How to design an absolute encoder for EMC?

Absolute encoders typically employ digital communication (such as SSI, Biss-C, EnDat, etc.), and their EMC design focuses on ensuring the integrity of high-speed data communication. Key design considerations for Eintraelectronics include:

1) Power isolation: Using isolated DC-DC power supplies for the encoder and interface circuits to block ground noise.

2) Signal isolation: Electrically isolating communication signals (clock, data) using high-speed digital isolators (such as ADuM) or optocouplers.

3) Interface filtering: Applying RC filtering (R=22Ω, C=100pF) to the signal lines on both sides of the isolator and adding TVS protection (such as ESDLC3V3D3B).

4) Protocol fault tolerance: Selecting a communication protocol with CRC check and retransmission mechanism.

5) Connectors and cables: Using high-quality shielded connectors, and twisted-pair shielded cables with the shield grounded at the driver end.

Through the above design, the absolute encoder interface can withstand ±2kV EFT testing and ±8kV ESD contact discharge testing, with a data error rate below 10^-12, meeting the requirements of high-reliability servo applications.