DS3231S Datasheet – RTC Module ( Arduino )

DS3231S is a real-time clock (RTC) IC, a device that provides accurate date and time information. This IC uses a highly accurate internal clock and a dedicated crystal oscillator to keep time, and operates with low power consumption.

Part number : DS3231S, DS3231, DS3231SN

Functions : Extremely Accurate I2C-Integrated RTC / TCXO / Crystal

Package information : SO-16 Type

Manufacturer : Maxim Integrated Products, Analog Devices

DS3231S Datasheet



The DS3231S is a low-cost, extremely accurate I2C real-time clock (RTC) with an integrated temperature-compensated crystal oscillator (TCXO) and crystal.

The DS3231S is a highly accurate I2C-interface real-time clock (RTC). This module tracks seconds, minutes, hours, days, dates, months, and years, and can correct for leap years up to 2100. It also has two calendar alarm functions.

The device incorporates a battery input, and maintains accurate timekeeping when main power to the device is interrupted. The integration of the crystal resonator enhances the long-term accuracy of the device as well as reduces the piece-part count in a manufacturing line. The DS3231 is available in commercial and industrial temperature ranges, and is offered in a 16-pin, 300-mil SO package.

The RTC maintains seconds, minutes, hours, day, date, month, and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in either the 24-hour or 12-hour format with an AM/PM indicator. Two programmable time-of-day alarms and a programmable square-wave output are provided. Address and data are transferred serially through an I2C bidirectional bus.



One of the most important features of this module is the built-in temperature compensated quartz crystal (TCXO) with a frequency of 32 kHz. This TCXO uses a quartz crystal to track time, while a temperature sensor detects temperature changes and compensates for changes in the crystal’s frequency.

1. Internally uses high-precision crystal oscillators to provide highly accurate time keeping.

2. Low-power operation is possible and can be operated by batteries or external power.

3. Can track and display date, day, hour, minute and second.

4. Temperature can be measured and corrected using the internal temperature sensor.

5. Can communicate with peripheral devices through I2C interface. This allows data exchange with microcontrollers or other devices.



1. Highly Accurate RTC Completely Manages All Timekeeping Functions

• Real-Time Clock Counts Seconds, Minutes, Hours, Date of the Month, Month, Day of the Week, and Year, with Leap-Year Compensation Valid Up to 2100

• Accuracy ±2ppm from 0°C to +40°C

• Accuracy ±3.5ppm from -40°C to +85°C

• Digital Temp Sensor Output: ±3°C Accuracy

• Register for Aging Trim

• RST Output/Pushbutton Reset Debounce Input

• Two Time-of-Day Alarms

• Programmable Square-Wave Output Signal


2. Simple Serial Interface Connects to Most Microcontrollers

• Fast (400kHz) I2C Interface


3. Battery-Backup Input for Continuous Timekeeping

• Low Power Operation Extends Battery-Backup Run Time



DS3231S pinout


Can communicate with peripheral devices through I2C interface. This allows data exchange with microcontrollers or other devices.

1. Servers

2. Telematics

3. Utility Power Meters

4. GPS


DS3231S vs DS3231SN

The difference between the last subscripts S and SN is the difference in operating temperature range.

1. DS3231S#  0°C to +70°C 16 SO

2. DS3231SN#  -40°C to +85°C 16 SO


Reference Site

1. Arduino and DS3231 Real Time Clock Tutorial – How To Mechatronics

2. DS3231 Datasheet and Product Info | Analog Devices


DS3231S Datasheet PDF


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