AT45DB641E datasheet(35/78 Pages) RENESAS

35 / 78 page

DS-AT45DB641E-027 Rev. O

Page 35

6/30/23

AT45DB641E Datasheet

9.1.1

Read Sector Lockdown Register

The nonvolatile Sector Lockdown Register specifies which sectors in the main memory are currently unlocked or

have been permanently locked down. The Sector Lockdown Register is a read-only register and contains 32 bytes

of data which correspond to Sectors 0 through 31. To read the Sector Lockdown Register, an opcode of 35h must

be clocked into the device followed by three dummy bytes. After the last bit of the opcode and dummy bytes have

been clocked in, the data for the contents of the Sector Lockdown Register are clocked out on the SO pin. The

first byte (byte location 0) corresponds to Sector 0 (0a and 0b), the second byte corresponds to Sector 1, and the

last byte (byte location 31) corresponds to Sector 31. After the last byte of the Sector Lockdown Register has

been read, additional pulses on the SCK pin results in undefined data being output on the SO pin.

Deasserting the CS pin terminates the Read Sector Lockdown Register operation and put the SO pin into a high-

impedance state. Table 15 details the format the Sector Lockdown Register.

Figure 12. Read Sector Lockdown Register

Table 15. Sector Lockdown Register

Sector Number

0 (0a, 0b)

1 to 31

Locked

See Table 16

FFh

Unlocked

00h

Table 16. Sector 0 (0a and 0b) Sector Lockdown Register Byte Value

Bit 7:6

Bit 5:4

Bit 3:2

Bit 1:0

Data

Value

Sector 0a

(Page 0-7)

Sector 0b

(Page 8-1023)

N/A

Sectors 0a and 0b Unlocked

00h

Sector 0a Locked

C0h

Sector 0b Locked

30h

Sectors 0a and 0b Locked

F0h

Table 17. Read Sector Lockdown Register Command

Command

Byte 1

Byte 2

Byte 3

Byte 4

Read Sector Lockdown Register

35h

XXh

32h

Data

n + 1

Data

n + 31

Each transition represents eight bits

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