Fermion: SD3031 Precision RTC Module

This real-time clock (RTC) module uses the SD3031 chip, which has an integrated crystal oscillator and temperature compensator. This provides high-precision timing and stability. At a temperature of 25 °C, the accuracy is maintained at ±3.8ppm (±0.32832 seconds/day).

The SD3031 can be powered by button-cell batteries. This allows for accurate timing even when the main power source is interrupted. The RTC keeps track of seconds, minutes, hours, days of the week, dates of the month, and months and years. It also automatically adjusts the date at the end of each month and includes leap year corrections. The SD3031 has a built-in 70-byte SRAM for low-power data storage.

Please note that due to recent air cargo regulations, special items such as batteries, magnets, and liquids are strictly audited for air transport. As a result, the RTC module does not come with batteries. You will need to purchase them locally. The button cell model that is compatible with this module is the CR1220.

Connection Example - Fermion: SD3031 and Arduino Uno

Features

• Low power consumption, operating current of only 1.8µA when powered by a button cell battery
• High precision, ±3.8ppm@25℃
• Integrated temperature compensator, small temperature drift
• Readable button cell voltage
• Built-in 70Byte SRAM

Specification

• Supply Voltage: 3.3V
• I2C Address: 0x32
• SRAM: 70 Byte (0x2C-0x71)
• Timing Year Range: 2000 - 2099
• Operating Temperature: -10℃ to +70℃
• Timing Accuracy: ±3.8ppm @ 25℃
• Dimension: 22.5x21mm

Resources

• Product wiki
• Schematics

Pinout

Num	Silkscreen	Description
1	VCC	Power +
2	GND	Power -
3	SCL	I2C clock line
4	SDA	I2C data line
5	INT	Active-low interrupt or 1Hz square wave output
6	NC	NC
7	32K	32.768KHz pulse output

Package Contents

• 1x Fermion: SD3031 RTC module (Breakout)
• 1x 2.54-7P Black Single-row Pin Connector