AT45DB081E datasheet(28/79 Pages) DIALOG

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AT45DB081E

DS-AT45DB081E–028K–03-2021

effective in the prevention of accidental programming or erasing of the device. If 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 are

protected.

Table 8-6.

Erase Sector Protection Register Command

Figure 8-4. Erase Sector Protection Register

8.3.2

Program Sector Protection Register

Once the Sector Protection Register has been erased, it can be reprogrammed using the Program Sector

Protection Register command.

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

clocked into the device followed by sixteen bytes of data corresponding to Sectors 0 through 15. After the last bit of

the opcode sequence and data have been clocked in, the CS pin must be deasserted to initiate the internally self-

timed program cycle. Programming the Sector Protection Register takes a maximum time of tP. 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

erase cycle is done, then the contents of the Sector Protection Register cannot be guaranteed.

If the proper number of data bytes is not clocked in before the CS pin is deasserted, then the protection status of

the sectors corresponding to the bytes not clocked in cannot be guaranteed.

Example:

If only the first two bytes are clocked in instead of the complete sixteen bytes, then the protection status of

the last 14 sectors cannot be guaranteed. Furthermore, if more than sixteen bytes of data is clocked into the

device, then the data wraps back around to the beginning of the register. For instance, if seventeen bytes of

data are clocked in, then the seventeenth byte is stored at byte location 0 of the Sector Protection Register.

The data bytes clocked into the Sector Protection Register need to be valid values (0xh, 3xh, Cxh, and Fxh for

Sector 0a or Sector 0b, and 00h or FFh for other sectors) in order for the protection to function correctly. If a non-

valid value is clocked into a byte location of the Sector Protection Register, then the protection status of the sector

corresponding to that byte location cannot be guaranteed.

Example:

If a value of 17h is clocked into byte location 2 of the Sector Protection Register, then the protection status

of Sector 2 cannot be guaranteed.

The Sector Protection Register can be reprogrammed while the sector protection is enabled or disabled. Being

able to reprogram the Sector Protection Register with the sector protection enabled allows the user to temporarily

disable the sector protection to an individual sector rather than disabling sector protection completely.

The Program Sector Protection Register command uses Buffer 1 for processing. Therefore, the contents of Buffer

1 are altered from its previous state when this command is issued.

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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