
June 9, 2004 30167A+1
S25FL Family (Serial Peripheral Interface)
17
P r e l i m i n a r y  I n f o r m a t i o n
Table 6. Protection Modes 
5. As defined by the values in the Block Protect (BP1, BP0) bits of the Status Register, as shown in Table 
1
and
Table 
2
.
The protection features of the device are summarized in Table 
6
.
When the Status Register Write Disable (SRWD) bit of the Status Register is 0 (its 
initial delivery state), it is possible to write to the Status Register provided that 
the Write Enable Latch (WEL) bit has previously been set by a Write Enable 
(WREN) instruction, regardless of the whether Write Protect (W#) is driven High 
or Low.
When the Status Register Write Disable (SRWD) bit of the Status Register is set 
to 1, two cases need to be considered, depending on the state of Write Protect 
(W#):
 If Write Protect (W#) is driven High, it is possible to write to the Status Reg-
ister provided that the Write Enable Latch (WEL) bit has previously been set 
by a Write Enable (WREN) instruction.
 If Write Protect (W#) is driven Low, it is not possible to write to the Status 
Register even if the Write Enable Latch (WEL) bit has previously been set by 
a Write Enable (WREN) instruction. (Attempts to write to the Status Register 
are rejected, and are not accepted for execution). As a consequence, all the 
data bytes in the memory area that are software protected (SPM) by the 
Block Protect (BP1, BP0) bits of the Status Register, are also hardware pro-
tected against data modification.
Regardless of the order of the two events, the Hardware Protected Mode (HPM) 
can be entered:
 by setting the Status Register Write Disable (SRWD) bit after driving Write 
Protect (W#) Low
 or by driving Write Protect (W#) Low after setting the Status Register Write 
Disable (SRWD) bit.
The only way to exit the Hardware Protected Mode (HPM) once entered is to pull 
Write Protect (W#) High.
If Write Protect (W#) is permanently tied High, the Hardware Protected Mode 
(HPM) can never be activated, and only the Software Protected Mode (SPM), 
using the Block Protect (BP1, BP0) bits of the Status Register, can be used.
Read Data Bytes (READ)
The device is first selected by driving Chip Select (CS#) Low. The instruction code 
for the Read Data Bytes (READ) instruction is followed by a 3-byte address (ad-
dress bits A23 to A18 are Don’t Care), each bit being latched-in during the rising 
edge of Serial Clock (SCK). Then the memory contents, at that address, are 
W# Signal
SRWD Bit
Mode 
Write Protection of the Status 
Register
Protected Area 
(Note 1)
Unprotected Area 
(Note 1)
1
1
Software 
Protected 
(SPM)
Status Register is Writeable (if the 
WREN instruction has set the WEL 
bit)
The values in the SRWD, BP1 and 
BP0 bits can be changed
Protected against Page 
Program and Erase 
(SE, BE)
Ready to accept Page 
Program and Sector 
Erase Instructions
1
0
0
0
0
1
Hardware 
Protected 
(HPM)
Status Register is Hardware write 
protected
The values in the SRWD, BP1 and 
BP0 bits cannot be changed
Protected against Page 
Program and Erase 
(SE, BE)
Ready to accept Page 
Program and Sector 
Erase Instructions