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STMicroelectronics M41T56MH6E
- Part No.:
- M41T56MH6E
- Manufacturer:
- STMicroelectronics
- Category:
- Real Time Clocks
- Package:
- 28-SOP (0.350", 8.89mm Width) with SNAPHAT Sockets
- Datasheet:
-
M41T56MH6E.pdf
- Description:
- IC RTC CLK/CALENDAR I2C 28SOH
- Quantity:
- Payment:
- Shipping:
Inventory:3,552
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Product details
Overview
M41T56MH6E from STMicroelectronics is a serial real-time clock (RTC) IC with integrated 32.768 kHz crystal oscillator, 56-byte 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 requiring accurate calendar functions down to 2.5 V.
For engineers reviewing the M41T56MH6E datasheet, M41T56MH6E pinout, M41T56MH6E application, or M41T56MH6E equivalent, this page delivers verified timing accuracy (±2 ppm after calibration), leap-year compensation, software-adjustable oscillator drift, and SO8 package compatibility for embedded systems with long-term battery backup.
Technical Context
The M41T56MH6E 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 read/write of registers and RAM, and features hardware power-fail detection that disables access and switches to VBAT when VCC drops below VPFD (~4.25 V min), entering ultra-low-power retention mode (<450 nA).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Interface | I²C bus, 100 kHz max clock frequency - compatible with standard microcontroller I²C peripherals without speed negotiation. |
| Timekeeping Supply Range | 2.5 V to 5.5 V - maintains calendar accuracy during brownout conditions common in industrial power rails. |
| Battery Current (Typ) | 450 nA at 3 V - enables >10-year data retention using a standard 50 mAh lithium coin cell. |
| Oscillator Accuracy | ±2 ppm after software calibration at 25 °C - reduces monthly drift from ±1.53 min to <±5.3 sec/month. |
| Operating Temperature | –40 °C to +85 °C - qualified for use in uncontrolled industrial enclosures and outdoor metering equipment. |
| NVRAM Size | 56 bytes of battery-backed SRAM - stores configuration, event logs, or calibration offsets across power cycles. |
| Crystal Integration | On-chip 12.5 pF load capacitance - eliminates external capacitors, simplifying PCB layout and improving oscillator stability. |
Pinout & Package
Supplied in an 8-lead, 150-mil plastic SOIC (SO8) package compliant with RoHS and JEDEC MS-012 standards.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SDA) | Serial Data I/O | Open-drain bidirectional I²C data line - requires external pull-up resistor (typically 4.7 kΩ). |
| 2 (VSS) | Ground | Reference return path for all digital and analog circuitry; must be low-impedance connection. |
| 3 (SCL) | Serial Clock Input | Master-generated I²C clock signal - controls timing of data sampling on SDA line. |
| 4 (FT/OUT) | Frequency Test / Output Driver | Open-drain output providing 1 Hz or 32.768 kHz test signal; configurable via control register. |
| 5 (OSCO) | Oscillator Output | Drives external 32.768 kHz crystal; paired with OSCI to form Pierce oscillator loop. |
| 6 (OSCI) | Oscillator Input | Input node of internal inverter; completes crystal oscillator circuit with OSCO and integrated 12.5 pF caps. |
| 7 (VCC) | Main Supply Voltage | Primary 5 V ±10% power input; monitored for power-fail detection and automatic VBAT switchover. |
| 8 (VBAT) | Battery Backup Supply | Connects to lithium coin cell; powers RTC and NVRAM when VCC falls below switchover threshold (~2.5 V). |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Power-Fail Detection | Hardware-monitored VCC with VPFD threshold (~4.25 V) triggers immediate switch to VBAT and write-protection to prevent corruption. |
| Software Clock Calibration | 5-bit signed calibration byte (±31 steps) adjusts oscillator division ratio at 256× stage - corrects temperature-induced drift without external components. |
| Leap-Year Compensation | Firmware-transparent logic automatically increments year on Feb 29 every 4 years (excluding non-leap centuries unless CE bit enabled). |
| Century Bit Handling | Dedicated CEB/CB bits in hours register enable century rollover (2000→2100) with user-controlled toggle behavior. |
| Sequential Register Access | Auto-incrementing address pointer allows single-start burst reads/writes across clock registers or NVRAM - reduces I²C transaction overhead. |
Applications
| Industrial PLC Time Stamping | Smart Energy Meter Logging |
|---|---|
|
Use Scenario: Recording timestamped sensor events (e.g., temperature alarms, valve actuations) in programmable logic controllers deployed in factory automation. IC Role / Device Role / Timing Role: Primary RTC source providing BCD-formatted wall-clock time synchronized to UTC via periodic host update; retains time during AC mains interruption. Use Value: Enables deterministic event sequencing and audit-trail compliance per IEC 61131-3, with <±5.3 sec/month accuracy ensuring long-term log integrity without manual recalibration. |
Use Scenario: Storing hourly consumption data, tamper timestamps, and firmware update history in ANSI C12.22-compliant electricity meters. IC Role / Device Role / Timing Role: Battery-backed timekeeper and NVRAM storage for critical billing intervals and security logs - powered by onboard CR2032 during grid outages. Use Value: Guarantees >10-year data retention with 450 nA battery draw, meeting ANSI C12.19 Class 0.5 timekeeping requirements under –40 °C to +85 °C ambient conditions. |
| Medical Infusion Pump Scheduling | Building Automation System Clock |
|
Use Scenario: Managing drug delivery schedules, dose timers, and maintenance alerts in FDA-cleared infusion pumps operating in clinical environments. IC Role / Device Role / Timing Role: Fail-safe time source with automatic VCC/VBAT switchover - ensures uninterrupted therapy timing even during brief power loss or battery replacement. Use Value: Meets IEC 62304 Class C software safety requirements by preventing time discontinuity; BCD register format simplifies deterministic firmware parsing for ISO 13485 traceability. |
