1/20

PRELIMINARY DATA

March 2000

This is preliminary information on a new product now in development or undergoing evaluation. Details are subject to change without notice.

M48T212A

s

CONVERTS LOW POWER SRAM into

NVRAMs

s

YEAR 2000 COMPLIANT (4-Digit Year)

s

USES SUPER CAPACITOR or LITHIUM

BATTERY (User Supplied)

s

BATTERY LOW FLAG

s

INTEGRATED REAL TIME CLOCK,

POWER-FAIL CONTROL CIRCUIT

s

AUTOMATIC POWER-FAIL CHIP DESELECT

and WRITE PROTECTION

s

WATCHDOG TIMER

s

WRITE PROTECT VOLTAGES

– M48T212A: 2.7V

s

MICROPROCESSOR POWER-ON RESET

s

PROGRAMMABLE ALARM OUTPUT ACTIVE

in the BATTERY BACKED-UP MODE

DESCRIPTION

The M48T212A is a self-contained device that in-

cludes 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.

A built-in 32.768 kHz oscillator (external crystal

controlled) is used for the clock/calendar function.

Access to all TIMEKEEPER functions and the ex-

ternal RAM is the same as conventional byte-wide

SRAM. The 16 TIMEKEEPER Registers offer

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

Second, Control, Calibration, Alarm, Watchdog,

and Flags. Externally attached static RAMs are

Automatic backup and write protection for an ex-

voltage specifications, for both the controller chip

and external SRAM chosen, are similar).

Figure 1. Logic Diagram

AI03047

4

A0-A3

A

DQ0-DQ7

VCC

M48T212A

G

VSS

8

EX

E2CON

E1CON

W

RSTIN2

RSTIN1

RST

IRQ/FT

VOUT

WDI

E

VCAP

X0

XI

VCCSW

VBAT–

SOH44 (MH)

44

1