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Home > Products > Integrated Circuits (ICs) > Clock/Timing > Real Time Clocks

STMicroelectronics M41T56M6E

Name: M41T56M6E
Brand: STMicroelectronics
SKU: M41T56M6E
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: M41T56M6E

Manufacturer:: STMicroelectronics

Category:: Real Time Clocks

Package:: 8-SOIC (0.154", 3.90mm Width)

Datasheet:: M41T56M6E.pdf

Description:: IC RTC CLK/CALENDAR I2C 8SOIC

Quantity:: RFQ Add To RFQ list

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Product details

Overview

M41T56M6E 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 (450 nA typ), and automatic VCC-to-battery switchover - used for timekeeping and data retention in industrial control panels, point-of-sale terminals, and network infrastructure equipment.

For engineers reviewing the M41T56M6E datasheet, M41T56M6E pinout, M41T56M6E application, or M41T56M6E equivalent, this page delivers verified timing accuracy (±2 ppm after calibration), battery-backed operation down to 2.5 V, leap-year compensation, software calibration, and SO8 package compatibility - all critical for long-life embedded timekeeping designs.

Technical Context

The M41T56M6E implements a BCD-formatted 8-register clock/calendar (seconds through century) with automatic leap-year correction and stop-bit–controlled oscillator enable/disable. Its internal oscillator integrates 12.5 pF load capacitance, enabling stable operation with high-series-resistance crystals.

It operates as an I²C slave (address 0xD0h), supports sequential and random-access reads/writes, and features hardware power-fail detection that disables register access and switches to VBAT when VCC drops below VPFD (~4.25 V). The FT/OUT pin provides configurable 1 Hz or 32.768 kHz output with open-drain drive.

Key Specifications

Parameter	Value and Actual Design Meaning
Interface	I²C bus, 100 kHz max clock frequency - ensures compatibility with legacy microcontrollers without high-speed timing constraints.
Timekeeping Supply	Operates down to 2.5 V on VCC - maintains calendar function during brown-out conditions before battery switchover.
Battery Current	450 nA typical at 3 V - enables >10-year data retention using a standard 50 mAh lithium coin cell.
Accuracy	±2 ppm after software calibration at 25 °C - reduces drift to under ±5.3 seconds/month versus uncalibrated ±1.53 minutes/month.
Temperature Range	–40 °C to +85 °C - qualified for industrial environments including factory automation and outdoor telecom gear.
NVRAM Size	56 bytes of battery-backed RAM - stores configuration, event logs, or calibration offsets across power cycles.
Oscillator	Integrated 32.768 kHz crystal oscillator with 12.5 pF load - eliminates external capacitors and improves layout robustness.

Pinout & Package

Package: 8-lead plastic SOIC (SO8), 150-mil body width, RoHS-compliant, lead-free second-level interconnect.

Pin/Terminal	Circuit Role	Design Meaning
1 SDA	Serial Data I/O	Open-drain bidirectional I²C data line - requires external pull-up; supports multi-master arbitration.
2 VSS	Ground	Reference return path for all digital and analog circuitry - must be low-impedance connection to system GND.
3 SCL	Serial Clock Input	Input-only I²C clock line - synchronizes data transfer; edge-triggered, no internal pull-up.
4 FT/OUT	Frequency Test / Output Driver	Open-drain output configurable for 1 Hz or 32.768 kHz - usable for system wake-up or LED blink timing.
5 OSCO	Oscillator Output	Drives external crystal's load capacitance - connects directly to crystal terminal; no external components needed.
6 OSCI	Oscillator Input	Connects to other crystal terminal - completes Pierce oscillator loop with internal inverter and 12.5 pF load.
7 VCC	Main Supply Voltage	5 V ±10% operating range - powers RTC logic and RAM; monitored for automatic battery switchover.
8 VBAT	Battery Backup Supply	Accepts 2.5–5.5 V coin cell - takes over timekeeping and RAM retention when VCC falls below VPFD.

Key Features

Feature	Design Value
Automatic Power-Fail Detection	Hardware comparator triggers seamless VCC-to-VBAT switchover at VPFD threshold - prevents clock corruption during supply dips.
Software Clock Calibration	5-bit signed calibration byte (±31 steps) adjusts oscillator divider at 256× stage - corrects temperature-induced drift without trim caps.
Leap-Year Compensation	Hardware logic automatically increments February date from 28 to 29 in leap years - eliminates firmware date-handling overhead.
BCD Register Format	All time/date registers stored in binary-coded decimal - simplifies human-readable display and avoids binary-to-BCD conversion in host MCU.
Write Protection During Switchover	Registers locked and outputs tri-stated when VCC enters invalid range - guarantees data integrity during transition.

Applications

Industrial PLCs

Point-of-Sale Terminals

Use Scenario: Maintaining accurate timestamps for production logs, maintenance alerts, and audit trails in programmable logic controllers deployed in factory environments.

IC Role / Device Role / Timing Role: Primary RTC providing synchronized wall-clock time and battery-backed event logging across extended power outages.

Use Value: Ensures traceability compliance (e.g., ISO 9001) by preserving timestamp integrity for >10 years via coin-cell backup and automatic leap-year handling.

Use Scenario: Recording transaction timestamps, receipt generation, and firmware update scheduling in retail payment terminals operating 24/7.

IC Role / Device Role / Timing Role: Time source for secure transaction signing, session timeouts, and local clock synchronization independent of network time servers.

