STMicroelectronics M41T11MH6F

Overview

M41T11MH6F from STMicroelectronics is a serial real-time clock (RTC) IC with integrated 32.768 kHz crystal oscillator, 56 bytes of NVRAM, I²C interface (100 kHz), ultra-low battery current (0.8 μA typ. at 3 V), and automatic power switchover between VCC and VBAT. It provides BCD-formatted timekeeping (seconds to century), leap-year compensation, and software calibration for temperature-induced crystal drift - deployed in industrial control panels requiring long-term timestamp integrity during mains failure.

For engineers reviewing the M41T11MH6F datasheet, M41T11MH6F pinout, M41T11MH6F application, or M41T11MH6F equivalent, this page delivers verified technical context, package-specific pin functions, calibrated timing accuracy data, and validated alternatives for battery-backed RTC design in embedded systems operating across –40°C to +85°C.

Technical Context

The M41T11MH6F implements a slave-mode I²C interface with fixed 7-bit address 0xD0h, supporting sequential read/write access to 64-byte memory space (8 registers + 56 NVRAM bytes). Its internal oscillator integrates 12.5 pF load capacitance, enabling stable operation with high-series-resistance crystals up to 70 kΩ.

Power management includes voltage-sense circuitry that triggers automatic switchover to VBAT when VCC drops below VSO (typ. 2.0 V), disabling bus interface and entering <0.8 μA retention mode. Clock updates are synchronized to prevent mid-read corruption, with 250 ms delay applied only during register reads - preserving real-time accuracy without interrupting timebase continuity.

Key Specifications

Pinout & Package

Package: 28-lead SOIC (SOH28) with SNAPHAT® top-mount battery/crystal housing interface - gold-plated dual-end sockets enable post-reflow assembly of the M4Txx-BR12SH housing, preventing thermal damage to lithium cell and crystal during reflow.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS1337+T&R and PCF8563T, the M41T11MH6F uniquely combines integrated oscillator load, software calibration, SNAPHAT® modularity, and 56-byte NVRAM - making it the only option that simultaneously satisfies industrial logging accuracy, long-term battery life, and post-SMT serviceability requirements.

Availability

M41T11MH6F is available at Aetrix Electronics and suitable for industrial PLC HMIs, smart energy meters, medical infusion pumps, and building automation controllers requiring stable component supply with guaranteed long-term availability and traceable sourcing.

Supply support for M41T11MH6F 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 specializing in automotive, industrial, and power management solutions, with over 45 years of analog and mixed-signal IC expertise.

The M41T11 belongs to ST's real-time clock product line, engineered specifically for industrial and medical applications demanding high-accuracy, battery-backed timekeeping with minimal external components and robust thermal resilience.

FAQ

What is the function of the FT/OUT pin on the M41T11MH6F?

The FT/OUT pin is an open-drain output configurable as either a 1 Hz square wave or a 32.768 kHz signal. It serves dual purposes: providing a precise timing reference for microcontroller wake-up or LED blinking, and enabling functional verification of oscillator operation during production test - all without requiring external drivers or dividers.

How does the M41T11MH6F handle power transitions between VCC and VBAT?

When VCC falls below the switchover threshold (VSO ≈ 2.0 V), the device immediately terminates I²C communication, disables the SDA/SCL interface, and switches to VBAT power within microseconds. During this transition, the oscillator and NVRAM remain fully operational - ensuring zero time loss and data integrity without firmware intervention.

Can the M41T11MH6F operate without an external crystal?

No. The M41T11MH6F requires an external 32.768 kHz tuning-fork crystal connected between OSCI and OSCO pins. Its integrated 12.5 pF load capacitance eliminates the need for external capacitors, but the crystal itself is mandatory for oscillator functionality - no internal RC oscillator is present.

What is the purpose of the SNAPHAT® housing compatibility in the SOH28 package?

The SNAPHAT® housing (e.g., M4Txx-BR12SH) contains the lithium coin cell and crystal, and mounts directly onto the SOH28 IC via gold-plated sockets. This design allows the battery and crystal to be installed after PCB reflow - preventing thermal degradation of the lithium cell and crystal, which would occur if they were surface-mounted with the IC.