at49bv040-15ci ATMEL Corporation, at49bv040-15ci Datasheet - Page 2

• Manufacturer Part Number: at49bv040-15ci
• Description: 4-megabit 512k X 8 Single 2.7-volt Battery-voltage Flash Memory
• Manufacturer: ATMEL Corporation

To allow for simple in-system reprogrammability, the
AT49BV/LV040 does not require high input voltages for
programming. Three-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/LV040 is performed by eras-
ing the entire 4 megabits of memory and then programming
on a byte-by-byte basis. The typical byte programming
time is a fast 30 s. 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
Block Diagram
Device Operation
READ: The AT49BV/LV040 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 con-
tention.
ERASURE: Before a byte can be reprogrammed, the
512K bytes memory array (or 496K 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 t
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 pro-
grammed back to a “1”; only erase operations can convert
2
AT49BV/LV040
ADDRESS
EC
INPUTS
. If the boot block lockout feature has
GND
V
WE
OE
CE
CC
OE, CE, AND WE
Y DECODER
X DECODER
LOGIC
DATA INPUTS/OUTPUTS
BLOCK (16K BYTES)
OPTIONAL BOOT
INPUT/OUTPUT
MAIN MEMORY
(496K BYTES)
DATA LATCH
Y-GATING
AT49BV/LV040
I/O7 - I/O0
BUFFERS
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 repro-
gramming write lock out feature to provide data integrity.
The boot sector is designed to contain user secure code,
and when the feature is enabled, the boot sector is perma-
nently protected from being reprogrammed.
“0”s to “1”s. Programming is accomplished via the internal
device command register and is a 4 bus cycle operation
(please refer to the Command Definitions table). The
device will automatically generate the required internal pro-
gram 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 t
cycle time. The DATA polling feature may 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 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 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
o p t i o n a l t o t h e u s e r . T h e a d d r e s s r a n g e o f t h e
AT49BV/LV040 boot block is 00000H to 03FFFH while the
address range of the AT49BV/LV040T boot block is
7C000H to 7FFFFH.
8
7FFFFH
03FFFH
00000H
DATA INPUTS/OUTPUTS
BLOCK (16K BYTES)
OPTIONAL BOOT
INPUT/OUTPUT
MAIN MEMORY
(496K BYTES)
DATA LATCH
AT49BV/LV040T
Y-GATING
I/O7 - I/O0
BUFFERS
8
7FFFFH
7C000H
00000H
BP