M48T254V datasheet(3/24 Pages) STMICROELECTRONICS

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M48T254V

SUMMARY DESCRIPTION

The M48T254V TIMEKEEPER® RAM is a 2Mbit x

8 non-volatile static RAM and real time clock orga-

nized as 2,097,152 words by 8 bits. The special

BGA package provides a fully integrated battery

back-up memory and real time clock solution. In

the event of power instability or absence, a self-

contained battery maintains the timekeeping oper-

ation and provides power for a CMOS static RAM.

Control circuitry monitors VCC and invokes write

protection to prevent data corruption in the memo-

ry and RTC.

The clock keeps track of tenths/hundredths of sec-

onds, seconds, minutes, hours, day, date, month,

and year information. The last day of the month is

automatically adjusted for months with less than

31 days, including leap year correction.

The clock operates in one of two formats:

– a 12-hour mode with an AM/PM indicator; or

– a 24-hour mode

The M48T254V is a 168-ball PBGA module that in-

tegrates the RTC, the battery, and SRAM in one

package.

Figure 3. Logic Diagram

Table 1. Signal Names

AI04217

VCC

M48T254V

VSS

A0 – A20

DQ0 – DQ7

A0 - A20

Address Inputs

DQ0 - DQ7

Data Input/Output

Chip Enable

WRITE Enable Inputs

Output Enable

Battery Low Output (Open Drain)

No Connect

VCC

Supply Voltage

VSS

Ground

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