2 Megabit
(256K x 8)
3-volt Only
CMOS Flash
Memory

Features

Single Voltage, Range 3V to 3.6V Supply

3-Volt-Only Read and Write Operation

Software Protected Programming

Fast Read Access Time - 200 ns

Low Power Dissipation

15 mA Active Current
20

A 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

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 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 200 ns with power dissipation of just 54 mW over the commer-
cial temperature range. When the device is deselected, the CMOS standby current is
less than 20

A. 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 opera-
tion of the device. Reading data out of the device is similar to reading from an

(continued)

AT29LV020

Pin Configurations

Pin Name

Function

A0 - A17

Addresses

Chip Enable

Output Enable

Write Enable

I/O0 - I/O7

Data Inputs/Outputs

No Connect

TSOP Top View

Type 1

PLCC

Top View

0565A

AT29LV020

4-73

(continued)

Block Diagram

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 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.

Description (Continued)

Device Operation

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 or OE is high. This dual-
line control gives designers flexibility in preventing bus
contention.

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 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
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 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

, 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 erased to read FFH. Once the bytes of a
sector are loaded into the device, they are simultaneously
programmed during the internal programming period. Af-
ter 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

s 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

s 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
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. Once a programming
operation has been initiated, and for the duration of t

, a

read operation will effectively be a polling operation.

4-74

AT29LV020

(continued)

Temperature Under Bias................. -55

C to +125

Storage Temperature...................... -65

C to +150

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

+ 0.6V

Voltage on A9
(including NC Pins)
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 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*

HARDWARE DATA PROTECTION: Hardware features
protect against inadvertent programs to the AT29LV020 in
the following ways: (a) V

sense-- if V

is below 1.8V

(typical), the program function is inhibited. (b) V

power

on delay-- once V

has reached the V

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 3.3V

10%

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 be driven from 0 to 3.6V.

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 modes.

DATA POLLING: The AT29LV020 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

Device Operation (Continued)

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
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.

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.

BOOT BLOCK PROGRAMMING LOCKOUT: The
AT29LV020 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 AT29LV020 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.

AT29LV020

4-75

1. After power is applied and V

is at the minimum specified data sheet value, the system should wait 20 ms before an operational

mode is started.

Operating Modes

Mode

I/O

Read

OUT

Program

(2)

Standby/Write Inhibit

(1)

High Z

Program Inhibit

Output Disable

High Z

Product Identification

Hardware

VIL

A1 - A17 = V

, A9 = V

(3)

A0 = V

Manufacturer Code

(4)

A1 - A17 = V

, A9 = V

(3)

A0 = V

Device Code

(4)

Software

(5)

A0 = V

Manufacturer Code

(4)

A0 = V

Device Code

(4)

4. Manufacturer Code: 1F, Device Code: BA.
5. See details under Software Product Identification Entry/Exit.

Notes: 1. X can be V

or V

2. Refer to AC Programming Waveforms.

3. V

= 12.0V

0.5V.

DC Characteristics

Symbol

Parameter

Condition

Min

Max

Units

Input Load Current

= 0V to V

Output Leakage Current

I/O

= 0V to V

SB1

Standby Current CMOS

CE = V

- 0.3V to V

Com.

Ind.

SB2

Standby Current TTL

CE = 2.0V to V

Active Current

f = 5 MHz; I

OUT

= 0 mA; V

= 3.6V

Input Low Voltage

0.6

Input High Voltage

2.0

Output Low Voltage

= 1.6 mA; V

= 3.0V

.45

Output High Voltage

= -100

A; V

= 3.0V

2.4

DC and AC Operating Range

AT29LV020-20

AT29LV020-25

Operating
Temperature (Case)

Com.

C - 70

Ind.

-40

C - 85

-40

C - 85

Power Supply

(1)

3.3V

0.3V

3.3V

0.3V

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.

Device Operation (Continued)

4-76

AT29LV020

AC Read Characteristics

AT29LV020-20

AT29LV020-25

Symbol Parameter

Min

Max

Min

Max

Units

ACC

Address to Output Delay

200

250

(1)

CE to Output Delay

200

250

(2)

OE to Output Delay

100

120

(3, 4)

CE or OE to Output Float

Output Hold from OE, CE or Address,
whichever occurred first

Notes: 1. CE may be delayed up to t

ACC

- t

after the address

transition without impact on t

ACC

2. OE may be delayed up to t

- t

after the falling

edge of CE without impact on t

or by t

ACC

- t

after an address change without impact on t

ACC

3. t

is specified from OE or CE whichever occurs first

= 5 pF).

4. This parameter is characterized and is not 100% tested.

AC Read Waveforms

(1, 2, 3, 4)

, t

< 5 ns

Input Test Waveforms and Measurement Level

Output Test Load

Pin Capacitance

(f = 1 MHz, T = 25°C)

(1)

Typ

Max

Units

Conditions

= 0V

OUT

= 0V

Note:

1. These parameters are characterized and not 100% tested.

AT29LV020

4-77

Part Number AT29LV020