MAX31329 I2C Real-Time Clock (RTC) Analog Devices MAX31329 I2C Real-Time Clock (RTC) is a low-current timekeeping device that provides timekeeping current in nanoamps (nA), thus extending battery life. This device incorporates an integrated 32.768kHz crystal, that eliminates the need for an external crystal. The MAX31329 RTC features one digital Schmitt trigger input (DIN) and generates an interrupt output on a falling or rising edge of this digital input. The MAX31329 RTC maintains a clock/calendar that provides seconds, minutes, hours, day, date, month, and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in either 24-hour or 12-hour format and the RTC also includes a clock input for synchronization.