A29L800A Series
Word/Byte Configuration
The
BYTE
pin determines whether the I/O pins I/O
15
-I/O
0
operate in the byte or word configuration. If the
BYTE
pin is
set at logic ”1”, the device is in word configuration, I/O
15
-I/O
0
are active and controlled by
CE
and
OE
.
If the
BYTE
pin is set at logic “0”, the device is in byte
configuration, and only I/O
0
-I/O
7
are active and controlled by
CE
and
OE
. I/O
8
-I/O
14
are tri-stated, and I/O
15
pin is used as
an input for the LSB(A-1) address function.
Characteristics" section contains timing specification tables and
timing diagrams for write operations.
Program and Erase Operation Status
During an erase or program operation, the system may check
the status of the operation by reading the status bits on I/O
7
-
I/O
0
. Standard read cycle timings and I
CC
read specifications
apply. Refer to "Write Operation Status" for more information,
and to each AC Characteristics section for timing diagrams.
Standby Mode
When the system is not reading or writing to the device, it can
place the device in the standby mode. In this mode, current
consumption is greatly reduced, and the outputs are placed in
the high impedance state, independent of the
OE
input.
The device enters the CMOS standby mode when the
CE
&
RESET
pins are both held at VCC
±
0.3V. (Note that this is a
more restricted voltage range than V
IH
.) If
CE
and
RESET
are
held at V
IH
, but not within VCC
±
0.3V, the device will be in the
standby mode, but the standby current will be greater. The
device requires the standard access time (t
CE
) before it is ready
to read data.
If the device is deselected during erasure or programming, the
device draws active current until the operation is completed.
I
CC3
and I
CC4
in the DC Characteristics tables represent the
standby current specification.
Requirements for Reading Array Data
To read array data from the outputs, the system must drive the
CE
and
OE
pins to V
IL
.
CE
is the power control and selects
the device.
OE
is the output control and gates array data to
the output pins.
WE
should remain at V
IH
all the time during
read operation. The
BYTE
pin determines whether the device
outputs array data in words and bytes. The internal state
machine is set for reading array data upon device power-up, or
after a hardware reset. This ensures that no spurious alteration
of the memory content occurs during the power transition. No
command is necessary in this mode to obtain array data.
Standard microprocessor read cycles that assert valid
addresses on the device address inputs produce valid data on
the device data outputs. The device remains enabled for read
access until the command register contents are altered.
See "Reading Array Data" for more information. Refer to the
AC Read Operations table for timing specifications and to the
Read Operations Timings diagram for the timing waveforms,
l
CC1
in the DC Characteristics table represents the active
current specification for reading array data.
Automatic Sleep Mode
The automatic sleep mode minimizes Flash device energy
consumption. The device automatically enables this mode
when addresses remain stable for t
ACC
+30ns. The automatic
sleep mode is independent of the
CE
,
WE
and
OE
control
signals. Standard address access timings provide new data
when addresses are changed. While in sleep mode, output
data is latched and always available to the system. I
CC4
in the
DC Characteristics table represents the automatic sleep mode
current specification.
Writing Commands/Command Sequences
To write a command or command sequence (which includes
programming data to the device and erasing sectors of
memory), the system must drive
WE
and
CE
to V
IL
, and
OE
to V
IH
. For program operations, the
BYTE
pin determines
whether the device accepts program data in bytes or words,
Refer to “Word/Byte Configuration” for more information. The
device features an Unlock Bypass mode to facilitate faster
programming. Once the device enters the Unlock Bypass
mode, only two write cycles are required to program a word or
byte, instead of four. The “Word / Byte Program Command
Sequence” section has details on programming data to the
device using both standard and Unlock Bypass command
sequence. An erase operation can erase one sector, multiple
sectors, or the entire device. The Sector Address Tables
indicate the address range that each sector occupies. A "sector
address" consists of the address inputs required to uniquely
select a sector. See the "Command Definitions" section for
details on erasing a sector or the entire chip, or
suspending/resuming the erase operation.
After the system writes the autoselect command sequence, the
device enters the autoselect mode. The system can then read
autoselect codes from the internal register (which is separate
from the memory array) on I/O
7
- I/O
0
. Standard read cycle
timings apply in this mode. Refer to the "Autoselect Mode" and
"Autoselect Command Sequence" sections for more
information.
I
CC2
in the DC Characteristics table represents the active
current specification for the write mode. The "AC
Output Disable Mode
When the
OE
input is at V
IH
, output from the device is
disabled. The output pins are placed in the high impedance
state.
RESET
: Hardware Reset Pin
The
RESET
pin provides a hardware method of resetting the
device to reading array data. When the system drives the
RESET
pin low for at least a period of t
RP
, the device
immediately terminates any operation in progress, tristates all
data output pins, and ignores all read/write attempts for the
duration of the
RESET
pulse. The device also resets the
internal state machine to reading array data. The operation that
was interrupted should be reinitiated once the device is ready
to accept another command sequence, to ensure data integrity.
Current is reduced for the duration of the
RESET
pulse. When
RESET
is held at VSS
±
0.3V, the device draws CMOS
standby current (I
CC4
). If
RESET
is held at V
IL
but not within
VSS
±
0.3V, the standby current will be greater.
The
RESET
pin may be tied to the system reset circuitry. A
system reset would thus also reset the Flash memory, enabling
(June, 2005, Version 1.1)
6
AMIC Technology, Corp.
AMICC [ AMIC TECHNOLOGY ]
