Features
•
Single Voltage Operation
•
•
•
– 5V Read
– 5V Reprogramming
Fast Read Access Time - 55 ns
Internal Program Control and Timer
Sector Architecture
– One 16K Byte Boot Block with Programming Lockout
– Two 8K Byte Parameter Blocks
– Two Main Memory Blocks (96K, 128K) Bytes
Fast Erase Cycle Time - 10 seconds
Byte By Byte Programming - 10
µ
s/Byte Typical
Hardware Data Protection
DATA Polling For End Of Program Detection
Low Power Dissipation
– 50 mA Active Current
– 100
µ
A CMOS Standby Current
Typical 10,000 Write Cycles
•
•
•
•
•
•
Description
The AT49F002(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 275 mW over the commercial temperature range.
2-Megabit
(256K x 8)
5-volt Only
CMOS Flash
Memory
AT49F002T
AT49F002NT
Pin Configurations
Pin Name
A0 - A17
CE
OE
WE
RESET
I/O0 - I/O7
NC
Function
Addresses
Chip Enable
Output Enable
Write Enable
RESET
Data Inputs/Outputs
No Connect
PLCC Top View
A12
A15
A16
RESET *
VCC
WE
A17
(continued)
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
TSOP Top View
Type 1
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
29
28
27
26
25
24
23
22
21
A14
A13
A8
A9
A11
OE
A10
CE
I/O7
0920B-B–12/97
*Note: This pin is a NC on the AT49F002NT.
1
When the device is deselected, the CMOS standby current
is less than 100
µA.
For the AT49F002NT 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
AT49F002(N)T does not require high input voltages for pro-
gramming. Five-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; it
has standard CE, OE, and WE inputs to avoid bus conten-
tion. Reprogramming the AT49F002(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 50
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 pro-
gram 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 controls the erase opera-
tions. There are two 8K byte parameter block sections and
two main memory blocks.
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 feature to provide data integrity. The boot sector is
designed to contain user secure code, and when the fea-
ture is enabled, the boot sector is protected from being
reprogrammed.
In the AT49F002NT, once the boot block programming
lockout feature is enabled, the contents of the boot block
are permanent and cannot be changed. In the AT49F002T,
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
DATA INPUTS/OUTPUTS
I/O7 - I/O0
V
CC
GND
OE
WE
CE
RESET
8
INPUT/OUTPUT
BUFFERS
PROGRAM
DATA LATCHES
Y-GATING
3FFFF
X DECODER
BOOT BLOCK
(16K BYTES)
PARAMETER
BLOCK 1
(8K BYTES)
PARAMETER
BLOCK 2
(8K BYTES)
MAIN MEMORY
BLOCK 1
(96K BYTES)
MAIN MEMORY
BLOCK 2
(128K BYTES)
3C000
3BFFF
CONTROL
LOGIC
Y DECODER
ADDRESS
INPUTS
3A000
39FFF
38000
37FFF
20000
1FFFF
00000
2
AT49F002(N)T
AT49F002(N)T
Device Operation
READ:
The AT49F002(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 conten-
tion.
COMMAND SEQUENCES:
When the device is first pow-
ered 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 (respec-
tively) 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 loca-
tions used in the command sequences are not affected by
entering the command sequences.
RESET:
A RESET input pin is provided to ease some sys-
tem 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 impedence state. If the
RESET pin makes a high to low transition during a program
or erase operation, the operation may not be sucessfully
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 reprogrammed
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 AT49F002NT.
0ERASURE:
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 operation 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, and Main Mem-
ory Block 2 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.
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 two main memory blocks. The 8K-byte parameter
block sections can be independently erased and repro-
grammed. The two main memory sections are designed to
be used as alternative memory sectors. That is, whenever
one of the blocks has been erased and reprogrammed, the
other block should be erased and reprogrammed before
the first block is again erased. 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
automatically 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 con-
vert “0”s to “1”s. Programming is accomplished via the
internal device command register and is a 4 bus cycle oper-
ation (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
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 acti-
vated; the boot block’s usage as a write protected region is
optional to the user. The address range of the boot block is
3C000 to 3FFFF.
