RTC with SPI and NVSRAM for embedded timekeeping
The DS1306+ is a real-time clock (RTC) from Analog Devices in the standard 16-pin DIP package (16-PDIP), designed for through-hole mounting. It communicates over an SPI interface and tracks time in HH:MM:SS (12/24 hr) with a YY-MM-DD-dd date format. On-chip features include an alarm, leap-year compensation, 96 bytes of NVSRAM for user data, a programmable square-wave output, and a trickle charger for backup battery management.
Timekeeping current and battery backup
Timekeeping current draw is 25.3 µA to 81 µA across the 2 V to 5 V supply range — low enough for battery-backed operation over extended periods. The separate battery supply pin (2 V to 5.5 V) keeps the clock running when the main supply drops, with the trickle charger maintaining the backup cell. Operating temperature is rated 0 °C to 70 °C, suitable for commercial and industrial indoor environments where the board sees ambient conditions rather than extreme heat or cold.