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AT49F8011 Datasheet(PDF) 4 Page - ATMEL Corporation

Part No. AT49F8011
Description  8-megabit (512K x 16/ 1M x 8) 5-volt Only Flash Memory
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Maker  ATMEL [ATMEL Corporation]
Homepage  http://www.atmel.com
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AT49F8011 Datasheet(HTML) 4 Page - ATMEL Corporation

 
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AT49F8011(T)
1264D–FLASH–5/03
ERASURE: Before a byte/word can be reprogrammed, it must be erased. The erased state of
memory bits is a logical “1”. The entire device can be erased by using the Chip Erase com-
mand or individual sectors can be erased by using the Sector Erase commands.
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 tEC.
If the sector lockout has been enabled, the Chip Erase will not erase the data in the sector that
has been locked; it will erase only the unprotected sectors. 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 22 sec-
tors that can be individually erased. 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 on 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. The maximum time to erase a section is tSEC. When the sector program-
ming lockout feature is not enabled, the sector will erase (from the same sector erase
command). Once a sector has been protected, data in the protected sectors cannot be
changed unless the RESET pin is taken to 12V ± 0.5V. An attempt to erase a sector that has
been protected will result in the operation terminating in 2 µs.
BYTE/WORD PROGRAMMING: Once a memory block is erased, it is programmed (to a logi-
cal “0”) on a byte-by-byte or on a word-by-word basis. Programming is accomplished via the
internal device command 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 happens 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 tBP cycle
time. The DATA polling feature or the toggle bit feature may be used to indicate the end of a
program cycle.
SECTOR PROGRAMMING LOCKOUT: Each sector has a programming lockout feature. This
feature prevents programming of data in the designated sectors once the feature has been
enabled. These sectors 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 activated; any sector’s usage as a write
protected region is optional to the user.
Once the feature is enabled, the data in the protected sectors can no longer be erased or pro-
grammed when input levels of 5.5V or less are used. Data in the remaining sectors 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.
SECTOR LOCKOUT DETECTION: A software method is available to determine if program-
ming of a sector is locked out. When the device is in the software product identification mode
(see Software product Identification Entry and Exit sections) a read from address location
00002H within a sector will show if programming the sector is locked out. If the data on I/O0 is
low, the sector can be programmed; if the data on I/O0 is high, the program lockout feature
has been enabled and the sector cannot be programmed. The software product identification
exit code should be used to return to standard operation.
SECTOR PROGRAMMING LOCKOUT OVERRIDE: The user can override the sector pro-
gramming lockout by taking the RESET pin to 12V ± 0.5V. By doing this protected data can be
altered through a chip erase, sector erase or byte/word programming. When the RESET pin is
brought back to TTL levels the sector programming lockout feature is again active.


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