Gravity: I2C SD2405 RTC Module

The Gravity: I2C SD2405 RTC Module is a high-precision real-time clock designed for reliable timekeeping in microcontroller projects. Operating across industrial temperature ranges, it is an ideal solution for students, makers, and engineers building data loggers, alarm clocks, and automated timing systems.

High-precision industrial timekeeping

Powered by the SD2405AL chip, the module maintains an accuracy of plus-minus 5ppm across temperatures from minus 40 to 85 degrees Celsius. It tracks seconds, minutes, hours, day, date, month, and year with automatic leap year compensation valid through 2099, supporting both 12-hour and 24-hour formats.

Automatic dual-power backup

Featuring an internal rechargeable battery, the module automatically switches power sources when the main supply drops. It draws an ultra-low 1uA of current on battery backup, keeping time accurately for 5 to 8 years without external power.

Flexible alarms and clock outputs

The module provides three customisable alarm interrupts configurable by year, month, date, weekday, hour, minute, and second, alongside a countdown timer. It also offers programmable square-wave clock outputs ranging from 32.768kHz down to 1/16Hz to drive external microcontrollers.

On-chip SRAM and time trimming

An integrated 12-byte general-purpose SRAM provides non-volatile data storage for small system variables. An internal time-trimming circuit allows precise clock adjustment by compensating for crystal oscillator frequency variations.

Plug-and-play Gravity interface

The module runs on 3.3V to 5.5V logic and supports fast 400kHz I2C communication. It connects seamlessly to microcontrollers using the standard Gravity I2C pinout.

Included accessories

Each unit comes supplied with one Gravity I2C 4-pin sensor cable and one XH2.54 5-pin header for easy breadboard and PCB integration.

Downloads & documentation

• Product wiki (DFRobot)