AT45DB021E datasheet(22/74 Pages) DIALOG

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AT45DB021E

DS-AT45DB021E—8789J—03/2021

8.1.2

Disable Sector Protection

To disable the sector protection, a four-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.

Table 8-2.

Disable Sector Protection Command

Figure 8-2. Disable Sector Protection Timing

8.2

Hardware Controlled Protection

Sectors specified for protection in the Sector Protection Register and the Sector Protection Register itself can be

protected from program and erase operations by asserting the WP pin and keeping the pin in its asserted state.

The Sector Protection Register and any sector specified for protection cannot be erased or programmed as long as

the WP pin is asserted. In order to modify the Sector Protection Register, the WP pin must be deasserted. If the

WP pin is permanently connected to GND, then the contents of the Sector Protection Register cannot be changed.

If the WP pin is deasserted or permanently connected to VCC, then the contents of the Sector Protection Register

can be modified.

The WP pin overrides the software controlled protection method, but only for protecting the sectors.

Example:

If the sectors are not previously protected by the Enable Sector Protection command, then asserting the WP

pin enables the sector protection within the maximum specified tWPE time. When the WP pin is deasserted,

however, the sector protection is no longer enabled (after the maximum specified tWPD time) as long as the

Enable Sector Protection command was not issued while the WP pin was asserted. If the Enable Sector

Protection command was issued before or while the WP pin was asserted, then deasserting the WP pin

does not disable the sector protection. In this case, the Disable Sector Protection command must be issued

while the WP pin is deasserted to disable the sector protection. The Disable Sector Protection command is

also ignored whenever the WP pin is asserted.

A noise filter is incorporated to help protect against spurious noise that my inadvertently assert or deassert the WP

pin.

Figure 8-3 and Table 8-3 detail the sector protection status for various scenarios of the WP pin, the Enable Sector

Protection command, and the Disable Sector Protection command.

Figure 8-3. WP Pin and Protection Status Timing

Command

Byte 1

Byte 2

Byte 3

Byte 4

Disable Sector Protection

3Dh

2Ah

7Fh

9Ah

3Dh

2Ah

7Fh

9Ah

Each transition represents eight bits

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