I have a question about ADuM140x.
I was checking Rev.K and Rev.L.
Why did you change the insulation voltage?
It is a long story, so pull up a chair :-)
This was one of the very first generation devices certified at CSA. The policy at CSA has been to specify the working voltage based on the crepage and an assumption of Material Group III and pollution degree 2. They measured the creepage, came up with 8mm which is adequate for 400V reinforced. ADI did not do measurements of Material group and used the default value of III.
Then a few years later, but still many years ago they got better measurement equipment and standardized their method of determining creepage. That package was measured on subsequent products as 7.8mm in the Jedec standard SOIC-W which corresponds to 390Vac working voltage. However they do not go back to automatically update certificates unless they need recertification. That product did not need recertification until recently when ADI changed the mold compound as part of an assembly transfer. At that point this was a unique situation for this device and the change was swept up into the PCN for the assembly change which did modify the creepage a bit..
ADI does not consider this to be a critical issue since we now specify the Material Group for the mold compound as II, as reflected in the current certificate, so when the rating for the mold compound is taken into account, the part still supports the original 400V reinforced rating.
If you have any further concerns let me know.
It is complicated story...
So if the other iCoupler (maybe ADuM321x??) compound change , the CSA value will change?
Is it written at the datasheet that ADuM140x supports original 400V reinforced rating?
Also I think ADuM140x support original 800V basic rating.
Is this correct?
All of the CSA certs involved in the transfer were changed.
A1) The ADuM321x is in a different package than the ADuM140x and there was not the same history. In many cases the creepage went up a bit since we got rid of a tie bar at each end, in most cases there was no change, just a recognition of the new BOM.
A2) Not explicitly, it quotes the certificate. You need to reinterpret the values yourself. By creepage it could support much higher voltages, around 600V, but our lifetime of the internal insulation does not support that voltage, we still recommend 400V max for both basic and reinforced.
A3) The package supports 800V basic, but internal insulation is still rated at 400V by ADI.
Thank you for your support.
Your answer help us very much.
Sorry that I don't know about certification so much.
So does CSA certification for just for package?
Not for internal insulation?
For lifetime under working voltage, it is determined by the external tracking/creepage requirements. For internal insulation the withstand is tested, but there is no effective test for insulation lifetime until the new IEC60747-17 standard is released (probably in 2018). The VDE-0884-11 standard does lifetime testing and is the basis for the new IEC standard.
The system standards rely on review of internal structures, requirements can vary from standard to standard. But they really only test for transient immunity after environmental tests. Currently it is the responsibility of the manufacturers to provide internal insulation lifetime guidance.
Thank you for your reply.
I understood what you said!
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