Features
•
Single-voltage Operation
•
•
•
– 5V Read
– 5V Reprogramming
Fast Read Access Time – 55 ns
Internal Program Control and Timer
Sector Architecture
– One 16K Bytes Boot Block with Programming Lockout
– Two 8K Bytes Parameter Blocks
– Four Main Memory Blocks (One 32K Bytes, Three 64K Bytes)
Fast Erase Cycle Time – 4 Seconds
Byte-by-Byte Programming – 20 µs/Byte Typical
Hardware Data Protection
DATA Polling for End of Program Detection
Low Power Dissipation
– 25 mA Active Current
– 100 µA CMOS Standby Current
Typical 10,000 Write Cycles
•
•
•
•
•
•
2-megabit
(256K x 8)
5-volt Only
Flash Memory
AT49F002A
AT49F002AN
AT49F002AT
AT49F002ANT
Description
The AT49F002A(N)(T) is a 5-volt only in-system reprogrammable Flash memory. Its
2 megabits of memory is organized as 262,144 words by 8 bits. Manufactured with
Atmel’s advanced nonvolatile CMOS technology, the device offers access times to
55 ns with power dissipation of just 137 mW over the industrial temperature range.
Pin Configurations
Pin Name
A0 - A17
CE
OE
WE
RESET
I/O0 - I/O7
Function
Addresses
Chip Enable
Output Enable
Write Enable
RESET
Data Inputs/Outputs
DIP Top View
* RESET
A16
A15
A12
A7
A6
A5
A4
A3
A2
A1
A0
I/O0
I/O1
I/O2
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
VCC
WE
A17
A14
A13
A8
A9
A11
OE
A10
CE
I/O7
I/O6
I/O5
I/O4
I/O3
PLCC Top View
VSOP Top View (8 x 14 mm) or
TSOP Top View (8 x 20 mm)
Type 1
A14
A13
A8
A9
A11
OE
A10
CE
I/O7
A11
A9
A8
A13
A14
A17
WE
VCC
* RESET
A16
A15
A12
A7
A6
A5
A4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
OE
A10
CE
I/O7
I/O6
I/O5
I/O4
I/O3
GND
I/O2
I/O1
I/O0
A0
A1
A2
A3
I/O1
I/O2
GND
I/O3
I/O4
I/O5
I/O6
14
15
16
17
18
19
20
A7
A6
A5
A4
A3
A2
A1
A0
I/O0
5
6
7
8
9
10
11
12
13
4
3
2
1
32
31
30
A12
A15
A16
RESET *
VCC
WE
A17
29
28
27
26
25
24
23
22
21
3354D–FLASH–8/03
Note:
*This pin is a NC on the AT49F002AN(T).
1
When the device is deselected, the CMOS standby current is less than 100 µA. For the
AT49F002AN(T) pin 1 for the DIP and PLCC packages and pin 9 for the TSOP package are no
connect pins.
To allow for simple in-system reprogrammability, the AT49F002A(N)(T) does not require high
input voltages for programming. Five-volt-only commands determine the read and program-
ming operation of the device. Reading data out of the device is similar to reading from an
EPROM; it has standard CE, OE, and WE inputs to avoid bus contention. Reprogramming the
AT49F002A(N)(T) is performed by erasing a block of data and then programming on a byte by
byte basis. The byte programming time is a fast 20 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 number of program
and erase cycles is in excess of 10,000 cycles.
The device is erased by executing the erase command sequence; the device internally con-
trols the erase operations. There are two 8K byte parameter block sections, four main memory
blocks, and one boot block.
The device has the capability to protect the data in the boot block; this feature is enabled by a
command sequence. The 16K-byte boot block section includes a reprogramming lock out fea-
ture to provide data integrity. The boot sector is designed to contain user secure code, and
when the feature is enabled, the boot sector is protected from being reprogrammed.
In the AT49F002A(N)(T), once the boot block programming lockout feature is enabled, the
contents of the boot block are permanent and cannot be changed. In the AT49F002A(T), once
the boot block programming lockout feature is enabled, the contents of the boot block cannot
be changed with input voltage levels of 5.5 volts or less.
Block Diagram
AT49F002A(N)
DATA INPUTS/OUTPUTS
I/O7 - I/O0
VCC
GND
OE
WE
CE
RESET
8
INPUT/OUTPUT
BUFFERS
PROGRAM
DATA LATCHES
Y-GATING
MAIN MEMORY
BLOCK 4
(64K BYTES)
MAIN MEMORY
BLOCK 3
(64K BYTES)
MAIN MEMORY
BLOCK 2
(64K BYTES)
MAIN MEMORY
BLOCK 1
(32K BYTES)
PARAMETER
BLOCK 2
(8K BYTES)
PARAMETER
BLOCK 1
(8K BYTES)
BOOT BLOCK
(16K BYTES)
3FFFF
AT49F002A(N)T
DATA INPUTS/OUTPUTS
I/O7 - I/O0
8
INPUT/OUTPUT
BUFFERS
PROGRAM
DATA LATCHES
Y-GATING
3FFFF
BOOT BLOCK
(16K BYTES)
PARAMETER
BLOCK 1
(8K BYTES)
PARAMETER
BLOCK 2
(8K BYTES)
MAIN MEMORY
BLOCK 1
(32K BYTES)
MAIN MEMORY
BLOCK 2
(64K BYTES)
MAIN MEMORY
BLOCK 3
(64K BYTES)
MAIN MEMORY
BLOCK 4
(64K BYTES)
3C000
3BFFF
CONTROL
LOGIC
Y DECODER
ADDRESS
INPUTS
X DECODER
30000
2FFFF
20000
1FFFF
3A000
39FFF
10000
0FFFF
38000
37FFF
08000
07FFF
30000
2FFFF
06000
05FFF
20000
1FFFF
04000
03FFF
00000
10000
0FFFF
00000
2
AT49F002A(N)(T)
3354D–FLASH–8/03
AT49F002A(N)(T)
Device
Operation
READ:
The AT49F002A(N)(T) 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.
