2
Data Sheet
512 Kbit / 1 Mbit / 2 Mbit / 4 Mbit Multi-Purpose Flash
SST39LF512 / SST39LF010 / SST39LF020 / SST39LF040
SST39VF512 / SST39VF010 / SST39VF020 / SST39VF040
©2003 Silicon Storage Technology, Inc. S71150-07-000 11/03
Device Operatio n
Commands are used to initiate the memory operation func-
tions of the device. Commands are written to the device
using standard microprocessor write sequences. A com-
mand is written by asse rtin g WE# low while keepi ng CE#
low. The address b us is latched on the f alling edge of WE#
or CE#, whichever oc curs l ast. T he data bus is latc hed o n
the rising edge of WE# or CE#, whichev er occurs first.
Read
The Rea d op era tio n o f the S ST3 9LF 5 12/ 01 0/0 20/ 040 an d
SST39VF512/010/020/040 device is controlled by CE#
and OE#, both hav e to be low for the system to obtain data
from the outputs. CE# is used for device selection. When
CE# is high, the chip is deselected and only standby power
is consumed. OE# is the output control and is used to gate
data from the output pins. The data bus is in high imped-
ance state when either CE# or OE# is high. Refer to the
Read cycl e timing diagra m f or furth er details (Fig ure 5).
Byte-P rogram Opera ti on
The SST39LF512/010/020/040 and SST39VF512/010/
020/040 are programmed on a byte-by-byte basis. Before
programming, the sector where the byte exists must be
fully erased. The Program operation is accomplished in
three s teps. The first step is the thr ee-byte load s equenc e
for Software Data Protection. The second step is to load
byte address and byte data. During the Byte-Program
operation, the addresses are latched on the falling edge of
either CE# or WE#, whichever occurs last. The data is
latched on the rising edge of either CE# or WE#, whichev er
occurs first. The third step is the internal Progr am operation
which is i niti ate d a fte r t he rising edge of the fourth WE# or
CE#, whic hever occur s firs t. The Pr ogram operat ion, on ce
initiated, will be completed, within 20 µs. See Figures 6 and
7 for WE# and CE# controlled Program operation timing
diagrams and Figure 16 f or flowcharts. During the Program
operatio n, the only valid reads ar e Data# Poll ing and Tog-
gle Bit. During the inter nal Program operation, the host is
free to perform additional tasks. Any commands written
during the internal Program operation will be ignored.
Sector-Erase Operation
The Sector-Erase operation allows the system to erase the
device on a sector-by-sector ba sis. The sector architecture
is based on uniform sector size of 4 KByte. The Sector-
Erase operation is initiated by executing a six-byte com-
mand sequence with Sector-Erase command (30H) and
sector address (SA) in the last bus cycle. The sector
address is latched on the falling edge of the sixth WE#
pulse, while the command (30H) is latched on the rising
edge o f the si xt h WE # pulse. The inte r n al Era se op erat io n
begins after the sixth WE# pulse . The End-of-Erase can be
deter mined using either Data# Polling or Toggle Bit meth-
ods. See Figur e 10 for timing wavefor ms. Any commands
written during the Sector-Erase operation will be ignored.
Chip-Erase Operation
The SST39LF512/010/020/040 and SST39VF512/010/
020/040 devices provide a Chip-Erase operation, which
allows the user to erase the entire memory array to the ‘1’s
state. This is useful when the entire device must be quickly
erased.
The Chip-Erase operation is initiated by executing a six-
byte Software Data Protection command sequence with
Chip-Erase command (10H) with address 5555H in the last
byte sequence. The internal Erase operation begins with
the risi ng ed ge of th e si xth WE # o r CE# , which eve r oc cu rs
first. During the internal Erase operation, the only valid read
is Toggle Bit or Data# P olling. See Table 4 f or the command
sequenc e, Figur e 11 for ti ming diagram, an d Fi gure 19 for
the flowchart. Any commands written during the Chip-
Erase operation will be ignored.
Write Opera ti on Status De te ct ion
The SST39LF512/010/020/040 and SST39VF512/010/
020/040 devices provide two software means to detect the
completion of a Write (Program or Erase) cycle, in order to
optimize the system write cycle time. The software detec-
tion in cl ud es two s ta tus b it s: Dat a# Poll in g (D Q 7) and Tog-
gle Bit (DQ6). The End-of-Write detection mode is enabled
after the rising edge of WE# which initiates the internal Pro-
gr am or E rase op er ation.
The act ual co mple tion of the nonvolatile wr ite is as ynchr o-
nous with the system; therefore, either a Data# Polling or
Toggle Bit read may be simultaneous with the completion
of the Write cycle. If this occurs, the system may possibly
get an erroneous result, i.e., valid data may appear to con-
flict with either DQ7 or DQ6. In order to prevent spurious
rejection, if an erroneous result occurs, the software routine
should include a loop to read the accessed location an
additional two (2) times. If both reads are valid, then the
device has completed the Write cycle, otherwise the rejec-
tion is valid.