ATMEL AT29BV020-35JC, AT29BV020-25TI, AT29BV020-25TC, AT29BV020-25JI, AT29BV020-25JC Datasheet
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Features
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AT29BV020
0402B
Single Supply Voltage, Range 2.7V to 3.6V
•
Single Supply for Rea d an d Wri te
•
Software Protected Program ming
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Fast Read Access Time - 250 ns
•
Low Power Dissipation
•
15 mA Active Current
20 µA CMOS Standby Curre nt
Sector Program Operatio n
•
Single Cycle Repro gra m (Eras e and Program)
1024 Sectors (256 bytes /s ec tor)
Internal Address and Data Latches for 256-Bytes
Two 8 KB Boot Blocks with Lockout
•
Fast Sector Program Cycl e Ti me - 20 ms Max.
•
Internal Program Control and Timer
•
DATA Polling for End of Program Detec tio n
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Typical Endurance > 10,000 Cycles
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CMOS and TTL Compatible Inputs and Outputs
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Commercial and Industrial Temperature Ranges
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AT29BV020
2 Megabit
(256K x 8)
Single 2.7-volt
Battery-Voltage
CMOS Flash
Description
The AT29BV020 is a 2.7-volt-only in-system Flash Programmable and Erasable Read
Only Memory (PEROM). Its 2 megabits of memory is organized as 262,144 words by
8 bits. Manufactured with Atmel’s advanced nonvolatile CMOS EEPROM technology,
the device offers access times up to 250 ns, and a low 54 mW power dissipation.
When the device is deselected, the CMOS standby current is less than 20 µA. The
device endurance is such that any sector can typically be written to in excess of
10,000 times. The programming algorithm is compatible with other devices in Atmel’s
Low Voltage Flash family of products.
Pin Configurations
Pin Name Function
A0 - A17 Addresses
CE Chip Enable
OE Output Enable
WE Write Enable
I/O0 - I/O7 Data Inputs/Outputs
NC No Connect
TSOP Top View
Type 1
PLCC Top View
Memory
4-13
Description (Continued)
To allow for simple in-system reprogrammability, the
AT29BV020 does not require high input voltages for programming. The device can be operated with a single 2.7V
to 3.6V supply. Reading data out of the device is similar to
reading from an EPROM. Reprogramming the
AT29BV020 is performed on a sector basis; 256-bytes of
data are loaded into the device and then simultaneously
programmed.
Block Diagram
During a reprogram cycle, the address locations and 256bytes 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
ing of I/O7. Once the end of a program cycle has been
detected, a new access for a read or program can begin.
DATA poll-
Device Operation
READ: The AT29BV020 is accessed like an EPROM.
CE and OE are low and WE is high, the data stored
When
at the memory location determined by the address pins is
asserted on the outputs. The outputs are put in the high
impedance state whenever
line control gives designers flexibility in preventing bus
contention.
SOFTWARE DATA PROTECTION PROGRAMMING:
The AT29BV020 has 1024 individual sectors, each 256bytes. Using the software data protection feature, byte
loads are used to enter the 256-bytes of a sector to be
programmed. The AT29BV020 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
data in any byte that is not loaded during the programming
of its sector will be indeterminate. The AT29BV020 automatically does a sector erase prior to loading the data into
the sector. An erase command is not required.
Software data protection protects the devic e 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
CE or OE is high. This dual-
will not reset the software data protection feature, however
the softw are feature will guard against i nadvertent pr ogram 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
, a read operation will effectively be a polling operation.
t
WC
After the software data protection’s 3-byte command code
is given, a byte load is performed by applying a low pulse
on the
and
CE or WE, whichever occurs last. The data is latched by
the first rising edge of
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 indeterminate. Once the bytes of a sector
are loaded into the device, they are simultaneously programmed during the internal programming period. After
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 trans ition
on
WE (or CE) of the preceding byte. If a high to low 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 addr ess. The
WE or CE input with CE or WE low (respectively)
OE high. The address is latched on the falling edge of
CE or WE.
WE (or CE) within 150 µs of the low to high transition of
(continued)
4-14 AT29BV020
Device Operation (Continued)
sector address must be valid during each high to low transition of
within the sector. The bytes may be loaded in any order;
sequential loading is not required.
HARDWARE DATA PROTECTION: Hardware features
protect against inadvertent programs to the AT29BV020 in
the following ways: (a) V
(typical), the program function is inhibited. (b) V
on delay— once V
the device will automatically time out 10 ms (typical) before programming. (c) Program inhibit— holding any one
of
Noise filter— pulses of less than 15 ns (typical) on the
or
INPUT LEVELS: While operating with a 2.7V to 3.6V
power supply, the address inputs and control inputs (
CE and WE) may be driven from 0 to 5.5V without adversely affecting the operation of the device. The I/O lines
can only be driven from 0 to V
PRODUCT IDE NTIFICATION: 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 us ed 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 th is 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 methods of identification.
WE (or CE). A0 to A7 specify the byte address
sense— if VCC is below 2.0V
CC
power
CC
has reached the VCC sense level,
CC
OE low, CE high or WE high inhibits program cycles. (d)
WE
CE inputs will not initiate a program cycle.
OE,
+ 0.6V.
CC
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
Voltage on A9
(including NC Pins)
with Respect to Ground ................... -0.6V to +13.5V
+ 0.6V
CC
AT29BV020
DATA POLLING: The AT29BV020 features DATA poll-
ing 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.
may begin at any time during the program cycle.
TOGGLE BIT: In addition to
AT29BV020 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.
OPTIONAL CHIP E RASE MODES: The entire device
may be erased by using a 6-byte software code. Please
see Software Chip Erase application note for details.
BOOT BLOCK PROGRAMMING LOCKOUT: The
AT29BV020 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
. Secure code which will bring up a system can be
blocks
contained in a boot block. The AT29BV020 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 st ill 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.
If the boot block lockout feature has been activated on
either block, the chip erase function will be disabled.
*NOTICE: Stresses beyond those listed un der “Abso lute Maxi-
mum Ratings” may cause permanen t dama ge to th e de vice .
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.
DATA p o l li n g th e
DATA polling
boot
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4-15
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