25LC320

DS21158B-page 6

Preliminary

© 1996 Microchip Technology Inc.

FIGURE 2-1: WRITE TO STATUS REGISTER AND/OR ARRAY FLOWCHART

CS Returns High

Continue

WEL = 1?

WEL = 1?

WP is low?

WPEN = 1?

Write

Write to

Status Register

Do not write to

Status Register

Write to the

Unprotected Block

Do not write to

Array

No

No

No

No

Yes

Yes

Yes

Yes

No

Yes

No

Yes

To other

Commands

From other

Commands

Write

to Status

Reg?

to array?

2.3

Write Status Register (WRSR)

The WRSR instruction allows the user to select one of

four protection options for the array by writing to the

appropriate bits in the status register. The array is

divided up into four segments. The user has the ability

to write protect none, one, two, or all four of the seg-

ments of the array. The partitioning is controlled as illus-

trated in Table 2-3.

See Figure 3-6 for WRSR timing sequence.

TABLE 2-3:

ARRAY PROTECTION

BP1

BP0

Array Addresses

Write Protected

0

0

none

0

1

upper 1/4

0C00h - 0FFFh

1

0

upper 1/2

0800h - 0FFFh

1

1

all

0000h - 0FFFh