DS1307 datasheet by Dallas Semiconductor

DS1307 Frequently Asked Questions (FAQs)

• What is the minimum voltage required to maintain the clock and RAM data?
  The minimum voltage required to maintain the clock and RAM data is 2.0V. However, it's recommended to keep the voltage above 2.5V for reliable operation.
• How accurate is the internal oscillator?
  The internal oscillator has an accuracy of ±20 ppm (parts per million) at 25°C, which translates to about 1 minute per year.
• Can I use the DS1307 as a standalone clock without an external crystal?
  Yes, the DS1307 has an internal oscillator that can be used as a clock source. However, the accuracy may not be as good as using an external crystal, and the frequency may drift over time.
• How do I set the clock to start counting from a specific date and time?
  You need to write the desired date and time to the clock registers (seconds, minutes, hours, day, date, month, and year) using the I2C interface. The clock will start counting from the set value.
• What happens when the battery is removed and reinserted?
  When the battery is removed, the clock and RAM data are maintained by the internal capacitor. When the battery is reinserted, the clock will continue from where it left off, and the RAM data will be retained.