General Description

The DS1308 serial real-time clock (RTC) is a low-power, full binary-coded decimal (BCD) clock/calendar plus 56 bytes of NV RAM. Address and data are transferred serially through an I2C interface. The 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. The DS1308 has a built-in power-sense circuit that detects power failures and automatically switches to the backup supply, maintaining time and date operation.

Features

♦ Low Timekeeping Current of 250nA (typ)

♦ Compatible with Crystal ESR Up to 100kω

♦ RTC Counts Seconds, Minutes, Hours, Date, Month, Day of the Week, and Year with Leap-Year Compensation Up to 2400

♦ 56-Byte, Battery-Backed, General-Purpose RAM with Unlimited Writes

♦ I2C Serial Interface

♦ External Clock Source for Synchronization Clock Reference (e.g., 32kHz, 50Hz/60Hz Powerline, GPS 1PPS)

♦ Programmable Square-Wave Output Signal

♦ Automatic Power-Fail Detect and Switch Circuitry

♦ -40NC to +85NC Operating Temperature Range

♦ Underwriters Laboratories (UL) Recognized

Applications

  Handhelds (GPS, POS Terminal)

  Consumer Electronics (Set-Top Box, Digital Recording, Network Appliance)

  Office Equipment (Fax/Printer, Copier)

  Medical (Glucometer, Medicine Dispenser)

  Telecommunications (Router, Switcher, Server)

  Other (Utility Meter, Vending Machine, Thermostat, Modem)