**Description** The M41T00 is a low power serial real time clock with a built-in 32.768 kHz oscillator (external crystal controlled). Eight bytes of the RAM are used for the clock/calendar function and are configured in binary coded decimal (BCD) format. Addresses and data are transferred serially via a two-line bidirectional bus. The built-in address register is incremented automatically after each WRITE or READ data byte.