M41T00 is a low power serial real-time clock with a built-in 32.768 kHz oscillator. It features counters for seconds, minutes, hours, day, month, years, and century, supports I2C bus (100 kHz protocol), operates at a clock voltage of 2.0 to 5.5 V, has an ultra low battery supply current of 0.8 µA, and includes automatic switchover and deselect circuitry, software clock calibration, and automatic leap year compensation.