DS1302 Real-Time

A real-time clock/calendar and 31 bytes of static RAM are included in the DS1302 timekeeping chip. It uses a simple serial interface to communicate with a CPU. The real-time clock/calendar displays information in seconds, minutes, hours, days, dates, months, and years. For months with fewer than 31 days, the end of the month date is automatically modified, including leap year corrections. The clock has an AM/PM indicator and works in either a 24-hour or 12-hour mode. Using a synchronous serial connection to connect the DS1302 to a microprocessor simplifies the operation. To connect with the clock/RAM, only three wires are required: CE, I/O (data line), and SCLK (serial clock).

Data can be sent one byte at a time or in bursts of up to 31 bytes to and from the clock/RAM. The DS1302 is designed to run on extremely little power, requiring less than 1uW to preserve data and clock information. DS1302 is DS1202's successor. The DS1302 contains dual power pins for primary and backup power supply, a programmed trickle charger for VCC1, and seven additional bytes of scratchpad memory in addition to the basic timekeeping functionality of the DS1202.

Specification:

1. 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
2. 31 x 8 Battery-Backed General-Purpose RAM
3. Serial I/O for Minimum Pin Count
4. 2.0V to 5.5V Full Operation
5. Uses Less than 300nA at 2.0V
6. Single-Byte or Multiple-Byte (Burst Mode)
7. Data Transfer for reading or Write of Clock or RAM Data
8. Simple 3-wire interface
9. TTL-Compatible (VCC = 5V)
10. Optional Industrial Temperature Range: -40°C to +85°C
11. DS1202 Compatible
12. Supplied with CR2032 battery