STMicroelectronics M41T83ZQA6F

Overview

M41T83ZQA6F from STMicroelectronics is a serial I²C real-time clock (RTC) with embedded 32.768 kHz crystal, ultra-low battery current (365 nA), factory-calibrated ±5 ppm accuracy (SOX18), and integrated power-fail switchover circuitry. It provides BCD-encoded century/year/month/date/hour/minute/second/tenths-hundredths-of-second counters, programmable alarm interrupts, watchdog timer, 8-bit counter/timer, and 7-byte battery-backed SRAM - deployed in industrial control panels requiring long-term timekeeping during AC loss.

For engineers reviewing the M41T83ZQA6F datasheet, M41T83ZQA6F pinout, M41T83ZQA6F application, or M41T83ZQA6F equivalent, key selection criteria include V_CC operating range (2.38–5.5 V), battery switchover threshold (2.32 V), I²C 400 kHz compliance, SQW output default (32 kHz), and SOX18 package integration of oscillator and crystal.

Technical Context

The M41T83ZQA6F implements a fully autonomous RTC subsystem with dual-alarm interrupt generation, oscillator fail detection, and automatic calendar correction for leap years and variable month lengths. Its internal 32.768 kHz oscillator uses an embedded crystal in the SOX18 package, eliminating external component count and layout sensitivity.

Power management includes a fixed-reference switchover circuit (V_SO = V_RST = 2.32 V), battery low flag, and halt bit (HT) for precise power-down timestamping. The I²C interface supports standard-mode (100 kHz) and fast-mode (400 kHz) operation with auto-incrementing address register and open-drain SDA/SCL drivers.

Key Specifications

Pinout & Package

QFN16 (4 mm × 4 mm) package with exposed thermal pad; lead-free, RoHS-compliant. Pin 1 marked by dot; pins 2–3 and 16–17 internally shorted per datasheet Figure 5.

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 M41T83ZQA6F uniquely balances ultra-low battery drain (365 nA), embedded crystal reliability, and integrated safety features (watchdog, oscillator fail detection) - making it optimal for industrial systems needing decade-long unattended operation with deterministic fault response.

Availability

M41T83ZQA6F is available at Aetrix Electronics and suitable for industrial PLC time stamping, smart energy meter logging, medical infusion pump scheduling, and building automation HVAC control requiring stable component supply across extended product lifecycles.

Supply support for M41T83ZQA6F 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 specializing in microcontrollers, power management, sensors, and timing solutions for industrial, automotive, and consumer markets.

The M41T83 series belongs to ST's precision real-time clock product line, engineered for systems demanding long-term timekeeping integrity, seamless power switchover, and minimal external component count in space-constrained industrial designs.

FAQ

What is the battery switchover voltage threshold for M41T83ZQA6F?

The M41T83ZQA6F uses a fixed-reference switchover circuit with V_SO = V_RST = 2.32 V (Z-grade). When V_CC falls below this threshold, the device automatically transfers operation to V_BAT without glitch or time loss, ensuring continuous RTC functionality during brownout conditions.

Does M41T83ZQA6F require an external crystal?

No. The M41T83ZQA6F is supplied in the SOX18 package, which integrates a factory-tuned 32.768 kHz crystal and matching load capacitors. This eliminates external crystal placement, layout sensitivity, and aging-related calibration drift - confirmed in ST's DocID012578 Rev 19, Section 1 and Figure 5.

How many bytes of user-accessible memory does M41T83ZQA6F provide?

The M41T83ZQA6F provides exactly 7 bytes of battery-backed SRAM, mapped to register addresses 26h–2Ch. These locations retain data during main power loss and are accessible via the same I²C interface used for clock registers - verified in Table 4 (M41T83 register map) and Section 3.6 of the datasheet.

Can the square wave output be disabled or reconfigured?

Yes. The SQW output defaults to 32 kHz on power-up but is fully programmable via the SQWE (square wave enable) bit and frequency select bits (RS0, RS1). Valid frequencies include 1 Hz, 1.024 kHz, 4.096 kHz, and 32.768 kHz - all generated from the internal oscillator without external components, as specified in Table 13 and Section 3.9.