AM29BDD160G datasheet(44/80 Pages) AMD

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Am29BDD160G

command is issued again, only this time with the

next part of the password. If WORD# = 1, the sec-

ond Password Unlock command is the final command

before the PPB Lock Bit is cleared (assuming a valid

password). If WORD# = 0, this is the fourth Pass-

word Unlock command. In x16 mode, four Password

Unlock commands are required to successfully clear

the PPB Lock Bit. As with the first Password Unlock

command, the RY/BY# signal goes LOW and reading

the device results in the DQ6 pin toggling on succes-

sive read operations until complete. It is the

responsibility of the microprocessor to keep track of

the number of Password Unlock commands (2 for

x32 bus and 4 for x16 bus), the order, and when to

read the PPB Lock bit to confirm successful password

unlock

The Password Unlock command is permitted if the

SecSi sector is enabled.

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 (A18–A11) are written at

the same time as the program command 60h with

A6 = 0. If the PPB Lock Bit is set and the corre-

sponding PPB is set for the sector, the PPB Program

command will not execute and the command will

time-out without programming the PPB.

The host system must determine whether a PPB has

been fully programmed by noting the status of DQ0

in the sixth cycle of the PPB Program command. If

DQ0 = 0, the entire six-cycle PPB Program command

sequence must be reissued until DQ0 = 1.

The All PPB Erase command is used to erase all PPBs

in bulk. There is no means for individually erasing a

specific PPB. Unlike the PPB program, no specific

sector address is required. However, when the PPB

erase command is written (60h) and A6 = 1, all Sec-

tor PPBs are erased in parallel. If the PPB Lock Bit is

set the ALL PPB Erase command will not execute and

the command will time-out without erasing the PPBs.

The host system must determine whether all PPB has

been fully erased by noting the status of DQ0 in the

sixth cycle of the All PPB Erase command. If DQ0 =

1, the entire six-cycle All PPB Erase command se-

quence must be reissued until DQ0 = 1.

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 guaran-

teed.

The All PPB Erase command is permitted if the SecSi

sector is enabled.

DYB Write

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

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 vola-

tile bit, removing power or resetting the device will

clear the DYBs. The bank address is latched when

the command is written.

The DYB Write command is permitted if the SecSi

sector is enabled.

PPB Lock Bit Set

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

sector 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 command is written.

The PPB Lock command is permitted if the SecSi sec-

tor is enabled.

DYB Status

The programming of the DYB for a given sector can

be verified by writing a DYB status verify command

to the device.

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

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

tor can be verified by writing a PPB Lock Bit status

verify command to the device.

Non-volatile Protection Bit Program And

Erase Flow

The device uses a standard command sequence for

programming or erasing the SecSi Sector Protection,

Password Locking, Persistent Sector Protection Mode

Locking, or Persistent Protection Bits. Unlike devices

that have the Single High Voltage Sector Unprotect/

Protect feature, the Am29BDD160 has the standard

two-cycle unlock followed by 60h, which places the

device into non-volatile bit program or erase mode.

Once the mode is entered, the specific non-volatile

bit status is read on DQ0. Figure 4 shows a typical

flow for programming the non-volatile bit and Figure

5 shows a typical flow for erasing the non-volatile

bits. The SecSi Sector Protection, Password Locking,

Persistent Sector Protection Mode Locking bits are

not erasable after they are programmed. However,

the PPBs are both erasable and programmable (de-

pending upon device security).

Unlike Single High Voltage Sector Protect/Unprotect,

the A6 pin no longer functions as the program/erase

AM29BDD160G Datasheet(PDF) 44 Page - Advanced Micro Devices

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