AT45DB021E datasheet(21/69 Pages) RENESAS

21 / 69 page

DS-AT45DB021E-8789 Rev. N

Page 21

3/24/26

AT45DB021E Datasheet

Sector Protection

Two protection methods, hardware and software controlled, are provided for protection against inadvertent or

erroneous program and erase cycles. The software controlled method relies on the use of software commands to

enable and disable sector protection while the hardware controlled method employs the use of the Write Protect

(WP) pin. The selection of which sectors that are to be protected or unprotected against program and erase

operations is specified in the nonvolatile Sector Protection Register. The status of whether or not sector protection

has been enabled or disabled by either the software or the hardware controlled methods can be determined by

checking the Status Register.

9.1

Software Sector Protection

Software controlled protection is useful in applications in which the WP pin is not or cannot be controlled by a host

processor. In such instances, the WP pin can be left floating (the WP pin is internally pulled high) and sector

protection can be controlled using the Enable Sector Protection and Disable Sector Protection commands.

If the device is power cycled, then the software controlled protection is disabled. Once the device is powered up,

the Enable Sector Protection command must be reissued if sector protection is desired and if the WP pin is not

used.

9.1.1

Enable Sector Protection

Sectors specified for protection in the Sector Protection Register can be protected from program and erase

operations by issuing the Enable Sector Protection command. To enable the sector protection, a 4-byte command

sequence of 3Dh, 2Ah, 7Fh, and A9h 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 enable the Sector Protection.

Table 5. Enable Sector Protection Command

Figure 5. Enable Sector Protection

9.1.2

Disable Sector Protection

To disable the sector protection, a 4-byte command sequence of 3Dh, 2Ah, 7Fh, and 9Ah 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 disable

the sector protection.

Figure 6. Disable Sector Protection

Command

Byte 1

Byte 2

Byte 3

Byte 4

Enable Sector Protection

3Dh

2Ah

7Fh

A9h

Table 6. Disable Sector Protection Command

Command

Byte 1

Byte 2

Byte 3

Byte 4

Disable Sector Protection

3Dh

2Ah

7Fh

9Ah

3Dh

2Ah

7Fh

A9h

Each transition represents eight bits

3Dh

2Ah

7Fh

9Ah

Each transition represents eight bits

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