MCP79402T-I/MNY

Real Time Clock Overview

The MCP79402T-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 operates on a supply voltage range of 1.8V to 5.5V, drawing 1.2 µA at 3.3V during timekeeping. It features 64 bytes of battery-backed SRAM and an 8-byte protected EEPROM area preprogrammed with an EUI-64 MAC address. The IC communicates via an I2C interface supporting clock rates up to 400 kHz and is housed in an 8-WFDFN package.

Real Time Clock Feature Summary

• Integrated RTCC with dual programmable alarms and power-fail timestamp logging
• 64-bit protected EEPROM area containing a factory-programmed EUI-64 MAC address
• 64 bytes of general-purpose battery-backed SRAM
• On-chip digital trimming for oscillator calibration with ±1 ppm resolution

Real Time Clock Applications

• Systems requiring accurate timekeeping with backup power support
• Devices needing unique hardware identification via preprogrammed EUI-64 addresses
• Data logging applications utilizing power-fail timestamps for event tracking

Real Time Clock Procurement Notes

Verify the specific suffix 'I/MNY' corresponds to the Industrial temperature range (-40°C to +85°C) and the 8-TDFN (2x3) package type. Confirm that the EUI-64 MAC address is required for the application, as this distinguishes the MCP79402 from the unprogrammed MCP79400 or EUI-48 programmed MCP79401 variants within the same family.

Real Time Clock Selection Notes

Select this component when an I2C-compatible RTCC with integrated identity storage is needed. Ensure the design accommodates external load capacitors for a 32.768 kHz crystal optimized for 6-9 pF load capacitance. Verify that the system voltage remains within the 1.8V to 5.5V operating range to maintain specified current consumption and timing accuracy.

Real Time Clock Part Context

This part belongs to the MCP7940X family of battery-backed RTCCs. The MCP79402 variant is specifically distinguished by its factory-programmed EUI-64 MAC address in the protected EEPROM section. Other family members include the MCP79400 (unprogrammed) and MCP79401 (EUI-48), sharing identical timekeeping and memory architectures but differing in EEPROM content.

Real Time Clock Replacement Considerations

Direct functional replacements within the same package and feature set are limited due to the unique EUI-64 programming. The MCP79401 serves as a substitute if only an EUI-48 address is acceptable. For generic RTCC functionality without identity requirements, the MCP79400 is compatible.