AM29PDL640G datasheet(34/61 Pages) AMD

34 / 61 page

Am29PDL640G

December 13, 2005

D A TA SH EE T

of the password when programming. There are no pro-

visions for entering the 2-cycle unlock cycle, the pass-

word program command, and all the password data.

There is no special addressing order required for pro-

gramming the password. Also, when the password is

undergoing programming, Simultaneous Operation is

disabled. Read operations to any memory location will

return the programming status. Once programming is

complete, the user must issue a Read/Reset com-

mand to return the device to normal operation. Once

the Password is written and verified, the Password

Mode Locking Bit must be set in order to prevent verifi-

cation. The Password Program Command is only ca-

pable of programming “0”s. Programming a “1” after a

cell is programmed as a “0” results in a time-out by the

Embedded Program Algorithm™ with the cell remain-

ing as a “0”. The password is all ones when shipped

from the factory. All 64-bit password combinations are

valid as a password.

Password Verify Command

The Password Verify Command is used to verify the

Password. The Password is verifiable only when the

Password Mode Locking Bit is not programmed. If the

Password Mode Locking Bit is programmed and the

user attempts to verify the Password, the device will al-

ways drive all F’s onto the DQ data bus.

The Password Verify command is permitted if the

SecSi sector is enabled. Also, the device will not oper-

ate in Simultaneous Operation when the Password

Verify command is executed. Only the password is re-

turned regardless of the bank address. The lower two

address bits (A1-A0) are valid during the Password

Verify. Writing the Read/Reset command returns the

device back to normal operation.

Password Protection Mode Locking Bit

Program Command

The Password Protection Mode Locking Bit Program

Command programs the Password Protection Mode

Locking Bit, which prevents further verifies or updates

to the Password. Once programmed, the Password

Protection Mode Locking Bit cannot be erased! If the

Password Protection Mode Locking Bit is verified as

program without margin, the Password Protection

Mode Locking Bit Program command can be executed

to improve the program margin. Once the Password

Protection Mode Locking Bit is programmed, the Per-

sistent Sector Protection Locking Bit program circuitry

is disabled, thereby forcing the device to remain in the

Password Protection mode. Exiting the Mode Locking

Bit Program command is accomplished by writing the

Read/Reset command.

Persistent Sector Protection Mode

Locking Bit Program Command

The Persistent Sector Protection Mode Locking Bit

Program Command programs the Persistent Sector

Protection Mode Locking Bit, which prevents the Pass-

word Mode Locking Bit from ever being programmed.

If the Persistent Sector Protection Mode Locking Bit is

verified as programmed without margin, the Persistent

Sector Protection Mode Locking Bit Program Com-

mand should be reissued to improve program margin.

By disabling the program circuitry of the Password

Mode Locking Bit, the device is forced to remain in the

Persistent Sector Protection mode of operation, once

this bit is set. Exiting the Persistent Protection Mode

Locking Bit Program command is accomplished by

writing the Read/Reset command.

SecSi Sector Protection Bit Program

Command

The SecSi Sector Protection Bit Program Command

programs the SecSi Sector Protection Bit, which pre-

vents the SecSi sector memory from being cleared. If

the SecSi Sector Protection Bit is verified as pro-

grammed without margin, the SecSi Sector Protection

Bit Program Command should be reissued to improve

program margin. Exiting the V

CC-level SecSi Sector

Protection Bit Program Command is accomplished by

writing the Read/Reset command.

PPB Lock Bit Set Command

The PPB Lock Bit Set command is used to set the

PPB Lock bit if it is cleared either at reset or if the

Password Unlock command was successfully exe-

cuted. There is no PPB Lock Bit Clear command.

Once the PPB Lock Bit is set, it cannot be cleared un-

less the device is taken through a power-on clear or

the Password Unlock command is executed. Upon set-

ting the PPB Lock Bit, the PPBs are latched into the

DYBs. If the Password Mode Locking Bit is set, the

PPB Lock Bit status is reflected as set, even after a

power-on reset cycle. Exiting the PPB Lock Bit Set

command is accomplished by writing the Read/Reset

command (only in the Persistent Protection Mode).

DYB Write Command

The DYB Write command is used to set or clear a DYB

for a given sector. The high order address bits

(A21–A12) are issued at the same time as the code

01h or 00h on DQ7-DQ0. All other DQ data bus pins

are ignored during the data write cycle. The DYBs are

modifiable at any time, regardless of the state of the

PPB or PPB Lock Bit. The DYBs are cleared at

power-up or hardware reset.Exiting the DYB Write

command is accomplished by writing the Read/Reset

command.

AM29PDL640G 数据表(PDF) 34 Page - Advanced Micro Devices

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