ESMT
F25L32PA
Write-Status-Register (WRSR)
The Write Status Register instruction writes new values to the
BP2, BP1, BP0, BPL (Status Register) bits of the status register.
When WP is high, the lock-down function of the BPL bit is
disabled and the BPL, BP0, BP1,and BP2 bits in the status
CE must be driven low before the command sequence of the
WRSR instruction is entered and driven high before the WRSR
register can all be changed. As long as BPL bit is set to 0 or WP
pin is driven high (VIH) prior to the low-to-high transition of the
instruction is executed. CE must be driven high after the eighth
bit of data that is clocked in. If it is not done, the WRSR
instruction will not be issued. See Figure 23 for EWSR or WREN
and WRSR instruction sequences.
CE pin at the end of the WRSR instruction, the bits in the status
register can all be altered by the WRSR instruction. In this case,
a single WRSR instruction can set the BPL bit to “1” to lock down
the status register as well as altering the BP0; BP1 and BP2 bits
Executing the Write Status Register instruction will be ignored
at the same time. See Table 4 for a summary description of WP
and BPL functions.
when WP is low and BPL bit is set to “1”. When the WP is
low, the BPL bit can only be set from “0” to “1” to lock down the
status register, but cannot be reset from “1” to “0”.
CE
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
8
7
9 10 11 12 13 14 15
MODE3
MODE0
SCK
Stauts Register
Data In
50 or 06
01
6
4
3
2
0
1
SI
5
MSB
MSB
HIGH IMPENANCE
SO
Figure 23: Enable-Write-Status-Register (EWSR) or Write-Enable (WREN) and Write-Status-Register (WRSR)
Enter OTP Mode (ENSO)
The ENSO (B1H) instruction is for entering the additional 2K
bytes secured OTP mode. The additional 2K bytes secured OTP
sector is independent from main array, which may use to store
unique serial number for system identifier. User must unprotect
whole array (BP0=BP1=BP2=0), prior to any Write (Program/
Erase) operation in OTP sector. After entering the secured OTP
mode, only the secured OTP sector can be accessed and user
can follow the standard Read or Write procedure except for Block
Erase and Chip Erase. The secured OTP data cannot be
updated again once it is lock down. In secured OTP mode,
WRSR command will ignore the input data and lock down the
secured OTP sector (OTP_lock bit =1). To exit secured OTP
mode, user must execute WRDI command. RES can be used to
verify the secured OTP status as shown in Table 6.
Figure 24: Enter OTP Mode (ENSO) Sequence
Elite Semiconductor Memory Technology Inc.
Publication Date: Mar. 2009
Revision: 1.0
22/36
ESMT [ ELITE SEMICONDUCTOR MEMORY TECHNOLOGY INC. ]
