AT29BV020
Features
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Single Supply Voltage, Range 2.7V to 3.6V
Single Supply for Read and Write
Software Protected Programming
Fast Read Access Time - 250 ns
Low Power Dissipation
15 mA Active Current
20
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 8 KB Boot Blocks with Lockout
Fast Sector Program Cycle Time - 20 ms Max.
Internal Program Control and Timer
DATA Polling for End of Program Detection
Typical Endurance > 10,000 Cycles
CMOS and TTL Compatible Inputs and Outputs
Commercial and Industrial Temperature Ranges
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.
(continued)
2 Megabit
(256K x 8)
Single 2.7-volt
Battery-Voltage
™
CMOS Flash
Memory
AT29BV020
Pin Configurations
Pin Name
A0 - A17
CE
OE
WE
I/O0 - I/O7
NC
Function
Addresses
Chip Enable
Output Enable
Write Enable
Data Inputs/Outputs
No Connect
TSOP Top View
PLCC Top View
Type 1
0402B
4-13
Description
(Continued)
To allow for simple in-system reprogrammability, the
AT29BV020 does not require high input voltages for pro-
gramming. 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.
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 cy-
cle, 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 poll-
ing of I/O7. Once the end of a program cycle has been
detected, a new access for a read or program can begin.
Block Diagram
Device Operation
READ:
The AT29BV020 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.
SOFTWARE DATA PROTECTION PROGRAMMING:
The AT29BV020 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 AT29BV020 can only be programmed
or reprogrammed using the software data protection fea-
ture. The device is programmed on a sector basis. If a byte
of data within the sector is to be changed, data for the en-
tire 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 auto-
matically 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 inadver-
tent 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 op-
eration. 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 pro-
gram cycles during power transitions.
Any attempt to write to the device without the 3-byte com-
mand sequence will start the internal write timers. No data
will be written to the device; however, for the duration of
t
WC
, a read operation 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 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.
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 pro-
grammed during the internal programming period. After
the first data byte has been loaded into the device, suc-
cessive bytes are entered in the same manner. Each new
byte to be programmed must have its high to low transition
on WE (or CE) within 150
µs
of the low to high transition of
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 transi-
tion, the load period will end and the internal programming
period will start. A8 to A17 specify the sector address. The
(continued)
4-14
AT29BV020
AT29BV020
Device Operation
(Continued)
sector address must be valid during each high to low tran-
sition of WE (or CE). A0 to A7 specify the byte address
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
CC
sense— if V
CC
is below 2.0V
(typical), the program function is inhibited. (b) V
CC
power
on delay— once V
CC
has reached the V
CC
sense level,
the device will automatically time out 10 ms (typical) be-
fore programming. (c) Program inhibit— holding any one
of OE low, CE high or WE high inhibits program cycles. (d)
Noise filter— pulses of less than 15 ns (typical) on the WE
or CE inputs will not initiate a program cycle.
INPUT LEVELS:
While operating with a 2.7V to 3.6V
power supply, the address inputs and control inputs
(OE,
CE and WE) may be driven from 0 to 5.5V without ad-
versely affecting the operation of the device. The I/O lines
can only be driven from 0 to V
CC
+ 0.6V.
PRODUCT IDENTIFICATION:
The product identifica-
tion mode identifies the device and manufacturer as At-
mel. It may be accessed by hardware or software opera-
tion. The hardware operation mode can be used by an ex-
ternal programmer to identify the correct programming al-
gorithm 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 op-
erations. 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 sys-
tem 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.
DATA POLLING:
The AT29BV020 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:
I n a d d i t i o n t o DATA p o l l i n g t h e
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 ERASE 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 pro-
gramming 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 inde-
pendently 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 AT29BV020 blocks are lo-
cated 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.
If the boot block lockout feature has been activated on
either block, the chip erase function will be disabled.
(continued)
*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 conditions beyond those indi-
cated in the operational sections of this specification is not
implied. Exposure to absolute maximum rating conditions
for extended periods may affect device reliability.
