M48T212V datasheet(4/32 Pages) STMICROELECTRONICS

4 / 32 page

M48T212Y, M48T212V

4/32

DESCRIPTION

The M48T212Y/V are self-contained devices that

include a real time clock (RTC), programmable

alarms, a watchdog timer, and two external chip

enable outputs which provide control of up to four

(two in parallel) external low-power static RAMs.

Access to all TIMEKEEPER® functions and the

external RAM is the same as conventional byte-

wide SRAM. The 16 TIMEKEEPER Registers offer

Century, Year, Month, Date, Day, Hour, Minute,

Second, Calibration, Alarm, Watchdog, and Flags.

Externally attached static RAMs are controlled by

the M48T212Y/V via the E1CON and E2CON sig-

nals (see Table 3., page 8).

The 44-pin, 330mil SOIC provides sockets with

gold plated contacts at both ends for direct con-

nection to a separate SNAPHAT® housing con-

taining the battery and crystal. The unique design

allows the SNAPHAT battery 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 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-44 lead SOIC, the bat-

tery/crystal package (e.g., SNAPHAT) part num-

ber

“M4TXX-BR12SH”

(see

Table

20., page 30).

Caution: Do not place the SNAPHAT battery/crys-

tal top in conductive foam, as this will drain the lith-

ium button-cell battery.

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