Summary

M41T256Y

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Summary

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.

built-in address register is incremented automatically after each WRITE or READ data byte.

The M41T256Y 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 SRAM and clock operations can be supplied by a lithium button-cell

supply when a power failure occurs. Functions available to the user include a non-volatile,

time-of-day clock/calendar, and power-on reset. The eight clock address locations contain

the year, month, date, day, hour, minute, second, and tenths/hundredths of seconds in 24-

hour BCD format. Corrections for 28, 29 (leap year - valid until year 2100), 30 and 31 day

months are made automatically. The first clock address location (7FF8h) stores the clock

software calibration settings as well as the write clock bit.

both crystal and battery in a single SNAPHAT top). The 44-pin, 330mil SOIC provides

sockets with gold-plated contacts at both ends for direct connection to a separate

SNAPHAT housing containing the battery and crystal. The unique design allows the

SNAPHAT battery/crystal package to be mounted on top of the SOIC package after the

completion of the surface-mount process.

Insertion of the SNAPHAT housing after reflow prevents potential battery and crystal

damage due to the high temperatures required for device surface-mounting. The SNAPHAT

housing is also keyed to prevent reverse insertion. The 44-pin SOIC and crystal/battery

packages are shipped separately in plastic, anti-static tubes or in Tape & Reel form. For the

44-lead SOIC, the battery/crystal package (e.g., SNAPHAT) part number is “M4Txx-

BR12SH” (see Table 14 on page 28).

Caution:

Do not place the SNAPHAT battery/crystal top in conductive foam, as this will drain the

lithium, button-cell battery.