D A T A S H E E T
before programming begins. This resets the device to Flash Memory Region” on page 18 for further
reading array data (also applies to programming in
Erase Suspend mode). Once programming begins,
however, the device ignores reset commands until the
operation is complete.
information.
Word/Byte 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
command 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 tim-
ings. The device automatically generates the program
pulses and verifies the programmed cell margin.
Table 12, on page 26 shows the address and data
requirements for the byte program command
sequence.
The reset command may be written between the
sequence cycles in an autoselect command sequence.
Once in the autoselect mode, the reset command must
be written to return to reading array data (also applies
to autoselect during Erase Suspend).
If DQ5 goes high during a program or erase operation,
writing the reset command returns the device to
reading array data (also applies during Erase
Suspend).
See “AC Characteristics” on page 35 for parameters, and
to Figure 14, on page 36 for the timing diagram.
When the Embedded Program algorithm is complete,
the device then returns to reading array data and
addresses are no longer latched. The system can
determine the status of the program operation by using
DQ7, DQ6, or RY/BY#. See “Write Operation Status”
on page 27 for information on these status bits.
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.
Table 12, on page 26 shows the address and data
requirements. This method is an alternative to that
shown in Table 4, on page 14, which is intended for
PROM programmers and requires VID on address bit
A9.
Any commands written to the device during the
Embedded Program Algorithm are ignored. Note that a
hardware reset immediately terminates the program-
ming operation. The Byte Program command
sequence should be reinitiated once the device resets
to reading array data, to ensure data integrity.
The autoselect command sequence is initiated by
writing two unlock cycles, followed by the autoselect
command. The device then enters the autoselect
mode, and the system may read at any address any
number of times, without initiating another command
sequence. A read cycle at address XX00h retrieves the
manufacturer code. A read cycle at address 01h in
word mode (or 02h in byte mode) returns the device
code. A read cycle containing a sector address (SA)
and the address 02h in word mode (or 04h in byte
mode) returns 01h if that sector is protected, or 00h if it
is unprotected. Refer to Table 2, on page 12 and
Table 3, on page 13 for valid sector addresses.
Programming is allowed in any sequence and across
sector boundaries. A bit cannot be programmed
from a “0” back to a “1”. Attempting to do so may halt
the operation and set DQ5 to “1”, or cause the Data#
Polling algorithm to indicate the operation was suc-
cessful. However, a succeeding read shows that the
data is still “0”. Only erase operations can convert a “0”
to a “1”.
Unlock Bypass Command Sequence
The unlock bypass feature allows the system to
program bytes or words to the device faster than using
the standard program command sequence. The unlock
bypass command sequence is initiated by first writing
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. Additional data is programmed in
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. Table 12, on page 26 shows the
requirements for the command sequence.
The system must write the reset command to exit the
autoselect mode and return to reading array data.
Enter SecSi Sector/Exit SecSi Sector Com-
mand Sequence
The SecSi Sector region provides a secured data area
containing a random, sixteen-byte electronic serial
number (ESN). The system can access the SecSi
Sector region by issuing the three-cycle Enter SecSi
Sector command sequence. The device continues to
access the SecSi Sector region until the system issues
the four-cycle Exit SecSi command sequence. The Exit
SecSi command sequence returns the device to
normal operation. Table 12, on page 26 shows the
address and data requirements for both command
sequences. See also “Secured Silicon (SecSi) Sector
22
Am29SL160C
21635C5 January 23, 2007
AMD [ AMD ]
