MCP79400-I/SN

Real Time Clock Overview

The MCP79400-I/SN is a battery-backed I2C Real-Time Clock/Calendar (RTCC) IC manufactured by Microchip Technology in an 8-lead SOIC package. 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 primary supply of 1.8V to 5.5V and supports backup voltage from 1.3V to 5.5V. Typical timekeeping current is 1.2µA at 3.3V. It includes 64 bytes of SRAM and unprogrammed protected EEPROM. Features include dual alarms, a multifunction output pin, power-fail timestamping, and digital trimming for oscillator calibration.

Real Time Clock Feature Summary

• Real-Time Clock/Calendar with 12/24-hour modes and automatic leap year compensation
• 64-byte battery-backed SRAM and 8-byte protected EEPROM area
• Dual programmable alarms and versatile multifunction output pin
• On-chip digital trimming for ±1 ppm resolution oscillator calibration

Real Time Clock Applications

• General purpose real-time clock and calendar tracking
• Power-fail event timestamp logging
• Backup memory storage for system configuration data

Real Time Clock Procurement Notes

Verify the specific suffix 'I/SN' corresponds to the Industrial temperature range (-40°C to +85°C) and 8-pin SOIC package. Confirm that the 'MCP79400' variant contains unprogrammed EEPROM, distinct from the pre-programmed EUI addresses found in MCP79401/MCP79402 models. Ensure compatibility with the required I2C pull-up resistor values based on the operating voltage.

Real Time Clock Selection Notes

Select this component when an unprogrammed protected EEPROM area is required for custom unique IDs or critical data storage. Choose the MCP79400 over MCP79401/MCP79402 if MAC address programming is not needed. Verify that the application requires the 8-SOIC package format and industrial temperature rating. Consider the need for external load capacitors matching the crystal's specified load capacitance (6-9 pF).

Real Time Clock Part Context

The MCP79400 is part of the MCP7940X family, which also includes the MCP79401 and MCP79402. These variants share identical functionality regarding timekeeping, SRAM, and alarms. The primary distinction lies in the protected EEPROM section: the MCP79400 has unprogrammed EEPROM, while the MCP79401 and MCP79402 are factory-preprogrammed with EUI-48 and EUI-64 MAC addresses, respectively.

Real Time Clock Replacement Considerations

The MCP79401T-I/SN and MCP79402T-I/SN are functionally compatible replacements if the application can utilize pre-programmed EUI addresses or ignore the EEPROM content. Other packages such as MSOP, TSSOP, and TDFN are available within the same family but require pinout verification.