AT25DF641-S3H-T Atmel, AT25DF641-S3H-T Datasheet - Page 28

• Manufacturer Part Number: AT25DF641-S3H-T
• Description: IC FLASH 64MBIT 100MHZ 16SOIC
• Manufacturer: Atmel

Specifications of AT25DF641-S3H-T

• Format - Memory: FLASH
• Memory Type: DataFLASH
• Memory Size: 64M (32K pages x 256 bytes)
• Speed: 100MHz
• Interface: SPI, 3-Wire Serial
• Voltage - Supply: 2.7 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 16-SOIC (0.300", 7.5mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

9.
9.1.
28
Table 8-5.
Security Commands
Sector Lockdown
Certain applications require that portions of the Flash memory array be permanently protected against malicious
attempts at altering program code, data modules, security information, or encryption/decryption algorithms, keys,
and routines. To address these applications, the device incorporates a sector lockdown mechanism that allows
any combination of individual 64-Kbyte sectors to be permanently locked so that they become read only. Once a
sector is locked down, it can never be erased or programmed again, and it can never be unlocked from the locked
down state.
Each 64-Kbyte physical sector has a corresponding single-bit Sector Lockdown Register that is used to control
the lockdown status of that sector. These registers are nonvolatile and will retain their state even after a device
power-cycle or reset operation. The following table outlines the two states of the Sector Lockdown Registers.
Table 9-1.
Issuing the Sector Lockdown command to a particular sector address will set the corresponding Sector Lockdown
Register to the logical “1” state. Each Sector Lockdown Register can only be set once; therefore, once set to the
logical “1” state, a Sector Lockdown Register cannot be reset back to the logical “0” state.
Atmel AT25DF641
W
0
0
1
1
P
Value
0
1
SPRL
0
1
0
1
Hardware and Software Locking
Sector Lockdown Register Values
Sector Lockdown Status
Sector is not locked down and can be programmed and erased. This is the default state.
Sector is permanently locked down and can never be programmed or erased again.
Locking
Hardware
Locked
Software
Locked
SPRL Change Allowed
Can be modified from 0 to 1
Locked
Can be modified from 0 to 1
Can be modified from 1 to 0
Sector Protection Registers
Unlocked and modifiable using the Protect and Unprotect
Sector commands. Global Protect and Unprotect can also be
performed.
Locked in current state. Protect and Unprotect Sector
commands will be ignored. Global Protect and Unprotect
cannot be performed.
Unlocked and modifiable using the Protect and Unprotect
Sector commands. Global Protect and Unprotect can also be
performed.
Locked in current state. Protect and Unprotect Sector
commands will be ignored. Global Protect and Unprotect
cannot be performed.
3680F–DFLASH–4/10