Questions about M48T201V

[MATRIX7878]

Hello,

     I am designing with the aforementioned RTC and have the following questions.  I contacted ST support and the solution was to ask the forums.  So here are my questions:

1. What is the date output (i.e. binary, BCD, YY:MM:DD:dd, HH:MM:SS:hh, etc.)?
2. The crystal and battery are in a separate module and are not integrated with the IC itself. I want to make sure that it is compatible with both types (the 48 and 120 mAh).
3. What does the chip control in terms of the NVSRAM? Is it a buffer? What does it do?
4. Unrelated to this chip in particular, does ST have a RTC with an integrated (non-seperate SNAPHAT) crystal and no battery pin, just VDD? I do not need a backup battery, or a pin for it.

Thank you

[Tesla DeLorean · Accepted solution]

It's not "output", you get to read bytes from the RTC memory, and you'd combine them, and convert to ASCII to construct a time/day stamp.

https://www.st.com/resource/en/datasheet/m48t201v.pdf#page=18

There's an 19-bit address bus, and 8-bit data bus. On the STM32 you might be able to map it into the FSMC/FMC address space.

The RTC registers shadow in the last 16 bytes in the 512KB linear address space.

[MATRIX7878]

Hello,

     Ah, I see what you mean.  That does make sense.  Thank you.  So, the data that is read is in binary, it needs to be converted.  The SRAM ability is to turn an SRAM into an NVSRAM (because it has the battery).  From what I understand.

     As for my other questions, it seems like it is compatible with both SNAPHATS and there is no RTC with an embedded crystal and no battery pin.  If I am wrong, please let me know.

Thank you.

[Peter BENSCH]

Yes, there are TIMEKEEPER RTCs with crystal and without SNAPHAT:

• M41T81SMY6F
• M41T83xMY6F (x=S, R, Z)
• M41T93xMY6F (x=S, R, Z)

Please note that only the package variants MY contain the crystal, otherwise it has to be connected externally.

[MATRIX7878]

Thank you for letting me know.