Microchip Technology MCP79411T-I/MNY

Overview

MCP79411T-I/MNY from Microchip Technology is a battery-backed I²C Real-Time Clock/Calendar (RTCC) IC with integrated 64-byte SRAM, 1 Kbit EEPROM, and 64-bit protected EEPROM preprogrammed with EUI-48™ MAC address. It maintains time across 1.8–5.5 V operation, achieves ±1 ppm digital trimming resolution, supports dual programmable alarms, and logs power-fail/power-up timestamps. Used in industrial metering, smart sensors, and backup-critical embedded systems.

For engineers reviewing the MCP79411T-I/MNY datasheet, MCP79411T-I/MNY pinout, MCP79411T-I/MNY application, or MCP79411T-I/MNY equivalent, key selection criteria include its 32.768 kHz crystal interface with 6–9 pF load optimization, 925 nA VBAT timekeeping current at 3.0 V, I²C up to 400 kHz, -40°C to +85°C industrial temperature range, and EUI-48™-preprogrammed protected memory.

Technical Context

The MCP79411T-I/MNY implements a fully autonomous RTCC using an on-chip oscillator circuit optimized for external 32.768 kHz tuning fork crystals, with digital trimming capability (±129 ppm range, ±1 ppm resolution) to compensate for crystal tolerance and temperature drift. Its I²C slave interface uses two distinct control bytes: '1101111X' for RTCC/SRAM access and '1010111X' for EEPROM operations.

Power management includes automatic switchover between VCC (1.8–5.5 V) and VBAT (1.3–5.5 V) with precise 1.3–1.7 V trip threshold, plus dedicated power-fail timestamp registers (PWRDN/PWRUP) that log exact time of transition. The open-drain MFP supports alarm assertion, selectable square-wave output (1 Hz to 32.768 kHz), or general-purpose output under register control.

Key Specifications

Pinout & Package

Package: 8-pin TDFN (2 mm × 3 mm, exposed pad). Pinout validated per DS20002266J-page 8 Table 3-1 and Figure 1-1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar real-time clock/calendar applications.

Compared with MCP79412T-I/MNY, the MCP79411T-I/MNY provides EUI-48™ addressing ideal for Ethernet/Wi-Fi MAC layers, while DS3231M+ trades memory and MAC features for higher oscillator accuracy-making MCP79411T-I/MNY the balanced choice for embedded systems needing time, memory, and identity in one package.

Availability

MCP79411T-I/MNY is available at Aetrix Electronics and suitable for smart metering, industrial HMI, medical sensor hubs, and building automation controllers requiring stable component supply across long product lifecycles.

Supply support for MCP79411T-I/MNY includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Microchip Technology Inc. is a leading provider of microcontrollers, analog, FPGA, and timing solutions, headquartered in Chandler, Arizona.

The MCP7941X product line delivers highly integrated RTC/Calendar ICs with embedded memory and unique identifiers, designed specifically for industrial, metering, and IoT edge devices requiring long-term timekeeping reliability and secure device identity.

FAQ

What is the primary function of the MCP79411T-I/MNY?

The MCP79411T-I/MNY is a battery-backed I²C Real-Time Clock/Calendar IC that maintains accurate time and date (including leap-year compensation to 2399), provides dual programmable alarms, logs power-fail/power-up events, and integrates 64-byte SRAM, 1 Kbit EEPROM, and 64-bit EUI-48™-preprogrammed protected memory. Its core role is precision timekeeping with persistent storage and hardware identity in resource-constrained embedded systems.

Does the MCP79411T-I/MNY require external load capacitors for its crystal oscillator?

Yes, the MCP79411T-I/MNY requires external load capacitors on X1 and X2 pins when using a 32.768 kHz crystal. It is optimized for crystals with 6–9 pF load capacitance. Capacitor values must be selected to match the crystal's specified CL, accounting for pin capacitance (~3 pF) and PCB stray capacitance, per Equation 5-1 in the datasheet. Omitting or mis-sizing these capacitors causes frequency inaccuracy or oscillator failure.

How does the MCP79411T-I/MNY handle power transitions between VCC and VBAT?

The MCP79411T-I/MNY automatically switches to VBAT when VCC drops below the 1.3–1.7 V switchover threshold (VTRIP), preserving RTCC operation and SRAM contents. Upon VCC restoration, it seamlessly returns to main supply. Crucially, the power-fail timestamp registers (PWRDNMIN–PWRUPMTH) log the exact time of both transitions, enabling system-level diagnostics and data integrity verification in the MCP79411T-I/MNY.

Can the MCP79411T-I/MNY generate a square-wave output, and how is it configured?

Yes, the MCP79411T-I/MNY can generate a square-wave output on the MFP pin. Configuration is done via the CONTROL register: set SQWEN = 1 and select frequency using SQWFS[1:0] bits (00 = 1 Hz, 01 = 1.024 kHz, 10 = 4.096 kHz, 11 = 32.768 kHz). The MFP is open-drain, so an external pull-up resistor to VCC is required. This feature eliminates the need for external clock buffers in timing-critical subsystems using the MCP79411T-I/MNY.

Is the EUI-48™ address in the MCP79411T-I/MNY writable or fixed?

The EUI-48™ address in the MCP79411T-I/MNY is factory-preprogrammed into the 64-bit protected EEPROM region (addresses 0xF0–0xF7) and is permanently fixed. Writing to this area requires a robust unlock sequence defined in the datasheet, and even then, the EUI-48™ portion is read-only. This ensures hardware-level uniqueness and prevents accidental or malicious overwrite-making the MCP79411T-I/MNY suitable for secure device identification in networked applications.