The MCP79400 is a low-power I²C RTCC that tracks seconds, minutes, hours, day-of-week, date, month, and year, with leap-year compensation up to year 2399 and selectable 12/24-hour formats. It is designed for embedded systems that require reliable real-time clock functionality and event logging.

The device features automatic switchover to battery backup. When the primary supply is removed and a backup source is present, timekeeping and SRAM contents are preserved, and the transition events are recorded using a power-fail timestamp. The on-chip protected EEPROM (8 bytes) requires a specific unlock sequence, helping safeguard critical data.

Variant note: MCP79400 provides an unprogrammed protected EEPROM. MCP79401 and MCP79402 variants include factory-programmed EUI-48™ and EUI-64™ identifiers respectively.

MCP79400-I/SN denotes the Industrial temperature grade supplied in an SN package, which is an 8-lead SOIC (3.90 mm body) surface-mount package. Always verify land pattern and mechanical dimensions using the official Microchip package drawing.

The SOIC-8 pinout integrates crystal connections, I²C interface pins, a backup supply input, and a multifunction output for alarm or clock signaling.

• X1 / X2: 32.768 kHz crystal connections
• VBAT: Backup battery supply input
• VSS: Ground
• VCC: Main power supply
• MFP: Multifunction open-drain output
• SCL: I²C serial clock
• SDA: I²C serial data

Devices within the MCP7940X family share the same electrical and pin-compatible design, with differences primarily in EEPROM programming.

• MCP79401-I/SN - Same family; factory-programmed EUI-48™ identifier
• MCP79402-I/SN - Same family; factory-programmed EUI-64™ identifier
• DS1307ZN+ - Basic I²C RTC (verify feature set and voltage compatibility)
• PCF8563T/F4,112 - Low-power I²C RTC (confirm register behavior and backup scheme)

Note: Always verify register map, timing behavior, and PCB footprint before approving substitutes in production designs.

Microchip Technology Inc. supplies microcontrollers, analog ICs, and embedded solutions used across industrial, automotive, communications, and consumer markets. The MCP7940X family delivers low-power real-time clock functionality with integrated memory for embedded systems.