February 7, 2007 S29GL-M_00_B8
S29GL-M MirrorBitTM Flash Family
23
Data
Sheet
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 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 con-
tents are altered.
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 4 words/8 bytes. The appropriate page is selected by the higher
address bits A(max)–A2. Address bits A1–A0 in word mode (A1–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 tACC or tCE and subsequent page read accesses (as
long as the locations specified by the microprocessor falls within that page) is equivalent to tPACC.
When CE# is deasserted and reasserted for a subsequent access, the access time is tACC or tCE.
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 VIL, and OE# to VIH.
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
using both standard and Unlock Bypass command sequences.
An erase operation can erase one sector, multiple sectors, or the entire device.
Table 6 and
Table 16 indicates the address space that each sector occupies.
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 pro-
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 pri-
marily intended to allow faster manufacturing throughput at the factory.
If the system asserts VHH on this pin, the device automatically enters the aforementioned Unlock
Bypass mode, temporarily unprotects any protected sector groups, 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 VHH 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 VHH for operations other than accelerated program-
ming, or device damage may result. WP# has an internal pullup; when unconnected, WP# is at
VIH.
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.
See Autoselect