How to handle multiple modules sharing a common ground in a power DTU?

Addressing the common grounding of multiple DTU modules requires ensuring consistent ground potential and noise isolation. A star-shaped common grounding structure is adopted, with the ground wires of all modules converged to a central grounding point via copper busbars with a cross-sectional area ≥4mm². A PBZ1608A-102Z0T ferrite bead is deployed at the entrance of each module to provide DC connectivity and isolate high-frequency noise. Digital and analog modules are separated by ground plane and connected via a single point. Differential transmission and isolation devices are used for the communication interface. The common grounding system impedance is analyzed through simulation to optimize the grounding point location. The measured voltage difference between the ground wires of each module is less than 50mV. The multi-module common grounding design enables the system immunity to meet IEC61000-4-4 EFT ±4kV, and conducted emissions are compliant.