STMicroelectronics M41T80M6E

Overview

M41T80M6E from STMicroelectronics is a serial-access real-time clock (RTC) with integrated 32.768 kHz crystal oscillator, I²C interface (400 kHz), alarm interrupt capability, and programmable square wave output (1 Hz to 32 kHz). It maintains time-of-day and calendar data-including century-aware BCD-encoded year/month/date/hour/minute/second/tenths-hundredths of second-and operates across –40 to +85 °C at 2.0–5.5 V supply. Used in industrial control panels for timestamped event logging and power-fail recovery.

For engineers reviewing the M41T80M6E datasheet, M41T80M6E pinout, M41T80M6E application, or M41T80M6E equivalent, this page delivers verified functional identity, validated I²C timing compliance, confirmed alarm register mapping, and exact SOIC-8 package alignment-enabling direct integration into battery-backed embedded systems requiring traceable timekeeping.

Technical Context

The M41T80M6E implements a slave-mode I²C interface with fixed 7-bit address 0xD0h, supporting sequential read/write access across 20 registers. Its internal BiPORT™ architecture separates volatile user-accessible registers from synchronized internal counters to prevent read corruption during clock updates.

It integrates a precision 32.768 kHz oscillator with built-in 12.5 pF load capacitance, enabling stable operation with high-series-resistance crystals. Alarm functionality uses five repeat-control bits (RPT1–RPT5) to configure match modes-from once-per-second to annual repetition-with flag latching and interrupt assertion on IRQ/OUT/SQW pin.

Key Specifications

Pinout & Package

Package: 8-pin SOIC (SO8), 150 mil body width, ECOPACK® RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS1307+ and PCF8563, the M41T80M6E uniquely combines century-aware BCD calendar, integrated 12.5 pF crystal loading, and dual-output capability (IRQ/OUT/SQW + F32K) - making it optimal for new industrial and medical designs requiring >20-year date validity and minimal external components.

Availability

M41T80M6E is available at Aetrix Electronics and suitable for industrial data loggers, smart energy meters, medical infusion pumps, and building HVAC controllers requiring stable component supply across extended product lifecycles.

Supply support for M41T80M6E 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, analog ICs, MEMS, and power devices for industrial, automotive, and consumer markets.

The M41T80 belongs to ST's real-time clock product line, engineered specifically for battery-backed, low-power embedded systems demanding high-accuracy timekeeping, alarm-driven event handling, and seamless I²C integration without external timing components.

FAQ

Does M41T80M6E require external load capacitors for the 32.768 kHz crystal?

No. The M41T80M6E integrates 12.5 pF load capacitance internally, eliminating the need for external capacitors. This simplifies PCB layout, reduces bill-of-materials count, and improves oscillator stability across temperature and aging - confirmed in Section 1 and Table 11 of ST's Doc ID 9074 Rev 5.

How does the M41T80M6E handle leap years, especially year 2100?

The M41T80M6E implements hardware-based leap-year correction valid until year 2100, automatically adjusting February length. However, it does not account for the Gregorian calendar exception that skips leap year in 2100; users must implement software correction for dates beyond 2099, as documented in Section 1 and Table 3 register definitions.

Can the IRQ/OUT/SQW pin output both alarm interrupt and 32 kHz square wave simultaneously?

No. IRQ/OUT/SQW is a single open-drain terminal configurable as alarm interrupt, general-purpose output, or programmable square wave (1 Hz–32 kHz) - but not concurrently with the dedicated F32K pin, which provides a separate, always-active 32 kHz square wave output per Section 3.3 and Figure 2.

What happens to the clock during an I²C read of time registers?

During I²C reads of clock registers (addresses 00h–07h), the M41T80M6E halts internal clock register updates to prevent read corruption. Updates resume after STOP condition or when pointer increments past 07h to 08h, ensuring atomic, glitch-free time reads - detailed in Section 3.1 and Figure 8 timing diagrams.