D A T A
again read array data with the same exception. See
the Erase Suspend/Erase Resume Commands sec-
tion 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.
See also Requirements for Reading Array Data in the
The Read-Only Operations table provides the read pa-
rameters, and Figure 13 shows the timing diagram.
S H E E T
mode. The autoselect command may not be written
while the device is actively programming 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 at any address within
the same bank any number of times without initiating
another autoselect command sequence:
■
A read cycle at address (BA)XX00h (where BA is
the bank address) returns the manufacturer code.
■
A read cycle at address (BA)XX01h in word mode
(or (BA)XX02h in byte mode) returns the device
code.
■
A read cycle to an address containing a sector ad-
dress (SA) within the same bank, and the address
02h on A7–A0 in word mode (or the address 04h on
A6–A-1 in byte mode) returns 01h if the sector is
protected, or 00h if it is unprotected. (Refer to Ta-
bles 3–6 for valid sector addresses).
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).
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
comm and re tur n s tha t ba nk to th e era se-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).
Enter Secured Silicon Sector/Exit Secured
Silicon Sector Command Sequence
The Secured Silicon Sector region provides a secured
data area containing a random, sixteen-byte electronic
serial number (ESN). The system can access the Se-
cured Silicon Sector region by issuing the three-cycle
Enter Secured Silicon Sector command sequence.
The device continues to access the Secured Silicon
Sector region until the system issues the four-cycle
Exit Secured Silicon Sector command sequence. The
Exit Secured Silicon Sector command sequence re-
turns the device to normal operation. The Secured Sil-
icon Sector is not accessible when the device is
executing an Embedded Program or Embedded Erase
algorithm. Table 14 shows the address and data re-
quirements for both command sequences. See also
ther information.
Byte/Word Program Command Sequence
The system may program the device by word or byte,
depending on the state of the BYTE# pin. Program-
ming is a four-bus-cycle operation. The program com-
mand sequence is initiated by writing two unlock write
cycles, followed by the program set-up command. The
program address and data are written next, which in
turn initiate the Embedded Program algorithm. The
system is
not
required to provide further controls or
timings. The device automatically provides internally
generated program pulses and verifies the pro-
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.
This method is an alternative to that shown in Table 7,
which is intended for PROM programmers and re-
quires V
ID
on address pin A9. The autoselect com-
mand sequence may be written to an address within a
bank that is either in the read or erase-suspend-read
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