Serial I2C Bus RTC With Battery Switchover

The M41T82 M41T83 are low power serial I C Real-Time Clocks with a built-in 32.768kHz Oscillator (external crystal-controlled for the QFN16 and SO8 packages, embedded crystal for the SOX18 package). Eight bytes of the Register Map (see Table 2 on page 23) are used for the Clock calendar function and are configured in binary coded decimal (BCD) format. An additional 17 bytes of the Register Map provide status/control of the two Alarms, Watchdog, 8-bit Counter and Square Wave functions. An additional seven bytes are made available as user SRAM By STMicroelectronics