M750000007 datasheet(57/129 Pages) SPANSION

57 / 129 page

February 6, 2004

Am75PDL191BHHa/Am75PDL193BHHa

ADV ANCE

I N FO RMAT I O N

Password Unlock Command

The Password Unlock command is used to clear the

PPB Lock Bit so that the PPBs can be unlocked for

modification, thereby allowing the PPBs to become ac-

cessible for modification. The exact password must be

entered in order for the unlocking function to occur.

This command cannot be issued any faster than 2 µs

at a time to prevent a hacker from running through all

64-bit combinations in an attempt to correctly match a

password. If the command is issued before the 2 µs

execution window for each portion of the unlock, the

command will be ignored.

Once the Password Unlock command is entered, the

RY/BY# indicates that the device is busy. Approxi-

mately 1 µs is required for each portion of the unlock.

Once the first portion of the password unlock com-

pletes (RY/BY# is not low or DQ6 does not toggle

when read), the next part of the password is written.

The system must thus monitor RY/BY# or the status

bits to confirm when to write the next portion of the

password. Seven cycles are required to successfully

clear the PPB Lock Bit.

PPB Program Command

The PPB Program command is used to program, or

set, a given PPB. Each PPB is individually pro-

grammed (but is bulk erased with the other PPBs).

The specific sector address (A21–A12) are written at

the same time as the program command 60h with A6

= 0. If the PPB Lock Bit is set and the corresponding

PPB is set for the sector, the PPB Program command

will not execute and the command will time-out without

programming the PPB.

After programming a PPB, two additional cycles are

needed to determine whether the PPB has been pro-

grammed with margin. If the PPB has been pro-

grammed without margin, the program command

should be reissued to improve the program margin.

Also note that the total number of PPB program/erase

cycles is limited to 100 cycles. Cycling the PPBs be-

yond 100 cycles is not guaranteed.

The PPB Program command does not follow the Em-

bedded Program algorithm.

All PPB Erase Command

The All PPB Erase command is used to erase all

PPBs in bulk. There is no means for individually eras-

ing a specific PPB. Unlike the PPB program, no spe-

cific sector address is required. However, when the

PPB erase command is written all Sector PPBs are

erased in parallel. If the PPB Lock Bit is set the ALL

PPB Erase command will not execute and the com-

mand will time-out without erasing the PPBs. After

erasing the PPBs, two additional cycles are needed to

determine whether the PPB has been erased with

margin. If the PPBs has been erased without margin,

the erase command should be reissued to improve the

program margin.

It is the responsibility of the user to preprogram all

PPBs prior to issuing the All PPB Erase command. If

the user attempts to erase a cleared PPB, over-era-

sure may occur making it difficult to program the PPB

at a later time. Also note that the total number of PPB

program/erase cycles is limited to 100 cycles. Cycling

the PPBs beyond 100 cycles is not guaranteed.

DYB Write Command

The DYB Write command is used for setting the DYB,

which is a volatile bit that is cleared at reset. There is

one DYB per sector. If the PPB is set, the sector is pro-

tected regardless of the value of the DYB. If the PPB is

cleared, setting the DYB to a 1 protects the sector from

programs or erases. Since this is a volatile bit, remov-

ing power or resetting the device will clear the DYBs.

The bank address is latched when the command is

written.

PPB Lock Bit Set Command

The PPB Lock Bit set command is used for setting the

DYB, which is a volatile bit that is cleared at reset.

There is one DYB per sector. If the PPB is set, the sec-

tor is protected regardless of the value of the DYB. If

the PPB is cleared, setting the DYB to a 1 protects the

sector from programs or erases. Since this is a volatile

bit, removing power or resetting the device will clear

the DYBs. The bank address is latched when the com-

mand is written.

PPB Status Command

The programming of the PPB for a given sector can be

verified by writing a PPB status verify command to the

device.

PPB Lock Bit Status Command

The programming of the PPB Lock Bit for a given sec-

tor can be verified by writing a PPB Lock Bit status ver-

ify command to the device.

Sector Protection Status Command

The programming of either the PPB or DYB for a given

sector or sector group can be verified by writing a Sec-

tor Protection Status command to the device.

Note that there is no single command to independently

verify the programming of a DYB for a given sector

group.

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