Description
The M41T80 is a low power serial RTC with a built-in 32.768 kHz oscillator (external crystal controlled). Eight registers (see Table 3: Clock register map on page 14) are used for the clock/calendar function and are configured in binary coded decimal (BCD) format. An additional 12 registers provide status/control of alarm, 32 KHz output, and square wave functions. Addresses and data are transferred serially via a two line, bi-directional I2C interface. The built-in address register is incremented automatically after each WRITE or READ data byte.
   
Features
■ 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)
■ 2.0 to 5.5 V clock operating voltage
■ 32 KHz square wave on power-up to drive a
    microcontroller in low-power mode
■ Programmable (1 Hz to 32 KHz) square wave
■ Programmable alarm and interrupt function
■ Low operating current of 200 µA
■ Operating temperature of –40 to 85 °C
■ ECOPACK® package available