DS1302 Trickle-Charge Timekeeping Chip

Analog Devices DS1302 trickle-charge timekeeping chip contains a real-time clock/calendar (RTC) and 31 bytes of static RAM. The DS1302 trickle-charge timekeeping chip communicates with a microprocessor via a simple serial interface. The RTC provides seconds, minutes, hours, day, date, month, and year information. The end-of-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 the DS1302 with a microprocessor is simplified by using synchronous serial communication. Data can be transferred to and from the clock/RAM 1 byte at a time or in a burst of up to 31 bytes. The DS1302 is designed to operate on very low power and retain data and clock information on less than 1µW. This Analog Devices timekeeping chip also features dual power pins for primary and backup power supplies, programmable trickle charger for Vcc₁, and seven additional bytes of scratchpad memory.