S25FS256S datasheet(82/154 Pages) SPANSION

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S25FS-S Family

S25FS-S_00_04 November 6, 2013

Data

Sheet

(Pre limin ar y)

9.4.2

Persistent Protection Bits

The Persistent Protection Bits (PPB) are located in a separate non-volatile flash array. One of the PPB bits is

related 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 have the

same program and erase endurance as the main flash memory array. Preprogramming and verification prior

to erasure are handled by the device.

Programming a PPB bit requires the typical page programming time. Erasing all the PPBs requires typical

Sector Erase time. During PPB bit programming and PPB bit erasing, status is available by reading the Status

Notes:

1. Each PPB is individually programmed to 0 and all are erased to 1 in parallel.

2. If the PPB Lock bit is 0, the PPB Program or PPB Erase command does not execute and fails

without programming or erasing the PPB.

3. The state of the PPB for a given sector can be verified by using the PPB Read command.

9.4.3

Dynamic Protection Bits

Dynamic Protection Bits are volatile and unique for each sector and can be individually modified. DYB only

control the protection for sectors that have their PPB set to 1. By issuing the DYB Write command, a DYB is

cleared to 0 or set to 1, thus placing each sector in the protected or unprotected 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 DYBs can be set or cleared as often as needed as they

are volatile bits.

9.4.4

PPB Lock Bit (PPBL[0])

The PPB Lock Bit is a volatile bit for protecting all PPB bits. When cleared to 0, it locks all PPBs, when set to

1, it allows the PPBs to be changed. See Section 8.6.9, PPB Lock Register (PPBL) on page 74 for more

information.

The PLBWR command is used to clear the PPB Lock 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 to 0,

no software command sequence can set the PPB Lock bit to 1, only another hardware reset or power-up can

set the PPB Lock bit.

In the Password Protection mode, the PPB Lock bit is cleared to 0 during POR or a hardware reset. The PPB

Lock bit can only be set to 1 by the Password Unlock command.

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