Summary
The M41T256Y Serial TIMEKEEPER® SRAM is a low power 256Kbit static CMOS SRAM organized as 32K words by 8 bits. A built-in 32.768kHz oscillator (external crystal controlled) and 8 bytes of the SRAM (see Table 3 on page 18) are used for the clock/calendar function and are configured in binary coded decimal (BCD) format.

FEATUREs
■ 5V operating voltage
■ Serial interface supports extended I2C bus addressing (400kHz)
■ Automatic switchover and deselect circuitry
■ Power-fail deselect voltages:
   – M41T256Y: VCC = 4.5 V to 5.5V;
      VPFD = 4.2V < VPFD < 4.5V
■ Counters for tenths/hundredths of seconds, seconds, minutes, hours, day, date, month, and year
■ Programmable software clock calibration
■ 32,752 bytes of general purpose RAM
■ Microprocessor power-on reset
■ Holds microprocessor in reset until supply voltage reaches stable operating level
■ Automatic address-incrementing
■ Tamper indication circuit with time-stamp
■ Sleep mode function
■ Available in ST’s 44-lead SNAPHAT® SOIC - mates with ST’s removable/replaceable SNAPHAT® battery/crystal top (ordered separately)
■ RoHS compliant
   – Lead-free second level interconnect