S71PL512ND0 Datasheet, PDF (47/90 Pages) SPANSION – Two S29PL256N Devices (32 M x 16-Bit) CMOS 3.0-Volt only Simultaneous Read/Write, Page-Mode Flash Memory

Preliminary
10.1
Lock Register
As shipped from the factory, all devices default to the persistent mode when power is applied, and
all sectors are unprotected, unless otherwise chosen through the DYB ordering option (see Or-
dering Information). The device programmer or host system must then choose which sector
protection method to use. Programming (setting to 0) any one of the following two one-time pro-
grammable, non-volatile bits locks the part permanently in that mode:
„ Lock Register Persistent Protection Mode Lock Bit (DQ1)
„ Lock Register Password Protection Mode Lock Bit (DQ2)
Table 10.1 Lock Register
Device
S29PL256N
DQ15 – 05
DQ4
Undefined
DYB Lock Boot Bit
0 = sectors
power up
protected
1 = sectors
power up
unprotected
DQ3
DQ2
DQ1
DQ0
PPB One-Time
Programmable Bit
0 = All PPB erase
command disabled
1 = All PPB Erase
command enabled
Password
Protection
Mode Lock Bit
Persistent
Protection
Mode Lock Bit
Secured
Silicon Sector
Protection Bit
For programming lock register bits see Table 15.2.
Notes
1. If the password mode is chosen, the password must be programmed before setting the cor-
responding lock register bit.
2. After the Lock Register Bits Command Set Entry command sequence is written, reads and
writes for Bank A are disabled, while reads from other banks are allowed until exiting this
mode.
3. If both lock bits are selected to be programmed (to zeros) at the same time, the operation
aborts.
4. Once the Password Mode Lock Bit is programmed, the Persistent Mode Lock Bit is perma-
nently 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.
After selecting a sector protection method, each sector can operate in any of the following three
states:
1. Constantly locked. The selected sectors are protected and cannot be reprogrammed unless
PPB lock bit is cleared via a password, hardware reset, or power cycle.
2. Dynamically locked. The selected sectors are protected and can be altered via software
commands.
3. Unlocked. The sectors are unprotected and can be erased and/or programmed.
These states are controlled by the bit types described in Sections 10.2 – 10.6.
10.2
Persistent Protection Bits
The Persistent Protection Bits are unique and nonvolatile for each sector and have the same en-
durances as the Flash memory. Preprogramming and verification prior to erasure are handled by
the device, and therefore do not require system monitoring.
November 23, 2005 S29PL-N_M0_A4
S29PL-N MirrorBit™ Flash Family
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