The M41T81M6E is a low-power serial RTC with a built-in 32.768 kHz oscillator (external crystal controlled). Eight bytes of the SRAM are used for the clock/calendar function and are configured in binary-coded decimal (BCD) format.
M41T81M6E Features
For all new designs use M41T81S
Counters for tenths/hundredths of seconds, seconds, minutes, hours, days, dates, months, years, 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) allows 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 for crystal deviation due to temperature