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Flash retention at high temperatures

We need to ensure flash retention for >10 years @ 85C on nRF52840. Currently its datasheet says 10y @ 40C, but this seems to claim that 10y @ 85C is more accurate. While that is close to what we need, it seems that in order to be on the safe side we will need to refresh flash content periodically (e.g. every few years). Therefore, I have few questions:

- does Nordic have any reference implementation, which would refresh the whole flash safely, or one need to start from scratch? Any pointers? 

- if chip is powered on most of the time (more like 24/7 or at least 50% of the time), is the retention the same? Or the years specified are for offline storage, but in power-on situation the retention is improved?

Thanks in advance.

  • - does Nordic have any reference implementation, which would refresh the whole flash safely, or one need to start from scratch? Any pointers? 

     No, I guess a DFU would be the closest to look at. 

    - if chip is powered on most of the time (more like 24/7 or at least 50% of the time), is the retention the same? Or the years specified are for offline storage, but in power-on situation the retention is improved?

     It's the same.

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