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

STMicroelectronics M41T56C64MY6E

Name: M41T56C64MY6E
Brand: STMicroelectronics
SKU: M41T56C64MY6E
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: M41T56C64MY6E

Manufacturer:: STMicroelectronics

Category:: Real Time Clocks

Package:: 18-SOX, 18-SOIC with Crystal (7.5mm Width)

Datasheet:: M41T56C64MY6E.pdf

Description:: IC RTC CLK/CALENDAR I2C 18SOX

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Product details

Overview

M41T56C64MY6E from STMicroelectronics is a serial real-time clock (RTC) with integrated 64 Kbit EEPROM and 56-byte NVRAM, operating at 5V ±10% with I²C interface (100 kHz for RTC, 400 kHz for EEPROM), embedded 32.768 kHz crystal, and –40°C to +85°C temperature range-used in industrial control panels for timestamped event logging and battery-backed configuration storage.

For engineers reviewing the M41T56C64MY6E datasheet, M41T56C64MY6E pinout, M41T56C64MY6E application, or M41T56C64MY6E equivalent, key selection considerations include battery-backup current (450 nA), dual I²C address space (M41T56 + M24C64), automatic power-fail switchover, software calibration register at 1550h, and SOX18 18-pin SOIC package with embedded crystal.

Technical Context

The device integrates two independent I²C peripherals on a single die: an M41T56 RTC core with BCD-formatted calendar registers (seconds through century), automatic leap-year compensation, and open-drain FT/OUT for frequency test or alarm output; and an M24C64 EEPROM with 8192 × 8-bit organization, page-write capability (up to 32 bytes), and >1 million endurance cycles.

Power management includes a dedicated voltage-sense circuit that detects VCC dropout and seamlessly switches to VBAT (2.5–3.5 V), sustaining RTC and SRAM operation from a BR1225/BR1632 coin cell; calibration is factory-programmed into EEPROM address 1550h to achieve ±5 ppm accuracy at 25°C post-reflow, with aging drift of ±1 ppm/year after Year 1.

Key Specifications

Parameter	Value and Actual Design Meaning
Supply Voltage	4.5–5.5 V - compatible with standard 5V logic rails and tolerant of ±10% variation.
RTC I²C Speed	100 kHz - matches standard-mode I²C timing, enabling interoperability with legacy microcontrollers.
EEPROM I²C Speed	400 kHz - fast-mode I²C support reduces firmware write latency for configuration updates.
Battery Current	450 nA typical - enables >10-year data retention using a 50 mAh 3V lithium coin cell.
Crystal Accuracy	±5 ppm at 25°C - factory-calibrated offset compensates for crystal aging and thermal drift.
Data Retention	40+ years - guaranteed EEPROM data integrity without refresh under specified storage conditions.
Operating Temp	–40°C to +85°C - qualified for industrial-grade ambient environments without derating.

Pinout & Package

Package: SOX18 - 18-pin plastic small-outline IC (300-mil width) with embedded 32.768 kHz crystal; RoHS-compliant ECOPACK®; lead-free reflow peak 240°C (90–150 s thermal budget).

Pin/Terminal	Circuit Role	Design Meaning
VCC	Main supply input	5V system rail; powers RTC, EEPROM, and interface logic during normal operation.
VBAT	Battery backup supply	Connects to 3V coin cell; automatically takes over during VCC failure via internal switch.
SCL	I²C clock input/output	Open-drain, requires external pull-up; controls timing for both RTC and EEPROM transactions.
SDA	I²C bidirectional data line	Shared bus line for all I²C reads/writes; supports clock stretching by slave devices.
FT/OUT	Frequency test / open-drain output	Configurable as 1 Hz square wave, alarm signal, or general-purpose output; requires pull-up.
WC	Write control enable	Hardware write-protect: low = EEPROM writes disabled; high = writes enabled.
E0–E2	Chip select address inputs	Set I²C slave address bits A2–A0 for EEPROM (M24C64); RTC uses fixed address 0xD0.
VSS	Ground reference	Common return path for VCC, VBAT, and I/O; pins 2/3 and 16/17 internally shorted.

Key Features

Feature	Design Value
Embedded crystal oscillator	Eliminates external crystal and load capacitors, reducing BOM count and PCB layout sensitivity.
Automatic power-fail switchover	Zero-latency transition to battery power ensures uninterrupted timekeeping and SRAM retention.
Software clock calibration	Factory-programmed value at EEPROM address 1550h enables precise long-term accuracy without user tuning.
Dual I²C address spaces	RTC (0xD0) and EEPROM (0xA0–0xA7) operate independently on same bus, avoiding address conflicts.
56-byte NVRAM	Nonvolatile RAM retains critical runtime parameters (e.g., calibration offsets, last-error codes) across power cycles.

Applications

Industrial HMI Logging

Smart Meter Time Stamping

Use Scenario: Industrial human-machine interface records operator actions, fault events, and process alarms with precise timestamps.

IC Role / Device Role / Timing Role: Primary RTC source providing BCD-formatted date/time to MCU via I²C; NVRAM stores last-known state during brownouts.

Use Value: Ensures traceable, battery-backed event chronology even during extended AC outages-critical for compliance reporting.

Use Scenario: Electricity meter logs energy consumption intervals and tamper events with certified time stamps.

IC Role / Device Role / Timing Role: Time-of-use (TOU) scheduler and secure time anchor; EEPROM stores tariff tables and firmware update metadata.