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 A9
(including NC Pins)
with Respect to Ground ................... -0.6V to +13.5V
4-15
Device Operation
(Continued)
BOOT BLOCK LOCKOUT DETECTION:
A software
method is available to determine whether programming of
either boot block section is locked out. See Software Prod-
uct 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 ad-
dress boot block is locked out while reading location
FFFF2H 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.
DC and AC Operating Range
AT29BV020-25
Operating
Temperature (Case)
V
CC
Power Supply
(1)
AT29BV020-35
0°C - 70°C
-40°C - 85°C
2.7V to 3.6V
Com.
Ind.
0°C - 70°C
-40°C - 85°C
2.7V to 3.6V
1. After power is applied and V
CC
is at the minimum specified data sheet value, the system should wait 20 ms before an
operational mode is started.
Operating Modes
Mode
Read
Program
(2)
Standby/Write Inhibit
Program Inhibit
Program Inhibit
Output Disable
Product Identification
Hardware
(5)
CE
V
IL
V
IL
V
IH
X
X
X
OE
V
IL
V
IH
X
(1)
WE
V
IH
V
IL
X
V
IH
X
X
Ai
Ai
Ai
X
I/O
D
OUT
D
IN
High Z
X
V
IL
V
IH
High Z
A1 - A17 = V
IL
, A9 = V
H (3)
,
A0 = V
IL
A1 - A17 = V
IL
, A9 = V
H (3)
,
A0 = V
IH
A0 = V
IL,
A1 - A17 = V
IL
A0 = V
IH,
A1 - A17 = V
IL
Manufacturer Code
(4)
Device Code
(4)
Manufacturer Code
(4)
Device Code
(4)
V
IL
V
IL
V
IH
Software
Notes: 1. X can be V
IL
or V
IH
.
2. Refer to AC Programming Waveforms.
3. V
H
= 12.0V
±
0.5V.
4. Manufacturer Code is 1F. The Device Code is BA.
5. See details under Software Product Identification Entry/Exit.
DC Characteristics
Symbol
I
LI
I
LO
I
SB1
I
SB2
I
CC
V
IL
V
IH
V
OL
V
OH
4-16
Parameter
Input Load Current
Output Leakage Current
V
CC
Standby Current CMOS
V
CC
Standby Current TTL
V
CC
Active Current
Input Low Voltage
Input High Voltage
Output Low Voltage
Output High Voltage
I
OL
= 1.6 mA; V
CC
= 3.0V
I
OH
= -100
µA;
V
CC
= 3.0V
2.4
2.0
0.45
Condition
V
IN
= 0V to V
CC
V
I/O
= 0V to V
CC
CE = V
CC
- 0.3V to V
CC
CE = 2.0V to V
CC
f = 5 MHz; I
OUT
= 0 mA; V
CC
= 3.6V
Com.
Ind.
Min
Max
1
1
20
50
1
15
0.6
Units
µA
µA
µA
µA
mA
mA
V
V
V
V
AT29BV020
AT29BV020
AC Read Characteristics
AT29BV020-25
Symbol
t
ACC
t
CE (1)
t
OE (2)
t
DF (3, 4)
t
OH
Parameter
Address to Output Delay
CE to Output Delay
OE to Output Delay
CE or OE to Output Float
Output Hold from OE, CE or Address,
whichever occurred first
0
0
0
Min
Max
AT29BV020-35
Min
Max
Units
ns
ns
ns
ns
ns
250
250
120
60
0
0
0
350
350
150
75
AC Read Waveforms
Notes: 1. CE may be delayed up to t
ACC
- t
CE
after the address
transition without impact on t
ACC
.
2. OE may be delayed up to t
CE
- t
OE
after the falling
edge of CE without impact on t
CE
or by t
ACC
- t
OE
after an address change without impact on t
ACC
.
3. t
DF
is specified from OE or CE whichever occurs first
(C
L
= 5 pF).
4. This parameter is characterized and is not 100% tested.
Input Test Waveforms and Measurement Level
Output Test Load
t
R
, t
F
< 5 ns
Pin Capacitance
(f = 1 MHz, T = 25°C)
(1)
Typ
C
IN
C
OUT
Note:
Max
6
12
Units
pF
pF
Conditions
V
IN
= 0V
V
OUT
= 0V
4
8
1. These parameters are characterized and not 100% tested.
4-17
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