512 Kbit / 1 Mbit / 2 Mbit / 4 Mbit Multi-Purpose Flash
SST39LF512 / SST39LF010 / SST39LF020 / SST39LF040
SST39VF512 / SST39VF010 / SST39VF020 / SST39VF040
Data Sheet
Device Operation
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 asserting WE# low while keeping CE#
low. The address bus is latched on the falling edge of WE#
or CE#, whichever occurs last. The data bus is latched on
the rising edge of WE# or CE#, whichever occurs first.
edge of the sixth WE# pulse. The internal Erase operation
begins after the sixth WE# pulse. The End-of-Erase can be
determined using either Data# Polling or Toggle Bit meth-
ods. See Figure 10 for timing waveforms. 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 rising edge of the sixth WE# or CE#, whichever occurs
first. During the internal Erase operation, the only valid read
is Toggle Bit or Data# Polling. See Table 4 for the command
sequence, Figure 11 for timing diagram, and Figure 19 for
the flowchart. Any commands written during the Chip-
Erase operation will be ignored.
Read
The Read operation of the SST39LF512/010/020/040 and
SST39VF512/010/020/040 device is controlled by CE#
and OE#, both have 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 cycle timing diagram for further details (Figure 5).
Byte-Program Operation
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 steps. The first step is the three-byte load sequence
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#, whichever
occurs first. The third step is the internal Program operation
which is initiated after the rising edge of the fourth WE# or
CE#, whichever occurs first. The Program operation, once
initiated, will be completed, within 20 µs. See Figures 6 and
7 for WE# and CE# controlled Program operation timing
diagrams and Figure 16 for flowcharts. During the Program
operation, the only valid reads are Data# Polling and Tog-
gle Bit. During the internal Program operation, the host is
free to perform additional tasks. Any commands written
during the internal Program operation will be ignored.
Write Operation Status Detection
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 includes two status bits: Data# Polling (DQ
7
) and Tog-
gle Bit (DQ
6
). The End-of-Write detection mode is enabled
after the rising edge of WE# which initiates the internal Pro-
gram or Erase operation.
The actual completion of the nonvolatile write is asynchro-
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 DQ
7
or DQ
6
. 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.
Sector-Erase Operation
The Sector-Erase operation allows the system to erase the
device on a sector-by-sector basis. 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
©2005 Silicon Storage Technology, Inc.
S71150-09-000
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