Use Value: Meets IEC 62056 requirements for time accuracy (±5 ppm) and 10+ year battery-backed operation without recalibration.

Medical Device Audit Trail

POS Terminal Configuration Backup

Use Scenario: Infusion pump logs therapy start/stop times, dosage changes, and error conditions for FDA audit trails.

IC Role / Device Role / Timing Role: Tamper-resistant time source synchronized to UTC; SRAM caches unsent logs before EEPROM commit.

Use Value: Provides cryptographically verifiable timestamps with >40-year EEPROM data retention for regulatory record-keeping.

Use Scenario: Point-of-sale terminal stores tax rates, receipt templates, and user preferences across firmware updates.

IC Role / Device Role / Timing Role: Configuration manager using EEPROM for field-updatable settings; RTC enables scheduled firmware checks.

Use Value: Enables zero-downtime parameter updates and rollback-safe configuration versioning without external memory.

Equivalent & Alternatives

The following parts are listed as comparable options for similar RTC+EEPROM integration applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
DS1340Z-33+T&R	3.3V-only supply (2.7–3.6V); no integrated EEPROM; external crystal required.	Lacks nonvolatile storage; requires separate EEPROM and crystal for full functionality.	Select only if system operates at 3.3V and external memory is already present.
M41T81SM6F	Same 5V supply and SOX18 package; includes 64 Kbit EEPROM but no NVRAM; uses different calibration method.	Missing 56-byte SRAM for volatile runtime data; calibration stored in RTC registers, not EEPROM.	Choose when NVRAM is unnecessary and simpler calibration handling is preferred.

Compared with DS1340Z-33+T&R and M41T81SM6F, the M41T56C64MY6E uniquely combines 5V operation, embedded crystal, 56-byte NVRAM, and factory-calibrated EEPROM-stored trim-making it optimal for cost-sensitive, space-constrained industrial designs requiring full time+storage integration in one package.

Availability

M41T56C64MY6E is available at Aetrix Electronics and suitable for industrial HMI logging, smart meter time stamping, and medical device audit trail systems requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for M41T56C64MY6E 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 M41T56C64 belongs to ST's serial RTC product line, engineered specifically for battery-backed timekeeping and nonvolatile data storage in resource-constrained embedded systems where board space, BOM count, and long-term reliability are critical.

FAQ

What is the function of the WC pin on the M41T56C64MY6E?

The WC (Write Control) pin is a hardware write-protect input for the EEPROM section. When pulled low, it disables all EEPROM write operations-including byte, page, and erase commands-preventing accidental data corruption during power transitions or firmware errors. It must be held high to enable writes, and its state is sampled at the start of each I²C transaction.

How does the M41T56C64MY6E handle power failure detection and battery switchover?

The device features an internal voltage-sense circuit that continuously monitors VCC. When VCC drops below the switchover threshold (~2.5 V), it automatically disconnects VCC and connects VBAT to sustain RTC counting and SRAM retention within nanoseconds-no external circuitry or host intervention required. This ensures uninterrupted timekeeping and data integrity during brownouts or main power loss.

Can the FT/OUT pin be used as a general-purpose output, and what are its electrical limits?

Yes, FT/OUT is a configurable open-drain output capable of driving external loads such as LEDs or interrupt lines. It supports 1 Hz square-wave output for time monitoring or can be programmed as an alarm signal. Its absolute maximum sink current is 20 mA, and it requires an external pull-up resistor (typically 4.7 kΩ to VCC or VBAT). Voltage ratings match VCC/VBAT domains per JEDEC specifications.

Is the embedded crystal in the SOX18 package field-replaceable or serviceable?

No-the 32.768 kHz crystal is permanently molded inside the SOX18 package during manufacturing and cannot be replaced or serviced in the field. ST performs final calibration after SMT reflow and programs the trim value into EEPROM address 1550h. Any physical attempt to access the crystal will destroy the device and void calibration guarantees.

M41T56C64MY6E Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 18-SOX, 18-SOIC with Crystal (7.5mm Width)

Packaging:: Tube

Product Status:: Obsolete

Programmable:: Not Verified

Type:: Clock/Calendar

Features:: EEPROM, Leap Year, NVSRAM

Memory Size:: 56B, 8KB

Time Format:: HH:MM:SS

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:: 18-SOX

M41T56C64MY6E FAQ

1.How can I place an order for M41T56C64MY6E through Aetrix?

Please submit a Request for Quotation (RFQ) for M41T56C64MY6E 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 M41T56C64MY6E reliable?

The price and inventory of M41T56C64MY6E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M41T56C64MY6E is usually 5 days.

3.What payment methods are accepted for M41T56C64MY6E?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M41T56C64MY6E transactions.

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4.How is shipping managed for M41T56C64MY6E?

M41T56C64MY6E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your M41T56C64MY6E 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 M41T56C64MY6E?

For technical support, including M41T56C64MY6E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M41T56C64MY6E requirements.

6.How does Aetrix verify that M41T56C64MY6E is sourced from the original manufacturer or authorized distributors?

All M41T56C64MY6E 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 M41T56C64MY6E meets industry standards.

7.What is the process for return or replacement of M41T56C64MY6E?

All M41T56C64MY6E units undergo pre-shipment inspection (PSI). If there is an issue with M41T56C64MY6E, 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 M41T56C64MY6E part is unused and in its original packaging.

Return procedure for M41T56C64MY6E:

1.Submit a request within 90 days.

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

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