AT25DF021-SSH-T Atmel, AT25DF021-SSH-T Datasheet - Page 16

• Manufacturer Part Number: AT25DF021-SSH-T
• Description: IC FLASH 2MBIT 70MHZ 8SOIC
• Manufacturer: Atmel

Specifications of AT25DF021-SSH-T

• Format - Memory: FLASH
• Memory Type: DataFLASH
• Memory Size: 2M (256K x 8)
• Speed: 70MHz
• Interface: SPI, 3-Wire Serial
• Voltage - Supply: 2.7 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

16
AT25DF021
Table 9-2.
Essentially, if the SPRL bit of the Status Register is in the logical “0” state (Sector Protection
Registers are not locked), then writing a 00h to the first byte of the Status Register will perform a
Global Unprotect without changing the state of the SPRL bit. Similarly, writing a 7Fh to the first
byte of the Status Register will perform a Global Protect and keep the SPRL bit in the logical “0”
state. The SPRL bit can, of course, be changed to a logical “1” by writing an FFh if software-lock-
ing or hardware-locking is desired along with the Global Protect.
If the desire is to only change the SPRL bit without performing a Global Protect or Global Unpro-
tect, then the system can simply write a 0Fh to the first byte of the Status Register to change the
State
WP
0
0
1
1
Current
SPRL
Value
0
1
0
1
Valid SPRL and Global Protect/Unprotect Conditions
New Write Status
Register Byte 1
7 6 5 4 3 2 1 0
0 x 0 0 0 0 x x
0 x 0 0 0 1 x x
0 x 1 1 1 0 x x
0 x 1 1 1 1 x x
1 x 0 0 0 0 x x
1 x 0 0 0 1 x x
1 x 1 1 1 0 x x
1 x 1 1 1 1 x x
0 x 0 0 0 0 x x
0 x 0 0 0 1 x x
0 x 1 1 1 0 x x
0 x 1 1 1 1 x x
1 x 0 0 0 0 x x
1 x 0 0 0 1 x x
1 x 1 1 1 0 x x
1 x 1 1 1 1 x x
0 x 0 0 0 0 x x
0 x 0 0 0 1 x x
0 x 1 1 1 0 x x
0 x 1 1 1 1 x x
1 x 0 0 0 0 x x
1 x 0 0 0 1 x x
1 x 1 1 1 0 x x
1 x 1 1 1 1 x x
x x x x x x x x
Data
Bit
Protection Operation
Global Unprotect – all Sector Protection Registers reset to 0
No change to current protection.
No change to current protection.
No change to current protection.
Global Protect – all Sector Protection Registers set to 1
Global Unprotect – all Sector Protection Registers reset to 0
No change to current protection.
No change to current protection.
No change to current protection.
Global Protect – all Sector Protection Registers set to 1
No change to the current protection level. All sectors currently
protected will remain protected and all sectors currently unprotected
will remain unprotected.
The Sector Protection Registers are hard-locked and cannot be
changed when the WP pin is LOW and the current state of SPRL is 1.
Therefore, a Global Protect/Unprotect will not occur. In addition, the
SPRL bit cannot be changed (the WP pin must be HIGH in order to
change SPRL back to a 0).
Global Unprotect – all Sector Protection Registers reset to 0
No change to current protection.
No change to current protection.
No change to current protection.
Global Protect – all Sector Protection Registers set to 1
Global Unprotect – all Sector Protection Registers reset to 0
No change to current protection.
No change to current protection.
No change to current protection.
Global Protect – all Sector Protection Registers set to 1
No change to the current protection level. All sectors
currently protected will remain protected, and all sectors
currently unprotected will remain unprotected.
The Sector Protection Registers are soft-locked and cannot
be changed when the current state of SPRL is 1. Therefore,
a Global Protect/Unprotect will not occur. However, the
SPRL bit can be changed back to a 0 from a 1 since the WP
pin is HIGH. To perform a Global Protect/Unprotect, the
Write Status Register command must be issued again after
the SPRL bit has been changed from a 1 to a 0.
3677D–DFLASH–04/09
SPRL
Value
New
0
0
0
0
0
1
1
1
1
1
0
0
0
0
0
1
1
1
1
1
0
0
0
0
0
1
1
1
1
1