Description :

         This battery powered clock allows you to keep reasonably accurate time even when your Arduino is powered off.  Its very useful in data logging and other time sensitive applications.The device uses I2C to communicate with your Arduino.

        Tiny RTC Module, for Arduino, contains a DS1307 real-time clock IC with a backup battery. It's one of the easiest to use RTCs out there, with Arduino and other libraries or simply use I2C commands to set and retreive the time and date.  It's very easy to use, and with our Arduino tutorial you'll be up and running in no time.
 
        Along with the DS1307 real time clock, the module also has an Atmel 24C32 EEPROM chip which is handy for storing data without worrying about power loss. There is also space on the board to solder your own DS18B20 temperature sensor.

Features :

•    Consumes less than 500nA in battery-backup mode with oscillator running
•    Automatic power-fail detection
•    Backup by AT24C32 32Kbit
•    Working voltage: 5V
•    Two wire I2C interface
•    Hour : Minutes : Seconds AM/PM
•    Day Month, Date - Year
•    Leap year compensation
•    Accurate calendar up to year 2100
•    Consumes Less than 500nA in Battery-Backup
•    56-Byte, battery-backed, general-purpose RAM
•    1Hz output pin
•    56 Bytes of Non-volatile memory available to user
•    4KB of serial electrically erasable and programmable read only memory (EEPROM)
•    Embed DS18B20 temperature sensor interface with the pull-up resistor
•    Dimensions: 28mm x 25mm x 8mm

Datasheets