M4T32-BR12SH STMICROELECTRONICS [STMicroelectronics], M4T32-BR12SH Datasheet - Page 4

• Manufacturer Part Number: M4T32-BR12SH
• Description: 5.0 OR 3.0V, 512 bit 64 x 8 SERIAL RTC and NVRAM SUPERVISOR
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

M41ST85Y, M41ST85W
SUMMARY DESCRIPTION
The M41ST85Y/W Serial TIMEKEEPER
troller SRAM is a low power 512-bit, static CMOS
SRAM organized as 64 words by 8 bits. A built-in
32.768 kHz oscillator (external crystal controlled)
and 8 bytes of the SRAM (see
are used for 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 two line, bi-directional I
built-in address register is incremented automati-
cally after each WRITE or READ data byte. The
M41ST85Y/W has a built-in power sense circuit
which detects power failures and automatically
switches to the battery supply when a power fail-
ure occurs. The energy needed to sustain the
SRAM and clock operations can be supplied by a
small lithium button-cell supply when a power fail-
ure occurs.
Functions available to the user include a non-vol-
atile, 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 loca-
tions 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.
4/34
Table 2., page
2
C interface. The
®
/Con-
14)
The M41ST85Y/W is supplied in a 28-lead SOIC
SNAPHAT
tal 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 SOIC and battery/crystal packages are
shipped separately in plastic anti-static tubes or in
Tape & Reel form. For the 28-lead SOIC, the bat-
tery/crystal package (e.g., SNAPHAT) part num-
ber
19., 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.
is
32).
®
package (which integrates both crys-
“M4TXX-BR12SH”
(see
Table