at49bv4096 ATMEL Corporation, at49bv4096 Datasheet - Page 3

• Manufacturer Part Number: at49bv4096
• Description: 4-megabit 256k X 16 3-volt Only Flash Memory
• Manufacturer: ATMEL Corporation

CHIP ERASE: The entire device can be erased at one time
by using the 6-byte chip erase software code. After the chip
erase has been initiated, the device will internally time the
erase operation so that no external clocks are required.
The maximum time to erase the chip is t
If the boot block lockout has been enabled, the Chip Erase
will not erase the data in the boot block; it will erase the
main memory block and the parameter blocks only. After
the chip erase, the device will return to the read or standby
mode.
SECTOR ERASE: As an alternative to a full chip erase, the
device is organized into three sectors that can be individu-
ally erased. There are two 8K word parameter block sec-
tions and one sector consisting of the boot block and the
main memory array block. The Sector Erase command is a
six bus cycle operation. The sector address is latched on
the falling WE edge of the sixth cycle while the 30H data
input command is latched at the rising edge of WE. The
sector erase starts after the rising edge of WE of the sixth
cycle. The erase operation is internally controlled; it will
automatically time to completion. When the boot block pro-
gramming lockout feature is not enabled, the boot block
and the main memory block will erase together (from the
same sector erase command). Once the boot region has
been protected, only the main memory array sector will
erase when its sector erase command is issued.
WORD PROGRAMMING: Once a memory block is erased,
it is programmed (to a logical “0”) on a word-by-word basis.
Programming is accomplished via the internal device com-
mand register and is a 4 bus cycle operation. The device
will automatically generate the required internal program
pulses.
Any commands written to the chip during the embedded
programming cycle will be ignored. If a hardware reset hap-
pens during programming, the data at the location being
programmed will be corrupted. Please note that a data “0”
cannot be programmed back to a “1”; only erase operations
can convert “0”s to “1”s. Programming is completed after
the specified t
also be used to indicate the end of a program cycle.
BOOT BLOCK PROGRAMMING LOCKOUT: The device
has one designated block that has a programming lockout
feature. This feature prevents programming of data in the
designated block once the feature has been enabled. The
size of the block is 8K words. This block, referred to as the
boot block, can contain secure code that is used to bring up
the system. Enabling the lockout feature will allow the boot
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 01FFFH.
BP
cycle time. The DATA polling feature may
EC
.
Once the feature is enabled, the data in the boot block can
no longer be erased or programmed when input levels of
5.5V or less are used. Data in the main memory block can
still be changed through the regular programming method.
To activate the lockout feature, a series of six program
commands to specific addresses with specific 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 enabled and the block cannot be pro-
grammed. The software product identification exit code
should be used to return to standard operation.
BOOT BLOCK PROGRAMMING LOCKOUT OVERRIDE:
The user can override the boot block programming lockout
by taking the RESET pin to 12
protected boot block data can be altered through a chip
erase, sector erase or word programming. When the
RESET pin is brought back to TTL levels the boot block
programming lockout feature is again active.
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 (for hardware operation)
or Software Product Identification. The manufacturer and
device code is the same for both modes.
DATA POLLING: The AT49BV4096/LV4096 features DATA
polling to indicate the end of a program cycle. During a pro-
gram 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. During a chip
or sector erase operation, an attempt to read the device will
give a “0” on I/O7. Once the program or erase cycle has
completed, true data will be read from the device. 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 DATA p o l l i n g t h e
AT49BV4096/LV4096 provides another method for deter-
mining the end of a program or erase cycle. During a pro-
gram 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
toggling and valid data will be read. Examining the toggle
bit may begin at any time during a program cycle.
0.5 volts. By doing this
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