Summary description
The M41T80 is a low power Serial RTC with a built-in 32.768kHz 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, 32kHz 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.
   
Feature summary
■ Counters for tenths/hundredths of seconds,
    seconds, minutes, hours, day, date, month,
    year, and century
■ 32KHz crystal oscillator integrating load
    capacitance (12.5pF) providing exceptional
    oscillator stability and high crystal series
    resistance operation
■ Serial interface supports I2C bus (400kHz)
■ 2.0 to 5.5V clock operating voltage
■ 32KHz square wave on power-up to drive a
    microcontroller in low power mode
■ Programmable (1Hz to 32KHz) square wave
■ Programmable Alarm and Interrupt function
■ Low operating current of 200µA
■ Operating temperature of –40 to 85°C
■ ECOPACK® package available