Operation modes

M48T35AV

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2.5V, an internal Battery Not OK (BOK) flag will be set. The BOK flag can be checked after

power up. If the BOK flag is set, the first WRITE attempted will be blocked. The flag is

automatically cleared after the first WRITE, and normal RAM operation resumes. Figure 8

illustrates how a BOK check routine could be structured.

For more information on Battery Storage Life refer to the Application Note AN1012.

Figure 8.

Checking the BOK flag status

READ DATA

AT ANY ADDRESS

AI00607

IS DATA

COMPLEMENT

OF FIRST

READ?

(BATTERY OK)

POWER-UP

YES

NO

WRITE DATA

COMPLEMENT BACK

TO SAME ADDRESS

READ DATA

AT SAME

ADDRESS AGAIN

NOTIFY SYSTEM

OF LOW BATTERY

(DATA MAY BE

CORRUPTED)

WRITE ORIGINAL

DATA BACK TO

SAME ADDRESS

(BATTERY LOW)

CONTINUE