Download File 1. DS1307 64X8 Serial Real Time Clock — Maxim

The DS1307 serial real-time clock (RTC) is a lowpower, 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. 14 pages.

Download File 2. DS1307 Crystal Application Note 58

This application note describes crystal selection and layout techniques for connecting a 32,768Hz crystal to a real-time clock (RTC). It also provides information about oscillator circuit-design criteria, system design, and manufacturing issues. 8 pages.

Download File 3. PCF8583 Real Time Clock/Calendar with 240 X 8-bit RAM — Phillips

A clock/calendar circuit based on a 2048-bit static CMOS RAM organized as 256 words by 8 bits. Addresses and data are transferred serially via the two-line bidirectional I2C-bus. 28 pages.