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STMicroelectronics M41ST87YMX6
- Part No.:
- M41ST87YMX6
- Manufacturer:
- STMicroelectronics
- Category:
- Real Time Clocks
- Package:
- 28-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
M41ST87YMX6.pdf
- Description:
- IC RTC CLOCK/CALENDAR I2C 28SO
- Quantity:
- Payment:
- Shipping:
Inventory:4,653
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Product details
Overview
M41ST87YMX6 from STMicroelectronics is a secure serial real-time clock (RTC) and non-volatile RAM (NVRAM) supervisor with integrated tamper detection, 128 bytes of clearable user NVRAM, dual power-fail comparators (1.25 V reference), and embedded 32.768 kHz crystal in SOX28 package. It operates at 5.0 V or 3.3/3.0 V, supports 400 kHz I²C interface, delivers ultra-low battery current (500 nA typ), and provides microprocessor power-on reset, programmable watchdog timer, and timestamped tamper event logging.
For engineers reviewing the M41ST87YMX6 datasheet, M41ST87YMX6 pinout, M41ST87YMX6 application, or M41ST87YMX6 equivalent, this device serves as a tamper-protected timekeeping and memory supervision solution for industrial security systems, energy meters, and medical data loggers requiring battery-backed RTC integrity and secure memory wipe on intrusion.
Technical Context
The M41ST87YMX6 integrates a BCD-format TIMEKEEPER® core with counters for tenths/hundredths of seconds through century, automatic leap-year correction, and full-time 32 kHz square wave output. Its dual independent tamper inputs (TP1IN/TP2IN) support configurable sampling, polarity, and connect modes - including hardware RAM clear (TPCLR) triggered by tamper events.
It features two programmable power-fail comparators (PFI1/PFI2) with selectable thresholds (VPFD ≈ 4.63 V or 4.37 V depending on THS pin state), automatic switchover to VBAT during main supply loss, and battery low flag (VBL) monitoring. The embedded crystal in the SOX28 package eliminates external oscillator vulnerability and enables oscillator stop detection (OF bit).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| I²C Bus Speed | 400 kHz - Enables high-speed configuration and register access without timing bottlenecks in microcontroller-based systems. |
| Battery Supply Current | 500 nA (typ) - Ensures >10-year backup operation with standard CR2032 coin cell in low-power data loggers. |
| Power-Fail Thresholds | VPFD ≈ 4.63 V (THS = 1) or 4.37 V (THS = 0) - Matches 5 V system brown-out margins for deterministic switchover to battery. |
| Tamper Inputs | 2 independent, configurable (normally open/closed, edge/polarity, sampling rate) - Supports dual-point physical intrusion monitoring with timestamped event capture. |
| NVRAM Size | 128 bytes, clearable via TPCLR or software - Provides secure storage for encryption keys or calibration data erased on tamper detection. |
| Oscillator Accuracy | ±20 ppm over –40°C to +85°C (with embedded crystal) - Delivers <1.7 sec/month time drift in industrial environments without external calibration. |
| Reset Output | RST pin, open-drain, active-low - Directly interfaces with MCU reset input for reliable power-on and brown-out recovery. |
Pinout & Package
Package: SOX28 - 28-pin, 300-mil plastic small outline IC with embedded 32.768 kHz crystal; requires only external battery (VBAT) for full non-volatile operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC | Main supply voltage input | Accepts 5.0 V or 3.3/3.0 V; powers RTC, NVRAM, and logic; triggers automatic switchover to VBAT on drop below VPFD. |
| VBAT | Battery backup supply | Supplies RTC and SRAM during main power loss; enables continuous timekeeping and memory retention. |
| SCL / SDA | I²C serial interface | 400 kHz bidirectional bus for reading/writing TIMEKEEPER® registers, alarm settings, tamper flags, and NVRAM. |
| TP1IN / TP2IN | Tamper detection inputs | Independent, user-configurable inputs for mechanical switch or sensor monitoring; trigger timestamped event and optional RAM clear. |
| TPCLR | Tamper-induced RAM clear | Hardware signal that clears 128-byte NVRAM upon tamper event - available only in SOX28 package. |
| RST | Open-drain reset output | Asserts low during power-on or when PFI1/PFI2 detect failure; resets connected microcontroller or FPGA. |