Use Scenario: Providing centralized time reference for HVAC scheduling, lighting control, and access logging across multi-floor commercial buildings. IC Role / Device Role / Timing Role: Low-power RTC node in BACnet MSTP or Modbus RTU gateways - synchronizes zone controllers and reports daylight-saving transitions. Use Value: Delivers ±2 ppm accuracy post-calibration to maintain schedule fidelity across seasonal temperature swings, reducing HVAC energy waste from timing drift. |
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 | 3-wire interface (I²C-compatible but no FT/OUT pin); no integrated oscillator load caps; higher battery current (600 nA). | Lacks built-in 1 Hz output and crystal tuning simplicity - requires external 12.5 pF caps and separate driver for time-pulse signaling. | Select if legacy DS13xx firmware reuse is prioritized over oscillator integration and lowest battery drain. |
| PCF8563T | Lower accuracy (±3 ppm uncalibrated); no software calibration register; 20-byte NVRAM only; no century bit support. | Suitable for cost-sensitive consumer devices where leap-year handling and long-term drift correction are non-critical. | Choose for basic timekeeping in white goods or IoT nodes where extended battery life and calendar precision are secondary to BOM cost. |
Compared with DS1337+T&R and PCF8563T, the M41T56MH6E uniquely combines on-die oscillator load capacitance, ±2 ppm calibrated accuracy, 56-byte NVRAM, and century-aware BCD calendar - making it optimal for industrial and medical systems demanding guaranteed time integrity across 10+ year deployments.
Availability
M41T56MH6E is available at Aetrix Electronics and suitable for industrial PLCs, smart energy meters, medical infusion pumps, and building automation systems requiring stable component supply with guaranteed long-term manufacturability.
Supply support for M41T56MH6E 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, specializing in automotive, industrial, and power management ICs with strong emphasis on reliability and longevity.
The M41T56MH6E belongs to ST's real-time clock product line, designed specifically for industrial and medical applications requiring extended battery life, wide temperature operation, and calendar accuracy without external trimming components.
FAQ
What is the function of the FT/OUT pin on the M41T56MH6E?
The FT/OUT pin is an open-drain output that can be configured via the control register to provide either a 1 Hz square wave or the raw 32.768 kHz oscillator signal. It serves as a diagnostic test point or timing reference for external circuitry such as LED blinkers or microcontroller wake-up sources, and requires an external pull-up resistor to operate.
How does the M41T56MH6E handle leap years and century rollovers?
The M41T56MH6E implements automatic leap-year calculation based on Gregorian calendar rules, including exclusion of non-leap centuries (e.g., 1900, 2100). The century enable bit (CEB) and century bit (CB) in the hours register allow explicit control of century rollover behavior - enabling seamless transition from year 2099 to 2100 when CEB is set.
Can the M41T56MH6E operate without an external crystal?
No - the M41T56MH6E requires an external 32.768 kHz tuning-fork crystal connected between OSCI and OSCO pins. However, its integrated 12.5 pF load capacitance eliminates the need for external load capacitors, simplifying design and improving oscillator stability across temperature and aging.
What happens during a power failure, and how fast does the switchover occur?
When VCC drops below the power-fail detect threshold (VPFD ≈ 4.25 V), the device immediately halts I²C communication, disables register writes, and switches to VBAT within 1 µs. All outputs go high-impedance, and the RTC continues running from battery with <450 nA current draw - ensuring zero time loss and data retention without interruption.
M41T56MH6E Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 28-SOP (0.350", 8.89mm Width) with SNAPHAT Sockets
- 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:
- 28-SOH
M41T56MH6E FAQ
1.How can I place an order for M41T56MH6E through Aetrix?
Please submit a Request for Quotation (RFQ) for M41T56MH6E 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 M41T56MH6E reliable?
The price and inventory of M41T56MH6E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M41T56MH6E is usually 5 days.
3.What payment methods are accepted for M41T56MH6E?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M41T56MH6E transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for M41T56MH6E?
M41T56MH6E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your M41T56MH6E 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 M41T56MH6E?
For technical support, including M41T56MH6E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M41T56MH6E requirements.
6.How does Aetrix verify that M41T56MH6E is sourced from the original manufacturer or authorized distributors?
All M41T56MH6E 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 M41T56MH6E meets industry standards.
7.What is the process for return or replacement of M41T56MH6E?
All M41T56MH6E units undergo pre-shipment inspection (PSI). If there is an issue with M41T56MH6E, 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 M41T56MH6E part is unused and in its original packaging.
Return procedure for M41T56MH6E:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
M41T56MH6E Tags
-
MCP7940N-I/SN
Microchip Technology
-
MCP7940MT-I/MNY
Microchip Technology
-
PCF85063ATL/1,118
NXP USA Inc.
-
MCP7940NT-I/SN
Microchip Technology
-
MCP7940NT-I/MS
Microchip Technology
-
MCP7940N-I/MS
Microchip Technology
-
PCF85063AT/AY
NXP USA Inc.
-
PCF85063TP/1Z
NXP Semiconductors
-
PCF85063ATT/AJ
NXP USA Inc.
-
MCP7940NT-E/SN
Microchip Technology
-
MCP7940NT-I/MNY
Microchip Technology
-
MCP79400T-I/SN
Microchip Technology
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