AM29BDD160G datasheet(38/79 Pages) AMD

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Am29BDD160G

June 7, 2006

the same manner. This mode dispenses with the initial

two unlock cycles required in the standard program

command sequence, resulting in faster total program-

ming time. Tables 18 and 20 show the requirements for

the command sequence.

During the unlock bypass mode, only the Unlock By-

pass Program and Unlock Bypass Reset commands

are valid. To exit the unlock bypass mode, the system

must issue the two-cycle unlock bypass reset com-

mand sequence. The first cycle must contain the data

90h; the second cycle the data 00h. Addresses are

don’t care for both cycles. The device then returns to

reading array data.

Figure 5 illustrates the algorithm for the program oper-

ation. See the Erase/Program Operations table in AC

Characteristics for parameters, and to Figure 22 for

timing diagrams.

Unlock Bypass Entry Command

The Unlock Bypass command, once issued, is used to

bypass the “unlock” sequence for program, chip erase,

and CFI commands. This feature permits slow PROM

programmers to significantly improve program-

ming/erase throughput since the command sequence

often requires microseconds to execute a single write

operation. Therefore, once the Unlock Bypass com-

mand is issued, only the two-cycle program and erase

bypass commands are required. The Unlock Bypass

Command is ignored if the SecSi sector is enabled. To

return back to normal operation, the Unlock Bypass

Reset Command must be issued.

The following four sections describe the commands

that may be executed within the unlock bypass mode.

Unlock Bypass Program Command

The Unlock Bypass Program command is a two-cycle

command that consists of the actual program com-

mand (A0h) and the program address/data combina-

tion. This command does not require the two-cycle

“unlock” sequence since the Unlock Bypass command

was previously issued. As with the standard program

command, multiple Unlock Bypass Program com-

mands can be issued once the Unlock Bypass com-

mand is issued.

To return back to standard read operations, the Unlock

Bypass Reset command must be issued.

The Unlock Bypass Program Command is ignored if

the SecSi sector is enabled.

Unlock Bypass Chip Erase Command

The Unlock Bypass Chip Erase command is a 2-cycle

command that consists of the erase setup command

(80h) and the actual chip erase command (10h). This

command does not require the two-cycle “unlock” se-

quence since the Unlock Bypass command was previ-

ously issued. Unlike the standard erase command,

there is no Unlock Bypass Erase Suspend or Erase

Resume commands.

To return back to standard read operations, the Unlock

Bypass Reset command must be issued.

The Unlock Bypass Program Command is ignored if

the SecSi sector is enabled.

Unlock Bypass CFI Command

The Unlock Bypass CFI command is available for

PROM programmers and target systems to read the

CFI codes while in Unlock Bypass mode. See Com-

mon Flash Memory Interface (CFI) for specific CFI

codes.

To return back to standard read operations, the Unlock

Bypass Reset command must be issued.

The Unlock Bypass Program Command is ignored if

the SecSi sector is enabled.

START

Write Program

Command Sequence

Data Poll

from System

Verify Data?

Yes

Last Address?

Yes

Programming

Completed

Increment Address

Embedded

Program

algorithm

in progress

Note: See Tables 18 and 20 for program command se-

quence.

Figure 4.

Program Operation

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