AM29LV2562M AMD [Advanced Micro Devices], AM29LV2562M Datasheet - Page 37

• Manufacturer Part Number: AM29LV2562M
• Manufacturer: AMD [Advanced Micro Devices]

Enter SecSi Sector/Exit SecSi Sector
Command Sequence
The SecSi Sector region provides a secured data area
containing an 8-doubleword/16-word random Elec-
tronic 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 Sector com-
mand sequence. The Exit SecSi Sector command se-
quence returns the device to normal operation. Tables
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both command sequences. See also “SecSi (Secured
Silicon) Sector Flash Memory Region” for further infor-
mation. Note that the ACC function and unlock bypass
modes are not available when the SecSi Sector is en-
abled.
Doubleword/Word Program Command
Sequence
Programming is a four-bus-cycle operation. The pro-
gram 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 al-
gorithm. The system is not required to provide further
controls or timings. The device automatically provides
internally generated program pulses and verifies the
programmed cell margin. Tables
address and data requirements for the word program
command sequence.
When the Embedded Program algorithm is complete,
the device then returns to the read mode and ad-
dresses are no longer latched. The system can deter-
mine the status of the program operation by using
DQ7 and DQ15 or DQ6 and DQ14. Refer to the
Operation Status
tus bits.
Any commands written to the device during the Em-
bedded Program Algorithm are ignored. Note that a
hardware reset immediately terminates the program
operation. The program command sequence should
be reinitiated once the device has returned to the read
mode, to ensure data integrity. Note that the SecSi
Sector, autoselect, and CFI functions are unavailable
when a program operation is in progress
Programming is allowed in any sequence and across
sector boundaries. A bit cannot be programmed
from “0” back to a “1.” Attempting to do so may
cause the device to set DQ5 and/or DQ13 = 1, or
cause the DQ7 and/or DQ15, and DQ6 and/or DQ14
status bits to indicate the operation was successful.
However, a succeeding read will show that the data is
still “0.” Only erase operations can convert a “0” to a
“1.”
December 16, 2005
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D A T A S H E E T
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Am29LV2562M
Unlock Bypass Command Sequence
The unlock bypass feature allows the system to pro-
gram words to the device faster than using the stan-
dard program command sequence. The unlock bypass
command sequence is initiated by first writing two un-
lock cycles. This is followed by a third write cycle con-
taining the unlock bypass command, 2020h. The
device then enters the unlock bypass mode. A two-cy-
cle 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, A0A0h; the second cycle contains the pro-
gram address and data. Additional data is pro-
grammed in the same manner. This mode dispenses
with the initial two unlock cycles required in the stan-
dard program command sequence, resulting in faster
total programming time. Tables
quirements for the command sequence.
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 system
must issue the two-cycle unlock bypass reset com-
mand sequence. The first cycle must contain the data
9090h. The second cycle must contain the data 00h.
The device then returns to the read mode.
Write Buffer Programming
Write Buffer Programming allows the system write to a
maximum of 16 doublewords/32 words in one pro-
gramming operation. This results in faster effective
programming time than the standard programming al-
gorithms. The Write Buffer Programming command
sequence is initiated by first writing two unlock cycles.
This is followed by a third write cycle containing the
Write Buffer Load command written at the Sector Ad-
dress in which programming will occur. The fourth
cycle writes the sector address and the number of
word locations, minus one, to be programmed. For ex-
ample, if the system will program 6 unique address lo-
cations, then 0505h should be written to the device.
This tells the device how many write buffer addresses
will be loaded with data and therefore when to expect
the Program Buffer to Flash command. The number of
locations to program cannot exceed the size of the
write buffer or the operation will abort.
The fifth cycle writes the first address location and
data to be programmed. The write-buffer-page is se-
lected by address bits A23–A4. All subsequent ad-
d r e s s / d a t a
selected-write-buffer-page. The system then writes the
remaining address/data pairs into the write buffer.
Write buffer locations may be loaded in any order.
The write-buffer-page address must be the same for
all address/data pairs loaded into the write buffer.
(This means Write Buffer Programming cannot be per-
formed across multiple write-buffer pages. This also
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