How to solve the interference caused by internal cable coupling in HMI (Human Machine Delivery) systems?

Solving internal cable coupling interference in HMI requires addressing three aspects: reducing the intensity of interference sources, decreasing coupling path efficiency, and improving the immunity of affected cables. First, identify and suppress strong interference sources. For example, shield noisy cables such as switching power supply modules and motor drive lines, or use ferrite beads for filtering at the source end, such as connecting a PBZ1608E102Z0T in series on the fan motor power line. Second, optimize cable layout and routing. The basic principle is to separate strong and weak currents, and high and low speed signals, avoiding long-distance parallel proximity between sensitive signal lines and interfering lines. When parallel proximity cannot be avoided, increase the spacing between lines or install grounded shielding wires between them.

For sensitive signal lines, such as touchscreen cables and analog sensor lines, use shielded cables, and ensure the shielding layer is properly grounded at both ends or one end (depending on the grounding strategy). Using twisted-pair cables to transmit differential signals can effectively suppress magnetic field coupling interference. At cable connectors, use connectors with filtering functions or add filtering components to the signal lines, such as adding an ESD protection device ESD3V3D3B and a small series resistor to the I2C clock line. By routing cables as close as possible to the metal chassis or ground plane, the mirror effect can be used to reduce radiative coupling. Using ESD protection devices and filtering beads from Audiotech, combined with proper cable shielding and wiring specifications, crosstalk between internal cables can be systematically resolved, improving the overall EMC performance of the HMI.