The 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, day, date, month, and year information. The end of the month date 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 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.

Although the term often refers to the devices in personal computers, servers and embedded systems, RTCs are present in almost any electronic device which needs to keep accurate time.

The term real-time clock is used to avoid confusion with ordinary hardware clocks which are only signals that govern digital electronics, and do not count time in human units. RTC should not be confused with real-time computing, which shares its three-letter acronym but does not directly relate to time of day.

Although keeping time can be done without an RTC, using one has benefits such as Low power consumption (important when running from alternate power), frees the main system for time-critical tasks and sometimes more accurate than other methods

A GPS receiver can shorten its startup time by comparing the current time, according to its RTC, with the time at which it last had a valid signal. If it has been less than a few hours, then the previous ephemeris is still usable.

Features/Specs:

• Completely Manages All Timekeeping Functions


• Real-Time Clock Counts Seconds, Minutes, Hours, Date of the Month, Month, Day of the Week, and Year with Leap-Year Compensation Valid Up to 2100


• 56-Byte, Battery-Backed, General-Purpose RAM with Unlimited Writes


• Programmable Square-Wave Output Signal


• Simple Serial Port Interfaces to Most Microcontrollers
  
  
  
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    • I2C Serial Interface
    
    
    
    
  
  
  • Low Power Operation Extends Battery Backup Run Time
    
    
    
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      • Consumes Less than 500nA in Battery-Backup Mode with Oscillator Running
      
      
      • Automatic Power-Fail Detect and Switch Circuitry
      
      
      
      
    
    
    • 8-Pin DIP and 8-Pin SO Minimizes Required Space
    
    
    • Optional Industrial Temperature Range: -40�C to +85�C Supports Operation in a Wide Range of Applications
    
    
    • Underwriters Laboratories (UL) Recognized
    
    
    • Max Voltage Range on Any Pin Relative to Ground: -0.5V to +7.0V
    
    
    • Operating Temperature Range (Noncondensing): Commercial:- 0�C to +70�C, Industrial:- -40�C to +85�C
    
    
    • Storage Temperature Range: -55�C to +125�C
    
    
    • Soldering Temperature (surface mount): JPC/JEDEC J-STD-020 Specification
    
    
    
    
  
  
  
  

Application:

• Mobile telephones


• Portable instruments


• Electronic metering


• Battery powered products