D A T A S H E E T
COMMAND DEFINITIONS
Writing specific address and data commands or
sequences into the command register initiates device
operations. Table 10 defines the valid register
command sequences. Writing incorrect address and
data values or writing them in the improper sequence
resets the device to reading array data.
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 operation,
or if the bank is in the autoselect mode. See the next
section, Reset Command, for more information.
See also Requirements for Asynchronous
Read Operation (Non-Burst) and Requirements for
Synchronous (Burst) Read Operation in the Device
Bus Operations section for more information. The
Asynchronous Read and Synchronous/Burst Read
tables provide the read parameters, and Figures 9 and
11 show the timings.
All addresses are latched on the rising edge of AVD#.
All data is latched on the rising edge of WE#. 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 in asynchronous mode. Each bank is
ready to read array data after completing an Embedded
Program or Embedded Erase algorithm.
Set Configuration Register Command Se-
quence
The configuration register command sequence
instructs the device to set a particular number of clock
cycles for the initial access in burst mode. The number
of wait states that should be programmed into the
device is directly related to the clock frequency. The
first two cycles of the command sequence are for
unlock purposes. On the third cycle, the system should
write C0h to the address associated with the intended
wait state setting (see Table 8). Address bits A16–A12
determine the setting. Note that addresses A19–A17
are shown as “0” but are actually don’t care.
After the device accepts an Erase Suspend command,
the corresponding bank enters the erase-sus-
pend-read mode, after which the system can read data
from any non-erase-suspended sector. After com-
pleting a programming operation in the Erase Suspend
mode, the system may once again read array data with
the same exception. See the Erase Suspend/Erase
Resume Commands section for more information.
Table 8. Burst Modes
Third Cycle Addresses for Wait States
Wait States
0
1
2
3
4
5
Burst
Mode
Clock Cycles
2
3
4
5
6
7
Continuous
00555h
08555h
10555h
18555h
01555h
09555h
11555h
19555h
02555h
0A555h
12555h
1A555h
03555h
0B555h
13555h
1B555h
04555h
0C555h
14555h
1C555h
05555h
0D555h
15555h
1D555h
8-word Linear
16-word Linear
32-word Linear
Note: The burst mode is set in the third cycle of the Set Wait State command sequence.
Upon power up, the device defaults to the maximum
seven cycle wait state setting. It is recommended that
the wait state command sequence be written, even if
the default wait state value is desired, to ensure the
device is set as expected. A hardware reset will set the
wait state to the default setting.
Handshaking Feature
The host system should set address bits A16–A12 to
“00010” for a clock frequency of 40 MHz or to “00011”
for a clock frequency of 54 or 66 MHz, assuming con-
tinuous burst is desired in both cases.
Table 9 describes the typical number of clock cycles
(wait states) for various conditions.
20
Am29BDS643G
25692A2 May 8, 2006
SPANSION [ SPANSION ]
