MCP79412T-I/MNY

Real Time Clock Overview

The MCP79412T-I/MNY is a battery-backed I2C Real-Time Clock/Calendar (RTCC) IC manufactured by Microchip Technology. It tracks time using internal counters for hours, minutes, seconds, day of week, date, month, and year, with leap year compensation through 2399. The device features 64 bytes of battery-backed SRAM, 1 Kbit of EEPROM, and a preprogrammed 64-bit EUI-64 protected EEPROM area. It operates on a supply voltage of 1.8V to 5.5V with a backup range of 1.3V to 5.5V. Typical timekeeping current is 1.2µA at 3.3V from VCC and 925nA at 3.0V from VBAT. It supports I2C communication up to 400 kHz and functions within an industrial temperature range of -40°C to +85°C.

Real Time Clock Feature Summary

• Integrated 64-bit Protected EEPROM preprogrammed with a unique EUI-64 MAC address.
• Dual programmable alarms with flexible comparison options and oscillator failure detection.
• Automatic power-fail timestamp logging upon switchover to and from battery backup.
• On-chip digital trimming with ±1 ppm resolution for frequency calibration.

Real Time Clock Applications

• Systems requiring precise timekeeping with non-volatile memory for configuration data.
• Devices needing secure storage of unique identifiers such as MAC addresses.
• Applications requiring automatic tracking of power loss and restoration events.

Real Time Clock Procurement Notes

Verify the specific package suffix 'MNY' corresponds to the 8-WFDFN (2x3) exposed pad package. Confirm the 'I' designation indicates the industrial temperature range (-40°C to +85°C). Ensure the ordering part number matches the required tape and reel or cut tape quantity if applicable.

Real Time Clock Selection Notes

Select this model over the MCP79410 or MCP79411 if a preprogrammed 64-bit EUI-64 address is required for network identification. Choose the TDFN package for compact surface-mount designs. Ensure external load capacitors are selected to match the crystal's specified load capacitance (6-9 pF) for accurate timing.

Real Time Clock Part Context

This component belongs to the MCP7941X family of battery-backed RTCCs. The MCP79412 variant is distinguished by its factory-programmed EUI-64 protected EEPROM, whereas the MCP79410 has unprogrammed protected EEPROM and the MCP79411 has an EUI-48 address. All variants share identical pinouts and core functionality.

Real Time Clock Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided source material. Designers should verify compatibility with existing firmware and hardware constraints when considering alternative RTC devices.

Real Time Clock FAQ

What is the purpose of the protected EEPROM area in the MCP79412?

The protected EEPROM area contains 64 bits preprogrammed with a unique EUI-64 MAC address. It requires a robust write unlock sequence to access, making it suitable for storing critical information like unique IDs.

How does the device handle power loss?

The MCP79412 automatically switches to the VBAT supply when VCC drops below the trip voltage. It logs the exact time of power failure and power restoration in dedicated timestamp registers.

Can the MCP79412 operate without a battery?

Yes, but timekeeping will stop when main power is removed. If no battery backup is used, the VBAT pin must be connected to VSS (Ground).