How to isolate strong and weak current on the I/O module PCB?

Effective isolation between high-voltage and low-voltage circuits on the I/O module PCB is fundamental to ensuring safety and reliability. First, physical partitioning is implemented, clearly separating high-voltage, high-current power areas from low-voltage, sensitive signal areas, with sufficient creepage distances and clearances to meet safety regulations. An isolation strip is created between the two areas, and isolation devices such as optocouplers, isolation transformers, or isolation operational amplifiers may be installed within the strip to achieve electrical signal isolation. Power isolation uses isolated DC-DC modules, and the primary and secondary sides should also meet the corresponding isolation voltage requirements.

In terms of layout, isolation devices should be connected across the isolation strip, with their input and output sections belonging to their respective areas. During wiring, high-voltage and low-voltage traces must cross the isolation strip perpendicularly, never parallel or crossing it. The ground plane also needs corresponding segmentation; high-voltage ground is typically noise ground, and low-voltage ground is signal ground, with the two connected only at a single point at the power input filter capacitor or completely isolated by isolation devices. The effectiveness of the isolation is verified through withstand voltage and insulation resistance tests.