ATMEL AT29LV020 User Manual
BDTIC www.BDTIC.com/ATMEL
Features
• Single Voltage, Range 3V to 3.6V Supply
• 3-volt Only Read and Write Operation
• Software Protected Programming
• Fast Read Access Time – 100 ns
• Low Power Dissipation
– 15 mA Active Current
– 50 µA CMOS Standby Current
• Sector Program Operation
– Single Cycle Reprogram (Erase and Program)
– 1024 Sectors (256 Bytes/Sector)
– Internal Address and Data Latches for 256 Bytes
• Two 8K Bytes Boot Blocks with Lockout
• Fast Sector Program Cycle Time – 20 ms
• Internal Program Control and Timer
• DATA Polling for End of Program Detection
• Typical Endurance > 10,000 Cycles
• CMOS and TTL Compatible Inputs and Outputs
• Green (Pb/Halide-free) Packaging Option
2-megabit
(256K x 8)
3-volt Only
Flash Memory
AT29LV020
1. Description
The AT29LV020 is a 3-volt-only in-system Flash programmable and erasable read
only memory (PEROM). Its 2 megabits of memory is organized as 262,144 bytes by
8 bits. Manufactured with Atmel’s advanced nonvolatile CMOS technology, the device
offers access times to 100 ns with power dissipation of just 54 mW over the industrial
temperature range. When the device is deselected, the CMOS standby current is less
than 50 µA. The device endurance is such that any sector can typically be written to in
excess of 10,000 times.
To allow for simple in-system reprogrammability, the AT29LV020 does not require
high input voltages for programming. Five-volt-only commands determine the operation of the device. Reading data out of the device is similar to reading from an
EPROM. Reprogramming the AT29LV020 is performed on a sector basis; 256 bytes
of data are loaded into the device and then simultaneously programmed.
During a reprogram cycle, the address locations and 256 bytes of data are captured at
microprocessor speed and internally latched, freeing the address and data bus for
other operations. Following the initiation of a program cycle, the device will automatically erase the sector and then program the latched data using an internal control
timer. The end of a program cycle can be detected by DATA
end of a program cycle has been detected, a new access for a read or program can
begin.
polling of I/O7. Once the
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2. Pin Configurations
5
6
7
8
9
10
11
12
13
29
28
27
26
25
24
23
22
21
A7
A6
A5
A4
A3
A2
A1
A0
I/O0
A14
A13
A8
A9
A11
OE
A10
CE
I/O7
432
1
323130
14151617181920
I/O1
I/O2
I/O3
I/O4
I/O5
I/O6
A12
A15
A16NCVCCWEA17
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
A11
A9
A8
A13
A14
A17
WE
VCC
NC
A16
A15
A12
A7
A6
A5
A4
OE
A10
CE
I/O7
I/O6
I/O5
I/O4
I/O3
GND
I/O2
I/O1
I/O0
A0
A1
A2
A3
Pin Name Function
A0 - A17 Addresses
CE Chip Enable
OE
WE
I/O0 - I/O7 Data Inputs/Outputs
NC No Connect
2.1 32-lead PLCC Top View
2.2 32-lead TSOP (Type 1) Top View
Output Enable
Write Enable
2
AT29LV020
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3. Block Diagram
4. Device Operation
4.1 Read
The AT29LV020 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
trol gives designers flexibility in preventing bus contention.
AT29LV020
or OE is high. This dual-line con-
4.2 Software Data Protection Programming
The AT29LV020 has 1024 individual sectors, each 256 bytes. Using the software data protection feature, byte loads are used to enter the 256 bytes of a sector to be programmed. The
AT29LV020 can only be programmed or reprogrammed using the software data protection feature. The device is programmed on a sector basis. If a byte of data within the sector is to be
changed, data for the entire 256-byte sector must be loaded into the device. The AT29LV020
automatically does a sector erase prior to loading the data into the sector. An erase command is
not required.
Software data protection protects the device from inadvertent programming. A series of three
program commands to specific addresses with specific data must be presented to the device
before programming may occur. The same three program commands must begin each program
operation. All software program commands must obey the sector program timing specifications.
Power transitions will not reset the software data protection feature, however the software feature will guard against inadvertent program cycles during power transitions.
Any attempt to write to the device without the 3-byte command sequence will start the internal
write timers. No data will be written to the device; however, for the duration of t
tion will effectively be a polling operation.
After the software data protection’s 3-byte command code is given, a byte load is performed by
applying a low pulse on the WE
address is latched on the falling edge of CE
the first rising edge of CE
or WE.
