S29PL-N SPANSION [SPANSION], S29PL-N Datasheet - Page 53

• Manufacturer Part Number: S29PL-N
• Description: 256/128/128 Mb (16/8/8 M x 16-Bit) CMOS, 3.0 Volt-only Simultaneous Read/Write, Page-Mode Flash Memory
• Manufacturer: SPANSION [SPANSION]

8.5
November 23, 2005 S29PL-N_00_A4
Password Protection Method
Notes
1.
2.
The Password Protection Method allows an even higher level of security than the Persistent Sector
Protection Mode by requiring a 64-bit password for unlocking the device PPB Lock Bit. In addition
to this password requirement, after power up and reset, the PPB Lock Bit is set 0 to maintain the
password mode of operation. Successful execution of the Password Unlock command by entering
the entire password clears the PPB Lock Bit, allowing for sector PPBs modifications.
Notes
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10. The Password Unlock command cannot be issued any faster than 1 µs at a time to prevent
11. Approximately 1 µs is required for unlocking the device after the valid 64-bit password is
12. Password verification is only allowed during the password programming operation.
13. All further commands to the password region are disabled and all operations are ignored.
14. If the password is lost after setting the Password Mode Lock Bit, there is no way to clear the
15. Entry command sequence must be issued prior to any of any operation and it disables reads
16. If the user attempts to program or erase a protected sector, the device ignores the com-
17. A program or erase command to a protected sector enables status polling and returns to
18. The programming of the DYB, PPB, and PPB Lock for a given sector can be verified by writing
No software command sequence unlocks this bit unless the device is in the password pro-
tection mode; only a hardware reset or a power-up clears this bit.
The PPB Lock Bit must be set (programmed to 0) only after all PPBs are configured to the
desired settings.
There is no special addressing order required for programming the password. Once the
Password is written and verified, the Password Mode Locking Bit must be set to prevent ac-
cess.
The Password Program Command is only capable of programming 0s. Programming a 1
after a cell is programmed as a 0 results in a time-out with the cell as a 0.
The password is all 1s when shipped from the factory.
All 64-bit password combinations are valid as a password.
There is no means to verify what the password is after it is set.
The Password Mode Lock Bit, once set, prevents reading the 64-bit password on the data
bus and further password programming.
The Password Mode Lock Bit is not erasable.
The lower two address bits (A1 – A0) are valid during the Password Read, Password Pro-
gram, and Password Unlock.
The exact password must be entered in order for the unlocking function to occur.
a hacker from running through all the 64-bit combinations in an attempt to correctly match
a password.
given to the device.
PPB Lock Bit.
and writes for Bank A. Reads and writes for other banks excluding Bank A are allowed.
mand and returns to read mode.
read mode without having modified the contents of the protected sector.
individual status read commands DYB Status, PPB Status, and PPB Lock Status to the
device.
P r e l i m i n a r y
S29PL-N MirrorBit™ Flash Family
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