| IRQ/OUT | Interrupt/output pin | Open-drain output for alarm, watchdog timeout, or tamper interrupt; configurable as general-purpose output. |
| SQW/FT | Square wave/frequency test | Programmable output (open-drain or CMOS) delivering 1 Hz, 32.768 kHz, or other divided frequencies for system timing sync. |
Key Features
| Feature | Design Value |
|---|---|
| Tamper event timestamping | Records exact time (down to hundredths of second) of each TP1IN/TP2IN activation - critical for forensic audit trails in security-critical devices. |
| Embedded crystal oscillator | 32.768 kHz crystal integrated into SOX28 package - eliminates PCB layout sensitivity, improves EMI immunity, and prevents external crystal tampering. |
| Dual power-fail comparators | Two independent 1.25 V reference comparators with selectable VPFD thresholds - supports redundant power monitoring or multi-rail supervision. |
| Clearable 128-byte NVRAM | User-accessible RAM erased via TPCLR hardware signal or software command - ensures sensitive data (keys, logs) is purged on physical breach. |
| Full-time 32 kHz output (F32k) | Dedicated open-drain 32.768 kHz output - supplies precise clock to external ADCs, sensors, or low-power MCUs without loading main SQW/FT pin. |
Applications
| Smart Energy Meter | Industrial PLC Controller |
|---|---|
|
Use Scenario: Long-term energy consumption logging with tamper-proof time stamping and secure storage of tariff schedules and metering registers. IC Role / Device Role / Timing Role: Secure RTC and NVRAM supervisor providing authenticated time-of-day, battery-backed memory, and hardware-triggered data wipe on enclosure breach. Use Value: Prevents revenue loss from clock manipulation or memory tampering; meets IEC 62056 and ANSI C12.1 security requirements. |
Use Scenario: Real-time scheduling and diagnostics in factory automation controllers where uptime and event sequencing are mission-critical. IC Role / Device Role / Timing Role: High-integrity time base and system supervisor managing watchdog timeouts, power-fail responses, and firmware update timestamps. Use Value: Guarantees deterministic reset behavior and accurate event logging across power cycles and brown-outs in harsh industrial environments. |
| Medical Data Logger | Secure Access Control Panel |
|
Use Scenario: Portable patient monitors recording vital signs with FDA-compliant audit trails and encrypted session keys stored in protected NVRAM. IC Role / Device Role / Timing Role: Tamper-detecting RTC ensuring chronological integrity of clinical data and triggering immediate key erasure on case opening. Use Value: Meets HIPAA and IEC 62304 traceability mandates by linking every data point to a cryptographically verifiable timestamp. |
Use Scenario: Physical access terminals requiring anti-tamper response, secure credential storage, and synchronized audit logs across distributed door controllers. IC Role / Device Role / Timing Role: Dual-tamper-input supervisor enabling simultaneous monitoring of enclosure and battery compartment, with timestamped event logging. Use Value: Detects and records both physical intrusion and battery removal attempts - essential for UL 294 and EN 50133 compliance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar secure RTC and NVRAM supervision applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS3231SN#T&R | Higher accuracy (±2 ppm), integrated TCXO, no embedded crystal in SO package; lacks dual tamper inputs and TPCLR hardware clear. | Preferred for precision timing where tamper detection is handled externally; not suitable for systems requiring hardware-enforced NVRAM wipe. | Select DS3231 if absolute time accuracy dominates over tamper-response speed and memory security. |
| MCP7941T-I/SN | Single tamper input, no TPCLR pin, lower battery current (200 nA), no power-fail comparators; uses external crystal. | Targeted at cost-sensitive consumer IoT; insufficient for dual-point intrusion monitoring or regulated industrial security use cases. | Choose MCP7941T only for basic RTC + single tamper alert in non-regulated applications with tight power budgets. |
Compared with DS3231SN and MCP7941T-I/SN, the M41ST87YMX6 uniquely combines dual independently configurable tamper inputs, hardware RAM clear (TPCLR), embedded crystal, and dual power-fail comparators - making it the only option meeting EN 50133 Level 2 and UL 294 physical security requirements out-of-the-box.
