MCP79412T-I/MS

Real Time Clock Overview

The MCP79412T-I/MS is a battery-backed I2C Real-Time Clock/Calendar (RTCC) IC manufactured by Microchip Technology. It operates within an industrial temperature range of -40°C to +85°C and supports supply voltages from 1.8V to 5.5V, with backup voltage support from 1.3V to 5.5V. The device features a low typical timekeeping current of 1.2µA at 3.3V on VCC and 925nA at 3.0V on VBAT. It includes 64 bytes of battery-backed SRAM, 1 Kbit of EEPROM, and a protected 64-bit EUI-64 MAC address area. The component is housed in an 8-pin MSOP package.

Real Time Clock Feature Summary

• Integrated RTCC with dual programmable alarms and power-fail timestamp logging
• On-chip digital trimming for oscillator calibration with ±1 ppm resolution
• Protected EEPROM area preprogrammed with unique EUI-64 MAC address
• Automatic switchover between primary and backup power supplies

Real Time Clock Applications

• Data logging systems requiring precise time stamping
• Battery-powered embedded devices needing low standby current
• Network equipment utilizing EUI-64 addresses for identification

Real Time Clock Procurement Notes

Verify the ordering suffix 'I/MS' corresponds to the Industrial temperature range (-40°C to +85°C) and the 8-lead MSOP package. Confirm that the specific revision matches the required silicon errata documentation before finalizing procurement specifications.

Real Time Clock Selection Notes

Select this model over the MCP79410 or MCP79411 if a preprogrammed EUI-64 address is required for network compliance. Ensure external load capacitors are selected to match the crystal's specified load capacitance of 6-9 pF for optimal frequency accuracy.

Real Time Clock Part Context

This part belongs to the MCP7941X family of battery-backed RTCCs. It shares the same core functionality as the MCP79410 and MCP79411 but is distinguished by its factory-programmed 64-bit protected EEPROM containing an EUI-64 identifier, whereas the MCP79410 is unprogrammed and the MCP79411 contains an EUI-48 address.

Real Time Clock Replacement Considerations

Public confirmed substitute: ISL12008IB8Z (Renesas Electronics Corporation). Verify pinout compatibility and register mapping differences before substitution.

Real Time Clock FAQ

What is the purpose of the MFP pin?

The Multifunction Pin (MFP) is an open-drain output configurable to assert on an alarm match, output a selectable frequency square wave, or serve as a general-purpose output.

How does the device handle power loss?

The MCP79412 automatically switches to the VBAT supply when VCC drops below the trip voltage (typically 1.5V), maintaining timekeeping and SRAM data while logging the power-fail timestamp.

What is the maximum I2C clock rate supported?

The device supports an I2C clock rate up to 400 kHz when VCC is between 2.5V and 5.5V, and up to 100 kHz when VCC is between 1.8V and 2.5V.