S71PL129JC0 datasheet(38/153 Pages) SPANSION

38 / 153 page

S71PL129JC0/S71PL129JB0/S71PL129JA0

S71PL129Jxx_00_A8 October 28, 2005

Advance

Info rmation

Password and Password Mode Locking Bit

In order to select the Password sector protection scheme, the customer must first

program the password. The password may be correlated to the unique Electronic

Serial Number (ESN) of the particular flash device. Each ESN is different for every

flash device; therefore each password should be different for every flash device.

While programming in the password region, the customer may perform Password

Verify operations.

Once the desired password is programmed in, the customer must then set the

Password Mode Locking Bit. This operation achieves two objectives:

Permanently sets the device to operate using the Password Protection Mode. It is

not possible to reverse this function.

Disables all further commands to the password region. All program, and read op-

erations are ignored.

Both of these objectives are important, and if not carefully considered, may lead

to unrecoverable errors. The user must be sure that the Password Protection

method is desired when setting the Password Mode Locking Bit. More importantly,

the user must be sure that the password is correct when the Password Mode

Locking Bit is set. Due to the fact that read operations are disabled, there is no

means to verify what the password is afterwards. If the password is lost after set-

ting the Password Mode Locking Bit, there is not any way to clear the PPB Lock bit.

The Password Mode Locking Bit, once set, prevents reading the 64-bit password

on the DQ bus and further password programming. The Password Mode Locking

Bit is not erasable. Once Password Mode Locking Bit is programmed, the Persis-

tent Sector Protection Locking Bit is disabled from programming, guaranteeing

that no changes to the protection scheme are allowed.

64-bit Password

The 64-bit Password is located in its own memory space and is accessible through

the use of the Password Program and Verify commands (see “Password Verify

Command”). The password function works in conjunction with the Password

Mode Locking Bit, which when set, prevents the Password Verify command from

reading the contents of the password on the pins of the device.

Write Protect (WP#)

The Write Protect feature provides a hardware method of protecting the upper

two and lower two sectors(PL127J: 0, 1, 268, and 269, PL064J: 0, 1, 140, and

141, PL032J: 0, 1, 76, and 77, PL129J: SA1-133, SA1-134,SA2-0 and SA2-1)

without using VID. This function is provided by the WP# pin and overrides the pre-

viously discussed method, “High Voltage Sector Protection” on page 37.

If the system asserts VIL on the WP#/ACC pin, the device disables program and

erase functions in the two outermost 4 Kword sectors on both ends of the flash

array independent of whether it was previously protected or unprotected.

If the system asserts VIH on the WP#/ACC pin, the device reverts the upper two

and lower two sectors to whether they were last set to be protected or unpro-

tected. That is, sector protection or unprotection for these sectors depends on

whether they were last protected or unprotected using the method described in

“High Voltage Sector Protection” on page 37.

Note that the WP#/ACC pin must not be left floating or unconnected; inconsistent

behavior of the device may result.

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