A high-precision I2C real-time clock (RTC) module from DFRobot's Gravity series, based on the SD2405AL chip. It features an internal rechargeable battery that keeps time for 5–8 years without external power, making it ideal for data logging, alarm clocks, and any project that needs reliable timekeeping.

The module includes crystal compensation for ±5 ppm accuracy across industrial temperature ranges, automatic power switching between primary and battery power, and a Gravity I2C connector for plug-and-play wiring.

Key Features

• Internal Rechargeable Battery – Keeps time for 5–8 years without external power
• High Accuracy – ±5 ppm from -40°C to +85°C with crystal compensation
• Ultra-Low Power – 1 µA typical on battery (at 25°C)
• Automatic Power Switching – Seamless switchover between primary and battery power
• Three Alarm Interrupts – Configurable by year, month, date, day, hour, minute, second
• Programmable Clock Output – 32.768 kHz to 1/16 Hz square wave
• Countdown Timer – With interrupt output
• 12-Byte SRAM – General-purpose on-chip storage
• Gravity I2C Connector – Plug-and-play with Gravity-compatible boards

Specifications

• Operating Voltage – 3.3–5.5V
• I2C Speed – Up to 400 kHz (at 4.5–5.5V)
• Accuracy – ±5 ppm (-40°C to +85°C)
• Timing Range – Up to 2099 (with leap year compensation)
• Clock Output – Selectable 32.768 kHz to 1/16 Hz
• Time Format – 12-hour or 24-hour selectable
• Dimensions – 35.5 × 22 mm (1.4 × 0.87″)
• Weight – 6 g

Ideal For

• Data logging with timestamps
• Alarm clocks and timer applications
• Scheduled task triggering
• Any project requiring accurate, battery-backed timekeeping

Package Contents

• 1× Gravity I2C SD2405 RTC Module
• 1× Gravity I2C 4-Pin Sensor Cable
• 1× XH2.54 5-Pin Header

Resources

• DFRobot Wiki