Skip to main content
1339 - Block Diagram
1339 - Pinout


Real-Time Clock With Serial I2C Interface

The 1339 serial real-time clock (RTC) is a low-power clock/date device with two programmable time-of-day alarms and a programmable square-wave output. Address and data are transferred serially through an I2C bus. The clock/date 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 the 24-hour or 12-hour format with AM/PM indicator. The 1339 has a built-in power-sense circuit that detects power failures and automatically switches to the backup supply, maintaining time, date, and alarm operation.


  • Real-Time Clock (RTC) counts seconds, minutes, hours, day, date, month, and year with leap-year compensation valid up to 2100
  • Packaged in 8-pin MSOP, 8-pin SOIC, or 16-pin SOIC (surface-mount package with an integrated crystal)
  • Fast mode I2C Serial interface
  • Two time-of-day alarms
  • Programmable square-wave output
  • Oscillator stop flag
  • Automatic power-fail detect and switch circuitry
  • Trickle-charge capability
  • Industrial temperature range (-40 to +85°C)
  • Underwriters Laboratory (UL) recognized

Product Specification

Outputs (#)Output TypeOutput Freq Range (kHZ)Input Freq (kHz)Inputs (#)Input TypeCore Voltage (V)
1LVCMOS0.001000, 4.096000, 8.192000, 32.76800032.7680001None (Internal), Crystal1.8, 2.5, 3.3, 5, 5.5

Product Options

Orderable Part IDPart StatusPkg. CodePkg. TypeLead Count (#)Temp. GradePb (Lead) FreeCarrier TypeSample & Buy
1339-2DCGIActiveDCG8SOIC8IYesTubeCheck Availability
1339-2DCGI8ActiveDCG8SOIC8IYesReelCheck Availability
1339-2DVGIActiveDVG8TSSOP8IYesTubeCheck Availability
1339-2DVGI8ActiveDVG8TSSOP8IYesReelCheck Availability
1339-31DCGIActiveDCG8SOIC8IYesTubeCheck Availability
1339-31DCGI8ActiveDCG8SOIC8IYesReelCheck Availability
1339-31DVGIActiveDVG8TSSOP8IYesTubeCheck Availability
1339-31DVGI8ActiveDVG8TSSOP8IYesReelCheck Availability
1339AC-2SRGIActivePIG16SOIC16IYesTubeCheck Availability
1339AC-2SRGI8ActivePIG16SOIC16IYesReelCheck Availability
1339AC-31SRGIActivePIG16SOIC16IYesTubeCheck Availability
1339AC-31SRGI8ActivePIG16SOIC16IYesReelCheck Availability
1339C-31SRINot Recommended
PI16SOIC16INoTubeCheck Availability
1339C-31SRI8Not Recommended
PI16SOIC16INoReelCheck Availability


Technical Documentation

Title Other Languages Type Format File Size Datesort icon
Datasheets & Errata
1339 Datasheet Datasheet PDF 342 KB Mar 11, 2015
Apps Notes & White Papers
AN-828 Termination - LVPECL Application Note PDF 229 KB Jul 5, 2016
AN-845 Termination - LVCMOS Application Note PDF 62 KB May 13, 2014
AN-844 Termination - AC Coupling Clock Receivers Application Note PDF 82 KB May 13, 2014
show all (10)
AN-842 Thermal Considerations in Package Design and Selection Application Note PDF 403 KB May 12, 2014
AN-840 Jitter Specifications for Timing Signals Application Note PDF 349 KB May 8, 2014
AN-838 Peak-to-Peak Jitter Calculations Application Note PDF 32 KB May 7, 2014
AN-839 RMS Phase Jitter Application Note PDF 149 KB May 7, 2014
AN-827 Application Relevance of Clock Jitter Application Note PDF 1.06 MB Apr 24, 2014
AN-815 Understanding Jitter Units Application Note PDF 476 KB Apr 24, 2014
AN-805 Recommended Ferrite Beads Application Note PDF 38 KB Jan 15, 2014
PCN# : A1602-01(R1) Add Greatek Taiwan as Alternate Assembly Product Change Notice PDF 611 KB Apr 14, 2016
PCN# : A1602-01 Add Greatek Taiwan as Alternate Assembly Product Change Notice PDF 611 KB Feb 15, 2016
PCN# : A1403-03 Gold wire to Copper wire Product Change Notice PDF 42 KB Oct 15, 2014
show all (8)
PCN# : W1101-02R4 Fab 4 to TSMC Product Change Notice PDF 70 KB Jul 1, 2014
PCN# : W1101-02R3 Fab 4 to TSMC Product Change Notice PDF 71 KB Apr 8, 2014
PCN# : W1101-02R2 Fab 4 to TSMC Product Change Notice PDF 67 KB Jan 26, 2014
PCN# : A1208-01R1 Gold to Copper Wire Product Change Notice PDF 254 KB Dec 21, 2012
PCN# : A1208-06 Changed of Assembly Location and Crystal Product Change Notice PDF 1.06 MB Nov 18, 2012
IDT Clock Generation Overview 日本語 Overview PDF 1.83 MB Apr 28, 2016
IDT Clock Distribution Overview 日本語 Overview PDF 3.79 MB Apr 25, 2016