How can isolation devices for power FTUs improve immunity?

Isolation devices improve immunity by breaking ground loops and suppressing common-mode interference. High isolation voltage devices are selected: ADUM1410 (3kVrms) for digital isolation, ISO7240C (3kVrms) for analog isolation, and WRB2405S-3W (1.5kVDC) for power isolation. Layout: Isolation devices are connected across the split ground planes, with a recessed area underneath for reinforced insulation. Filtering: RC filters are added before and after isolation. Through isolation, the common-mode transient rejection capability (CMTI) is greater than 25kV/μs, system immunity is improved by 30dB, and the surge test requirements of IEC 61000-4-5 are met.