AT48BV080-12TC 查看數據表（PDF） - Atmel Corporation
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AT48BV080-12TC Datasheet PDF : 12 Pages
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Description (Continued)
To allow for simple in-system reprogrammability, the
AT49BV/LV080 does not require high input voltages for
programming. 3-volt-only commands determine the read
and programming operation of the device. Reading data
out of the device is similar to reading from an EPROM.
Reprogramming the AT49BV/LV080 is performed by eras-
ing the entire 8 megabits of memory and then program-
ming on a byte-by-byte basis. The typical byte program-
ming time is a fast 30 µs. The end of a program cycle can
be optionally detected by the DATA polling feature. Once
the end of a byte program cycle has been detected, a new
access for a read or program can begin. The typical num-
ber of program and erase cycles is in excess of 10,000
cycles.
The optional 16K bytes boot block section includes a re-
programming write lock out feature to provide data integ-
rity. The boot sector is designed to contain user secure
code, and when the feature is enabled, the boot sector is
permanently protected from being reprogrammed.
Block Diagram
AT49BV/LV080
AT49BV/LV080T
VCC
GND
DATA INPUTS/OUTPUTS
I/O7 - I/O0
8
DATA INPUTS/OUTPUTS
I/O7 - I/O0
8
OE
OE, CE, AND WE
WE
LOGIC
CE
DATA LATCH
INPUT/OUTPUT
BUFFERS
DATA LATCH
INPUT/OUTPUT
BUFFERS
ADDRESS
INPUTS
Y DECODER
X DECODER
Device Operation
Y-GATING
MAIN MEMORY
(1008K BYTES)
OPTIONAL BOOT
BLOCK (16K BYTES)
FFFFFH
03FFFH
00000H
Y-GATING
OPTIONAL BOOT
BLOCK (16K BYTES)
MAIN MEMORY
(1008K BYTES)
FFFFFH
FC000H
00000H
READ: The AT49BV/LV080 is accessed like an EPROM.
When CE and OE are low and WE is high, the data stored
at the memory location determined by the address pins is
asserted on the outputs. The outputs are put in the high
impedance state whenever CE or OE is high. This dual-
line control gives designers flexibility in preventing bus
contention.
ERASURE: Before a byte can be reprogrammed, the
1024K bytes memory array (or 1008K bytes if the boot
block featured is used) must be erased. The erased state
of the memory bits is a logical “1”. The entire device can
be erased at one time by using a 6-byte software code.
The software chip erase code consists of 6-byte load com-
mands to specific address locations with a specific data
pattern (please refer to the Chip Erase Cycle Waveforms).
After the software chip erase has been initiated, the device
will internally time the erase operation so that no external
clocks are required. The maximum time needed to erase
the whole chip is tEC. If the boot block lockout feature has
been enabled, the data in the boot sector will not be
erased.
BYTE PROGRAMMING: Once the memory array is
erased, the device is programmed (to a logical “0”) on a
byte-by-byte basis. Please note that a data “0” cannot be
programmed back to a “1”; only erase operations can con-
vert “0”s to “1”s. Programming is accomplished via the in-
ternal device command register and is a 4 bus cycle op-
eration (please refer to the Command Definitions table).
The device will automatically generate the required inter-
nal program pulses.
The program cycle has addresses latched on the falling
edge of WE or CE, whichever occurs last, and the data
latched on the rising edge of WE or CE, whichever occurs
first. Programming is completed after the specified tBP cy-
cle time. The DATA polling feature may also be used to
indicate the end of a program cycle.
BOOT BLOCK PROGRAMMING LOCKOUT: The de-
vice 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 16K bytes. This block,
referred to as the boot block, can contain secure code that
is used to bring up the system. Enabling the lockout fea-
ture 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; the boot block’s usage as a write
protected region is optional to the user. The address
range of the AT49BV/LV080 boot block is 00000H to
03FFFH while the address range of the AT49BV/LV080T
boot block is FC000H to FFFFFH.
To activate the lockout feature, a series of six program
commands to specific addresses with specific data must
2 AT49BV/LV080
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