STMicroelectronics M41T83SQA6F

Overview

M41T83SQA6F from STMicroelectronics is a serial I²C real-time clock (RTC) with embedded 32.768 kHz crystal in QFN16 package, providing battery-backed timekeeping, dual alarms, watchdog timer, 8-bit counter/timer, and 7-byte SRAM. It delivers ±5 ppm factory-calibrated accuracy after two reflows, operates from 3.0 V to 5.5 V, and draws only 365 nA in battery backup mode - deployed in industrial control panels requiring long-term timestamp integrity during main power loss.

For engineers reviewing the M41T83SQA6F datasheet, M41T83SQA6F pinout, M41T83SQA6F application, or M41T83SQA6F equivalent, key selection criteria include ultra-low backup current, built-in analog/digital calibration, SQW output defaulting to 32 kHz on power-up, IRQ1/FT/OUT pin priority handling in backup mode, and SOX18 vs. QFN16 package trade-offs for board space versus crystal integration.

Technical Context

The M41T83SQA6F 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. Its I²C interface complies with 400 kHz Fast Mode timing, supports sequential read/write addressing, and includes automatic address incrementation across its 32-byte register map.

Power management integrates dual-voltage sensing: VSO (switchover) and VRST (reset) thresholds are fixed at 2.93 V (S-grade), enabling seamless transition to VBAT during brownout while asserting RST and maintaining timekeeping. The embedded crystal in SOX18 eliminates external load capacitor tuning, whereas QFN16 requires external 32.768 kHz crystal with programmable analog calibration (±12.5 pF range) and digital periodic correction (±127 ppm step).

Key Specifications

Pinout & Package

QFN16 (4 mm × 4 mm, 0.5 mm pitch) with wettable flanks; RoHS-compliant, lead-free termination. Exposed thermal pad connected to VSS for enhanced thermal dissipation in compact layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS3231M, M41T83SQA6F trades absolute temperature stability for ultra-low backup current and richer feature set (dual alarms, timer, SQW), while M41T82M6F offers pin-compatible simplification at the expense of integration and functionality - making M41T83SQA6F optimal for new designs prioritizing feature density and battery longevity in compact QFN layouts.

Availability

M41T83SQA6F is available at Aetrix Electronics and suitable for industrial data loggers, smart energy meters, medical infusion pumps, and building automation controllers requiring stable component supply with guaranteed long-term availability.

Supply support for M41T83SQA6F 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.

M41T83SQA6F belongs to the M41T8x RTC product line, engineered for high-accuracy, low-power timekeeping in space-constrained embedded systems where battery backup integrity and field-calibratable precision are mission-critical.

FAQ

What is the function of the DU pin on M41T83SQA6F?

The DU (Don't Use) pin must be tied to VCC and serves no functional purpose. Leaving it floating or connecting it to ground violates the datasheet requirement and may cause undefined behavior during power transitions. This pin exists solely for package compatibility with other variants in the M41T8x family and has no electrical connection internally.

Can the M41T83SQA6F operate without an external crystal?

Yes - the M41T83SQA6F in QFN16 package requires an external 32.768 kHz crystal connected between XI and XO pins, unlike the SOX18 variant which embeds the crystal. No crystal is needed for SOX18, but QFN16 will not oscillate without one. The crystal must meet specified load capacitance (12.5 pF programmable range) and drive-level limits per datasheet Section 22.

How does the battery switchover circuit respond during voltage droop?

The M41T83SQA6F monitors VCC against the fixed VSO threshold of 2.93 V (S-grade). When VCC falls below this level, the device automatically switches to VBAT within 1 µs, preserves all register contents including time and alarm states, and asserts RST if VCC drops below VRST (also 2.93 V). Switchover is seamless and does not require host intervention or register writes.

Is the 7-byte user SRAM accessible during battery-only operation?

Yes - the 7-byte battery-backed SRAM remains fully readable and writable while operating solely on VBAT, with no performance degradation. Data retention is guaranteed for 10+ years at +25 °C when powered by a fresh CR2032 cell, and the SRAM shares the same power domain and write-protection logic as the clock registers.