S32K1xx Data retention for FlexMemory and DFlash

[s_grossmann]

Hello,

I have a project with S32K116 and want to configure it for a 8KB DFlash partition and the use of FlexRAM as Emulated EEPROM. I have some difficulties in understanding the reliability specifications (S32K1xx Data Sheet, Rev. 11, 06/2019, chapter 6.3.1.2). I have two questions about:

"When using NVM as Program and Data Flash data, retention after up to 1 K cycles is specified min. 20 years. When using FlexMemory feature, data retention is specified min. 5 years."

1. What is the condition for the FlexMemory? Is it meant to be 5 years after 100k writes (backup to FlexRAM ratio 1/16) or is it reduced to 5 years in the moment of partitioning? In other words: If I use FlexMemory and have only a few (5..10) write operations at the beginning of life time, will the data retention increase to nearly 20 years?

2. If the data retention is reduced by configuring FlexMemory, does this also affect the data retention for the remaining 8KB DFlash? I found this in the reference manual (S32K1xx Series Reference Manual, Rev. 11, 06/2019, chapter 36.5.2.1): "While different partitions of the FlexNVM block are available, the intention is that a single partition choice is used throughout
the entire lifetime of a given application. The FlexNVM partition code choices affect the endurance and data retention characteristics of the device."

I tried to find out something with the FlexMemory Endurance Calculator, but if my understanding is right, this gives no information about data retention.

Thank you for yout help to let me understand this the right way.

Regards,

Stefan

[dianabatrlova]

Hello,

1. 

The minimal data retention of FlexRAM as Emulated EEPROM is 5 years. It can be extended by EEPROM usage (refreshing the records). The number of years depends on how often you write to FlexRAM to cause the records to be updated. So, the worst case is when it is no write into FlexRAM for 5 years, in that case, the data retention is 5 years.

2.

The data retention of the DFlash which is not used for EEPROM backup is not affected.

I hope it helps

Best regards,

Diana