MX25U4035
MX25U8035
(20) Enter Secured OTP (ENSO)
The ENSO instruction is for entering the additional 512-bit secured OTP mode. The additional 512-bit secured OTP
is independent from main array, which may use to store unique serial number for system identifier. After entering the
Secured OTP mode, and then follow standard read or program, procedure to read out the data or update data. The
Secured OTP data cannot be updated again once it is lock-down.
The sequence of issuing ENSO instruction is: CS# goes low→ sending ENSO instruction to enter Secured OTP
mode→ CS# goes high.
Please note that WRSR/WRSCUR commands are not acceptable during the access of secure OTP region, once se-
curity OTP is lock down, only read related commands are valid.
(21) Exit Secured OTP (EXSO)
The EXSO instruction is for exiting the additional 512-bit secured OTP mode.
The sequence of issuing EXSO instruction is: CS# goes low→ sending EXSO instruction to exit Secured OTP
mode→ CS# goes high.
(22) Read Security Register (RDSCUR)
The RDSCUR instruction is for reading the value of Security Register bits. The Read Security Register can be read
at any time (even in program/erase/write status register/write security register condition) and continuously.
The sequence of issuing RDSCUR instruction is : CS# goes low→ send ing RDSCUR instruction →Security Regis-
ter data out on SO→ CS# goes high.
The definition of the Security Register bits is as below:
Secured OTP Indicator bit. The Secured OTP indicator bit shows the chip is locked by factory before ex- factory or
not. When it is "0", it indicates non- factory lock; "1" indicates factory- lock.
Lock-down Secured OTP (LDSO) bit. By writing WRSCUR instruction, the LDSO bit may be set to "1" for custom-
er lock-down purpose. However, once the bit is set to "1" (lock-down), the LDSO bit and the 512-bit Secured OTP
area cannot be update any more. While it is in 512-bit secured OTP mode, main array access is not allowed.
Continuously Program Mode( CP mode) bit. The Continuously Program Mode bit indicates the status of CP
mode, "0" indicates not in CP mode; "1" indicates in CP mode.
P/N: PM1394
REV. 1.0, MAR. 09, 2009
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