Low-Current SPI/3-Wire RTCs

Compatible with Any 32.768kHz Crystal

Please check latest availability status for a specific part variant.


The DS1343/DS1344 low-current real-time clocks (RTCs) are timekeeping devices that provide an extremely low standby current, permitting longer life from a backup supply source. The devices also support high-ESR crystals, broadening the pool of usable crystals for the devices. The clock/calendar provides 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 24-hour or 12-hour format with an active-low AM/PM indicator.

Address and data are transferred serially through an SPI™ or 3-wire interface. Two programmable time-of-day alarms are provided. Each alarm can generate an interrupt on a combination of seconds, minutes, hours, and day. Don't-care states can be inserted into one or more fields if it is desired for them to be ignored for the alarm condition. The time-of-day alarms can be programmed to assert two different interrupt outputs, or they can be combined to assert one common interrupt output. Both interrupt outputs operate when the device is powered by either VCC or VBAT.

The devices are available in a lead-free/RoHS-compliant, 20-pin TSSOP or 14-pin TDFN package, and support a -40°C to +85°C extended industrial temperature range.

Key Features

  • Low Timekeeping Current of 250nA (typ)
  • Compatible with Crystal ESR Up to 100kΩ
  • Versions Available to Support Either 6pF or 12.5pF Crystals
  • RTC Counts Seconds, Minutes, Hours, Day, Date, Month, and Year with Leap Year Compensation Valid Through 2099
  • Power-Fail and Switch Circuitry
  • Three Operating Voltages
    • 1.8V ±5%
    • 3.0V ±10%
    • 3.3V ±10%
  • Trickle-Charge Capability
  • Maintain Time Down to 1.15V (typ)
  • Support Motorola SPI Modes 1 and 3, or Standard 3-Wire Interface
  • Burst Mode for Reading/Writing Successive Addresses in Clock/RAM
  • 96-Byte Battery-Backed NV RAM for Data Storage
  • Two Time-of-Day Alarms with Two Interrupt Outputs
  • Industrial Temperature Range
  • 20-Pin TSSOP or 14-Pin TDFN Package


  • Embedded Timestamping
  • Handheld Devices
  • Medical
  • Telematics
Part NumberInterfaceVSUPPLY
Time Keeping Current
Memory TypeMemory Size
Time of Day AlarmsFunctionsPackage/PinsBudgetary
typSee Notes
$2.03 @1k
$2.05 @1k
See All Timekeeping & Real-Time Clocks (77)
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.

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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Related Resources

Low-Current, Real-Time Clock with I2C Interface and Power Management

  • Increases Battery Life
  • Provides Flexible Configurability
  • Saves Board Space

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