AT25DF321A-SH-B Atmel, AT25DF321A-SH-B Datasheet - Page 20

• 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

9.4
20
Figure 9-3.
Unprotect Sector
Issuing the Unprotect Sector command to a particular sector address will reset the corresponding Sector Protection
Register to the logical “0” state (see
has a corresponding single-bit Sector Protection Register that is used to control the software protection of a sector.
Before the Unprotect Sector command can be issued, the Write Enable command must have been previously issued to set
the WEL bit in the Status Register to a logical “1”. To issue the Unprotect Sector command, the CS pin must first be
asserted and the opcode of 39h must be clocked into the device. After the opcode has been clocked in, the three address
bytes designating any address within the sector to be unprotected must be clocked in. Any additional data clocked into the
device after the address bytes will be ignored. When the CS pin is deasserted, the Sector Protection Register
corresponding to the sector addressed by A23-A0 will be reset to the logical “0” state, and the sector itself will be
unprotected. In addition, the WEL bit in the Status Register will be reset back to the logical “0” state.
The complete three address bytes must be clocked into the device before the CS pin is deasserted, and the CS pin must
be deasserted on an even byte boundary (multiples of eight bits); otherwise, the device will abort the operation, the state
of the Sector Protection Register will be unchanged, and the WEL bit in the Status Register will be reset to a logical “0”.
As a safeguard against accidental or erroneous locking or unlocking of sectors, the Sector Protection Registers can
themselves be locked from updates by using the SPRL (Sector Protection Registers Locked) bit of the Status Register
(please refer to the Status Register description for more details). If the Sector Protection Registers are locked, then any
attempts to issue the Unprotect Sector command will be ignored, and the device will reset the WEL bit in the Status
Register back to a logical “0” and return to the idle state once the CS pin has been deasserted.
Figure 9-4.
SCK
SCK
Atmel AT25DF321A
SO
SO
CS
CS
SI
SI
Protect Sector
Unprotect Sector
MSB
HIGH-IMPEDANCE
MSB
HIGH-IMPEDANCE
0
0
0
0
0
0
1
1
1
1
2
2
OPCODE
OPCODE
1
1
3
3
0
1
4
4
1
0
5
5
1
0
6
6
0
1
7
Table 9-1
7
MSB
MSB
A
A
8
8
A
A
9
9
A
A
10 11
10 11
for Sector Protection Register values). Every physical sector of the device
A
A
ADDRESS BITS A23-A0
ADDRESS BITS A23-A0
A
A
12
12
A
A
A
A
26
26
A
A
27 28
27 28
A
A
A
A
29 30
29 30
A
A
A
A
31
31
3686D–DFLASH–12/09