AM29BDD160G datasheet(37/80 Pages) AMD

37 / 80 page

Am29BDD160G

device is in Unlock Bypass mode and during normal

read/reset operating mode.

In this mode, the write protection function is by-

passed unless the PPB Lock Bit = 1.

The Accelerated Program command is not permitted

if the SecSi sector is enabled.

Unlock Bypass Command Sequence

The unlock bypass feature allows the system to pro-

gram words to the device faster than using the

standard program command sequence. The unlock

bypass command sequence is initiated by first writ-

ing two unlock cycles. This is followed by a third

write cycle containing the unlock bypass command,

20h. The device then enters the unlock bypass

mode. A two-cycle unlock bypass program command

sequence is all that is required to program in this

mode. The first cycle in this sequence contains the

unlock bypass program command, A0h; the second

cycle contains the program address and data. Addi-

tional data is programmed in the same manner. This

mode dispenses with the initial two unlock cycles re-

quired in the standard program command sequence,

resulting in faster total programming time. Tables 18

and 20 show the requirements for the command se-

quence.

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 sys-

tem must issue the two-cycle unlock bypass reset

command 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 re-

turns to reading array data.

Figure 4 illustrates the algorithm for the program op-

eration. See the Erase/Program Operations table in

AC Characteristics for parameters, and to Figure 22

for timing diagrams.

Note:See Tables 18 and 20 for program command

sequence.

Figure 4. Program Operation

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 pro-

gramming/erase throughput since the command

sequence often requires microseconds to execute a

single write operation. Therefore, once the Unlock

Bypass command is issued, only the two-cycle pro-

gram and erase bypass commands are required. The

Unlock Bypass Command is ignored if the SecSi sec-

tor 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) a n d the program a ddress /data

combination. This command does not require the

two-cycle “unlock” sequence since the Unlock Bypass

command was previously issued. As with the stan-

dard program command, multiple Unlock Bypass

Program commands can be issued once the Unlock

Bypass command is issued.

To return back to standard read operations, the Un-

lock Bypass Reset command must be issued.

The Unlock Bypass Program Command is ignored if

the SecSi sector is enabled.

Start

AM29BDD160G Datasheet(PDF) 37 Page - Advanced Micro Devices

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