D A T A S H E E T
Word/Byte Configuration
The BYTE# pin controls whether the device data I/O
pins operate in the byte or word configuration. If the
BYTE# pin is set at logic ‘1’, the device is in word con-
figuration, DQ0–DQ15 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 data I/O pins DQ0–DQ7 are
active and controlled by CE# and OE#. The data I/O
pins DQ8–DQ14 are tri-stated, and the DQ15 pin is
used as an input for the LSB (A-1) address function.
asynchronous operation; the microprocessor supplies
the specific word location.
The random or initial page access is equal to t
ACC
or
t
CE
and subsequent page read accesses (as long as
the locations specified by the microprocessor falls
within that page) is equivalent to t
PACC
. When CE# is
deasserted and reasserted for a subsequent access,
the access time is t
ACC
or t
CE
. Fast page mode ac-
cesses are obtained by keeping the “read-page ad-
dresses” constant and changing the “intra-read page”
addresses.
VersatileIO™ (V
IO
) Control
The
VersatileIO™
(V
IO
) control allows the host system
to set the voltage levels that the device generates and
tolerates on CE# and DQ I/Os to the same voltage
level that is asserted on V
IO
. See
“Ordering Informa-
tion” on page 9
for V
IO
options on this device.
For example, a V
I/O
of 1.65–3.6 volts allows for I/O at
the 1.8 or 3 volt levels, driving and receiving signals to
and from other 1.8 or 3 V devices on the same data
bus.
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 V
IL
, and OE# to V
IH
.
The device features an
Unlock Bypass
mode to facili-
tate faster programming. Once the device enters the
Unlock Bypass mode, only two write cycles are re-
quired 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 se-
quences.
An erase operation can erase one sector, multiple sec-
tors, or the entire device.
Table 2
indicates the address
space that each sector occupies.
Refer to the DC Characteristics table for the active
current specification for the write mode. The
AC Char-
acteristics
section contains timing specification tables
and timing diagrams for write operations.
Write Buffer
Write Buffer Programming allows the system to write a
maximum of 16 words/32 bytes in one programming
operation. This results in faster effective programming
time than the standard programming algorithms. See
“Write Buffer” for more information.
Accelerated Program Operation
The device offers accelerated program operations
through the ACC function. This is one of two functions
provided by the WP#/ACC pin. This function is prima-
rily intended to allow faster manufacturing throughput
at the factory.
If the system asserts V
HH
on this pin, the device auto-
matically enters the aforementioned Unlock Bypass
mode, temporarily unprotects any protected sectors,
and uses the higher voltage on the pin to reduce the
time required for program operations. The system
would use a two-cycle program command sequence
as required by the Unlock Bypass mode. Removing
V
HH
from the WP#/ACC pin returns the device to nor-
mal operation.
Note that the WP#/ACC pin must not be
11
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 con-
trol and gates array data to the output pins. WE#
should remain at V
IH
.
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 com-
mand 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-Only Operations
table for timing speci-
fications and to Figure 14 for the timing diagram. Refer
to the DC Characteristics table for the active current
specification on reading array data.
Page Mode Read
The device is capable of fast page mode read and is
compatible with the page mode Mask ROM read oper-
ation. This mode provides faster read access speed
for random locations within a page. The page size of
the device is 4 words/8 bytes. The appropriate page is
selected by the higher address bits A(max)–A2. Ad-
dress bits A1–A0 in word mode (A1–A-1 in byte mode)
determine the specific word within a page. This is an
December 14, 2005
Am29LV640MH/L
SPANSION [ SPANSION ]
