ANALOG DEVICES DS1302+

The DS1302+ is a trickle-charge Timekeeping Chip contains a real-time clock/calendar and 31bytes of static RAM. It communicates with a microprocessor via a simple serial interface. The real-time 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 an AM/PM indicator. Interfacing this with a microprocessor is simplified by using synchronous serial communication. Only three wires are required to communicate with the clock/RAM of CE, I/O (data line) and SCLK (serial clock). Data can be transferred to and from the clock/RAM 1 byte at a time or in a burst of up to 31bytes. This is designed to operate on very low power and retain data and clock information on less than 1µW.