How can EPS optocoupler isolation improve immunity?

Using optocouplers for signal isolation in EPS (Electrical Power Supply) is an effective way to improve system immunity, especially against common-mode interference and ground potential differences. Optocouplers cut off direct conductive paths in electrical connections through photoelectric conversion.

Applications for improved immunity include:

1. Isolation between strong and weak current interfaces: Using optocouplers between the control board (weak current) and power drive/sampling (strong current) blocks power ground noise from coupling to a clean control ground through signal lines.

2. Long-distance communication isolation: For long-distance communications such as RS485 and CAN, use transceiver modules with optocoupler isolation to prevent communication errors or damage caused by common-mode interference introduced by ground potential differences at both ends.

3. Digital switch input/output isolation.

Points to note when using optocouplers:

1. Provide independent isolation power supplies for both sides of the optocoupler.

2. Pay attention to the common-mode transient immunity (CMTI) parameter of the optocoupler; it should meet system requirements.

3. Ensure the speed and current transfer ratio (CTR) of the optocoupler meet signal requirements. Optocouplers provide a high-impedance barrier against interference currents.