STMicroelectronics M41T83ZMY6E

Overview

M41T83ZMY6E from STMicroelectronics is a serial I²C real-time clock (RTC) with embedded 32.768 kHz crystal in an 18-lead SOIC package, supporting battery switchover, ±5 ppm factory-calibrated accuracy (SOX18), 2.38 V to 5.5 V operating voltage, and 7 bytes of battery-backed SRAM. It delivers timekeeping for industrial control panels requiring long-term timestamping under intermittent power.

For engineers reviewing the M41T83ZMY6E datasheet, M41T83ZMY6E pinout, M41T83ZMY6E application, or M41T83ZMY6E equivalent, key selection criteria include backup voltage threshold (2.32 V), ultra-low 365 nA battery current, programmable analog/digital calibration, dual alarm interrupt capability, and SQW output defaulting to 32 kHz on power-up.

Technical Context

The M41T83ZMY6E integrates a temperature-compensated oscillator with embedded crystal in SOX18 packaging, enabling autonomous timekeeping without external timing components. Its I²C interface operates at up to 400 kHz, and internal power-sense circuitry triggers automatic switchover to VBAT when VCC drops below 2.32 V (Z-grade).

It implements BCD-encoded calendar registers (century, year, month, date, day, hour, minute, second, tenths/hundredths), automatic leap-year correction, and dual independent alarms with interrupt outputs (IRQ1/OUT/FT and IRQ2). The device supports oscillator fail detection, watchdog timer, and an 8-bit programmable countdown timer with interrupt enable (TIE).

Key Specifications

Pinout & Package

Package: SOX18 (18-lead plastic small outline, 300 mils, embedded crystal, 11.61 mm × 7.62 mm).

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 M41T83ZMY6E uniquely balances embedded-crystal simplicity, ±5 ppm factory accuracy, and dual-alarm programmability - making it optimal for industrial controllers needing robust, low-BOM timekeeping without TCXO cost or quartz layout complexity.

Availability

M41T83ZMY6E is available at Aetrix Electronics and suitable for industrial data loggers, smart energy meters, building automation controllers, and medical infusion pumps requiring stable component supply across extended product lifecycles.

Supply support for M41T83ZMY6E 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 IoT markets.

The M41T83 series belongs to ST's precision real-time clock product line, designed specifically for industrial and metering applications demanding high accuracy, ultra-low power, and embedded timing autonomy without external crystals.

FAQ

What is the minimum VCC voltage that maintains RTC functionality before switchover to VBAT?

The M41T83ZMY6E initiates automatic battery switchover when VCC falls below 2.32 V (Z-grade threshold). Below this level, the device continues full RTC operation-including calendar updates, alarms, and SRAM retention-using only VBAT. This threshold is fixed and non-programmable, ensuring deterministic behavior during brownout conditions.

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

No. The SOX18 package integrates a factory-matched 32.768 kHz crystal with optimized internal load capacitance. External load capacitors are unnecessary and must not be added, as they would detune the oscillator and degrade accuracy. The analog calibration register (0x09) allows fine-tuning via programmable capacitance steps (12.5–22.5 pF) if needed post-assembly.

Can both alarms operate simultaneously while the device is in battery backup mode?

Yes. Both Alarm 1 (IRQ1/FT/OUT) and Alarm 2 (IRQ2) remain fully functional during battery backup mode. Each alarm generates an open-drain interrupt independently, and their enable bits (A1IE, A2IE), mask settings, and repeat modes (daily, weekday, etc.) are preserved across VCC loss. This enables dual-event scheduling-such as daily calibration and weekly diagnostics-even during extended mains outages.

Is the 7-byte user SRAM retained during power-on reset (POR)?

Yes. The 7-byte battery-backed SRAM retains all stored data across power-on reset events, VCC cycling, and transitions between main and battery power. Its contents are only lost if VBAT drops below 1.0 V or if the device undergoes an OTP programming cycle (SOX18 only). No software initialization is required to preserve SRAM integrity during normal POR sequences.