MCP79402T-I/ST

Real Time Clock Overview

The MCP79402T-I/ST is a battery-backed I2C Real-Time Clock/Calendar (RTCC) 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 and an 8-byte protected EEPROM area preprogrammed with an EUI-64 MAC address. It operates on a single supply voltage ranging from 1.8V to 5.5V, with a backup supply range of 1.3V to 5.5V. Typical timekeeping current is 1.2 µA at 3.3V VCC and 925 nA at 3.0V VBAT. The industrial temperature grade (-40°C to +85°C) version is housed in an 8-lead TSSOP package.

Real Time Clock Feature Summary

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

Real Time Clock Applications

• Systems requiring precise timekeeping with non-volatile memory for device identification
• Industrial equipment operating within -40°C to +85°C environments
• Battery-powered devices utilizing low-power RTC functionality

Real Time Clock Procurement Notes

Verify the specific suffix 'T-I/ST' corresponds to the TSSOP-8 package and reel packaging configuration. Confirm the 'I' designation indicates the industrial temperature range of -40°C to +85°C. Ensure the EUI-64 programming status matches application requirements for network addressing.

Real Time Clock Selection Notes

Select this component when an EUI-64 identifier is required directly within the RTC EEPROM space. Compare against MCP79401 if only 48-bit addressing is needed. 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 MCP7940X family, which includes the MCP79400, MCP79401, and MCP79402. The primary distinction among these variants is the content of the protected EEPROM: unprogrammed (MCP79400), EUI-48 (MCP79401), or EUI-64 (MCP79402). All variants share identical pinouts, electrical characteristics, and functional registers.

Real Time Clock Replacement Considerations

The MCP79401T-I/ST serves as a direct hardware-compatible substitute if EUI-48 addressing is sufficient. The MCP79400T-I/ST is also compatible but requires custom EEPROM programming. Verify that any replacement maintains the same TSSOP-8 package and industrial temperature rating.