AM29PDL129H datasheet(29/49 Pages) AMD

29 / 49 page

November 2, 2005

Am29PDL129H

COMMAND DEFINITIONS

Enter /Exit Command Sequence

The region provides a secured data area containing a

random, eight word electronic serial number (ESN).

The system can access the region by issuing the

three-cycle Enter command sequence. The device

continues to access the region until the system issues

the four-cycle Exit command sequence. The Exit om-

mand sequence returns the device to normal opera-

tion. The SecSi Sector is not accessible when the

device is executing an Embedded Program or embed-

ded Erase algorithm. shows the address and data re-

quirements for both command sequences. See also

“SecSi Sector Flash Memory Region and Enter SecSi

Sector/Exit SecSi Sector Command Sequence” for fur-

ther information. Note that the ACC function and un-

lock bypass modes are not available when the SecSi

Sector is enabled.

Figure 5.

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.

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. µµAfter programming a PPB, two ad-

ditional cycles are needed to determine whether the

PPB has been programmed with margin. If the PPB

has been programmed without margin, the program

command should be reissued to improve the program

margin. Also note that the total number of PPB pro-

gram/erase cycles is limited to 100 cycles. Cycling the

PPBs beyond 100 cycles is not guaranteed.

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 with-

out margin, the erase command should be reissued to

improve the program margin.

PPB Lock Bit Status

Sector Protection Status The programming of

either the PPB or DYB for a given sector or sector

group can be verified by writing a Sector 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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