Microchip Technology MCP79411-I/SN

Overview

MCP79411-I/SN from Microchip Technology is a battery-backed I²C Real-Time Clock/Calendar (RTCC) IC with integrated 64-byte SRAM, 1 Kbit EEPROM, and EUI-48™ MAC address. It maintains time across power loss using automatic VCC/VBAT switchover, supports ±1 ppm digital trimming for 32.768 kHz crystals, and delivers dual programmable alarms with power-fail timestamp logging. Used in industrial metering, smart sensors, and embedded control systems requiring long-term time integrity.

For engineers reviewing the MCP79411-I/SN datasheet, MCP79411-I/SN pinout, MCP79411-I/SN application, or MCP79411-I/SN equivalent, key selection criteria include its 1.8–5.5 V operating range, 925 nA backup current at 3.0 V, I²C interface up to 400 kHz, EUI-48 preprogramming, and 8-pin SOIC/TSSOP/MSOP/TDFN package compatibility.

Technical Context

The MCP79411-I/SN implements a fully autonomous RTCC core with BCD-encoded time/date registers (seconds through year), leap-year compensation to 2399, and 12/24-hour mode support. Its oscillator circuit is optimized for 6–9 pF 32.768 kHz tuning-fork crystals and includes on-chip digital trimming (±129 ppm range, ±1 ppm resolution) to correct frequency drift.

Power management integrates automatic switchover at 1.3–1.7 V trip point, logging timestamps for both power-down and power-up events. The multifunction pin (MFP) supports alarm assertion, selectable square-wave output (1 Hz to 32.768 kHz), or general-purpose open-drain output - all configurable via the CONTROL register.

Key Specifications

Pinout & Package

Package: 8-pin SOIC (Small Outline Integrated Circuit), also available in MSOP, TSSOP, and 2×3 mm TDFN. All variants share identical pin mapping and electrical behavior.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP79410-I/SN, the MCP79411-I/SN adds factory-programmed EUI-48™ for plug-and-play network identity; compared with DS3231M+, it trades TCXO-level accuracy for integrated memory and lower system BOM count.

Availability

MCP79411-I/SN is available at Aetrix Electronics and suitable for smart metering, industrial HMI, medical sensor nodes, and building automation controllers requiring stable component supply with guaranteed long-term availability.

Supply support for MCP79411-I/SN 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 components, and timing solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The MCP7941X product line was designed specifically for embedded systems needing highly integrated, low-power RTC functionality with nonvolatile memory, network identity, and robust power-loss resilience - targeting industrial, medical, and energy infrastructure applications.

FAQ

What is the factory-programmed identifier in MCP79411-I/SN?

The MCP79411-I/SN contains a preprogrammed 48-bit EUI-48™ MAC address stored in its 64-bit protected EEPROM region. This identifier is written at manufacture and requires a specific unlock sequence to modify - ensuring device uniqueness for networked applications without requiring external provisioning. The MCP79411-I/SN uses this feature to enable immediate IEEE 802.3-compliant addressing upon deployment.

How does MCP79411-I/SN handle power transitions between VCC and VBAT?

The MCP79411-I/SN performs automatic switchover between VCC and VBAT when the main supply crosses the 1.3–1.7 V threshold. During transition, it logs exact timestamps for both power-down and power-up events into dedicated PWRDNxxx and PWRUPxxx registers. The RTCC and 64-byte SRAM remain fully operational throughout, preserving time accuracy and user data without interruption. The MCP79411-I/SN maintains this behavior across its full -40°C to +85°C operating range.

Can MCP79411-I/SN operate without an external crystal?

Yes - the MCP79411-I/SN supports external 32.768 kHz clock input on the X1 pin when the EXTOSC bit in the CONTROL register is set. In this mode, the X2 pin must be left floating, and the internal crystal oscillator circuit is disabled. This allows use with precision clock sources such as TCXOs or buffered oscillator modules, bypassing crystal load capacitance matching requirements while retaining full RTCC functionality. The MCP79411-I/SN behaves identically in both crystal and external-clock modes except for oscillator configuration.

What is the maximum I²C clock frequency supported by MCP79411-I/SN?

The MCP79411-I/SN supports I²C clock frequencies up to 400 kHz when VCC is 2.5 V or higher. At lower VCC (1.8 V ≤ VCC < 2.5 V), the maximum clock frequency is limited to 100 kHz to ensure reliable timing margins. Both modes comply with standard I²C protocol requirements including START/STOP conditions, ACK/NACK signaling, and data hold/setup times. The MCP79411-I/SN's I²C interface remains functional only when powered from VCC - it is disabled during pure VBAT operation.

How is digital trimming implemented in MCP79411-I/SN?

Digital trimming in the MCP79411-I/SN is performed via the OSCTRIM register (address 0x08), which provides ±129 ppm adjustment range in ±1 ppm steps using an 8-bit signed value (SIGN + TRIMVAL[6:0]). Trimming compensates for crystal frequency deviations caused by manufacturing tolerance and temperature effects. The MCP79411-I/SN applies the trim value directly to the oscillator feedback path, enabling field calibration without hardware changes. Trim settings persist in volatile registers and must be reloaded after power cycle unless stored in EEPROM by system firmware.