MX25L8005MI-12G 参数 Datasheet PDF下载

MX25L8005

(5) Write Status Register (WRSR)

The WRSR instruction is for changing the values of Status Register Bits. Before sending WRSR instruction, the Write

Enable (WREN) instruction must be decoded and executed to set the Write Enable Latch (WEL) bit in advance. The WRSR

instruction can change the value of Block Protect (BP2, BP1, BP0) bits to define the protected area of memory (as shown

in table 1). The WRSR also can set or reset the Status Register Write Disable (SRWD) bit in accordance with Write

Protection (WP#) pin signal. The WRSR instruction cannot be executed once the Hardware Protected Mode (HPM) is

entered.

The sequence of issuing WRSR instruction is: CS# goes low-> sending WRSR instruction code-> Status Register data

on SI-> CS# goes high. (see Figure 15)

The WRSR instruction has no effect on b6, b5, b1, b0 of the status register.

The CS# must go high exactly at the byte boundary; otherwise, the instruction will be rejected and not executed. The self-

timed Write Status Register cycle time (tW) is initiated as soon as Chip Select (CS#) goes high. The Write in Progress

(WIP) bit still can be check out during the Write Status Register cycle is in progress. The WIP sets 1 during the tW timing,

and sets 0 when Write Status Register Cycle is completed, and the Write Enable Latch (WEL) bit is reset.

Table 4. Protection Modes

Mode

Software protection

mode(SPM)

Status register condition

Status register can be written

in (WEL bit is set to "1") and

the SRWD, BP0-BP2

bits can be changed

WP# and SRWD bit status

WP#=1 and SRWD bit=0, or

WP#=0 and SRWD bit=0, or

WP#=1 and SRWD=1

Memory

The protected area cannot

be program or erase.

Hardware protection

mode (HPM)

The SRWD, BP0-BP2 of

status register bits cannot be

changed

WP#=0, SRWD bit=1

The protected area cannot

be program or erase.

Note:

1. As defined by the values in the Block Protect (BP2, BP1, BP0) bits of the Status Register, as shown in Table 1.

As the above table showing, the summary of the Software Protected Mode (SPM) and Hardware Protected Mode (HPM).

Software Protected Mode (SPM):

- When SRWD bit=0, no matter WP# is low or high, the WREN instruction may set the WEL bit and can change the values

of SRWD, BP2, BP1, BP0. The protected area, which is defined by BP2, BP1, BP0, is at software protected mode

(SPM).

- When SRWD bit=1 and WP# is high, the WREN instruction may set the WEL bit can change the values of SRWD, BP2,

BP1, BP0. The protected area, which is defined by BP2, BP1, BP0, is at software protected mode (SPM)

P/N: PM1237

12

REV. 2.2, OCT. 23, 2008