Maxim > Products > Real-Time Clocks > DS1340, DS1340C

DS1340, DS1340C

I²C RTC with Trickle Charger

I²C Real-Time Clock with Trickle Charger Offers Software Clock Calibration
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Status Explanations for product status codes

Part Number Status
DS1340 Active: In Production. See Ordering Information for details.
DS1340C Active: In Production. See Ordering Information for details.


The DS1340 is a real-time clock (RTC)/calendar that is pin compatible and functionally equivalent to the ST M41T00, including the software clock calibration. The device additionally provides trickle-charge capability on the VBACKUP pin, a lower timekeeping voltage, and an oscillator STOP flag. Block access of the register map is identical to the ST device. Two additional registers, which are accessed individually, are required for the trickle charger and flag. The clock/calendar provides seconds, minutes, hours, day, date, month, and year information. A built-in power-sense circuit detects power failures and automatically switches to the backup supply. The device is programmed serially through an I²C bidirectional bus.

Data Sheet

Download this datasheet in PDF formatDownload Rev 8 (PDF, 465.3kB)
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Key Features

  • Enhanced Second Source for the ST M41T00
  • Available in a Surface-Mount Package with an Integrated Crystal (DS1340C)
  • Fast (400kHz) I²C Interface
  • Software Clock Calibration
  • RTC Counts Seconds, Minutes, Hours, Day, Date, Month, and Year
  • Automatic Power-Fail Detect and Switch Circuitry
  • Trickle-Charge Capability
  • Low Timekeeping Voltage Down to 1.3V
  • Three Operating Voltage Ranges (1.8V, 3V, and 3.3V)
  • Oscillator Stop Flag
  • Available in 8-Pin µSOP or SO Packages
  • Underwriters Laboratories (UL) Recognized


  • Medical Equipment
  • Point-of-Sale Equipment
  • Portable Instrumentation
  • Telecommunications

Key Specifications:

Timekeeping & Real-Time Clocks
Part Number Interface VSUPPLY
Time Keeping Current
Memory Type Time of Day Alarms Integrated Resonator Budgetary
typ See Notes
DS1340  I2C
800 12.5 None 0 - $1.39 @1k
DS1340C  XTAL $2.58 @1k
See All Timekeeping & Real-Time Clocks (90)

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.


DS1340, DS1340C: Typical Operating Circuit
Typical Operating Circuit

More Information

New Product Press Release   2003-08-28 ]
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Information Index

Document Ref.: 19-5578 Rev 8; 2013-04-30
This page last modified: 2013-04-30