Real-time clocks (RTC) are, as the name implies, clock devices. The DS1307 real-time clock IC is an 8‑pin device with an I2C interface, a low-power calendar with 56 bytes of battery-backed SRAM. The clock/calendar provides seconds, minutes, hours, day, date, month and year. The end-of-month date for each month is adjusted automatically, specifically for months that have fewer than 31 days.

The main advantage of RTCs is that they have battery backup that keeps the clock/calendar running even during a power outage. RTCs require exceptionally little power to operate.

Technical specifications

• DS1307 RTC
• I²C interface
• for LIR2032 (not included)
• power consumption under 500 nA in standby