STMicroelectronics M41T62Q6F

Overview

M41T62Q6F from STMicroelectronics is an ultra-compact, low-power serial real-time clock (RTC) with integrated 32.768 kHz crystal in a 1.5 × 3.2 mm LCC8 package - no external oscillator components required. It delivers timekeeping down to 1.0 V, consumes only 350 nA at 3 V, supports I²C up to 400 kHz, and provides programmable alarm, 32 kHz square wave output (default on power-up), oscillator fail detection, and ±2 ppm software calibration - used in battery-backed IoT sensors and portable medical devices.

For engineers reviewing the M41T62Q6F datasheet, M41T62Q6F pinout, M41T62Q6F application, or M41T62Q6F equivalent, key selection criteria include embedded crystal integration, sub-1V timekeeping capability, open-drain IRQ/OUT interrupt pin behavior, and BCD-format calendar register mapping for deterministic firmware integration.

Technical Context

The M41T62Q6F implements a fully autonomous RTC subsystem with hardware-based leap-year compensation, automatic month-length correction (28–31 days), and a dedicated 16-byte memory-mapped register bank accessed via standard I²C slave address 0xD0h. Its oscillator stop detection circuit monitors 32.768 kHz oscillation integrity and asserts the OF flag when failure occurs.

Timekeeping data is stored in binary-coded decimal (BCD) across eight registers (00h–07h) covering tenths/hundredths of seconds through century; writes to any clock register halt the divider chain and freeze updates until completion, ensuring atomic time writes without race conditions during I²C transactions.

Key Specifications

Pinout & Package

Package: 1.5 × 3.2 mm, 8-pin ceramic leadless chip carrier (LCC8), ECOPACK2-compliant, with embedded 32.768 kHz crystal - no external load capacitors or crystal required.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS3231SN#T&R and PCF2129AATS/1, the M41T62Q6F uniquely combines embedded crystal, sub-1V operation, and 350 nA current in a 4.8 mm² LCC8 package - making it optimal for space-constrained, long-life battery systems where crystal placement and thermal drift are critical constraints.

Availability

M41T62Q6F is available at Aetrix Electronics and suitable for smart metering, portable medical monitoring, industrial sensor nodes, and asset tracking beacons requiring stable component supply across multi-year production cycles.

Supply support for M41T62Q6F 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, and precision analog ICs for industrial, automotive, and consumer markets.

The M41T62 series belongs to ST's low-power real-time clock product line, designed specifically for battery-critical applications demanding guaranteed timekeeping under brown-out, wide temperature, and minimal board area constraints.

FAQ

Does M41T62Q6F require external load capacitors for its embedded crystal?

No. The M41T62Q6F integrates precision load capacitors matched to its embedded 32.768 kHz crystal, eliminating all external components. This is confirmed in the DS3840 datasheet Section 1 ("ultra-small 1.5 x 3.2 mm LCC with embedded crystal – no external oscillator components required") and Figure 4 pinout notes ("XI/XO not bonded on LCC package").

How does the oscillator fail detection work, and can it trigger an interrupt?

Oscillator fail detection monitors the 32.768 kHz oscillator output and sets the OF (oscillator fail) bit in register 0Fh when oscillation stops. When OFIE (bit D7 of register 02h) is set to '1', this condition also asserts the IRQ/OUT pin low - providing hardware-level fault signaling without MCU polling.

What happens to the time registers during an I²C read sequence?

At the start of any I²C read, the RTC halts updates to the buffer/transfer registers, freezing the current time value. All bytes read (00h–07h) reflect the exact same instant - preventing inconsistent time reads due to mid-transfer counter increments. Updates resume after STOP condition.

Can the SQW output be disabled, and what is its default state on power-up?

Yes. The SQW output is enabled by default at power-up (32 kHz), and can be disabled by clearing the SQWE bit (D7 of register 0Ah). The output remains in high-impedance state when disabled, and resumes 32 kHz (or configured frequency) immediately upon re-enabling.