The VDE Viorm = 1250 Vpeak reinforced isolation rating for the AD7403 is much higher than the CSA reinforced rating of 415 Vrms (586 Vpeak). Why is this the case?
Different regulatory bodies such as VDE and CSA have different criteria for rating isolation. In the case of CSA their rating is dominated by the device creepage and clearance specification, >8.3mm.
It should be noted however that the isolation rating that CSA give is based on devices with a Material Group III for a pollution degree of 2 for altitudes <2000m. This is standard practice in CSA to rate all parts to these criteria. CSA have however qualified the AD7403 package to have a CTI of ≥600 V. This means the AD7403 is qualified as a Material Group I device. Devices with a Material Group I for a pollution degree 2 for altitudes <2000m with a 8.3mm creepage and clearance specification can have a 830 Vrms reinforced working voltage. See the Safety and Regulatory Compliance Information page,
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