Overview
The M41T81M6F is a low-power serial real-time clock (RTC) produced by STMicroelectronics. It features a built-in 32.768 kHz oscillator controlled by an external crystal and supports an I2C bus interface with a 400 kHz protocol. The device includes a non-volatile time-of-day clock/calendar, alarm interrupts, a watchdog timer, and a programmable square wave output. It is designed to operate with ultra-low battery supply current and automatic switchover to battery supply during power failures, making it suitable for applications requiring precise timekeeping and low power consumption.
Key Specifications
| Parameter | Value |
|---|---|
| Operating Voltage | 2.0 to 5.5 V |
| Battery Supply Current | 0.6 μA (typ at 3 V) |
| Oscillator Frequency | 32.768 kHz |
| Interface | I2C bus (400 kHz protocol) |
| Operating Temperature | –40 to 85 °C |
| Package Type | 8-pin SOIC |
| SRAM for Clock/Calendar | 8 bytes (BCD format) |
| Additional SRAM | 12 bytes (for alarm, watchdog, and square wave functions) |
| Watchdog Timer Range | 62.5 ms to 128 s |
Key Features
- Counters for tenths/hundredths of seconds, seconds, minutes, hours, day, date, month, year, and century in 24-hour BCD format.
- Automatic corrections for 28, 29 (leap year - valid until year 2100), 30, and 31 day months.
- Programmable alarm and interrupt function (valid even during battery backup mode).
- Accurate programmable watchdog timer (from 62.5 ms to 128 s).
- Software clock calibration to compensate for crystal deviation due to temperature.
- Ultra-low battery supply current.
- Automatic switchover and deselect circuitry for power failure detection.
- Power-down time stamp (HT bit) for determining time elapsed in battery backup.
- ECOPACK® package available.
Applications
The M41T81M6F is suitable for a variety of applications requiring precise timekeeping and low power consumption, such as:
- Embedded systems and IoT devices.
- Industrial automation and control systems.
- Medical devices and healthcare equipment.
- Consumer electronics, including smart home devices and wearables.
- Automotive systems, particularly those requiring reliable timekeeping during power cycles.
Q & A
- What is the operating voltage range of the M41T81M6F?
The operating voltage range is 2.0 to 5.5 V. - What is the typical battery supply current of the M41T81M6F?
The typical battery supply current is 0.6 μA at 3 V. - What type of interface does the M41T81M6F support?
The M41T81M6F supports an I2C bus interface with a 400 kHz protocol. - What is the operating temperature range of the M41T81M6F?
The operating temperature range is –40 to 85 °C. - What type of package is the M41T81M6F available in?
The M41T81M6F is available in an 8-pin SOIC package. - Does the M41T81M6F have automatic power failure detection and switchover?
Yes, it has a built-in power sense circuit that detects power failures and automatically switches to the battery supply. - Can the M41T81M6F be calibrated for crystal deviation due to temperature?
Yes, it supports software clock calibration to compensate for crystal deviation due to temperature. - What is the range of the programmable watchdog timer?
The programmable watchdog timer range is from 62.5 ms to 128 s. - Is the M41T81M6F RoHS compliant?
Yes, the M41T81M6F is RoHS compliant and available in ECOPACK® packages. - What additional functions does the M41T81M6F provide besides timekeeping?
Besides timekeeping, it provides programmable alarm and interrupt functions, a watchdog timer, and a programmable square wave output.
