How to design power isolation for I/O modules?

Designing a power isolation system for I/O modules requires determining isolation requirements and selecting a suitable solution. First, clarify the isolation voltage level; for example, safety extra-low voltage circuits may require 1.5kV, while industrial field interfaces may require 2.5kV or higher. A common solution is to use isolated DC-DC modules, which integrate transformers and feedback circuits and are easy to use. For multi-channel isolated power supplies, single-input multi-output isolation modules or multiple single-output modules can be used. If size and cost are a concern, a power supply based on isolated flyback or forward topologies can be designed, but this requires specialized power supply design knowledge.

Regardless of the solution, the creepage distance and clearance between the primary and secondary sides of the isolated power supply must meet safety regulations. In PCB layout, a slot should be cut below the isolation transformer or module, with primary and secondary components strictly separated on both sides, with no traces crossing in between. To suppress switching noise, filtering circuits, such as common-mode inductors and X/Y capacitors, should be configured at both the input and output terminals of the isolated power supply. After design, withstand voltage testing, insulation resistance testing, and conducted emission testing are required to ensure safety and EMC compliance.