Microchip’s MCP79411 general purpose I2C™Compatible real-time clock/calendar (RTCC) is highly integrated with nonvolatile memory and advanced features including a battery switchover circuit for backup power, a timestamp to log power failures and digital trimming for accuracy. It can use a low-cost 32.768 kHz crystal or other clock source and the chip operates over a supply range of 1.8 to 5.5 volts. Time can be tracked in either a 12-hour or 24-hour format with an AM/PM indicator and timing to the second, minute, hour, day of the week, day, month and year. As an interrupt or wakeup signal, a multifunction open drain output can be programmed as an alarm out or as a clock out that supports 4 selectable frequencies. In addition, non-volatile memory is included along with a unique ID in a locked section of EEPROM that is factory programmed with an EUI-48 MAC address.
According to the datasheet, the chip is available in the SOIC package and Microchip says samples are available.
This application note describes the build of a complete electronic watch using this chip.