, a read opera-
WC
or CE input with CE or WE low (respectively) and OE high. The
or WE, whichever occurs last. The data is latched by
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The 256 bytes of data must be loaded into each sector. Any byte that is not loaded during the
programming of its sector will be erased to read FFH. Once the bytes of a sector are loaded into
the device, they are simultaneously programmed during the internal programming period. After
3
the first data byte has been loaded into the device, successive bytes are entered in the same
manner. Each new byte to be programmed must have its high to low transition on WE
within 150 µs of the low to high transition of WE
transition is not detected within 150 µs of the last low to high transition, the load period will end
and the internal programming period will start. A8 to A17 specify the sector address. The sector
address must be valid during each high to low transition of WE
address within the sector. The bytes may be loaded in any order; sequential loading is not
required. Once a programming operation has been initiated, and for the duration of t
operation will effectively be a polling operation.
4.3 Hardware Data Protection
Hardware features protect against inadvertent programs to the AT29LV020 in the following
ways: (a) V
power on delay – once VCC has reached the VCC sense level, the device will automatically time
out 10 ms (typical) before programming; (c) Program inhibit – holding any one of OE
high or WE high inhibits program cycles; and (d) Noise filter – pulses of less than 15 ns (typical)
on the WE
CC
or CE inputs will not initiate a program cycle.
4.4 Input Levels
While operating with a 3.3V ± 10% power supply, the address inputs and control inputs (OE, CE
and WE) may be driven from 0 to 5.5V without adversely affecting the operation of the device.
The I/O lines can be driven from 0 to 3.6V.
(or CE)
(or CE) of the preceding byte. If a high to low
(or CE). A0 to A7 specify the byte
, a read
WC
sense – if VCC is below 1.8V (typical), the program function is inhibited; (b) V
low, CE
CC
4.5 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 programmer to identify the correct programming algorithm for the Atmel product.
In addition, users may wish to use the software product identification mode to identify the part
(i.e., using the device code), and have the system software use the appropriate sector size for
program operations. In this manner, the user can have a common board design for 256K to
4-megabit densities and, with each density’s sector size in a memory map, have the system software apply the appropriate sector size.
For details, see Operating Modes (for hardware operation) or Software Product Identification.
The manufacturer and device code is the same for both modes.
4.6 DATA Polling
The AT29LV020 features DATA polling to indicate the end of a program 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
4.7 Toggle Bit
In addition to DATA polling the AT29LV020 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 toggling and valid data will be read. Examining the toggle bit may
begin at any time during a program cycle.
polling may begin at any time during the program cycle.
4
AT29LV020
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4.8 Optional Chip Erase Mode
The entire device can be erased by using a 6-byte software code. Please see Software Chip
Erase application note for details.
4.9 Boot Block Programming Lockout
The AT29LV020 has two designated memory blocks that have a programming lockout feature.
This feature prevents programming of data in the designated block once the feature has been
enabled. Each of these blocks consists of 8K bytes; the programming lockout feature can be set
independently for either block. While the lockout feature does not have to be activated, it can be
activated for either or both blocks.
These two 8K memory sections are referred to as boot blocks. Secure code which will bring up a
system can be contained in a boot block. The AT29LV020 blocks are located in the first 8K bytes
of memory and the last 8K bytes of memory. The boot block programming lockout feature can
therefore support systems that boot from the lower addresses of memory or the higher
addresses. Once the programming lockout feature has been activated, the data in that block can
no longer be erased or programmed; data in other memory locations can still be changed
through the regular programming methods. To activate the lockout feature, a series of seven
program commands to specific addresses with specific data must be performed. Please see
Boot Block Lockout Feature Enable Algorithm.
AT29LV020
If the boot block lockout feature has been activated on either block, the chip erase function will
be disabled.
4.9.1 Boot Block Lockout Detection
A software method is available to determine whether programming of either boot block section is
locked out. See Software Product Identification Entry and Exit sections. When the device is in
the software product identification mode, a read from location 00002H will show if programming
the lower address boot block is locked out while reading location 3FFF2H will do so for the upper
boot block. If the data is FE, the corresponding block can be programmed; if the data is FF, the
program lockout feature has been activated and the corresponding block cannot be programmed. The software product identification exit mode should be used to return to standard
operation.
5. 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 VCC + 0.6V
*NOTICE: Stresses beyond those listed under “Absolute
Maximum 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 conditions beyond those indicated in the
operational sections of this specification is not
implied. Exposure to absolute maximum rating
conditions for extended periods may affect
device reliability.
Voltage on A9 (including NC Pins)
with Respect to Ground ...................................-0.6V to +13.5V
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