S29CD032J datasheet(45/81 Pages) SPANSION

45 / 81 page

October 11, 2012 S29CD-J_CL-J_00_B7

S29CD-J and S29CL-J Flash Family

Data

She e t

9.1

Advanced Sector Protection Overview

As shipped from the factory, all devices default to the persistent mode when power is applied, and all sector

groups are unprotected. The device programmer or host system must then choose which sector group

protection method to use. Programming (setting to “0”) any one of the following two one-time programmable,

non-volatile bits locks the device permanently in that mode:

 Persistent Protection Mode Lock Bit

 Password Protection Mode Lock Bit

After selecting a sector group protection method, each sector group can operate in any of the following three

states:

1. Persistently Locked. A sector group is protected and cannot be changed.

2. Dynamically locked. The selected sector groups are protected and can be altered via software

commands.

3. Unlocked. The sector groups are unprotected and can be erased and/or programmed.

These states are controlled by the bit types described in sections Persistent Protection Bits on page 45 to

Hardware Data Protection Methods on page 49.

Notes

1. If the password mode is chosen, the password must be programmed before setting the

corresponding lock register bit. The user must be sure that the password is correct when the

Password Mode Locking Bit is set, as there is no means to verify the password afterwards.

2. If both lock bits are selected to be programmed (to zeros) at the same time, the operation aborts.

3. 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.

4. It is important that the mode is explicitly selected when the device is first programmed, rather than

relying on the default mode alone. This is so that it is impossible for a system program or virus to

later set the Password Mode Locking Bit, which would cause an unexpected shift from the default

Persistent Sector Protection Mode into the Password Protection Mode.

5. If the user attempts to program or erase a protected sector, the device ignores the command and

returns to read mode. A program command to a protected sector enables status polling for

approximately 1 µs before the device returns to read mode without modifying the contents of the

protected sector. An erase command to a protected sector enables status polling for approximately

50 µs, after which the device returns to read mode without having erased the protected sector.

6. For the command sequence required for programming the lock register bits, refer to Command

Definitions on page 75.

9.2

Persistent Protection Bits

The Persistent Protection Bits are unique and nonvolatile. A single Persistent Protection Bit is assigned to a

maximum for four sectors (see the sector address tables for specific sector protection groupings). All eight-

Kbyte boot-block sectors have individual sector Persistent Protection Bits (PPBs) for greater flexibility.

Notes

1. Each PPB is individually programmed and all are erased in parallel. There are no means for

individually erasing a specific PPB and no specific sector address is required for this operation.

2. If a PPB requires erasure, all of the sector PPBs must first be programmed prior to PPB erasing. It

is the responsibility of the user to perform the preprogramming operation. Otherwise, an already

erased sector PPB has the potential of being over-erased. There is no hardware mechanism to

prevent sector PPB over-erasure.

3. If the PPB Lock Bit is set, the PPB Program or erase command does not execute and times-out

without programming or erasing the PPB.

S29CD032J Datasheet(PDF) 45 Page - SPANSION

S29CD032J Datasheet(HTML) 45 Page - SPANSION

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