The recommended crystal oscillator frequency for the DS3231 is 32.768 kHz.
The internal oscillator of the DS3231 has an accuracy of ±2 ppm at 25°C, which is sufficient for most applications. However, for more accurate timekeeping, an external crystal oscillator is recommended.
Yes, the DS3231 can be used in battery-backed mode. The device has a built-in battery switch that allows it to switch between the main power supply and a backup battery when the main power supply fails.
The maximum operating temperature range of the DS3231 is -40°C to +85°C.
The DS3231 automatically handles leap years, taking into account the extra day in February for years that are divisible by 4.
DS3231SN#T&R datasheet
by Maxim Integrated Products
