M41T256YMT7 STMicroelectronics, M41T256YMT7 Datasheet - Page 6

• Manufacturer Part Number: M41T256YMT7
• Description: Real Time Clock Serial 256K (32Kx8)
• Manufacturer: STMicroelectronics

Specifications of M41T256YMT7

• Function: Clock, Calendar
• Rtc Memory Size: 32768 B
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 4.5 V
• Maximum Operating Temperature: + 70 C
• Minimum Operating Temperature: - 25 C
• Mounting Style: SMD/SMT
• Rtc Bus Interface: Serial
• Package / Case: SO-44
• Time Format: HH:MM:SS:hh
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

1
Caution:
6/30
Summary
The M41T256Y Serial TIMEKEEPER
organized as 32K words by 8 bits. A built-in 32.768kHz oscillator (external crystal controlled)
and 8 bytes of the SRAM (see
and are configured in binary coded decimal (BCD) format.
Addresses and data are transferred serially via a two line, bi-directional I
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.
The M41T256Y is supplied in a 44-lead SOIC SNAPHAT
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
Do not place the SNAPHAT battery/crystal top in conductive foam, as this will drain the
lithium, button-cell battery.
Table 14 on page
Table 3 on page
28).
®
SRAM is a low power 256Kbit static CMOS SRAM
18) are used for the clock/calendar function
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package (MH - which integrates
2
C interface. The