User guide

AT25DL161 [DATASHEET]

8795E–DFLASH–12/2012

10.3 Read Sector Lockdown Registers

The Sector Lockdown Registers can be read to determine the current lockdown status of each physical 64KB sector. To

read the Sector Lockdown Register for a particular 64KB sector, the

CS pin must first be asserted and then the opcode

35h must be clocked in. Once the opcode has been clocked in, three address bytes designating any address within the

64KB sector must be clocked in. After the address bytes have been clocked in, data will be output on the SO pin during

every subsequent clock cycle. The data being output will be a repeating byte of either FFh or 00h to denote the value of

the appropriate Sector Lockdown Register.

At clock frequencies above f

CLK

, the first byte of data output will not be valid. Therefore, if operating at clock frequencies

above f

CLK

, at least two bytes of data must be clocked out from the device in order to determine the correct status of the

appropriate Sector Lockdown Register.

Deasserting the

CS pin will terminate the read operation and put the SO pin into a high-impedance state. The CS pin can

be deasserted at any time and does not require that a full byte of data be read.

Figure 10-3. Read Sector Lockdown Register

Table 10-2. Read Sector Lockdown Register – Output Data

Output Data Sector Lockdown Register Value

00h Sector Lockdown Register value is 0 (sector is not locked down).

FFh Sector Lockdown Register value is 1 (sector is permanently locked down).

SCK

MSB MSB

2310

00110101

675410119812 394243414037 3833 36353431 3229 30 44 47 484645

Opcode

AAAA AAAAA

MSB

XXXXXXXX

MSB MSB

DDDDDDDDDD

Address Bits A23-A0 Don't Care

Data Byte

High-impedance