Rainbow Electronics AT29BV020 User Manual
Features
• Single Supply Voltage, Range 2.7V to 3.6V
• Single Supply for Read and Write
• Software Protected Programming
• Fast Read Access Time - 120 ns
• Low Power Dissipation
– 15mAActiveCurrent
– 40 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 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 to 120 ns, and a low 54 mW power dissipation. When
the device is deselected, the CMOS standby current is less than 40 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.
2-megabit
(256K x 8)
Single 2.7-volt
Battery-Voltage
Flash Memory
AT29BV0 20
™
Pin Configurations
Pin Name Function
A0 - A17 Addresses
CE
OE
WE
I/O0 - I/O7 Data Inputs/Outputs
NC No Connect
A7
A6
A5
A4
A3
A2
A1
A0
I/O0
Chip Enable
Output Enable
Write Enable
PLCC Top View
A12
A15
A16NCVCCWEA17
432
1
I/O2
GND
I/O3
323130
I/O4
I/O5
29
28
27
26
25
24
23
22
21
I/O6
5
6
7
8
9
10
11
12
13
14151617181920
I/O1
A14
A13
A8
A9
A11
OE
A10
CE
I/O7
A11
A13
A14
A17
WE
VCC
NC
A16
A15
A12
TSOP Top View
Type 1
1
2
A9
3
A8
4
5
6
7
8
9
10
11
12
13
A7
14
A6
15
A5
16
A4
OE
32
A10
31
CE
30
I/O7
29
I/O6
28
I/O5
27
I/O4
26
I/O3
25
GND
24
I/O2
23
I/O1
22
I/O0
21
A0
20
A1
19
A2
18
A3
17
Rev. 0402D–FLASH–05/02
1
Block Diagram
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.
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
new access for a read or program can begin.
polling of I/O7. Once the end of a program cycle has been detected, a
Device Operation
2
AT29BV020
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
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 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 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.
or OE is high. This
0402D–FLASH–05/02
AT29BV020
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
ation 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
The address is latched on the falling edge of CE
latched by the first rising edge of CE
or CE input with CE or WE low (respectively) and OE high.
or WE, whichever occurs last. The data is
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 indeterminated. 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 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 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
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
the program function is inhibited; (b) V
power on delay – once VCChas reached the V
CC
sense – if VCCis below 2.0V (typical),
CC
sense level, the device will automatically time out 10 ms (typical) before programming; (c) Program inhibit – holding any one of OE
Noise filter – pulses of less than 15 ns (typical) on the WE
low, CE high or WE high inhibits program cycles; and (d)
or CE inputs will not initiate a pro-
gram cycle.
, a read oper-
WC
(or CE).
CC
INPUT LEVELS: While operating with a 2.7V to 3.6V power supply, the address inputs and
control inputs (OE
operation of the device. The I/O lines can only be driven from 0 to V
,CEand WE) may be driven from 0 to 5.5V without adversely affecting the
+0.6V.
CC
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’ssectorsizein
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.
DATA
POLLING: The AT29BV020 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
polling may begin at any time during
the program cycle.
TOGGLE BIT: In addition to DATA
polling the 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.
0402D–FLASH–05/02
3
OPTIONAL CHIP ERASE MODES: The entire device may be erased by using a 6-byte soft-
ware 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
a system can be 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 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.
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.
Absolute Maximum Ratings*
Temperature Under Bias ................................ -55°Cto+125°C
Storage Temperature ..................................... -65°Cto+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
boot blocks
*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.
. Secure code which will bring up
Voltage on A9 (Including NC Pins)
with Respect to Ground ...................................-0.6V to +13.5V
4
AT29BV020
0402D–FLASH–05/02
.
DC and AC Operating Range
AT29BV020
AT29BV020-12 AT29BV020-15 AT29BV020-25 AT29BV020-35
Operating
Temperature (Case)
V
Power Supply
CC
(1)
Com. 0°C-70°C0°C-70°C
Ind. -40°C-85°C-40°C-85°C
2.7V to 3.6V 2.7V to 3.6V 2.7V to 3.6V 2.7V to 3.6V
0°C-70°C 0°C-70°C
-40°C-85°C -40°C-85°C
Notes: 1. After power is applied and VCCis at the minimum specified datasheet value, the system should wait 20 ms before an opera-
tional mode is started.
2.
Not recommended for New Designs.
Operating Modes
Mode CE OE WE Ai I/O
Read V
Program
(2)
Standby/Write Inhibit V
IL
V
IL
IH
Program Inhibit X X V
Program Inhibit X V
Output Disable X V
Product Identification
Hardware V
Software
Notes: 1. X can be V
(5)
or VIH.
IL
IL
2. Refer to AC Programming Waveforms.
3. V
= 12.0V ± 0.5V.
H
4. Manufacturer Code is 1F. The Device Code is BA.
5. See details under Software Product Identification Entry/Exit.
V
IL
V
IH
(1)
X
IL
IH
V
IL
V
IH
V
IL
Ai D
Ai D
OUT
IN
XXHighZ
IH
X
XHighZ
V
IH
A1 - A17 = VIL,A9=V
A1 - A17 = VIL,A9=V
A0 = V
A0 = V
A1 - A17 = V
IL,
A1 - A17 = V
IH,
(3)
,A0=VILManufacturer Code
H
(3)
,A0=VIHDevice Code
H
IL
IL
Manufacturer Code
Device Code
(4)
(4)
(4)
(4)
DC Characteristics
Symbol Parameter Condition Min Max Units
I
LI
I
LO
I
SB1
I
SB2
I
CC
V
IL
V
IH
V
OL
V
OH
0402D–FLASH–05/02
Input Load Current VIN=0VtoV
Output Leakage Current V
=0VtoV
I/O
CC
CC
VCCStandby Current CMOS CE =VCC-0.3VtoV
CC
Com. 40 µA
1µA
1µA
Ind. 50 µA
VCCStandby Current TTL CE =2.0VtoV
VCCActive Current f = 5 MHz; I
OUT
CC
=0mA;VCC=3.6V 15 mA
1mA
Input Low Voltage 0.6 V
Input High Voltage 2.0 V
Output Low Voltage IOL=1.6mA;VCC=3.0V 0.45 V
Output High Voltage IOH=-100µA; VCC=3.0V 2.4 V
5
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