D at a
S hee t
8.2.1
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 in word mode (A2–A-1 in byte mode) 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
deasserted 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.
8.3
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 required to program a word, instead of four. The
contains 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. Tables
–
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.
8.3.1
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.
8.3.2
Accelerated Program Operation
The device offers accelerated program operations through the ACC function. This is one of two functions
provided by the WP#/ACC or ACC pin, depending on model number. This function is primarily intended to
allow faster manufacturing throughput at the factory.
If the system asserts V
HH
on this pin, the device automatically 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 or ACC pin, depending on model
number, returns the device to normal operation.
Note that the WP#/ACC or ACC pin must not be at V
HH
for
operations other than accelerated programming, or device damage may result. WP# contains an internal
pullup; when unconnected, WP# is at V
IH
.
8.3.3
Autoselect Functions
If 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 DQ7–
DQ0. Standard read cycle timings apply in this mode. Refer to
and
for more information.
18
S29GL-N MirrorBit
®
Flash Family
S29GL-N_01_09 November 16, 2007
SPANSION [ SPANSION ]
