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AT29C040A-12TC Datasheet(PDF) 4 Page - ATMEL Corporation

Part No. AT29C040A-12TC
Description  4-megabit (512K x 8) 5-volt Only 256-byte Sector Flash Memory
Download  17 Pages
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Maker  ATMEL [ATMEL Corporation]
Homepage  http://www.atmel.com
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AT29C040A-12TC Datasheet(HTML) 4 Page - ATMEL Corporation

 
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AT29C040A
0333I–FLASH–05/02
BOOT BLOCK PROGRAMMING LOCKOUT:
The AT29C040A has two designated memory
blocks that have a programming lockout feature. This feature prevents programming of data in
the designated block once the feature has been enabled. Each of these blocks consists of 16K
bytes; the programming lockout feature can be set independently for either block. While the
lockout feature does not have to be activated, it can be activated for either or both blocks.
These two 16K memory sections are referred to as
boot blocks. Secure code which will bring
up a system can be contained in a boot block. The AT29C040A blocks are located in the first
16K bytes of memory and the last 16K bytes of memory. The boot block programming lockout
feature can therefore support systems that boot from the lower addresses of memory or the
higher addresses. Once the programming lockout feature has been activated, the data in that
block can no longer be erased or programmed; data in other memory locations can still be
changed through the regular programming methods. To activate the lockout feature, a series
of seven program commands to specific addresses with specific data must be performed.
Please see Boot Block Lockout Feature Enable Algorithm.
If the boot block lockout feature has been activated on either block, the chip erase function will
be disabled.
BOOT BLOCK LOCKOUT DETECTION:
A software method is available to determine
whether programming of either boot block section is locked out. See Software Product Identifi-
cation Entry and Exit sections. When the device is in the software product identification mode,
a read from location 00002H will show if programming the lower address boot block is locked
out while reading location 7FFF2H will do so for the upper boot block. If the data is FE, the cor-
responding block can be programmed; if the data is FF, the program lockout feature has been
activated and the corresponding block cannot be programmed. The software product identifi-
cation exit mode should be used to return to standard operation.
Absolute Maximum Ratings*
Temperature Under Bias ................................ -55
°Cto+125°C
*NOTICE:
Stresses beyond those listed under “Absolute
Maximum Ratings” may cause permanent dam-
age to the device. This is a stress rating only and
functional operation of the device at these or any
other conditions beyond those indicated in the
operational sections of this specification is not
implied. Exposure to absolute maximum rating
conditions for extended periods may affect
device reliability.
Storage Temperature ..................................... -65
°Cto+150°C
All Input Voltages (including NC Pins)
with Respect to Ground ...................................-0.6V to +6.25V
All Output Voltages
with Respect to Ground .............................-0.6V to VCC +0.6V
Voltage on OE
with Respect to Ground ...................................-0.6V to +13.5V


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