S75WS256NDFBAWMB datasheet(55/216 Pages) SPANSION

55 / 216 page

February 17, 2005 S75WS-N-00_A0

S75WS256Nxx Based MCPs

Advance

Information

9.1

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. The device

programmer or host system must then choose which sector protection method to use. Program-

ming (setting to 0) any one of the following two one-time programmable, 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)

For programming lock register bits refer to Table 13.2.

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 0 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 permanently

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:

Constantly locked. The selected sectors are protected and can not be reprogrammed unless

PPB lock bit is cleared via a password, hardware reset, or power cycle.

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 9.2–9.6.

9.2

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.

Table 9.1 Lock Register

Device

DQ15-05

DQ4

DQ3

DQ2

DQ1

DQ0

S29WS256N

Password

Protection

Mode Lock Bit

Persistent

Protection

Mode Lock Bit

Customer

Secured Silicon

Sector

Protection Bit

S29WS128N/

S29WS064N

Undefined

DYB Lock Boot Bit

0 = sectors

power up

protected

1 = sectors

power up

unprotected

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

S75WS256NDFBAWMB Datasheet(PDF) 55 Page - SPANSION

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