AT25DF321A-SH-B Atmel, AT25DF321A-SH-B Datasheet - Page 24

• Manufacturer Part Number: AT25DF321A-SH-B
• Description: IC FLASH 32MBIT 100MHZ 8SOIC
• Manufacturer: Atmel

Specifications of AT25DF321A-SH-B

• Format - Memory: FLASH
• Memory Type: DataFLASH
• Memory Size: 32M (16384 pages x 256 Bytes)
• Speed: 100MHz
• Interface: SPI, RapidS
• Voltage - Supply: 2.7 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 8-SOIC (5.3mm Width), 8-SOP, 8-SOEIAJ
• Memory Configuration: 16384 Pages X 256 Bytes
• Interface Type: Serial, SPI
• Clock Frequency: 100MHz
• Supply Voltage Range: 2.7V To 3.6V
• Memory Case Style: SOIC
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

9.7
24
Protected States and the Write Protect (WP) Pin
The WP pin is not linked to the memory array itself and has no direct effect on the protection status or lockdown status of
the memory array. Instead, the WP pin, in conjunction with the SPRL (Sector Protection Registers Locked) bit in the Status
Register, is used to control the hardware locking mechanism of the device. For hardware locking to be active, two
conditions must be met-the WP pin must be asserted and the SPRL bit must be in the logical “1” state.
When hardware locking is active, the Sector Protection Registers are locked and the SPRL bit itself is also locked. Therefore,
sectors that are protected will be locked in the protected state, and sectors that are unprotected will be locked in the
unprotected state. These states cannot be changed as long as hardware locking is active, so the Protect Sector, Unprotect
Sector, and Write Status Register commands will be ignored. In order to modify the protection status of a sector, the WP
pin must first be deasserted, and the SPRL bit in the Status Register must be reset back to the logical “0” state using the
Write Status Register command. When resetting the SPRL bit back to a logical “0”, it is not possible to perform a Global
Protect or Global Unprotect at the same time since the Sector Protection Registers remain soft-locked until after the Write
Status Register command has been executed.
If the WP pin is permanently connected to GND, then once the SPRL bit is set to a logical “1”, the only way to reset the
bit back to the logical “0” state is to power-cycle the device. This allows a system to power-up with all sectors software
protected but not hardware locked. Therefore, sectors can be unprotected and protected as needed and then hardware
locked at a later time by simply setting the SPRL bit in the Status Register.
When the WP pin is deasserted, or if the WP pin is permanently connected to V
still be set to a logical “1” to lock the Sector Protection Registers. This provides a software locking ability to prevent
erroneous Protect Sector or Unprotect Sector commands from being processed. When changing the SPRL bit to a logical
“1” from a logical “0”, it is also possible to perform a Global Protect or Global Unprotect at the same time by writing the
appropriate values into bits five, four, three and two of the first byte of the Status Register.
Tables
Table 9-4.
Note:
Table 9-5.
Atmel AT25DF321A
WP
0
0
1
1
(Don't Care)
9-4
1. “n” represents a sector number
SPRL
WP
and
X
0
1
0
1
Sector Protection Register States
Hardware and Software Locking
9-5
Hardware
detail the various protection and locking states of the device.
Software
Locking
Locked
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 Register
n
(1)
0
1
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.
CC
, the SPRL bit in the Status Register can
Unprotected
Protected
Sector
n
(1)
3686D–DFLASH–12/09