The MCP79412 general purpose I²C™Compatible real-time clock/calendar (RTCC) is highly integrated with nonvolatile memory and advanced features normally found in higher priced devices. These features include a battery switchover circuit for backup power, a timestamp to log power failures and digital trimming for accuracy. 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. 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.

Timekeeping
• Battery-Backed Real-Time Clock/Calendar (RTCC)
  • Hours, Minutes, Seconds, Day of Week, Day, Month, Year
  • Leap year compensated  to 2399
  • 12/24 hour modes
• On-Chip Digital Trimming/Calibration
  • 1 PPM Resolution
  • ±129 PPM Range
• Dual Programmable Alarms
• Versatile Output Pin
  • Clock output with selectable frequency
  • Alarm output
  • General Purpose output
• Power-Fail Time-Stamp
  • Time logged on switchover to and from Battery Backup
• 2-Wire Serial Interface, I²C™Compatible
  • I²C Clock Frequency up to 400 kHz
User Memory
• 64 Bytes Battery-Backed SRAM
• 1Kb EEPROM Memory
• 64-bit Protected EEPROM Area
  • Robust write unlock sequence
  • Preprogrammed EUI-64™ MAC Address
Low-Power
• Wide Voltage Range
  • Operating Voltage 1.8V to 5.5V
  • Backup Voltage 1.3V to 5.5V
• Low Typical Timekeeping Current
• Automatic Switchover to Battery Backup