DS1307 Real Time Clock - great for Arduino

DS1307 Real Time ClockThe DS1307 serial real-time clock (RTC) is a low-power, full binary-coded decimal (BCD) clock/calendar plus 56 bytesof NV SRAM. Address and data are transferred serially through an I²C, buyirectional bus. The clock/calendar providesseconds, minutes, hours, day, date, month, and year information. The end of the month date is automatically adjustedfor months with fewer than 31 days, including corrections for leap year. The clock operates in either the 24-hour or12-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 thebackup supply.Key FeaturesReal-Time Clock (RTC) Counts Seconds, Minutes, Hours, Date of the Month, Month, Day of the week, and Year with Leap-Year Compensation Valid Up to 210056-Byte, Battery-Backed, General-Purpose RAM with Unlimited WritesI²C Serial InterfaceProgrammableSquare-Wave Output SignalAutomatic Power-Fail Detect and Switch CircuitryConsumes Less than 500nA in Battery-Backup Mode with Oscillator Running