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AM29LV200 View Datasheet(PDF) - Advanced Micro Devices

Part NameDescriptionManufacturer
AM29LV200 2 Megabit (256 K x 8-Bit/128 K x 16-Bit) CMOS 3.0 volt-only boot sector flash memory AMD
Advanced Micro Devices AMD
AM29LV200 Datasheet PDF : 37 Pages
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Hardware Data Protection
The command sequence requirement of unlock cycles
for programming or erasing provides data protection
against inadvertent writes (refer to Table 5 for com-
mand definitions). In addition, the following hardware
data protection measures prevent accidental erasure
or programming, which might otherwise be caused by
spurious system level signals during VCC power-up
and power-down transitions, or from system noise.
Low VCC Write Inhibit
When VCC is less than VLKO, the device does not ac-
cept any write cycles. This protects data during VCC
power-up and power-down. The command register and
all internal program/erase circuits are disabled, and the
device resets. Subsequent writes are ignored until VCC
is greater than VLKO. The system must provide the
proper signals to the control pins to prevent uninten-
tional writes when VCC is greater than VLKO.
Write Pulse “Glitch” Protection
Noise pulses of less than 5 ns (typical) on OE#, CE# or
WE# do not initiate a write cycle.
Logical Inhibit
Write cycles are inhibited by holding any one of OE# =
VIL, CE# = VIH or WE# = VIH. To initiate a write cycle,
CE# and WE# must be a logical zero while OE# is a
logical one.
Power-Up Write Inhibit
If WE# = CE# = VIL and OE# = VIH during power up, the
device does not accept commands on the rising edge
of WE#. The internal state machine is automatically
reset to reading array data on power-up.
Writing specific address and data commands or se-
quences into the command register initiates device op-
erations. Table 5 defines the valid register command
sequences. Writing incorrect address and data val-
ues or writing them in the improper sequence resets
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 appropriate timing diagrams in the
“AC Characteristics” section.
Reading Array Data
The device is automatically set to reading array data
after device power-up. No commands are required to
retrieve data. The device is also ready to read array
data after completing an Embedded Program or Em-
bedded Erase algorithm.
After the device accepts an Erase Suspend command,
the device enters the Erase Suspend mode. The sys-
tem can read array data using the standard read tim-
ings, except that if it reads at an address within erase-
suspended sectors, the device outputs status data.
After completing a programming operation in the Erase
Suspend mode, the system may once again read array
data with the same exception. See “Erase Sus-
pend/Erase Resume Commands” for more information
on this mode.
The system must issue the reset command to re-ena-
ble the device for reading array data if DQ5 goes high,
or while in the autoselect mode. See the “Reset Com-
mand” section, next.
See also “Requirements for Reading Array Data” in the
“Device Bus Operations” section for more information.
The Read Operations table provides the read parame-
ters, and Figure 12 shows the timing diagram.
Reset Command
Writing the reset command to the device resets the de-
vice to reading array data. Address bits are don’t care
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 device to reading array
data. Once erasure begins, however, the device ig-
nores reset commands until the operation is complete.
The reset command may be written between the se-
quence cycles in a program command sequence be-
fore programming begins. This resets the device to
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.
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 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 read-
ing array data (also applies during Erase Suspend).
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