AT45DB081E-MHN2B-T View Datasheet(PDF) - Unspecified
Part Name
Description
MFG CO.
AT45DB081E-MHN2B-T
Unspecified
'AT45DB081E-MHN2B-T' PDF : 69 Pages View PDF
Figure 7-4. Erase Sector Protection Register
CS
SI
3Dh
2Ah
7Fh
CFh
Each transition represents eight bits
7.3.2
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 4-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. The programming of the Sector Protection Register should take place in a maximum time of tP. During this time,
the RDY/BUSY bit in the Status Register will indicate 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.
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 will wrap back around to the beginning of the register. For instance, if seventeen bytes
of data are clocked in, then the seventeenth byte will be 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 utilizes Buffer 1 for processing. Therefore, the contents of Buffer 1
will be altered from its previous state when this command is issued.
Table 7-7. Program Sector Protection Register Command
Command
Program Sector Protection Register
Byte 1
3Dh
Byte 2
2Ah
Byte 3
7Fh
Byte 4
FCh
AT45DB081E [PRELIMINARY DATASHEET] 21
DS-45DB081E-028C–DFLASH–10/2013
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