Question about S32K1 series NVM reliability specifications

[Usagi_Summer]

I am using S32K146 FlexRAM as Emulated EEPROM. And I am wondering what does "Data retention up to 100% of write endurance" catagory mean?

Does it means that when the write endurance has reached 100% (i.e. write endurance has been completely depleted and no more data can be written), the data I stored on the emulated EEPROM can still be safely preserved more than 5 years? And "Data retention up to 10% of write endurance" catagory means when write endurance has only used 10%, the data stored on the emulated EEPROM can be safely preserved more than 20 years?

e.g. I have my chip EEPROM backup size set to 65536 Bytes, FlexRAM EEPROM size set to 4096 Bytes, that would be EEPROM backup to FlexRAM ratio = 16, and the application would completely overwrite the emulated EEPROM 100k times over the course of 10 years, the data last time written to the emulated EEPROM can still be safely preserved more than 5 years.

Are my understandings correct? Please correct me if it's wrong.

And will the way I am writing to the emulated EEPROM affect its data retention? I am using Processor Expert and S32 SDK to operate emulated EEPROM. Do I have to manually write data averagely all over the EEPROM? Or the driver will handle the optimization work?

Thanks!

[lama]

Hi,

It is a little bit complex topic so I suggest.

Could you please read the document?             

https://www.nxp.com/docs/en/application-note/AN11983.pdf

And, you can download and use flash memory calculator to calculate E/W cycles and retention. The tool helps you to correctly design necessary flash needed for required number of E/W cycles, E/W data sizes and data retention.

The SW.. Flex Memory Endurance Calculator

At the page:

https://www.nxp.com/products/processors-and-microcontrollers/s32-automotive-platform/s32k-auto-gener...

Best regards,

Ladislav

[Usagi_Summer]

So I tried using this calculator, filled in my configuration and estimated usage. This result means current configuration of emulated EEPROM can meet the data retention need for this product in the 20 years of use, right?

[lama · Accepted solution]

Hi,

Yes, in the calculator you have InSpec/OutOfSpec ranges which takes into account combination of all factors and implemented EEPROM algorithm. If you write, for example 20, into the Application Life then you expect the memory will keep all parameters guaranteed in the datasheet in this period. You know, the less data you will use and the less you are rewriting them then you have more memory cells into your disposal to be used for data refreshment. 

You did not reached any boundary which shows that you have think about retention or reliability so yes, your data and memory cells will keep guaranteed parameters from data sheet.

Best regards,

Ladislav