S29WS-P SPANSION [SPANSION], S29WS-P Datasheet - Page 54

• Manufacturer Part Number: S29WS-P
• Description: 512/256/128 Mb (32/16/8 M x 16 bit) 1.8 V Burst Simultaneous Read/Write MirrorBit Flash Memory
• Manufacturer: SPANSION [SPANSION]

8.4
8.5
52
Dynamic Protection Bits
Persistent Protection Bit Lock Bit
Dynamic Protection Bits are volatile and unique for each sector and can be individually modified. DYBs only
control the protection scheme for unprotected sectors that have their PPBs cleared (erased to 1). By issuing
the DYB Set or Clear command sequences, the DYBs are set (programmed to 0) or cleared (erased 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.
Notes
The Persistent Protection Bit Lock Bit is a global volatile bit for all sectors. When set (programmed to 0), it
locks all PPBs and when cleared (programmed to 1), allows the PPBs to be changed. There is only one PPB
Lock Bit per device.
Notes
1. The DYBs can be set (programmed to 0) or cleared (erased to 1) as often as needed.
2. The default state of DYB is unprotected after power up and all sectors can be modified depending
3. It is possible to have sectors that are persistently locked with sectors that are left in the dynamic
4. The DYB Set or Clear commands for the dynamic sectors signify protected or unprotected state of
5. Data polling is not available for DYB program / erase.
6. DYB read data can be done synchronously.
7. If the user attempts to program or erase a protected sector, the device ignores the command and
1. No software command sequence unlocks this bit unless the device is in the password protection
2. The PPB Lock Bit must be set (programmed to 0) only after all PPBs are configured to the desired
When the parts are first shipped, the PPBs are cleared (erased to 1).
on the status of PPB bit for that sector, (erased to 1). Then the sectors can be modified depending
upon the PPB state of that sector (see
state.
the sectors respectively. However, if there is a need to change the status of the persistently locked
sectors, a few more steps are required. First, the PPB Lock Bit must be cleared by either putting
the device through a power-cycle, or hardware reset. The PPBs can then be changed to reflect the
desired settings. Setting the PPB Lock Bit once again locks the PPBs, and the device operates
normally again.
returns to read mode.
mode; only a hardware reset or a power-up clears this bit.
settings.
D a t a
S h e e t
S29WS-P
( A d v a n c e
Table 8.1 on page
I n f o r m a t i o n )
49).
S29WS-P_00_A7 November 8, 2006