The MCP79401-I/SN Real Time Clock (RTC) ICClock/Calendar is an 8-pin Surface Mount Device (SMD) IC manufactured by Microchip and is designed to provide timekeeping and calendar functions. Its 64B I²C 2-wire Serial Interface allows it to communicate with a host microcontroller and other devices for synchronization of time between two systems. This device monitors and/or maintains time information and incorporates several features like 32.768 kHz Crystal, Voltage Monitoring and Supervisory Circuit, Battery Switchover, Watchdog Timer, and a Temperature sensor. It also incorporates an Automatic Programming Option for multiple years (Year 2000-2099), 12/24 hour Date Format, and Leap Year compensation as well. The IC is compact in size with dimensions of 0.154" (3.90mm) Width and is housed in a SOIC package.