Hello, I have some existing PCB that uses the DS3231 RTC module eeprom for some stuff.
I'd like to write something every second to the eeprom and currently by doing that I might kill the eeprom rather quickly, so would like to replace it with FRAM.
From what I can see the FM24C seems to have the same pinout as the AT24C, so I hope this could work.
The one thing worth checking is that the A0,A1,A2 pin behavior is the same. On the FM24C64B the A0,A1,A2 pins have internal pull downs so if there were an issue her you could just snip off the pins.
Be aware that the FRAM write endurance is not unlimited, if you write data at once every second the data sheet spec says the write limit will be reached in a little over 3 Million years, so take care.
The addressing scheme of AT and FM chips depends on the size, so a one-to-one replacement is guaranteed if the size of the AT24 EEPROM and the FRAM are the same.
What is the index of AT24 chip, that you going to desolder from RTC?
You might be limited to using a 5V supply if you make this switch. The DS3231 and the EEPROM both work at either 3.3V or 5V, but I think the FRAM is a 5V device.
Anyway, here's the schematic for the ZS-042 module in case it's needed:
I do it all the time but realize the packages although pined out the same are not the same, ,the FRAM is wider. I bend the pins to fit the foot print and carefully solder it in place. They work great. You can get them as low as 1V8. You will need to check the data sheet and be careful they are 30X faster then EEPROM when writing to them.
Thanks for all the helpful comments! That was really useful.
So basically I think I need to make sure I find an FRAM chip that covers all of these:
Same pinout
A0-A2 pulled down
Same package/similar size that can fit with slight bending
3.3V input for the FRAM - not 100% sure about this, here are the schematics of the PCB:
