s71ws256nc0bawa30 Meet Spansion Inc., s71ws256nc0bawa30 Datasheet - Page 61

• Manufacturer Part Number: s71ws256nc0bawa30
• Description: Stacked Multi-chip Product Mcp 256/512/128 Megabit 32m/16m/8m X 16 Bit Cmos 1.8 Volt-only Simultaneous Read/write, Burst-mode Flash Memory With 128/64megabit 8m/4m X 16-bit Psram.
• Manufacturer: Meet Spansion Inc.

11.4
11.5
September 15, 2005 S71WS-N_01_A4
Persistent Protection Bit Lock Bit
Password Protection Method
Notes
1.
When the parts are first shipped, the PPBs are cleared (erased to “1”) and upon power up or reset,
the DYBs can be set or cleared depending upon the ordering option chosen.
2.
3.
4.
5.
6.
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.
2.
The Password Protection Method allows an even higher level of security than the Persistent Sector
Protection Mode by requiring a 64 bit password for unlocking the device PPB Lock Bit. In addition
to this password requirement, after power up and reset, the PPB Lock Bit is set “0” to maintain
the password mode of operation. Successful execution of the Password Unlock command by en-
tering the entire password clears the PPB Lock Bit, allowing for sector PPBs modifications.
The DYBs can be set (programmed to “0”) or cleared (erased to “1”) as often as needed.
If the option to clear the DYBs after power up is chosen, (erased to “1”), then the sectors
may be modified depending upon the PPB state of that sector (see
The sectors would be in the protected state If the option to set the DYBs after power up is
chosen (programmed to “0”).
It is possible to have sectors that are persistently locked with sectors that are left in the
dynamic state.
The DYB Set or Clear commands for the dynamic sectors signify protected or unprotected
state of the sectors respectively. However, if there is a need to change the status of the per-
sistently 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.
To achieve the best protection, it is recommended to execute the PPB Lock Bit Set command
early in the boot code and protect the boot code by holding WP# = V
and DYB bits have the same function when ACC = V
No software command sequence unlocks this bit unless the device is in the password pro-
tection mode; only a hardware reset or a power-up clears this bit.
The PPB Lock Bit must be set (programmed to “0”) only after all PPBs are configured to the
desired settings.
A d v a n c e
I n f o r m a t i o n
S71WS-Nx0 Based MCPs
HH
as they do when ACC =V
Table
IL
. Note that the PPB
11.2).
IH
.
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