AM29PDL640G datasheet(30/61 Pages) AMD

30 / 61 page

Am29PDL640G

December 13, 2005

D A TA SH EE T

COMMAND DEFINITIONS

Writing specific address and data commands or se-

quences into the command register initiates device op-

erations. Table 14 defines the valid register command

sequences. Writing incorrect address and data values

or writing them in the improper sequence may place

the device in an unknown state. A reset command is

then required to return the device to reading array

data.

All addresses are latched on the falling edge of WE#

or CE#, whichever happens later. All data is latched on

the rising edge of WE# or CE#, whichever happens

first. Refer to the AC Characteristics section for timing

diagrams.

Reading Array Data

The device is automatically set to reading array data

after device power-up. No commands are required to

retrieve data. Each bank is ready to read array data

after completing an Embedded Program or Embedded

Erase algorithm.

After the device accepts an Erase Suspend command,

the correspo nding bank enter s the erase-sus-

pend-read mode, after which the system can read

data from any non-erase-suspended sector within the

same bank. The system can read array data using the

standard read timing, except that if it reads at an ad-

dress within erase-suspended sectors, the device out-

puts status data. After completing a programming

operation in the Erase Suspend mode, the system

may once again read array data with the same excep-

tion. See the Erase Suspend/Erase Resume Com-

mands section for more information.

The system must issue the reset command to return a

bank to the read (or erase-suspend-read) mode if DQ5

goes high during an active program or erase opera-

tion, or if the bank is in the autoselect mode. See the

next section, Reset Command, for more information.

Note that the ACC function and unlock bypass modes

are not available when the SecSi Sector is enabled.

See also Requirements for Reading Array Data in the

Device Bus Operations section for more information.

The Read-Only Operations table provides the read pa-

rameters, and Figure 12 shows the timing diagram.

Reset Command

Writing the reset command resets the banks to the

read or erase-suspend-read mode. Address bits are

don’t cares for this command.

The reset command may be written between the se-

quence cycles in an erase command sequence before

erasing begins. This resets the bank to which the sys-

tem was writing to the read mode. Once erasure be-

gins, however, the device ignores reset commands

until the operation is complete.

The reset command may be written between the

sequence cycles in a program command sequence

before programming begins. This resets the bank to

which the system was writing to the read mode. If the

program command sequence is written to a bank that

is in the Erase Suspend mode, writing the reset

com m an d r e tur n s th at b ank to the era s e-sus-

pend-read mode. Once programming begins, however,

the device ignores reset commands until the operation

is complete.

The reset command may be written between the se-

quence cycles in an autoselect command sequence.

Once in the autoselect mode, the reset command

must be written to return to the read mode. If a bank

entered the autoselect mode while in the Erase Sus-

pend mode, writing the reset command returns that

bank to the erase-suspend-read mode.

If DQ5 goes high during a program or erase operation,

writing the reset command returns the banks to the

read mode (or erase-suspend-read mode if that bank

was in Erase Suspend).

Autoselect Command Sequence

The autoselect command sequence allows the host

system to access the manufacturer and device codes,

and determine whether or not a sector is protected.

The autoselect command sequence may be written to

an address within a bank that is either in the read or

erase-suspend-read mode. The autoselect command

may not be written while the device is actively pro-

gramming or erasing in the other bank.

The autoselect command sequence is initiated by first

writing two unlock cycles. This is followed by a third

write cycle that contains the bank address and the au-

toselect command. The bank then enters the autose-

lect mode. The system may read any number of

autoselect codes without reinitiating the command se-

quence.

Table 14 shows the address and data requirements.

To determine sector protection information, the system

must write to the appropriate bank address (BA) and

sector address (SA). Table 4 shows the address range

and bank number associated with each sector.

The system must write the reset command to return to

the read mode (or erase-suspend-read mode if the

bank was previously in Erase Suspend).

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