The SD2403 Real-Time Clock (RTC) Module provides accurate timekeeping for Arduino and other microcontroller projects. With an integrated crystal oscillator achieving ±5 ppm accuracy, the clock drifts less than 2.5 minutes per year without calibration. Typical power consumption is just 1.1 µA, making it well suited for battery-backed and low-power applications.

The module communicates over I2C and supports both 3.3 V and 5 V logic levels, making it compatible with Arduino Uno (5 V), Arduino Due (3.3 V), and .NET Gadgeteer platforms. A time alarm function with interrupt output is also available.

Key Features

• High Accuracy – ±5 ppm with integrated crystal (less than 2.5 min/year drift)
• Ultra-Low Power – 1.1 µA typical consumption
• Battery Backup – CR1220 coin cell socket for timekeeping without external power
• I2C Interface – With 0.5 s auto-reset to prevent bus lockup
• Alarm with Interrupt – Configurable time alarm via interrupt output pin
• 3.3 V / 5 V Compatible – Works with both voltage levels; I2C pull-up resistor switch included
• 12/24 Hour Format – Selectable time format

Specifications

• RTC IC – SD2403
• Supply Voltage – 1.8–5.5 V
• Backup Battery – CR1220 (included)
• Accuracy – ±5 ppm
• Power Consumption – 1.1 µA typical
• Interface – I2C + interrupt output
• ESD Rating – >4 kV
• Operating Temperature – −40 °C to +85 °C (industrial grade)
• Dimensions – 36 × 36 × 14 mm

Ideal For

• Data logging with accurate timestamps
• Scheduled wake-up and alarm applications
• Battery-powered projects needing persistent timekeeping

Resources

• Product Wiki
• Schematic (PDF)
• SD2403 Datasheet (PDF)

Package Contents

• 1× SD2403 Real-Time Clock Module
• 1× Gadgeteer cable
• 1× CR1220 battery