MCP79401T-I/ST

Real Time Clock Overview

The MCP79401T-I/ST is a battery-backed I2C Real-Time Clock/Calendar (RTCC) integrated circuit 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 within a voltage range of 1.8V to 5.5V on VCC and 1.3V to 5.5V on the backup supply (VBAT). Typical timekeeping current is 1.2 µA at 3.3V VCC and 925 nA at 3.0V VBAT. It features 64 bytes of battery-backed SRAM and an 8-byte protected EEPROM preprogrammed with an EUI-48 MAC address. The unit supports I2C communication up to 400 kHz and functions in industrial temperatures from -40°C to +85°C.

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-48 MAC address
• On-chip digital trimming for oscillator calibration with ±1 ppm resolution
• Automatic switchover between primary power (VCC) and battery backup (VBAT)

Real Time Clock Applications

• Embedded systems requiring precise timekeeping and calendar functions
• Devices needing unique hardware identification via preprogrammed EUI-48 addresses
• Data logging applications utilizing battery-backed SRAM for non-volatile storage

Real Time Clock Procurement Notes

Verify that the specific part number corresponds to the TSSOP-8 package variant. Confirm the 'I' suffix indicates the industrial temperature range (-40°C to +85°C). Ensure the ordering code matches the tape-and-reel packaging format if required for automated assembly processes.

Real Time Clock Selection Notes

Select this component when an I2C interface is preferred over SPI for RTC connectivity. The MCP79401 is appropriate for designs requiring a unique network identifier without external memory. Consider the MCP79400 if the protected EEPROM is unnecessary, or the MCP79402 if an EUI-64 address is required instead of EUI-48.

Real Time Clock Part Context

This part belongs to the MCP7940X family of real-time clocks. The MCP79401 variant is distinguished by its preprogrammed EUI-48 MAC address in the protected EEPROM section. Other family members include the unprogrammed MCP79400 and the EUI-64 programmed MCP79402, all sharing identical functional specifications and pinouts.

Real Time Clock Replacement Considerations

The MCP79400 and MCP79402 are functionally compatible replacements regarding timekeeping and memory architecture. Substitution requires verification that the EEPROM content (EUI-48 vs. none vs. EUI-64) meets system requirements.