M41ST95WMH6TR STMICROELECTRONICS [STMicroelectronics], M41ST95WMH6TR Datasheet - Page 4

• Manufacturer Part Number: M41ST95WMH6TR
• Description: 5.0 or 3.0V, 512 bit (64 bit X 8) Serial RTC (SPI) SRAM and NVRAM Supervisor
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

M41ST95Y*, M41ST95W
SUMMARY DESCRIPTION
The M41ST95Y/W Serial TIMEKEEPER
is a low power, 512-bit static CMOS SRAM orga-
nized as 64 words by 8 bits. A built-in 32,768Hz
oscillator (external crystal controlled) and 8 bytes
of the SRAM (see
the clock/calendar function and are configured in
binary coded decimal (BCD) format.
An additional 12 bytes of RAM provide status/con-
trol of Alarm, Watchdog and Square Wave func-
tions. Addresses and data are transferred serially
via a serial SPI interface. The built-in address reg-
ister is incremented automatically after each
WRITE or READ data byte. The M41ST95Y/W
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 op-
erations can be supplied by a small lithium button-
cell supply when a power failure occurs. Functions
available to the user include a non-volatile, time-
of-day clock/calendar, Alarm interrupts, Watchdog
Timer and programmable Square Wave output.
Other features include a Power-On Reset as well
as two additional debounced inputs (RSTIN1 and
RSTIN2) which can also generate an output Reset
(RST). The eight clock address locations contain
the century, year, month, date, day, hour, minute,
second and tenths/hundredths of a second in 24
hour BCD format. Corrections for 28, 29 (leap year
- valid until year 2100), 30 and 31 day months are
made automatically.
4/35
Table 4., page
16) are used for
®
SRAM
The M41ST95Y/W is supplied in a 28-lead SOIC
SNAPHAT
crystal and battery in a single SNAPHAT top), or a
28-pin, 300mil SOIC package (MX) which includes
an embedded 32kHz crystal.
The 28-pin, 330mil SOIC provides sockets with
gold plated contacts at both ends for direct con-
nection to a separate SNAPHAT housing contain-
ing 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 sur-
face-mounting. The SNAPHAT housing is also
keyed to prevent reverse insertion.
The SNAPHAT SOIC and battery/crystal packag-
es are shipped separately in plastic anti-static
tubes or in Tape & Reel form. For the 28-lead SO-
IC, the battery/crystal package (e.g., SNAPHAT)
part number is “M4TXX-BR12SH” (see
20., page
Caution: Do not place the SNAPHAT battery/crys-
tal top in conductive foam, as this will drain the lith-
ium button-cell battery.
The 300mil, embedded crystal SOIC requires only
a user-supplied battery to provide non-volatile op-
eration.
33).
®
(MH) package (which integrates both
Table