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ISO7821: DWW package creepage distance

Part Number: ISO7821
Other Parts Discussed in Thread: ISO7841

Hi, 

My customer is evaluating ISO7821 in their 1500V solar inverter, they checked IEC62109-1 standard, Table 14, saying under pollution degree 2, material group 3b, ,RMS working voltage 1500V, the creepage distance should be 15mm according to the rule. But in ISO7821 datasheet, the minimum creepage distance is 14.5mm. So does ISO7821 pass iec62109-1? and can ISO7821 used in 1500V solar inverter system? Thanks.

Best Regards.

Chen

  • Hi Chen,

    Thanks for reaching out. I do not believe we certify our devices for IEC 62109-1.
    I do understand that the standard requires 15mm of creepage while the device ISO7821DWW has >14.5mm of creepage. We do know our device supports 1500Vrms and we do our device lifetime test (TDDB) under pollution degree 2 condition. Hence, we claim 1500Vrms on ISO7821DWW device.

    By looking at the IEC 62109-1 requirement and ISO7821DWW datasheet spec, you can say that the device doesn't meet the requirement by standard. But if customer can talk to the standard agency and check with them requesting if ISO7821DWW can be used in their application then he may have this answered. Please do share the TDDB data from datasheet section 6.18 of ISO7841. The ISO7821 datasheet isn't yet updated with TDDB plot but the TDDB plot in ISO7841 is the same one that is applicable to ISO7821DWW as well. Thanks.

    Regards,
    Koteshwar Rao

  • Hi Chen,

    I missed to mention that ISO7821 is categorized into insulating material group I, this means that ISO7821 only needs about 7.5mm of creepage under pollution degree 2 to support 1500Vrms. Hence, the device supports IEC 62109-1 and the standard agency should accept this as a valid solution.

    It is also important to note that along with ISO7821, the PCB also needs to meet IEC 62109-1. The PCB may not support material group I and hence might need higher creepage than what ISO7821 supports. To achieve higher creepage on PCB, customer can create groves or slots and then it should meet IEC 62109-1.

    Let me know if you have any questions, thank you.

    Regards,
    Koteshwar Rao