S29GL01GS datasheet(17/108 Pages) CYPRESS

17 / 108 page

Document Number: 001-98285 Rev. *R

Page 17 of 108

S29GL01GS/S29GL512S

S29GL256S/S29GL128S

As shipped from the factory, all devices default to the Persistent Protection method, with all sectors unprotected, when power is

applied. The device programmer or host system can then choose which sector protection method to use. Programming either of the

following two, one-time programmable, non-volatile bits, locks the part permanently in that mode:



Persistent Protection Mode Lock Bit (DQ1)



Password Protection Mode Lock Bit (DQ2)

If both lock bits are selected to be programmed at the same time, the operation will abort. Once the Password Mode Lock Bit is

programmed, the Persistent Mode Lock Bit is permanently disabled and no changes to the protection scheme are allowed. Similarly,

if the Persistent Mode Lock Bit is programmed, the Password Mode is permanently disabled.

If the password mode is to be chosen, the password must be programmed prior to setting the corresponding lock register bit. Setting

the Password Protection Mode Lock Bit is programmed, a power cycle, hardware reset, or PPB Lock Bit Set command is required to

set the PPB Lock bit to 0 to protect the PPB array.

The programming time of the Lock Register is the same as the typical word programming time. During a Lock Register programming

EA, Data polling Status DQ6 Toggle Bit I will toggle until the programming has completed. The system can also determine the status

of the lock register programming by reading the Status Register. See Status Register on page 34 for information on these status

bits.

The user is not required to program DQ2 or DQ1, and DQ6 or DQ0 bits at the same time. This allows the user to lock the SSR before

or after choosing the device protection scheme. When programming the Lock Bits, the Reserved Bits must be 1 (masked).

3.4.8

Persistent Protection Mode

The Persistent Protection method sets the PPB Lock to 1 during POR or Hardware Reset so that the PPB bits are unprotected by a

device reset. There is a command to clear the PPB Lock bit to 0 to protect the PPB. There is no command in the Persistent

Protection method to set the PPB Lock bit to 1 therefore the PPB Lock bit will remain at 0 until the next power-off or hardware reset.

3.4.9

Password Protection Mode

3.4.9.1

PPB Password Protection Mode

PPB Password Protection Mode allows an even higher level of security than the Persistent Sector Protection Mode, by requiring a

64-bit password for setting the PPB Lock. In addition to this password requirement, after power up and reset, the PPB Lock is

cleared to 0 to ensure protection at power-up. Successful execution of the Password Unlock command by entering the entire

password sets the PPB Lock to 1, allowing for sector PPB modifications.

Password Protection Notes:



The Password Program Command is only capable of programming 0’s.



The password is all 1’s when shipped from Cypress. It is located in its own memory space and is accessible through the

use of the Password Program and Password Read commands.



All 64-bit password combinations are valid as a password.



Once the Password is programmed and verified, the Password Mode Locking Bit must be set in order to prevent reading or

modification of the password.



The Password Mode Lock Bit, once programmed, prevents reading the 64-bit password on the data bus and further

password programming. All further program and read commands to the password region are disabled (data is read as 1's)

and these commands are ignored. There is no means to verify what the password is after the Password Protection Mode

Lock Bit is programmed. Password verification is only allowed before selecting the Password Protection mode.



The Password Mode Lock Bit is not erasable.



The exact password must be entered in order for the unlocking function to occur.



The addresses can be loaded in any order but all 4 words are required for a successful match to occur.

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