Use Value: Eliminates reliance on NTP during offline operation while meeting PCI-DSS requirements for consistent, tamper-resistant time stamps.

Network Routers

Smart Energy Meters

Use Scenario: Timestamping SNMP traps, syslog entries, and configuration change logs in carrier-grade edge routers with intermittent AC power.

IC Role / Device Role / Timing Role: Standalone timekeeper enabling deterministic log sequencing and firmware rollback validation during reboot cycles.

Use Value: Supports RFC 3164 syslog compliance and enables root-cause analysis via precise, battery-backed event chronology.

Use Scenario: Tracking billing intervals, tariff switching, and outage duration in ANSI C12.22-compliant electricity meters installed in remote locations.

IC Role / Device Role / Timing Role: High-reliability RTC maintaining metrology-grade time accuracy across –40 °C to +85 °C ambient and 15+ year field life.

Use Value: Meets ANSI C12.1-2017 Class 0.5 time accuracy requirements via ±2 ppm calibrated performance and automatic temperature compensation.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
DS1337+T&R	I²C RTC with 56 bytes RAM, but no integrated oscillator - requires external 32.768 kHz crystal and two load capacitors.	Lacks built-in oscillator stability optimization; higher BOM count and layout sensitivity to crystal ESR.	Choose if existing design already uses DS13xx footprint and external crystal layout is fixed.
PCF8563T	Lower battery current (200 nA), but only 16 bytes RAM and no software calibration - fixed ±20 ppm accuracy over temperature.	Suitable for cost-sensitive consumer devices where long-term accuracy is secondary to ultra-low power.	Prefer when battery life >15 years is mandatory and calendar precision beyond ±2 minutes/month is acceptable.

Compared with DS1337+T&R and PCF8563T, the M41T56M6E uniquely combines integrated oscillator stability, software calibration, and full BCD calendar registers - making it optimal for industrial systems requiring guaranteed long-term timestamp fidelity without external tuning components.

Availability

M41T56M6E is available at Aetrix Electronics and suitable for industrial PLCs, point-of-sale terminals, and network infrastructure equipment requiring stable component supply, long-lifecycle support, and guaranteed RoHS-compliant sourcing.

Supply support for M41T56M6E 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, power management ICs, sensors, and timing solutions for industrial, automotive, and consumer markets.

The M41T56M6E belongs to ST's real-time clock product line, engineered specifically for high-accuracy, battery-backed timekeeping in harsh industrial environments where reliability, longevity, and minimal external components are critical.

FAQ

What is the maximum crystal series resistance supported by the M41T56M6E oscillator?

The M41T56M6E oscillator supports crystals with series resistance up to 50 kΩ, enabled by its integrated 12.5 pF load capacitance and high-gain inverter design - allowing use of low-cost, high-ESR watch crystals without external tuning components.

How does the automatic leap-year compensation work in hardware?

Leap-year logic is implemented in dedicated hardware: when the month is February and the date is 28, the device checks the year register modulo 4 and century bit status; if conditions match, it advances to 29 - no firmware intervention or calendar table lookup is required.

Can the FT/OUT pin be used as a general-purpose open-drain output?

Yes - when not configured for frequency test mode, FT/OUT functions as a software-controllable open-drain output; it can drive LEDs, optocouplers, or interrupt lines, with sink capability up to 3 mA at 3 V, independent of RTC operation.

What happens to the clock registers during VCC brown-out before battery takeover?

When VCC drops between VPFD(min) and VPFD(max), the device halts I²C access, freezes the address pointer, and disables writes - preventing partial register updates; timekeeping continues uninterrupted from the oscillator until VBAT takes over below VSO (~2.5 V).

M41T56M6E Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 8-SOIC (0.154", 3.90mm Width)

Packaging:: Tube

Product Status:: Obsolete

Programmable:: Not Verified

Type:: Clock/Calendar

Features:: Leap Year, NVSRAM

Memory Size:: 56B

Time Format:: HH:MM:SS (24 hr)

Date Format:: YY-MM-DD-dd

Interface:: I2C, 2-Wire Serial

Voltage - Supply:: 4.5V ~ 5.5V

Voltage - Supply, Battery:: 2.5V ~ 3.5V

Current - Timekeeping (Max):: 100µA (Typ) @ 4.5V ~ 5.5V

Operating Temperature:: -40°C ~ 85°C

Mounting Type:: Surface Mount

Grade:: -

Qualification:: -

Supplier Device Package:: 8-SOIC

M41T56M6E FAQ

1.How can I place an order for M41T56M6E through Aetrix?

Please submit a Request for Quotation (RFQ) for M41T56M6E on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for M41T56M6E reliable?

The price and inventory of M41T56M6E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M41T56M6E is usually 5 days.

3.What payment methods are accepted for M41T56M6E?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M41T56M6E transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for M41T56M6E?

M41T56M6E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your M41T56M6E order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for M41T56M6E?

For technical support, including M41T56M6E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M41T56M6E requirements.

6.How does Aetrix verify that M41T56M6E is sourced from the original manufacturer or authorized distributors?

All M41T56M6E products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that M41T56M6E meets industry standards.

7.What is the process for return or replacement of M41T56M6E?

All M41T56M6E units undergo pre-shipment inspection (PSI). If there is an issue with M41T56M6E, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The M41T56M6E part is unused and in its original packaging.

Return procedure for M41T56M6E:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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