S29GL128S10DHI020 Spansion Inc., S29GL128S10DHI020 Datasheet - Page 20

• Manufacturer Part Number: S29GL128S10DHI020
• Manufacturer: Spansion Inc.

Specifications of S29GL128S10DHI020

• Lead Free Status / Rohs Status: Compliant

20
3.4.3
3.4.4
3.4.5
PPB Lock
Persistent Protection Bits (PPB)
Dynamic Protection Bits (DYB)
There is no command in the Persistent Protection method to set the PPB Lock bit therefore the PPB Lock bit
will remain at 0 until the next power-off or hardware reset. The Persistent Protection method allows boot code
the option of changing sector protection by programming or erasing the PPB, then protecting the PPB from
further change for the remainder of normal system operation by clearing the PPB Lock bit. This is sometimes
called Boot-code controlled sector protection.
The Password method clears the PPB Lock bit to 0 during POR or Hardware Reset to protect the PPB. A 64-
bit password may be permanently programmed and hidden for the password method. A command can be
used to provide a password for comparison with the hidden password. If the password matches the PPB Lock
bit is set to 1 to unprotect the PPB. A command can be used to clear the PPB Lock bit to 0. This method
requires use of a password to control PPB protection.
The selection of the PPB Lock management method is made by programming OTP bits in the Lock Register
so as to permanently select the method used.
The Lock Register also contains OTP bits, for protecting the SSR.
The PPB bits are erased so that all main flash array sectors are unprotected when shipped from Spansion.
The Secured Silicon Region can be factory protected or left unprotected depending on the ordering option
(model) ordered.
The Persistent Protection Bit Lock is a volatile bit for protecting all PPB bits. When cleared to 0, it locks all
PPBs and when set to 1, it allows the PPBs to be changed. There is only one PPB Lock Bit per device.
The PPB Lock command is used to clear the bit to 0. The PPB Lock Bit must be cleared to 0 only after all the
PPBs are configured to the desired settings.
In Persistent Protection mode, the PPB Lock is set to 1 during POR or a hardware reset. When cleared, no
software command sequence can set the PPB Lock, only another hardware reset or power-up can set the
PPB Lock bit.
In the Password Protection mode, the PPB Lock is cleared to 0 during POR or a hardware reset. The PPB
Lock can only set to 1 by the Password Unlock command sequence.
The Persistent Protection Bits (PPB) are located in a separate nonvolatile flash array. One of the PPB bits is
assigned to each sector. When a PPB is 0 its related sector is protected from program and erase operations.
The PPB are programmed individually but must be erased as a group, similar to the way individual words may
be programmed in the main array but an entire sector must be erased at the same time. The PPB may be
erased and reprogrammed up to 1K times. Preprogramming and verification prior to erasure are handled by
the EAC.
Programming a PPB bit requires the typical word programming time. During a PPB bit programming operation
or PPB bit erasing, Data polling Status DQ6 Toggle Bit I will toggle until the operation is complete. Erasing all
the PPBs requires typical sector erase time.
If the PPB Lock is 0, the PPB Program or erase command does not execute and times-out without
programming or erasing the PPB.
The protection state of a PPB for a given sector can be verified by writing a PPB Status Read command when
entered in the PPB ASO.
Dynamic Protection Bits are volatile and unique for each sector and can be individually modified. DYBs only
control protection for sectors that have their PPBs cleared. By issuing the DYB Set or Clear command
sequences, the DYB are set to 1 or cleared to 0, thus placing each sector in the unprotected or protected
state respectively. This feature allows software to easily protect sectors against inadvertent changes, yet
does not prevent the easy removal of protection when changes are needed.
The DYB can be set to 1 or cleared to 0 as often as needed.
D a t a
S h e e t
GL-S MirrorBit
( A d v a n c e
®
Family
I n f o r m a t i o n )
S29GL_128S_01GS_00_01 February 11, 2011