AT49F040B 查看數據表（PDF） - Atmel Corporation
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AT49F040B Datasheet PDF : 19 Pages
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AT49F040B
3. Block Diagram
VCC
GND
OE
WE
CE
ADDRESS
INPUTS
CONTROL
LOGIC
Y DECODER
X DECODER
DATA INPUTS/OUTPUTS
I/O7 - I/O0
8
INPUT/OUTPUT
BUFFERS
PROGRAM
DATA LATCHES
Y-GATING
MAIN MEMORY
SECTOR 8
(64K BYTES)
MAIN MEMORY
SECTOR 7
(64K BYTES)
MAIN MEMORY
SECTOR 6
(64K BYTES)
MAIN MEMORY
SECTOR 5
(64K BYTES)
MAIN MEMORY
SECTOR 4
(64K BYTES)
MAIN MEMORY
SECTOR 3
(64K BYTES)
MAIN MEMORY
SECTOR 2
(64K BYTES)
MAIN MEMORY
SECTOR 1
(32K BYTES)
PARAMETER
SECTOR 2
(8K BYTES)
PARAMETER
SECTOR 1
(8K BYTES)
BOOT SECTOR
(16K BYTES)
7FFFF
70000
6FFFF
60000
5FFFF
50000
4FFFF
40000
3FFFF
30000
2FFFF
20000
1FFFF
10000
0FFFF
08000
07FFF
06000
05FFF
04000
03FFF
00000
4. Device Operation
4.1 Command Sequences
When the device is first powered on, it will be reset to the read or standby mode depending upon
the state of the control line inputs. In order to perform other device functions, a series of com-
mand sequences are entered into the device. The command sequences are shown in the
Command Definitions table. The command sequences are written by applying a low pulse on the
WE or CE input with CE or WE low (respectively) and OE high. The address is latched on the
falling edge of CE or WE, whichever occurs last. The data is latched by the first rising edge of
CE or WE. Standard microprocessor write timings are used. The address locations used in the
command sequences are not affected by entering the command sequences.
4.2 Read
The AT49F040B 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 con-
trol gives designers flexibility in preventing bus contention.
4.3 Erase
Before a byte 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 command or individual sec-
tors can be erased by using the Sector Erase command.
3
3606A–FLASH–12/05
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