Diodes Incorporated
Back to Real Time Clock (RTC)


I2C interface and low power consumption RTC

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The PT7C43390 is a CMOS I2C-bus real-time clock IC,
which operates with the very low current consumption
and in the wide range of operation voltage. The
operation voltage is 1.35 V to 5.5 V so that the RTC can
be used for various power supplies from main supply to
backup battery. In the system which operates with a
backup battery, the included free registers can be used as
the function for user’s backup memory. Users always
can take back the information in the registers which is
stored before power-off the main power supply, after the
voltage is restored.
The IC has the function to correct advance / delay of the
clock data speed, in the wide range, which is caused by
the oscillation circuit’s frequency deviation. Correcting
according to the temperature change by combining this
function and a temperature sensor, it is possible to make
a high precise clock function which is not affected by
the ambient temperature.


  • Mobile game device, mobile phone
  • Industrial control
  • Electronic power meter
  • DVD recorder
  • Car navigation
  • IP Camera, DVR, NVR


  •  Low current consumption: 0.3μA typ. (VDD=3.0V, TA = 25°C)
  • Wide operating voltage range: 1.35 to 5.5 V
  • Minimum time keeping operation voltage: 1.25 V
  • Built-in clock adjustment function
  • Built-in free user register
  • 2-wire (I2C-bus) CPU interface
  • Built-in alarm interrupter
  • Built-in flag generator at power down or power on
  • Auto calendar up to the year 2099, automatic leap year calculation function
  • Built-in constant voltage circuit
  • Built-in 32 kHz crystal oscillator circuit
  • Package: SOIC-8L, TSSOP-8L, and TDFN2x3-8L

Product Specifications

Product Parameters

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

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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-2594 2022-08-31 2023-02-28 Device End of Life (EOL)
PCN-2510 2021-02-26 2021-05-26 Qualified Additional A/T Sites, Fab Site and Data Sheet Change


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