Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM

Completely Integrated, Accurate Timing Solution Provides Better than ±2.0 Minutes per Year Accuracy Over the Industrial Temperature Range and Requires No User Calibration

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The DS3234 is a low-cost, extremely accurate SPI™ bus real-time clock (RTC) with an integrated temperature-compensated crystal oscillator (TCXO) and crystal. The DS3234 incorporates a precision, temperature-compensated voltage reference and comparator circuit to monitor VCC. When VCC drops below the power-fail voltage (VPF), the device asserts the active-low RST output and also disables read and write access to the part when VCC drops below both VPF and VBAT. The active-low RST pin is monitored as a pushbutton input for generating a µP reset. The device switches to the backup supply 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 DS3234 is available in commercial and industrial temperature ranges, and is offered in an industry-standard 300-mil, 20-pin SO package.

The DS3234 also integrates 256 bytes of battery-backed SRAM. In the event of main power loss, the contents of the memory are maintained by the power source connected to the VBAT pin. 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 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 by an SPI bidirectional bus.
DS3234: Typical Operating Circuit DS3234: Typical Operating Circuit Enlarge+

Key Features

  • Highly Accurate RTC with Integrated Crystal and SRAM Completely Manages All Timekeeping Functions
    • Accuracy ±2ppm from 0°C to +40°C
    • Accuracy ±3.5ppm from -40°C to +85°C
    • Real-Time Clock Counts Seconds, Minutes, Hours, Day, Date, Month, and Year, with Leap Year Compensation Valid Up to 2099
    • Digital Temp Sensor Output: ±3°C Accuracy
    • Register for Aging Trim
    • Active-Low RST Input/Output
    • Two Time-of-Day Alarms
    • Programmable Square-Wave Output
  • Simple Serial Interface Connects to Most Microcontrollers
    • 4MHz SPI Bus Supports Modes 1 and 3
  • Battery-Backup Input for Continuous Timekeeping
    • Low Power Operation Extends Battery Backup Run Time
  • Operating Temperature Ranges: Commercial: 0°C to +70°C, Industrial: -40°C to +85°C
  • 300-Mil, 20-Pin SO Package
  • Underwriters Laboratories® (UL) Recognized


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See parametric specs for Oscillator Modules (4)

Part NumberFrequencyOsc. TypeTuning Adjustment TypeFrequency Output TypeFrequency Stability
Frequency Stability
Frequency Stability
Frequency Stability
0 to +40°C-40 to 0°C/ +40 to +85°Cvs. VCCvs. AgingSee Notes
DS3234 32.768kHzTCXODigitalCMOS Push-Pull23.51 (typ)5 (0-10 Years)
2.0 to 5.5
2.7 to 5.5
SOIC (W)/20
$4.16 @1k

See parametric specs for Timekeeping & Real-Time Clocks (78)

Part NumberInterfaceTime Keeping Current
Memory TypeMemory Size
Time of Day AlarmsIntegrated ResonatorFunctionsPackage/Pins
See Data Sheet

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.
Product Reliability Reports: DS3234.pdf 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

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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  • Highly Accurate RTC with Integrated MEMS Resonator Completely Manages All Timekeeping Functions
  • 64-Byte RAM for User Data Storage
  • Simple Serial Interface Connects to Most Microcontrollers