STMicroelectronics M41T0M6E

Overview

M41T0M6E from STMicroelectronics is a serial real-time clock IC with integrated 32.768 kHz crystal oscillator, I²C interface (400 kHz), and BCD-coded calendar registers for seconds through century. It operates from 2.0–5.5 V, draws 0.9 µA standby current at 3 V, and supports –40 to 85 °C industrial temperature range - used in embedded metering, industrial HMI, and battery-backed timekeeping systems.

For engineers reviewing the M41T0M6E datasheet, M41T0M6E pinout, M41T0M6E application, or M41T0M6E equivalent, key selection criteria include oscillator stability with internal 12.5 pF load capacitance, oscillator stop detection flag (OF bit), open-drain OUT pin programmability, and I²C timing compliance per Table 2 (tHD:STA ≥ 600 ns, tLOW ≥ 1.3 µs).

Technical Context

The M41T0M6E implements a slave-mode I²C interface with fixed 7-bit address 0xD0h, supporting sequential READ/WRITE of eight BCD registers (seconds to control). Clock updates are synchronized to avoid mid-read corruption via 250 ms register update delay.

Its on-chip 32.768 kHz oscillator integrates 12.5 pF load capacitance for stable crystal operation up to high series resistance; oscillator stop detection (OF bit) latches failure conditions including power-up, low VCC, STOP bit assertion, or crystal disconnection - requiring explicit software clear after ≥4 s oscillation.

Key Specifications

Pinout & Package

Supplied in SO8 (8-lead plastic small outline, 150 mils body width) package per Table 9 and Figure 2 - surface-mount compatible with standard reflow profiles (peak 260 °C).

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 M41T0M6E uniquely combines integrated 12.5 pF load capacitance, oscillator stop detection, and century-aware BCD registers - making it optimal for industrial applications requiring time integrity verification and long-term calendar accuracy without manual intervention.

Availability

M41T0M6E is available at Aetrix Electronics and suitable for smart metering, industrial HMI, and building automation controllers requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.

Supply support for M41T0M6E 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 analog, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The M41T0M6E belongs to ST's real-time clock product line, engineered specifically for robust, low-power, battery-backed timekeeping in industrial environments where oscillator reliability and calendar correctness are mission-critical.

FAQ

Does the M41T0M6E require external load capacitors for the 32.768 kHz crystal?

No. The M41T0M6E integrates 12.5 pF load capacitance internally on both OSCI and OSCO pins, eliminating the need for external capacitors. This reduces component count, PCB area, and crystal matching complexity - confirmed in Section 1 features and Table 8 of the datasheet.

How is oscillator failure detected and cleared in the M41T0M6E?

Oscillator failure sets the OF (oscillator fail) bit in the seconds register (Address 0, D6). It latches on power-up, low VCC, STOP bit assertion, or crystal removal. To clear it, firmware must write '0' to OF after confirming oscillator has run ≥4 seconds - verified in Section 3.2 and Table 3 register map.

What is the function of the NF pin on the M41T0M6E?

The NF (No Function) pin is unconnected internally and must be tied to VSS per datasheet Figure 2 and Section 1 note. It serves no electrical purpose and is retained for package compatibility - explicitly stated as "NF(1) 1. NF pin must be tied to VSS" in Table 1 and Figure 2 caption.

Can the M41T0M6E operate as a standalone RTC without a host microcontroller?

No. The M41T0M6E is an I²C slave device requiring a master controller to initialize registers, read time/date, and manage control bits (e.g., STOP, OUT, CEB). It contains no internal processor or autonomous alarm logic - its block diagram (Figure 3) shows no CPU or interrupt generation circuitry beyond the open-drain OUT pin.