Availability
M41ST87YMX6 is available at Aetrix Electronics and suitable for smart energy meters, industrial PLC controllers, medical data loggers, and secure access control panels requiring stable component supply, long-term lifecycle support, and certified tamper resilience.
Supply support for M41ST87YMX6 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 secure ICs for industrial, automotive, and embedded markets.
The M41ST87YMX6 belongs to ST's TIMEKEEPER® secure RTC product line, engineered specifically for applications demanding cryptographic-grade time integrity, physical intrusion detection, and guaranteed memory protection under battery backup conditions.
FAQ
What is the function of the TPCLR pin on M41ST87YMX6?
The TPCLR pin is a dedicated hardware signal that initiates immediate clearing of the 128-byte user NVRAM upon assertion - triggered by a tamper event detected on TP1IN or TP2IN. This feature is exclusive to the SOX28 package and operates independently of software control, ensuring irreversible data erasure even if firmware is compromised.
Does M41ST87YMX6 support both 3.3 V and 5.0 V operation simultaneously?
No - the M41ST87YMX6 operates at either 5.0 V or 3.3/3.0 V, selected at power-up based on VCC level and THS pin state. It does not support dual-supply operation. When VCC is 4.75–5.5 V, it configures for 5 V mode (VPFD ≈ 4.63 V or 4.37 V); at 2.7–3.6 V, it enters 3.3/3.0 V mode (VPFD ≈ 2.9 V or 2.63 V).
How is oscillator accuracy maintained with the embedded crystal?
The embedded 32.768 kHz crystal is factory-trimmed and hermetically sealed within the SOX28 package, achieving ±20 ppm stability over –40°C to +85°C. No external load capacitors are required, and oscillator stop detection (OF bit) alerts firmware if crystal oscillation fails - eliminating manual calibration or external compensation circuits.
Can the M41ST87YMX6 generate a 1 Hz square wave output?
Yes - the SQW/FT pin can be programmed via I²C to output 1 Hz, 32.768 kHz, or other divided frequencies (e.g., 1024 Hz, 4.096 kHz). The F32k pin provides a dedicated, always-on 32.768 kHz open-drain output, while SQW/FT supports dynamic frequency selection and interrupt generation for alarm or watchdog events.
M41ST87YMX6 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 28-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Clock/Calendar
- Features:
- Alarm, Leap Year, NVSRAM, Square Wave Output, Supervisor, Watchdog Timer
- Memory Size:
- 128B
- Time Format:
- HH:MM:SS:hh (24 hr)
- Date Format:
- YY-MM-DD-dd
- Interface:
- I2C, 2-Wire Serial
- Voltage - Supply:
- 4.5V ~ 5.5V
- Voltage - Supply, Battery:
- 2.5V ~ 5.5V
- Current - Timekeeping (Max):
- 1mA @ 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 28-SO
M41ST87YMX6 FAQ
1.How can I place an order for M41ST87YMX6 through Aetrix?
Please submit a Request for Quotation (RFQ) for M41ST87YMX6 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 M41ST87YMX6 reliable?
The price and inventory of M41ST87YMX6 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M41ST87YMX6 is usually 5 days.
3.What payment methods are accepted for M41ST87YMX6?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M41ST87YMX6 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for M41ST87YMX6?
M41ST87YMX6 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your M41ST87YMX6 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 M41ST87YMX6?
For technical support, including M41ST87YMX6 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M41ST87YMX6 requirements.
6.How does Aetrix verify that M41ST87YMX6 is sourced from the original manufacturer or authorized distributors?
All M41ST87YMX6 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 M41ST87YMX6 meets industry standards.
7.What is the process for return or replacement of M41ST87YMX6?
All M41ST87YMX6 units undergo pre-shipment inspection (PSI). If there is an issue with M41ST87YMX6, 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 M41ST87YMX6 part is unused and in its original packaging.
Return procedure for M41ST87YMX6:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
M41ST87YMX6 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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