DS1307 RTC I2C Real Time Clock Module


DS1307 serial real-time clock (RTC) is a low-power, full binary-coded decimal (BCD) clock/calendar plus 56 bytes of NV SRAM. Address and data are transferred serially through an I2C, bidirectional bus. The clock/calendar provides seconds, minutes, hours, days, dates, months, and year information. The end of the month date is automatically adjusted for months with fewer than 31 days, including corrections for leap year. A CR2032 battery can be used to power this module. The CR2032 lithium coin cell battery will ensure that in case of a power loss the module can be restarted from its last known state

DS1307 operates in either the 24-hour or 12-hour format with AM/PM indicator. The DS1307 has a built-in power-sense circuit that detects power failures and automatically switches to the backup supply. Timekeeping operation continues while the part operates from the backup supply. DS1307 RTC module houses all onboard components necessary for the proper operation of a DS3107 chip. Furthermore, it also has a holder for a 20mm 3V lithium coin battery.


DS1307 RTC Module Key Features

  • 56-byte, battery-backed, nonvolatile (NV) RAM for data storage
  • Two-wire serial interface
  • A programmable square wave output signal
  • Automatic power-fail detect and switch circuitry
  • Consumes less than 500nA in battery backup mode with oscillator running
  • Available in 8-pin DIP or SOIC
  • Underwriters Laboratory (UL) recognized
  • ESD protection
  • Overvoltage protection

DS1307 Pinout

Pin NamePin No.Description
DS1Data select (output temperature readings if your module has a DS18B20 temperature sensor installed
SCL2Serial Clock Pin
SDA3Serial Data Pin
VCC4Chip Supply Voltage
BAT6backup supply input for any standard 3V lithium cell
VCC8Chip Supply Voltage
SDA9data input/output for the I2C serial interface.
SCL10Serial Clock Pin (input for the I2C interface and is used to synchronize data movement on the serial interface.)
DS11Data select (output temperature readings if your module has a DS18B20 temperature sensor installed
SQ12outputs one of four square-wave frequencies 1Hz, 4kHz, 8kHz or 32kHz

DS1307 Specifications

  • I2C Interface RTC IC
  • Operating Voltage: 5V
  • Less than 500nA current when operating with a battery
  • 56 bytes SVRAM
  • Operates in power or battery mode
  • Programmable square wave output pin
  • Available in PDIP and SO package
  • Optional industrial temperature range: -40°C to +85°C


  • Usually required in design and applications where adequate time keeping is imperative such as Data logging systems, Mapping hardware & telemetry projects


You can download the datasheet for DS1307 RTC I2C Real Time Clock Module by clicking the link given below:

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