MCP7940M I²C Real-Time Clock/Calendars The Microchip MCP7940M is Real-Time Clock Calendar (RTCC) that supports I²C communications. The MCP7940M includes a digital trimming circuit for accuracy which can compensate for crystal tolerance and temperature.

The MCP7940M features a multi-functional output that can be configured as an alarm output, to output a selectable frequency square wave or as a general purpose output. Features 2-Wire Serial Interface, I²C™ Compatible: I²C clock rate up to 400 kHz
On-Chip Digital Trimming/Calibration: ±1 ppm resolution, ±129 ppm range
Tracks Hours, Minutes, Seconds, Day of Week, Day, Month and Year
Leap Year Compensated to 2399
12/24 Hour Modes
Oscillator for 32.768 kHz Crystals: Optimised for 6-9 pF crystals
Dual Programmable Alarms
Versatile Output Pin
Wide Operating Voltage Range: 1.8V to 5.5V
Low Typical Timekeeping Current: 1.2μA at 3.3V