AM29LV001B AMD [Advanced Micro Devices], AM29LV001B Datasheet - Page 12

• Manufacturer Part Number: AM29LV001B
• Description: 1 Megabit (128 K x 8-Bit) CMOS 3.0 Volt-only Boot Sector Flash Memory
• Manufacturer: AMD [Advanced Micro Devices]

Hardware Data Protection
The command sequence requirement of unlock cycles
for programming or erasing provides data protection
COMMAND DEFINITIONS
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.
Notes:
1. All protected sectors unprotected.
2. All previously protected sectors are protected once
Figure 2. Temporary Sector Unprotect Operation
again.
Unprotect Completed
Program Operations
Temporary Sector
Perform Erase or
RESET# = V
RESET# = V
(Note 1)
(Note 2)
START
ID
IH
21557C-5
P R E L I M I N A R Y
Am29LV001B
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 V
power-down transitions, or from system noise.
Low V
When V
cept any write cycles. This protects data during V
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 V
is greater than V
proper signals to the control pins to prevent uninten-
tional writes when V
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# =
V
CE# and WE# must be a logical zero while OE# is a
logical one.
Power-Up Write Inhibit
If WE# = CE# = V
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.
After the device accepts an Erase Suspend com-
mand, the device enters the Erase Suspend mode.
The system can read array data using the standard
read timings, except that if it reads at an address
within erase-suspended sectors, the device outputs
status data. After completing a programming opera-
tion in the Erase Suspend mode, the system may
once again read array data with the same exception.
See “Erase Suspend/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 13 shows the timing diagram.
IL
, CE# = V
CC
CC
Write Inhibit
is less than V
IH
or WE# = V
IL
LKO
and OE# = V
CC
. The system must provide the
is greater than V
LKO
IH
, the device does not ac-
. To initiate a write cycle,
IH
during power up, the
CC
LKO
power-up and
.
12
CC
CC