STMicroelectronics M41T83ZMY6F

Overview

M41T83ZMY6F from STMicroelectronics is a serial I²C real-time clock (RTC) with embedded 32.768 kHz crystal in SOX18 package, supporting battery switchover at VCC down to 2.38 V, ±5 ppm factory-calibrated accuracy (SOX18), and ultra-low 365 nA battery supply current. It integrates alarm interrupts, watchdog timer, 8-bit counter/timer, 32 kHz square wave output, and 7 bytes of battery-backed SRAM for industrial timekeeping in power-constrained systems.

For engineers reviewing the M41T83ZMY6F datasheet, M41T83ZMY6F pinout, M41T83ZMY6F application, or M41T83ZMY6F equivalent, key selection criteria include backup voltage threshold (2.38 V), embedded crystal integration (eliminating external XTAL layout), I²C 400 kHz timing compliance, and dual-alarm interrupt capability with battery-mode validity.

Technical Context

The M41T83ZMY6F implements a fully autonomous RTC core with BCD-encoded calendar registers (century, year, month, date, day, hour, minute, second, tenths/hundredths), automatic leap-year correction, and oscillator fail detection circuitry. Its power-sense architecture triggers seamless VCC-to-VBAT switchover at 2.32 V (Z-grade), maintaining timekeeping without interruption.

It features dual programmable alarms (IRQ1/IRQ2), a 32 kHz square wave output (SQW) defaulting on power-up, and a dedicated open-drain RST output with power-on reset timing (t_rec). The device supports digital and analog calibration-digital via periodic counter correction, analog via programmable load capacitance-to achieve <±5 ppm accuracy after reflow.

Key Specifications

Pinout & Package

Package: SOX18 (18-lead plastic small outline, 300 mil, embedded crystal, 11.61 mm × 7.62 mm). Pin functions validated per STMicroelectronics DocID012578 Rev 19, Figure 5 and Table 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS3231SN#T&R and PCF8563T/2,118, the M41T83ZMY6F uniquely combines embedded crystal integration, ultra-low 365 nA battery draw, dual alarms with backup-mode validity, and factory-trimmed ±5 ppm accuracy - making it optimal for space-constrained, long-life industrial designs where layout simplicity and guaranteed timing performance are critical.

Availability

M41T83ZMY6F is available at Aetrix Electronics and suitable for industrial PLC time stamping, smart meter data logging, medical infusion pump scheduling, and building automation HVAC scheduler applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for M41T83ZMY6F 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 microcontrollers, power management, sensors, and timing solutions for industrial, automotive, and consumer markets.

The M41T8x series was designed specifically for robust, low-power real-time clocking in harsh industrial environments - emphasizing battery longevity, embedded crystal reliability, and seamless power-fail resilience without external components.

FAQ

What is the minimum VCC voltage that triggers automatic battery switchover?

The M41T83ZMY6F switches to VBAT when VCC falls to 2.32 V (VSO/V_RST threshold for Z-grade). This value is fixed and non-adjustable, ensuring deterministic handover before host MCU brownout. The switchover occurs within 1 µs and preserves all register contents and timekeeping continuity.

Does the embedded crystal in the SOX18 package require external load capacitors?

No. The SOX18 package integrates a factory-tuned 32.768 kHz crystal with matched internal load capacitance. External load capacitors are neither required nor recommended. Adding them would detune the oscillator and degrade accuracy, violating the ±5 ppm factory calibration.

Can both alarm interrupts operate while the device is running on battery backup?

Yes. Both IRQ1 and IRQ2 remain fully functional during battery backup mode. Alarm registers retain their programmed values, and interrupt generation continues without interruption - enabling time-critical actions (e.g., safety shutdown, data save) even during main power loss.

What is the purpose of the DU pin, and how must it be connected?

The DU (Device Usage) pin must be hard-wired to VCC. It enables internal bias circuitry for stable oscillator operation and disables an alternate regulator path. Leaving DU floating or connecting it to VSS will cause erratic timekeeping or complete oscillator failure - per STMicroelectronics design requirement AI11198 footnote 3.