– 50 mA Active Current
– 100 µA CMOS Standby Current
•
Typical 10,000 Write Cycles
8-Megabit
(1M x 8)
5-volt Only
Description
The AT49F008 is a 5-volt-o nly in-sys tem Flash Me mory devi ce. Its 8- megabits of
memory is organized as 1,024,576 words by 8-bits. Manufactured with Atmel’s
advanced nonvol atile CMOS technology, the de vi ce of fer s ac ce ss t ime s to 90 ns wi th
power dissipatio n of just 27 5 mW ove r the co mmercia l temper atur e range . When the
device is deselected, the CMOS standby current is less than 100 µA.
To allow for simple in-system reprogrammability, the
AT49F008 does not require high input voltages for programming. 5-volt-only commands determine the read and
programming operation of the device. Reading data out of
the device is similar to reading from an EPROM. Repr ogramming the AT49F008 is performed by erasing the entire
8 megabits of memory and then programming on a byte-bybyte basis. The typical byte programming time is a fast 10
µs. The end of a program cycle can be optionally detected
by the DATA
polling feature. Once the end of a byte pro-
Block Diagram
V
CC
GND
OE
WE
CE
ADDRESS
INPUTS
OE, CE, AND WE
LOGIC
Y DECODER
X DECODER
gram cycle has been detected, a new access for a read or
program can begin. The typical number of program and
erase cycles is in excess of 10,000 cycles
The optional 16K bytes boot block section includes a reprogramming write lock out feature to provide data integrity.
The boot sector is design ed to contai n user secur e code,
and when the featur e is en abled , the b oot s ector i s perma nently protected from being reprogrammed.
DATA INPUTS/OUTPUTS
I/O7 - I/O0
8
DATA LATCH
INPUT/OUTPUT
BUFFERS
Y-GATING
MAIN MEMORY
(1008K BYTES)
OPTIONAL BOOT
BLOCK (16K BYTES)
FFFFFH
03FFFH
00000H
Device Operation
READ:
CE
memory location determined by the address pins is
asserted on the outputs . The outputs ar e put in the high
impedance state whenever CE
control gives designers flexibility in preventing bus contention.
ERASURE:
1024K bytes memo ry array (or 1008K bytes if the boot
block featured is used) must be erased. The erased state
of the memory bits is a logical “1”. The entire device can be
erased at one time by using a 6-byte software code. The
software chi p erase code c onsists of 6-b yte load co mmands to specific address locations with a specific data
pattern (please refer to the Chip Erase Cycle Waveforms).
After the software chip erase has been ini tiated , the devi ce
will internally time the eras e operatio n so that no ex ternal
clocks are required. The maximum time needed to erase
the whole chip is t
been enabled, the data in the boot sector will not be
erased.
BYTE PROGRAMMING:
erased, the device is programmed (to a logical “0”) on a
byte-by-byte bas is. Please note th at a data “0” ca nnot be
The AT49F008 is accessed like an EPROM. When
and OE are low and WE is hi gh, the data st ored at the
or OE is high. This dual-line
Before a byte can be reprogrammed, the
. If the boot block lockout feature has
EC
Once the memory array is
programmed ba ck to a “1”; only era se oper ation s can con vert “0”s to “1 ”s. Programmi ng is accom plished via the
internal device command register and is a 4 bus cycle operation (plea se refer to the Co mmand Defini tions ta ble). The
device will automatically generate the required internal program pulses.
The program cycle has addresses latched on the falling
edge of WE
latched on the rising edge of WE
first. Programming is completed after the specified t
or CE, whichever occurs last, and the data
or CE, whichever occurs
BP
cycle time. The DATA polling feature may also be used to
indicate the end of a program cycle.
BOOT BLOCK PROGRAMMING LOCKOUT:
The device
has one designated block that has a programming lockout
feature. This feature prevents programmin g of data in the
designated block once the feature has been enabled. The
size of the block is 16K bytes. This block, referred to as the
boot block, can contain secure code that is used to bring up
the system. Enablin g the l ocko ut feature will allow t he boot
code to stay in the device while data in the rest of the
device is updated. This feature does not have to be activated; the boot block’ s u sa ge a s a write protected region is
optional to the user. The address range of the AT49F008
boot block is 00000H to 03FFFH.
