SST25PF020B(2012) データシートの表示（PDF） - Microchip Technology
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SST25PF020B Datasheet PDF : 33 Pages
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SST25PF020B
4.2 Write Protection
SST25PF020B provides software Write protection. The
Write Protect pin (WP#) enables or disables the lock-
down function of the status register. The Block-Protec-
tion bits (BP1, BP0, and BPL) in the status register, and
the Top/Bottom Sector Protection Status bits (TSP and
BSP) in Status Register 1, provide Write protection to
the memory array and the status register. See Table 4-
4 for the Block-Protection description.
4.2.1 WRITE PROTECT PIN (WP#)
The Write Protect (WP#) pin enables the lock-down
function of the BPL bit (bit 7) in the status register.
When WP# is driven low, the execution of the Write-
Status-Register (WRSR) instruction is determined by
the value of the BPL bit (see Table 4-1). When WP# is
high, the lock-down function of the BPL bit is disabled.
TABLE 4-1: CONDITIONS TO EXECUTE WRITE-STATUS-REGISTER (WRSR) INSTRUCTION
WP#
BPL
Execute WRSR Instruction
L
1
Not Allowed
L
0
Allowed
H
X
Allowed
4.3 Status Register
The software status register provides status on
whether the flash memory array is available for any
Read or Write operation, whether the device is Write
enabled, and the state of the Memory Write protection.
During an internal Erase or Program operation, the sta-
tus register may be read only to determine the comple-
tion of an operation in progress. Table 4-2 describes
the function of each bit in the software status register.
TABLE 4-2:
Bit Name
0 BUSY
1 WEL
2 BP0
3 BP1
4:5 RES
6 AAI
7 BPL
SOFTWARE STATUS REGISTER
Function
1 = Internal Write operation is in progress
0 = No internal Write operation is in progress
1 = Device is memory Write enabled
0 = Device is not memory Write enabled
Indicates current level of block write protection (See Table 4-4)
Indicates current level of block write protection (See Table 4-4)
Reserved for future use
Auto Address Increment Programming status
1 = AAI programming mode
0 = Byte-Program mode
1 = BP1, BP0 are read-only bits
0 = BP1, BP0 are read/writable
Default at
Power-up
0
0
1
1
0
0
0
Read/Write
R
R
R/W
R/W
N/A
R
R/W
2012 Microchip Technology Inc.
DS25135A-page 5
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