s29gl128n Meet Spansion Inc., s29gl128n Datasheet - Page 62

• Manufacturer Part Number: s29gl128n
• Description: 3.0 Volt-only Page Mode Flash Memory Featuring 110 Nm Mirrorbit ?rocess Technology
• Manufacturer: Meet Spansion Inc.

D a t a
S h e e t
Once the Password is written and verified, the Password Protection Mode Lock Bit in the Lock
Register must be programmed in order to prevent verification. The Password Program com-
mand is only capable of programming 0s. Programming a 1 after a cell is programmed as a
TM
0 results in a time-out by the Embedded Program Algorithm
with the cell remaining as a 0.
The password is all F’s when shipped from the factory. All 64-bit password combinations are
valid as a password.
The Password Read command is used to verify the Password. The Password is verifiable only
when the Password Protection Mode Lock Bit in the Lock Register is not programmed. If the
P assword Protection Mode Lock Bit in the Lock Register is programmed and the user attempts
to read the Password, the device always drives all F’s onto the DQ databus.
The lower two address bits (A1–A0) for word mode and (A1–A-1) for by byte mode are valid
during the Password Read, Password Program, and Password Unlock commands. Writing a
1 to any other address bits (A
-A2) aborts the Password Read and Password Pro-
MAX
gram commands.
The Password Unlock command is used to clear the PPB Lock Bit to the unfreeze state so that
the PPB bits can be modified. The exact password must be entered in order for the unlocking
function to occur. This 64-bit Password Unlock command sequence takes at least 2 µs to pro-
cess each time to prevent a hacker from running through the all 64-bit combinations in an
attempt to correctly match the password. If another password unlock is issued before the
64-bit password check execution window is completed, the command is ignored. If the wrong
address or data is given during password unlock command cycle, the device may enter the
w r i t e - t o - b u f f e r a b o r t s t a t e . I n o r d e r t o e x i t t h e w r i t e - t o - ab o r t s t a t e , t h e
write-to-buffer-abort-reset command must be given. Otherwise the device hangs.
The Password Unlock function is accomplished by writing P assword Unlock command and data
to the device to perform the clearing of the PPB Lock Bit to the unfreeze state. The password
is 64 bits long. A1 and A0 are used for matching in word mode and A1, A0, A-1 in byte mode.
Writing the Password Unlock command does not need to be address order specific. An exam-
ple sequence is starting with the lower address A1-A0=00, followed by A1-A0=01, A1-A0= 10,
and A1-A0= 11 if the device is configured to operate in word mode.
Approximately 2 µs is required for unlocking the device after the valid 64-bit password is
given to the device. It is the responsibility of the microprocessor to keep track of the entering
the portions of the 64-bit password with the Password Unlock command, the order, and when
to read the PPB Lock bit to confirm successful password unlock. In order to re-lock the device
into the P assword Protection Mode, the PPB Lock Bit Set command can be re-issued.
Note: The P assword Protection Command Set Exit command must be issued after the exe-
cution of the commands listed previously to reset the device to read mode. Otherwise the
device hangs.
Note: Issuing the Password Protection Command Set Exit command re-enables reads and
writes for the main memory.
Non-Volatile Sector Protection Command Set Definitions
The Non-Volatile Sector Protection Command Set permits the user to program the Persistent
Protection Bits (PPB bits), erase all of the Persistent Protection Bits (PPB bits), and read the
logic state of the Persistent Protection Bits (PPB bits).
The Non-Volatile Sector Protection Command Set Entry command sequence must be is-
sued prior to any of the commands listed following to enable proper command execution.
Note that issuing the Non-Volatile Sector Protection Command Set Entry command dis-
ables reads and writes for the main memory.
T PPB Program Command
60
S29GL-N MirrorBit™ Flash Family
S29GL-N_00_B3 October 13, 2006