Extremely Accurate I²C-Integrated RTC/TCXO/Crystal

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The DS3231 is a low-cost, extremely accurate I²C real-time clock (RTC) with an integrated temperature-compensated crystal oscillator (TCXO) and crystal. 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 active-low 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.

A precision temperature-compensated voltage reference and comparator circuit monitors the status of VCC to detect power failures, to provide a reset output, and to automatically switch to the backup supply when necessary. Additionally, the active-low RST pin is monitored as a pushbutton input for generating a µP reset.

DS3231: Block Diagram DS3231: Block Diagram Enlarge+

Key Features

  • 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
    • Active-Low RST Output/Pushbutton Reset Debounce Input
    • Two Time-of-Day Alarms
    • Programmable Square-Wave Output Signal
  • Simple Serial Interface Connects to Most Microcontrollers
    • Fast (400kHz) I2C Interface
  • Battery-Backup Input for Continuous Timekeeping
    • Low Power Operation Extends Battery-Backup Run Time
    • 3.3V Operation
  • Operating Temperature Ranges: Commercial (0°C to +70°C) and Industrial (-40°C to +85°C)
  • Underwriters Laboratories® (UL) Recognized


  • Global Positioning Systems (GPS)
  • Servers
  • Telematics
  • Utility Power Meters
Part Number Freq. Osc. Type Tuning Adjustment Type Freq. Output Type Frequency Stability
Frequency Stability
Frequency Stability
Frequency Stability
Package/Pins Budgetary
0 to +40°C -40 to 0°C/ +40 to +85°C vs. VCC vs. Aging See Notes
DS3231  32.768kHz TCXO Digital CMOS Open-Drain 2 3.5 1 (typ) 5 (0-10 Years) 2.3 to 5.5
$3.85 @1k
See All Oscillator Modules (20)

Part Number Interface VSUPPLY
Time Keeping Current
Memory Type Time of Day Alarms Integrated Resonator Functions Package/Pins Budgetary
typ See Notes
DS3231  I2C 2.3 to 5.5 840 None 2 XTAL RTC
$3.85 @1k
See All Timekeeping & Real-Time Clocks (75)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

MAXPMBAE: Maxim Analog Essentials Collection of Peripheral Modules

Tools & Models

DS3231 IBIS Model

Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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