Electrical – DS3231 Real Time Clock i2c 3volt battery 5V arduino

power supplyrtc

I have a doubt I hope somebody can help me

I am thinking to add to my project using Arduino Mega 5V a DS3232 real time clock. I can see on data sheet some information about the MAX voltage for SCL SDA.
I know I can connect directly to 5V the DS3231, But If I disconnect the VCC to work only with 3V battery cr2032 …

My question is:

Will the I2C communication work? Because Arduino will use 5V and DS3231 3V. If not, why they add option to use battery, for MCU 3v3 ?

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Best Answer

This is my understanding of the question:

I know I can power DS3231 with +5V. But If I disconnect the Vcc to work only with 3V battery (CR2032), will I be able to communicate with the RTC?

If the Vcc is powered down and the RTC is powered only from the backup battery, the microcontroller (MCU) will not be able to communicate with it through I2C. I'm guessing that the MCU and RTC are powered from the same rail. So, when Vcc is powered down, the MCU itself is powered down, and it wouldn't be communicating.