STMicroelectronics M41T56C64MY6F

Overview

M41T56C64MY6F from STMicroelectronics is a serial real-time clock (RTC) with integrated 64 Kbit EEPROM and 56-byte NVRAM, operating at 4.5–5.5 V, –40 to 85°C, and featuring embedded 32.768 kHz crystal, I²C interface (100 kHz RTC / 400 kHz EEPROM), and ultra-low battery current of 450 nA. It serves as a timekeeping and nonvolatile data storage solution in industrial control panels requiring long-term timestamping and configuration retention.

For engineers reviewing the M41T56C64MY6F datasheet, M41T56C64MY6F pinout, M41T56C64MY6F application, or M41T56C64MY6F equivalent, this page delivers verified technical context, validated pin functions, confirmed timing accuracy (±5 ppm at 25°C), battery-backed operation behavior, and direct substitution guidance for legacy RTC+EEPROM integration.

Technical Context

The device integrates two independent I²C peripherals on a single die: an M41T56 RTC core with BCD-formatted calendar registers, automatic leap-year compensation, software calibration (stored at 1550h), and power-fail detection that triggers seamless VCC-to-VBAT switchover; and an M24C64 EEPROM with 8192 × 8-bit organization, 32-byte page write capability, and >1 million endurance cycles.

Its SOX18 package embeds a precision 32.768 kHz crystal with factory-trimmed calibration, enabling guaranteed ±3 ppm first-year drift and ±1 ppm/year aging after two SMT reflows. The FT/OUT pin provides programmable open-drain output for 1 Hz, alarm, or frequency test signals, while WC enables hardware write protection for EEPROM sectors.

Key Specifications

Pinout & Package

Package: 18-lead SOIC (SOX18), 300-mil width, with embedded 32.768 kHz crystal and RoHS-compliant ECOPACK® finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS1340Z+ and M41T81SMY6F, the M41T56C64MY6F uniquely combines timekeeping, battery-backed SRAM, and high-endurance EEPROM in one package - eliminating inter-chip timing skew, reducing I²C bus loading, and simplifying qualification for systems requiring both timestamping and secure parameter storage.

Availability

M41T56C64MY6F is available at Aetrix Electronics and suitable for industrial PLC HMIs, smart energy meters, medical infusion pumps, and building HVAC controllers requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for M41T56C64MY6F 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, analog ICs, MEMS, and power solutions for industrial, automotive, and consumer markets.

The M41T56C64 belongs to ST's serial RTC product line, engineered specifically for embedded systems needing highly reliable, low-power, integrated timekeeping and nonvolatile data storage without external crystals or discrete memory components.

FAQ

What is the function of the WC pin on M41T56C64MY6F?

The WC (Write Control) pin is an active-low hardware enable for EEPROM writes. When pulled low, it disables all EEPROM programming operations-including byte, page, and sequential writes-regardless of I²C commands sent. This provides fail-safe protection against unintended data corruption during power transients, firmware updates, or debugging sessions, and does not affect RTC or SRAM functionality.

How does the embedded crystal in the SOX18 package affect reflow soldering?

The SOX18 package embeds a 32.768 kHz crystal directly bonded to the die, requiring strict reflow profile adherence: peak temperature must not exceed 240°C for ≤150 seconds total thermal budget, with no infrared preheat or direct IR exposure. Exceeding these limits risks crystal fracture or frequency shift, invalidating the factory calibration and degrading long-term timing accuracy beyond ±5 ppm.

Can the FT/OUT pin generate a 1 Hz signal without external components?

Yes. The FT/OUT pin is a software-programmable open-drain output capable of generating a precise 1 Hz square wave directly from the internal 32.768 kHz oscillator divider chain. No external resistors or capacitors are needed - only a pull-up resistor (typically 4.7 kΩ to VCC) is required to establish logic-high level, making it ideal for driving LEDs, microcontroller interrupts, or external timing monitors.

What is the maximum endurance of the integrated EEPROM in M41T56C64MY6F?

The integrated 64 Kbit EEPROM (M24C64 core) is rated for more than 1 million erase/write cycles per memory location and guarantees greater than 40 years of data retention at 85°C. Endurance is maintained across the full industrial temperature range (–40 to 85°C), and self-timed write cycles prevent over-programming - enabling robust logging of infrequent but critical events like firmware updates or calibration adjustments.