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

The main advantage of RTCs is that they include battery backup, which keeps the clock/calendar running during power outages. RTCs require exceptionally little power to operate.

Technical specifications

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