AM29LV004 Просмотр технического описания (PDF) - Advanced Micro Devices
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AM29LV004
Advanced Micro Devices
AM29LV004 Datasheet PDF : 36 Pages
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PRELIMINARY
DEVICE BUS OPERATIONS
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 com-
mands, 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. Table 1 lists the device bus operations, the in-
puts and control levels they require, and the resulting
output. The following subsections describe each of
these operations in further detail.
Table 1. Am29LV004 Device Bus Operations
Read
Write
Standby
Operation
CE#
L
L
VCC ±
0.3 V
OE#
L
H
X
WE#
H
L
X
RESET#
H
H
VCC ±
0.3 V
Addresses (See Note)
AIN
AIN
X
DQ0–DQ7
DOUT
DIN
High-Z
Output Disable
L
H
H
H
X
High-Z
Reset
X
X
X
L
X
High-Z
Temporary Sector Unprotect
X
X
X
VID
AIN
DIN
Legend:
L = Logic Low = VIL, H = Logic High = VIH, VID = 12.0 ± 0.5 V, X = Don’t Care, AIN = Address In, DIN = Data In, DOUT = Data Out
Note: Addresses are A18–A0.
Requirements for Reading Array Data
To read array data from the outputs, the system must
drive the CE# and OE# pins to VIL. CE# is the power
control and selects the device. OE# is the output con-
trol and gates array data to the output pins. WE#
should remain at VIH.
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 mem-
ory content occurs during the power transition. No
command is necessary in this mode to obtain array
data. Standard microprocessor read cycles that as-
sert valid addresses on the device address inputs pro-
duce valid data on the device data outputs. The
device remains enabled for read access until the com-
mand register contents are altered.
See “Reading Array Data” for more information. Refer
to the AC Read Operations table for timing specifica-
tions and to Figure 12 for the timing diagram. ICC1 in
the DC Characteristics table represents the active cur-
rent specification for reading array data.
Writing Commands/Command Sequences
To write a command or command sequence (which in-
cludes programming data to the device and erasing
sectors of memory), the system must drive WE# and
CE# to VIL, and OE# to VIH.
An erase operation can erase one sector, multiple sec-
tors, or the entire device. Tables 2 and 3 indicate the
address space that each sector occupies. A “sector ad-
dress” consists of the address bits required to uniquely
select a sector. The “Command Definitions” section
has details on erasing a sector or the entire chip, or
suspending/resuming the erase operation.
After the system writes the autoselect command se-
quence, the device enters the autoselect mode. The
system can then read autoselect codes from the inter-
nal register (which is separate from the memory array)
on DQ7–DQ0. Standard read cycle timings apply in this
mode. Refer to the “Autoselect Mode” and “Autoselect
Command Sequence” sections for more information.
ICC2 in the DC Characteristics table represents the ac-
tive current specification for the write mode. The “AC
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 DQ7–DQ0. Standard read cycle timings and ICC
read specifications apply. Refer to “Write Operation
Status” for more information, and to “AC Characteris-
tics” for timing diagrams.
Am29LV004
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