How to design the EMC of the PCSCAN/Ethernet interface in an energy storage system?

The EMC design of the CAN and Ethernet interfaces of the PCS needs to balance signal integrity and interference immunity. 

For the CAN bus:

1. Common-mode filtering: Connect a common-mode inductor (such as CML3225A-101T) in series on the CAN_H and CAN_L lines to suppress common-mode noise on the bus.

2. Bus termination matching: Install a 120Ω terminating resistor at each end of the bus to suppress signal reflection.

3. Protection devices: Place a dedicated ESD protection device for the CAN bus, such as ESDCANFD24VAPB, near the interface after the common-mode inductor to provide electrostatic and surge protection.

For the Ethernet interface:

1. Integrated filtering and protection: Typically, an RJ45 connector (magnetic module) with an integrated common-mode choke and isolation transformer is used.

2. Additional protection: On the chip side of the magnetic module, a low-capacitance TVS array (such as the SRV series) can be added as needed for surge protection.

3. PCB design: Strictly follow differential pair routing rules (equal length, equal spacing, tight coupling) and maintain the integrity of the reference plane. Both require the metal casing at the interface to be grounded, and the cable to be shielded.