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December 15, 2004 S29GLxxxN_MCP_A1
S29GLxxxN MirrorBit
TM
Flash Family
85
A d v a n c e I n f o r m a t i o n
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” on page 127
for more information. Refer to the AC
Read-Only Operations table for timing specifications and to
Figure 11
for the tim-
ing 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 operation. This mode provides faster read access speed for
random locations within a page. The page size of the device is 8 words/16 bytes.
The appropriate page is selected by the higher address bits A(max)–A3. Address
bits A2–A0 determine the specific word within a page. This is an 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 de-asserted and reasserted
for a subsequent access, the access time is t
ACC
or t
CE
. Fast page mode accesses
are obtained by keeping the “read-page addresses” constant and changing the
“intra-read page” addresses.
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
.
The device features an
Unlock Bypass
mode to facilitate 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 Program Command
Sequence” section has details on programming data to the device using both
standard and Unlock Bypass command sequences.
An erase operation can erase one sector, multiple sectors, or the entire device.
Table 2
,
Table 4
, and
Table 5
indicate the address space that each sector occupies.
Refer to the DC Characteristics table for the active current specification for the
write mode. The AC Characteristics section contains timing specification tables
and timing diagrams for write operations.
Write Buffer
Write Buffer Programming allows the system write to 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 primarily
intended to allow faster manufacturing throughput at the factory.