MCP79400T-I/MNY

Real Time Clock Overview

The MCP79400T-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 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 1.2µA at 3.3V from VCC and 925nA at 3.0V from battery backup. It features 64 bytes of battery-backed SRAM and unprogrammed protected EEPROM. The industrial temperature range is -40°C to +85°C, and it utilizes an I2C interface supporting clock rates up to 400 kHz.

Real Time Clock Feature Summary

• Real-Time Clock/Calendar with dual programmable alarms and power-fail timestamp logging
• 64-byte battery-backed SRAM and 8-byte protected EEPROM area
• On-chip digital trimming/calibration with ±1 ppm resolution
• I2C compatible serial interface with clock rates up to 400 kHz

Real Time Clock Applications

• Industrial systems requiring accurate timekeeping in harsh environments
• Data logging applications utilizing the power-fail timestamp feature
• Embedded devices needing non-volatile memory for configuration or unique IDs

Real Time Clock Procurement Notes

Verify the specific package variant, as the base part number corresponds to multiple packages including TDFN, SOIC, MSOP, and TSSOP. Confirm that the 'MCP79400' designation indicates unprogrammed EEPROM, distinct from the pre-programmed EUI-48/64 variants. Ensure the 'I' suffix matches the required industrial temperature range of -40°C to +85°C. Check datasheet revisions for any pinout or electrical characteristic updates.

Real Time Clock Selection Notes

Select this component when an unprogrammed EEPROM is required, as opposed to the MCP79401 or MCP79402 which contain pre-burned EUI addresses. Ensure the application supports the I2C protocol and can provide the necessary pull-up resistors for SDA and SCL lines. Verify that the external crystal load capacitance requirements (6-9 pF) can be met with available components and PCB stray capacitance.

Real Time Clock Part Context

This part belongs to the MCP7940X family of RTCCs, which shares functional similarities but differs in EEPROM content. The MCP79400 specifically lacks the factory-programmed MAC address found in the MCP79401 (EUI-48) and MCP79402 (EUI-64). The 'T' in the part number typically denotes tape and reel packaging, while 'MNY' specifies the 8-WFDFN (2x3) package type.

Real Time Clock Replacement Considerations

Public confirmed substitute part numbers are not provided in the source material.