I've used a 24LC16B memory on an industrial digital regulator. The purpose of the memory is to store the configuration of the system, so is basically written on few hundred times upon user commissioning and read out at every system startup. data integrity is checked with CRC.
After 6 years of continuous service it happened that 4 regulator at same time (few days between each other) the data in memory become corrupted and after a rewrite on memory become corrupted again after few hours if the power supply is present or few minutes if power supply is not present.
The chip is supplied by 3.3V nominal (3.5V directly measured on terminals) by a switching regulator (LM2576S-ADJ) but no other component is damaged.
What can be happened? where I can find information about memory failure not related to write cycles?
Any suggestion is appreciated
Thanks in advance