3
Once the feature is enabled, the data in the boot block can
no longer be erased or programmed. Data in the main
memory block can still be changed through the regular pro-
gramming method. To activate the lockout feature, a series
of six program commands to specific addresses with spe-
cific data must be performed. Please refer to the Command
Definitions table.
BOOT BLOCK LOCKOUT DETECTION:
A software
method is available to determine if programming of the boot
block section is locked out. When the device is in the soft-
ware 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. If the data on I/O0 is low, the boot block can be
programmed; if the data on I/O0 is high, the program lock-
out feature has been activated and the block cannot be
programmed. The software product identification code
should be used to return to standard operation.
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, pro-
tected 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 AT49F002NT.
PRODUCT IDENTIFICATION:
The product identification
mode identifies the device and manufacturer as Atmel. It
may be accessed by hardware or software operation. The
hardware operation mode can be used by an external pro-
grammer to identify the correct programming algoithm 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 AT49F002(N)T features DATA poll-
ing to indicate the end of a program cycle. During a pro-
gram 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
AT49F002(N)T provides another method for determining
the end of a program or erase cycle. During a program or
erase operation, successive 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 tog-
gling 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 AT49F002(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 pro-
gram cycle.
4
AT49F002(N)T
AT49F002(N)T
Command Definition (in Hex)
(1)
Command
Sequence
Read
Chip Erase
Sector Erase
Byte Program
Boot Block Lockout
(2)
Product ID Entry
Product ID Exit
(3)
Product ID Exit
(3)
Notes:
Bus
Cycles
1
6
6
4
6
3
3
1
1st Bus
Cycle
Addr
Addr
5555
5555
5555
5555
5555
5555
XXXX
Data
D
OUT
AA
AA
AA
AA
AA
AA
F0
2AAA
2AAA
2AAA
2AAA
2AAA
2AAA
55
55
55
55
55
55
5555
5555
5555
5555
5555
5555
80
80
A0
80
90
F0
5555
5555
Addr
5555
AA
AA
D
IN
AA
2AAA
55
5555
40
2AAA
2AAA
55
55
5555
SA
(4)
10
30
2nd Bus
Cycle
Addr
Data
3rd Bus
Cycle
Addr
Data
4th Bus
Cycle
Addr
Data
5th Bus
Cycle
Addr
Data
6th Bus
Cycle
Addr
Data
1. The DATA FORMAT in each bus cycle is as follows: I/O7 - I/O0 (Hex)
2. The 16K byte boot sector has the address range 3C000H to 3FFFFH.
3. Either one of the Product ID Exit commands can be used.
4. SA = sector addresses:
SA = 3C000 to 3FFFF for BOOT BLOCK
If the boot block is not locked out, this command will erase - BOOT BLOCK, PB1, PB2 and MMB1
If the boot block is locked out, nothing will happen and the device goes back to the read mode in 100 ns
SA = 3A000 to 3BFFF for PARAMETER BLOCK 1
SA = 38000 to 39FFF for PARAMETER BLOCK 2
SA = 20000 to 37FFF for MAIN MEMORY ARRAY BLOCK 1
If the boot block is not locked out, this command will erase - BOOT BLOCK, PB1, PB2 and MMB1
If the boot block is locked out, this command will erase - PB1, PB2 and MMB1
SA = 00000 to IFFFF for MAIN MEMORY ARRAY BLOCK 2
Absolute Maximum Ratings*
Temperature Under Bias................................ -55°C to +125°C
Storage Temperature ..................................... -65°C to +150°C
All Input Voltages
(including NC Pins)
with Respect to Ground ...................................-0.6V to +6.25V
All Output Voltages
with Respect to Ground ............................ -0.6V to V
CC
+ 0.6V
Voltage on OE
with Respect to Ground ...................................-0.6V to +13.5V
*NOTICE:
Stresses beyond those listed under “Absolute Maxi-
mum Ratings” may cause permanent damage to the
device. This is a stress rating only and functional
operation of the device at these or any other condi-
tions beyond those indicated in the operational sec-
tions of this specification is not implied. Exposure to
absolute maximum rating conditions for extended
periods may affect device reliability.
5
Microcontroller MCU
京公网安备 11010802033920号
EEWORLD
