Maxim Integrated DS1308U-33+, Real Time Clock Serial-I2C, 8-Pin μSOP

Compatible with Crystal ESR Up to 100kΩ Allows a Crystal to be Optimized for Cost and Space
Low-Power Operation Extends Battery Backup Run Time
Low Timekeeping Current of 250nA (typ)
Automatic Power-Fail Detect and Switch Circuitry
Completely Manages All Timekeeping Functions
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 2400
External Clock Source for Synchronization Clock Reference (e.g., 32kHz, 50Hz/60Hz Powerline, GPS 1PPS)
56-Byte, Battery-Backed, General-Purpose RAM with Unlimited Writes
Programmable Square-Wave Output Signal
Simple Serial Port Interfaces with Most Microcontrollers
I2C Serial Interface
Industrial Temperature Range: -40°C to +85°C Supports Operation in a Wide Range of Applications

Applications
Consumer Electronics (Set-Top Box, Digital Recording, Network Appliance)
Handhelds (GPS, POS Terminal)
Medical (Glucometer, Medicine Dispenser)
Office Equipment (Fax/Printer, Copier)
Other (Utility Meter, Vending Machine, Thermostat, Modem)
Telecommunications (Router, Switcher, Server)