Diodes Incorporated
Back to Real Time Clock (RTC)

PT7C4339 (Not Recommended for New Design (NRND))

NRND = Not Recommended for New Design

Low power consumption and I2C RTC

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The PT7C4339 real-time clock is a low-power clock/calendar 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/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 the 24-hour or 12-hour format with AM/PM indicator. The PT7C4339 has a build-in power-sense circuit that detects power failures and automatically switch to the backup supply, maintaining time, date, and alarm operation.


  • Real-Time Clock (RTC) Including Time (Seconds, Minutes and Hours) and Calendar (Day, Date, Month and Year with Leap-Year Compensation Valid Up to 2100) counter functions (BCD code)
  • Available in a Surface-Mount Package with an Integrated Crystal (Only for PT7C4339C)
  • I2C Serial Interface supports I2C-Bus's high speed mode (400 kHz)
  • Programmable square wave output signal, defaults to 32 kHz on Power-up
  • Two Time-of-Day Alarms
  • Oscillator Stop Flag
  • Automatic Power-Fail Detect and Switch Circuitry
  • Temperature Range: -40°C to +85°C
  • Package: MSOP-8L and SOIC-8L for PT7C4339
  • TDFN4x4-8L for PT7C4339C

Product Specifications

Product Parameters

Compliance(Only Automotive supports PPAP) Standard
Time Display 12, 24
Interface I2C
Alarm Interrupt 1
Battery Backup 1
Clock Calibration 0

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Technical Documents

Recommended Soldering Techniques


Additional Technical Documents are available upon request:
Application information, Evaluation board, and Other technical documents

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Product Change Notices (PCNs)

A PCN may only apply to specific orderable part numbers in this datasheet. Please refer to the corresponding PCN to see the exact orderable part number(s) affected.

PCN # Issue Date Implementation Date Subject
PCN-2651 2023-11-13 2023-11-13 Qualified Additional Fab Source, Assembly Test Sites, Die Revision, BOM, Datasheet, Tape and Reel Packing Quantity.
PCN-2642 2023-09-05 2024-03-05 Device End of Life (EOL)
PCN-2493 2020-12-28 2021-03-28 Qualified Additional A/T Sites and Bill of Materials (BOM)