AT49F040B ATMEL [ATMEL Corporation], AT49F040B Datasheet - Page 3

• Manufacturer Part Number: AT49F040B
• Description: 4-megabit (512K x 8) 5-volt Only Flash Memory
• Manufacturer: ATMEL [ATMEL Corporation]

3. Block Diagram
4. Device Operation
4.1
4.2
4.3
3606A–FLASH–12/05
Command Sequences
Read
Erase
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.
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.
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.
ADDRESS
INPUTS
GND
VCC
WE
OE
CE
Y DECODER
X DECODER
CONTROL
LOGIC
DATA INPUTS/OUTPUTS
DATA LATCHES
INPUT/OUTPUT
MAIN MEMORY
MAIN MEMORY
MAIN MEMORY
MAIN MEMORY
MAIN MEMORY
MAIN MEMORY
MAIN MEMORY
MAIN MEMORY
BOOT SECTOR
PARAMETER
PARAMETER
(64K BYTES)
(64K BYTES)
(64K BYTES)
(64K BYTES)
(64K BYTES)
(64K BYTES)
(64K BYTES)
(32K BYTES)
(16K BYTES)
(8K BYTES)
(8K BYTES)
PROGRAM
SECTOR 8
SECTOR 7
SECTOR 6
SECTOR 5
SECTOR 4
SECTOR 3
SECTOR 2
SECTOR 1
SECTOR 2
SECTOR 1
Y-GATING
I/O7 - I/O0
BUFFERS
8
7FFFF
70000
6FFFF
60000
5FFFF
50000
4FFFF
40000
3FFFF
30000
2FFFF
20000
1FFFF
10000
0FFFF
08000
07FFF
06000
05FFF
04000
03FFF
00000
AT49F040B
3