M41ST84WMH ST Microelectronics, M41ST84WMH Datasheet - Page 4

• Manufacturer Part Number: M41ST84WMH
• Description: 5.0 or 3.0V / 512 bit 64 x 8 SERIAL RTC with SUPERVISORY FUNCTIONS
• Manufacturer: ST Microelectronics

M41ST84Y, M41ST84W
SUMMARY DESCRIPTION
The M41ST84Y/W Serial supervisory TIMEKEEP-
ER
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 Table 9, page 16)
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 I2C interface. The
built-in address register is incremented automati-
cally after each WRITE or READ data byte.
The M41ST84Y/W has a built-in power sense cir-
cuit which detects power failures and automatical-
ly 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
small lithium button-cell supply when a power fail-
ure 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 an additional input
(RSTIN) 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
Figure 3. Logic Diagram
Note: 1. For SO16 package only.
4/31
®
RSTIN
XO
SRAM is a low power 512-bit static CMOS
SDA
XI
SCL
WDI
PFI
(1)
(1)
V CC
M41ST84W
M41ST84Y
V SS
V BAT
(1)
RST
IRQ/FT/OUT
SQW
PFO
AI03677
hour BCD format. Corrections for 28, 29 (leap year
- valid until year 2100), 30 and 31 day months are
made automatically.
The M41ST84Y/W is supplied in a 28-lead SOIC
SNAPHAT
tal and battery in a single SNAPHAT top) or a 16-
pin SOIC. The 28-pin, 330mil SOIC provides sock-
ets with gold plated contacts at both ends for direct
connection to a separate SNAPHAT housing con-
taining 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
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 28-pin 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 is “M4TXX-BR12SH” (see Table 20, page 29).
Caution: Do not place the SNAPHAT battery/crys-
tal top in conductive foam, as this will drain the lith-
ium button-cell battery.
Table 1. Signal Names
Note: 1. For SO16 package only.
XI
XO
IRQ/FT/OUT
PFI
PFO
RST
RSTIN
SCL
SDA
SQW
WDI
V
V
V
CC
BAT
SS
(1)
(1)
(1)
®
package (which integrates both crys-
Oscillator Input
Oscillator Output
Interrupt/Frequency Test/Out
Output (Open Drain)
Power Fail Input
Power Fail Output
Reset Output (Open Drain)
Reset Input
Serial Clock Input
Serial Data Input/Output
Square Wave Output
Watchdog Input
Supply Voltage
Battery Supply Voltage
Ground
surface
mount process.