2
AT49F008
AT49F008
To activate the lockout feature, a series of six program
commands to specific addresses with specific data must be
performed. Please refer to the Command Definitions table.
BOOT BLOCK LOCKOUT DETECTION:
method is available to determine if programming of the boot
block section is locked out. When the device is in the software product iden tification mode (see Soft ware Produc t
Identification Entry and Exit sections) a read from address
location 00002H will sho w if progra mming th e boot blo ck is
locked out. If the d ata on I /O 0 i s low, the boo t bl oc k ca n be
programmed; if the data on I/O0 is high, the program lockout feature has been activated and the block cannot be
programmed. The software product identification exit code
should be used to return to standard operation.
BOOT BLOCK PROGRAMMING LOCKO UT OV ERRIDE:
The user can override the boot block programming lockout
by taking the RESET
tected boot block data can be altered through a chip erase,
or byte programming. When the RESET
to TTL levels, the boot block programming lockout feature
is again active.
PRODUCT IDENTIFICATION:
mode identifies the device and manufacturer as Atmel. It
may be accessed by hardware or software operation. The
hardware oper ation mode can be used by an exte rnal programmer to identify the correct programming algorithm for
the Atmel product.
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:
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 com pleted, true data is valid on all
outputs and the next cycle may begin . DATA
begin at any time during the program cycle.
pin to 12V ± 0.5V. By doing this, pr o-
The product identification
The AT49F008 features DATA
A software
pin is brought back
polling to
polling may
TOGGLE BIT:
provides another method for determining the end of a program or erase cycle. During a pro gram or er ase opera tion,
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.
RDY/BUSY
vides another method of detecting the end of a program or
erase operation. RDY/BUSY
the internal program and erase cycles and is released at
the completion of the cycle. The open drain connection
allows for OR - tying of sever al devices to the same
RDY/BUSY
RESET:
tem applications. When RESET
device is in its sta nda rd ope ra tin g mo de. A lo w level on the
RESET
outputs of the device in a high impedance state, and
reduces the curr ent draw n by the p art to a mi nimum . If the
RESET
or erase operation, the operation may not be successfully
completed and the oper ati on wil l ha ve t o be rep eated afte r
a high level is applied to the RESET
is reasserted on the RESET
read or standby mode, depending upon the state of the
control inputs. By applying a 12V ± 0.5V input signal to the
RESET
even if the boot block lockout feature has been enabled
(see Boot Block Programming Lockout Override section).
HARDWARE DATA PROTECTION:
protect against inadvertent programs to the AT49F008 in
the following ways: (a) V
(typical), the program function is inhibited. (b) Program
inhibit: holding any one of OE
inhibits program cycles. (c) Noise filter: pulses of less than
15 ns (typical) on the WE
gram cycle.
input halts the presen t device opera tion, puts the
pin makes a high to low transition during a program
Boot Block Lockout
Product ID Entry35555AA2AAA55555590
Product ID Exit
Product ID Exit
Notes: 1. The 16K byte boot sector has the address range 00000H to 03FFFH.
2. Either one of the Product ID Exit commands can be used.
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 OE
with Respect to Ground...................................-0.6V to +13.5V
+ 0.6V
CC
*NOTICE:Stresses beyond those listed under “Absolute
Maximum Ratings” may cause permanent damage to the dev ice . This is a s tress rating only an d
functional oper ation of the device at thes e o r any
other conditions beyond those indicated in the
operational sections of this specification is not
implied. Exposure to absolute maximum rating
conditions f or e xtended periods ma y af fect de vice
reliability .
IN
4
AT49F008
Loading...
+ 8 hidden pages
You need points to download manuals.
1 point = 1 manual.
You can buy points or you can get point for every manual you upload.