AT49BV-LV040 ATMEL Corporation, AT49BV-LV040 Datasheet - Page 3

• Manufacturer Part Number: AT49BV-LV040
• Description: 4-megabit (512K x 8) Single 2.7-volt Battery-Voltage Flash Memory
• Manufacturer: ATMEL Corporation

code to stay in the device while data in the rest of the
device is updated. This feature does not have to be acti-
vated; the boot block’s usage as a write-protected region is
optional to the user. The address range of the boot block is
00000H to 03FFFH.
Once the feature is enabled, the data in the boot block can
no longer be erased or programmed. Data in the main
memory block can still be changed through the regular pro-
gramming method. To activate the lockout feature, a series
of six program commands to specific addresses with spe-
cific data must be performed. Please refer to the Command
Definitions table.
BOOT BLOCK LOCKOUT DETECTION: A software
method is available to determine if programming of the boot
block section is locked out. When the device is in the soft-
ware product identification mode (see Software Product
Identification Entry and Exit sections) a read from address
location 00002H will show if programming the boot block is
locked out. If the data on I/O0 is low, the boot block can be
programmed; if the data on I/O0 is high, the program lock-
out feature has been activated and the block cannot be
programmed. The software product identification code
should be used to return to standard operation.
PRODUCT IDENTIFICATION: The product identification
mode identifies the device and manufacturer as Atmel.
It may be accessed by hardware or software operation. The
hardware operation mode can be used by an external pro-
grammer to identify the correct programming algorithm for
the Atmel product.
For details, see “Operating Modes” on page 5 (for hard-
ware operation) or “Software Product Identification
Entry/Exit” on page 10. The manufacturer and device
codes are the same for both modes.
DATA POLLING: The AT49BV/LV040 features Data Poll-
ing to indicate the end of a program cycle. During a
program cycle, an attempted read of the last byte loaded
will result in the complement of the loaded data on I/O7.
Once the program cycle has been completed, true data is
valid on all outputs and the next cycle may begin. Data
Polling may begin at any time during the program cycle.
TO G G L E B I T: I n a d d i t i o n t o D a t a P o l l i n g , t h e
AT49BV/LV040 provides another method for determining
the end of a program or erase cycle. During a program or
erase operation, successive attempts to read data from the
device will result in I/O6 toggling between one and zero.
Once the program cycle has completed, I/O6 will stop tog-
gling and valid data will be read. Examining the toggle bit
may begin at any time during a program cycle.
HARDWARE DATA PROTECTION: The Hardware Data
Protection feature protects against inadvertent programs to
the AT49BV/LV040 in the following ways: (a) V
V
ited. (b) Program inhibit: holding any one of OE low, CE
high or WE high inhibits program cycles. (c) Noise filter:
pulses of less than 15 ns (typical) on the WE or CE inputs
will not initiate a program cycle.
INPUT LEVELS: While operating with a 2.7V to 3.6V
power supply, the address inputs and control inputs (OE,
CE and WE) may be driven from 0 to 5.5V without
adversely affecting the operation of the device. The I/O
lines can only be driven from 0 to V
CC
is below 1.8V (typical), the program function is inhib-
AT49BV/LV040
CC
+ 0.6V.
CC
sense: if
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