and surge protection.

3) PCB design: Maintaining a complete ground plane beneath the Ethernet transceiver chip, with differential lines strictly controlled to 100Ω impedance, and equal length and spacing.

4) Connections and cables: Using RJ45 shielded connectors with metal sheaths, and Cat5e or higher shielded twisted-pair (STP) cables, with the shield terminated 360 degrees at the connector.

This design allows the EtherCAT port to pass ±2kV surge and ±8kV ESD tests and operate stably at a 100MHz communication rate, meeting the requirements of harsh industrial environments.