STMicroelectronics M41T0DS6E

Overview

M41T0DS6E from STMicroelectronics is a serial real-time clock IC with integrated 32.768 kHz crystal oscillator, I²C interface (400 kHz), BCD-formatted timekeeping registers (seconds to century), oscillator stop detection, and open-drain output driver - used for accurate time/date stamping in battery-backed embedded systems such as industrial controllers and smart meters.

For engineers reviewing the M41T0DS6E datasheet, M41T0DS6E pinout, M41T0DS6E application, or M41T0DS6E equivalent, key selection criteria include oscillator stability under high-series-resistance crystals, low 0.9 µA standby current at 3 V, –40 to 85 °C operating range, I²C timing compliance, and register-level control of century toggle and oscillator stop.

Technical Context

The M41T0DS6E operates as an I²C slave device with fixed 7-bit address 0xD0h, supporting sequential READ/WRITE access to eight BCD registers (seconds through control). Its internal oscillator integrates 12.5 pF load capacitance and supports crystal series resistance up to 100 kΩ for robust operation across temperature and aging.

It implements oscillator fail (OF) bit detection, automatic 250 ms clock update delay during register reads to prevent data corruption, and a software-controllable STOP bit that halts oscillation to reduce shelf current. The OUT pin reflects D7 of the control register and requires external pull-up.

Key Specifications

Pinout & Package

Supplied in SO8 (8-lead plastic small outline, 150 mils body width) package per JEDEC MS-012, with standard gull-wing lead form and 1.27 mm pitch.

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 M41T0DS6E uniquely combines century-aware BCD registers, oscillator fault detection, and integrated 12.5 pF load - making it optimal for industrial and metering applications demanding long-term accuracy, auditability, and robustness without external passive components.

Availability

M41T0DS6E is available at Aetrix Electronics and suitable for industrial data loggers, smart energy meters, programmable logic controllers, and medical diagnostic devices requiring stable component supply across extended product lifecycles.

Supply support for M41T0DS6E 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 timing solutions for industrial, automotive, and consumer markets.

The M41T0DS6E belongs to ST's real-time clock product line, engineered specifically for high-reliability, battery-backed timekeeping in harsh environments - emphasizing oscillator stability, low-power operation, and register-level fault visibility.

FAQ

What is the function of the NF pin on M41T0DS6E?

The NF (No Function) pin has no internal electrical connection and must be tied to VSS (ground) per the datasheet. Leaving it floating may introduce noise coupling or EMI susceptibility due to its proximity to sensitive oscillator pins OSCI and OSCO. Grounding ensures mechanical stability and electromagnetic compatibility in high-noise industrial layouts.

How does the oscillator stop detection (OF bit) behave after power-on reset?

Upon initial power application, the OF bit is set to '1' by default - indicating oscillator status is unknown until confirmed running. It remains '1' until firmware explicitly writes '0' to clear it, but only after the oscillator has run continuously for ≥4 seconds. This prevents premature clearing before stable oscillation is achieved.

Can the M41T0DS6E operate without an external crystal?

No. The M41T0DS6E requires an external 32.768 kHz tuning-fork crystal connected between OSCI and OSCO pins. Its internal oscillator circuit provides 12.5 pF load capacitance but does not generate frequency autonomously - the crystal is mandatory for timekeeping functionality.

What happens to the time registers during a read sequence?

When any of the seven time registers (addresses 0–6) is being read, the internal clock update is delayed by 250 ms to prevent mid-read corruption. This ensures atomic access: the host reads a consistent snapshot of seconds, minutes, hours, etc., without risk of partial updates crossing register boundaries.