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 command 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 com-
mand sequences.
RESET:
A RESET input pin is provided to ease some system applications. When RESET is at
a logic high level, the device is in its standard operating mode. A low level on the RESET input
halts the present device operation and puts the outputs of the device in a high impedance
state. If the RESET pin makes a high to low transition during a program or erase operation, the
operation may not be successfully completed and the operation will have to be repeated after
a high level is applied to the RESET pin. When a high level is reasserted on the RESET pin,
the device returns to the read or standby mode, depending upon the state of the control inputs.
By applying a 12V ± 0.5V input signal to the RESET pin, the boot block array can be repro-
grammed even if the boot block lockout feature has been enabled (see Boot Block
Programming Lockout Override section). The RESET feature is not available for the
AT49F002AN(T).
ERASURE:
Before a byte can be reprogrammed, the main memory block or parameter block
which contains the byte 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 commands 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 opera-
tion so that no external clocks are required. The maximum time needed to erase the whole
chip is t
EC
. If the boot block lockout feature has been enabled, the data in the boot sector will
not be erased.
CHIP ERASE:
If the boot block lockout has been enabled, the Chip Erase function will erase
Parameter Block 1, Parameter Block 2, Main Memory Block 1-4 but not the boot block. If the
Boot Block Lockout has not been enabled, the Chip Erase function will erase the entire chip.
After the full chip erase the device will return back to read mode. Any command during chip
erase will be ignored.
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3354D–FLASH–8/03
SECTOR ERASE:
As an alternative to a full chip erase, the device is organized into sectors
that can be individually erased. There are two 8K-byte parameter block sections and four main
memory blocks. The 8K-byte parameter block sections and the four main memory blocks can
be independently erased and reprogrammed. The Sector Erase command is a six bus cycle
operation. The sector address is latched on the falling WE edge of the sixth cycle while the
30H data input command is latched at the rising edge of WE. The sector erase starts after the
rising edge of WE of the sixth cycle. The erase operation is internally controlled; it will auto-
matically time to completion.
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 convert “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 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. Program-
ming is completed after the specified t
BP
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 activated; the boot block’s usage as
a write protected region is optional to the user. The address range of the boot block is 00000
to 03FFF for the AT49F002A(N) while the address range of the boot block is 3C000 to 3FFFF
for the AT49F002A(N)T.
Once the feature is enabled, the data in the boot block can no longer be erased or pro-
grammed with input voltage levels of 5.5V or less. Data in the main memory block can still be
changed through the regular programming method. To activate the lockout feature, a series of
six program commands to specific addresses with specific data must be performed. Please
refer to the Command Definitions table.
BOOT BLOCK LOCKOUT DETECTION:
A software method is available to determine if pro-
gramming of the boot block section is locked out. When the device is in the software product
identification mode (see Software Product Identification Entry and Exit sections) a read from
address location 00002H will show if programming the boot block is locked out for the
AT49F002A(N), and a read from address location 3C002H will show if programming the boot
block is locked out for AT49F002A(N)T. If the data on I/O0 is low, the boot block can be pro-
grammed; if the data on I/O0 is high, the program lockout feature has been activated and the
block cannot be programmed. The software product identification exit code should be used to
return to standard operation.
4
AT49F002A(N)(T)
3354D–FLASH–8/03
AT49F002A(N)(T)
BOOT BLOCK PROGRAMMING LOCKOUT OVERRIDE:
The user can override the boot
block programming lockout by taking the RESET pin to 12 volts. By doing this, protected boot
block data can be altered through a chip erase, sector erase or word programming. When the
RESET pin is brought back to TTL levels the boot block programming lockout feature is again
active. This feature is not available on the AT49F002AN(T).
PRODUCT IDENTIFICATION:
The product identification mode identifies the device and man-
ufacturer as Atmel. It may be accessed by hardware or software operation. The hardware
operation mode can be used by an external programmer to identify the correct programming
algorithm for the Atmel product.
For details, see Operating Modes (for hardware operation) or Software Product Identification.
The manufacturer and device code is the same for both modes.
DATA POLLING:
The AT49F002A(N)(T) features DATA polling to indicate the end of a pro-
gram cycle. During a program cycle an attempted read of the last byte loaded will result in the
complement of the loaded data on I/O7. Once the program cycle has been completed, true
data is valid on all outputs and the next cycle may begin. DATA polling may begin at any time
during the program cycle.
TOGGLE BIT:
In addition to DATA polling the AT49F002A(N)(T) provides another method for
determining the end of a program or erase cycle. During a program or erase operation, suc-
cessive attempts to read data from the device will result in I/O6 toggling between one and
zero. Once the program cycle has completed, I/O6 will stop toggling and valid data will be
read. Examining the toggle bit may begin at any time during a program cycle.
HARDWARE DATA PROTECTION:
Hardware features protect against inadvertent programs
to the AT49F002A(N)(T) in the following ways: (a) V
CC
sense: if V
CC
is below 3.8V (typical), the
program function is inhibited. (b) Program inhibit: holding any one of OE low, CE high or WE
high inhibits program cycles. (c) Noise filter: pulses of less than 15 ns (typical) on the WE or
CE inputs will not initiate a program cycle.
5
3354D–FLASH–8/03
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