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M48T212VSH

3.3V TIMEKEEPER® supervisor

STMicroelectronics 

M48T212V

1

Description

Description

Caution:

The M48T212V is a self-contained device that includes 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 M48T212V via the E1CON and E2CON signals (see Table 3 on

page 10).

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 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 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 battery/crystal package (e.g., SNAPHAT)

part number is “M4TXX-BR12SH” (see Table 20 on page 33).

Do not place the SNAPHAT battery/crystal top in conductive foam, as this will drain the

lithium button-cell battery.

Figure 1. Logic diagram

VCC VCCSW

4

A0-A3

A

E

EX

W

G

WDI

RSTIN1

RSTIN2

M48T212V

8

DQ0-DQ7

IRQ/FT

RST

E1CON

E2CON

VOUT

VSS

AI03019

5/35

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