Description
The M41T00S Serial Access TIMEKEEPER® SRAM is a low power serial RTC with a built in 32.768 kHz oscillator (external crystal controlled). Eight bytes of the SRAM (see Table 2 on page 13) 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 I2C interface. The built-in address register is incremented automatically after each WRITE or READ data byte.
The M41T00S has a built-in power sense circuit which detects power failures and automatically switches to the battery supply when a power failure occurs. The energy needed to sustain the clock operations can be supplied by a small lithium button supply when a power failure occurs. The eight clock address locations contain the century, year, month, date, day, hour, minute, and second in 24-hour BCD format. Corrections for 28, 29 (leap year - valid until year 2100), 30 and 31 day months are made automatically. The M41T00S is supplied in an 8-pin SOIC.

FEATUREs
■ 2.0 to 5.5 V clock operating voltage
■ Counters for seconds, minutes, hours, day, date, month, year, and century
■ Software clock calibration
■ Automatic switchover and deselect circuitry (fixed reference)
   – VCC = 2.7 to 5.5 V
     2.5V ≤ VPFD ≤ 2.7 V
■ Serial interface supports I2C bus (400 kHz protocol)
■ Low operating current of 300 µA
■ Oscillator stop detection
■ Battery or SuperCap™ backup
■ Operating temperature of –40 to 85°C
■ Ultra-low battery supply current of 1 µA