FLASH
Austin Semiconductor, Inc.
DEVICE BUS OPERATIONS
NOTE: All device/algorithm descriptions contained in this data
sheet reference each individual die.
This section describes the requirements and use of the
device bus operations, which are initiated through the internal
command register. The command register itself does not
occupy any addressable memory location. The register is
composed of latches that store the commands, along with the
address and data information needed to execute the command.
The contents of the register serve as inputs to the internal state
machine. The state machine outputs dictate the function of the
device. The appropriate device bus operations table lists the
inputs and control levels required, and the resulting output.
The following subsections describe each of these operations
in further detail.
AS8F128K32
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.
I
CC1
in the DC Characteristics table represents the active
current specification for reading array data.
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 WEx\ and CEx\ to V
IL
, and OE\ to V
IH
.
An erase operation can erase one sector, multiple sectors,
or the entire device. The Sector Address Tables indicate the
address space that each sector occupies. A “sector address”
consists of the address bits required to uniquely select a
sector. See the “Command Definitions” section for details on
erasing a sector or the entire chip.
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/O31–I/O0. 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
Characteristics” section contains timing specification tables
and timing diagrams for write operations.
Requirements for Reading Array Data
To read array data from the outputs, the system must drive
the CEx\ and OE\ pins to V
IL
. CEx\ is the power control and
selects the device. OE\ is the output control and gates array
data to the output pins. WEx\ should remain at V
IH
.
The internal state machine is set for reading array data
upon device power-up. 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
TABLE 1: Device Bus Operations
1
OPERATION
Read
Write
Standby
Output Disable
Hardware Reset
Temporary Sector Unprotect
CEx\
L
L
V
CC
± 0.5V
L
X
X
OE\
L
H
X
H
X
X
WEx\
H
L
X
H
X
X
ADRESSES
(A16:A0)
A
IN
A
IN
X
X
X
A
IN
I/O0 - I/O31
D
OUT
D
IN
High-Z
High-Z
High-Z
D
IN
LEGEND:
L = Logic Low = V
IL
, H = Logic High = V
IH
, V
ID
= 12.0 ± 0.5 V, X = Don’t Care, A
IN
= Addresses In, D
IN
= Data In, D
OUT
= Data Out
NOTES:
1. The sector protect and sector unprotect functions must be implemented via programming equipment. See the “Sector Protection/
Unprotection” section.
AS8F128K32
Rev. 2.0 5/03
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
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