Description
The M41T81 is a low-power serial RTC with a built-in 32.768 kHz oscillator (external crystal controlled).
   
Features
• For all new designs use M41T81S
• Counters for tenths/hundredths of seconds,
    seconds, minutes, hours, day, date, month,
    year, and century
• 32 KHz crystal oscillator integrating load
    capacitance (12.5 pF) providing exceptional
    oscillator stability and high crystal series
    resistance operation
• Serial interface supports I2C bus (400 kHz
    protocol)
• Ultra-low battery supply current of 0.6 ΜA
    (typ at 3 V)
• 2.0 to 5.5 V clock operating voltage
• Automatic switchover and deselect circuitry (for
    3 V application select M41T81S datasheet)
• Power-down time stamp (HT bit) allowing
    determination of time elapsed in battery
    backup
• 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
    crystal deviation due to temperature
• Operating temperature of –40 to 85 °C
• ECOPACK® package available