The MCP7940M I2CTM compatible real-time clock/calendar (RTCC) includes SRAM and a digital trimming circuit for accuracy which is normally found in higher priced devices. Using a low-cost 32,768 kHz crystal or other clock source, time is 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.