M48Z08, M48Z18

4/16

Figure 4. Block Diagram

OPERATION MODES

The M48Z08/18 also has its own Power-fail Detect

circuit. The control circuitry constantly monitors

the single 5V supply for an out of tolerance condi-

protects the SRAM, providing a high degree of

data security in the midst of unpredictable system

low approximately 3V, the control circuitry con-

nects the battery which maintains data until valid

power returns.

Table 2. Operating Modes

1. See Table 10., page 12 for details.

AI01394

LITHIUM

CELL

VPFD

VCC

VSS

VOLTAGE SENSE

AND

SWITCHING

CIRCUITRY

8K x 8

SRAM ARRAY

A0-A12

DQ0-DQ7

E

W

G

POWER

Mode

E

G

W

DQ0-DQ7

Power

Deselect

4.75 to 5.5V

or

4.5 to 5.5V

X

X

High Z

Standby

WRITE

X

Active

READ

Active

READ

High Z

Active

Deselect

(1)

X

X

X

High Z

CMOS Standby

Deselect

X

X

X

High Z

Battery Back-up Mode