AT45DB321E datasheet(30/80 Pages) RENESAS

30 / 80 page

DS-AT45DB321E-8784 Rev. N

Page 30

9/1/23

AT45DB321E Datasheet

7.16.1

Erase Sector Protection Register

In order to modify and change the values of the Sector Protection Register, it must first be erased using the Erase

Sector Protection Register command.

To erase the Sector Protection Register, a four-byte command sequence of 3Dh, 2Ah, 7Fh, and CFh must be

clocked into the device. After the last bit of the opcode sequence has been clocked in, the CS pin must be

deasserted to initiate the internally self-timed erase cycle. The erasing of the Sector Protection Register takes

place in a maximum time of tPE. During this time, the RDY/BUSY bit in the Status Register indicates that the

device is busy. If the device is powered-down before the completion of the erase cycle, then the contents of the

Sector Protection Register cannot be guaranteed.

The Sector Protection Register can be erased with sector protection enabled or disabled. Since the erased state

(FFh) of each byte in the Sector Protection Register is used to indicate that a sector is specified for protection,

leaving the sector protection enabled during the erasing of the register allows the protection scheme to be more

effective in the prevention of accidental programming or erasing of the device. If for some reason an erroneous

program or erase command is sent to the device immediately after erasing the Sector Protection Register and

before the register can be reprogrammed, then the erroneous program or erase command is not processed

because all sectors would be protected.

Table 11. Erase Sector Protection Register Command

Figure 8. Erase Sector Protection Register

Command

Byte 1

Byte 2

Byte 3

Byte 4

Erase Sector Protection Register

3Dh

2Ah

7Fh

CFh

3Dh

2Ah

7Fh

CFh

Each transition represents eight bits

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