2 Mbit / 4 Mbit / 8 Mbit Multi-Purpose Flash
SST39LF200A / SST39LF400A / SST39LF800A
SST39VF200A / SST39VF400A / SST39VF800A
Data Sheet
The actual completion of the nonvolatile write is asynchro-
Data Protection
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.
The SST39LF200A/400A/800A and SST39VF200A/400A/
800A provide both hardware and software features to pro-
tect nonvolatile data from inadvertent writes.
Hardware Data Protection
Noise/Glitch Protection: A WE# or CE# pulse of less than 5
ns will not initiate a write cycle.
VDD Power Up/Down Detection: The Write operation is
inhibited when VDD is less than 1.5V.
Write Inhibit Mode: Forcing OE# low, CE# high, or WE#
high will inhibit the Write operation. This prevents inadvert-
ent writes during power-up or power-down.
Data# Polling (DQ7)
When the SST39LF200A/400A/800A and SST39VF200A/
400A/800A are in the internal Program operation, any
attempt to read DQ7 will produce the complement of the
true data. Once the Program operation is completed, DQ7
will produce true data. Note that even though DQ7 may
have valid data immediately following the completion of an
internal Write operation, the remaining data outputs may
still be invalid: valid data on the entire data bus will appear
in subsequent successive Read cycles after an interval of
1 µs. During internal Erase operation, any attempt to read
DQ7 will produce a ‘0’. Once the internal Erase operation
is completed, DQ7 will produce a ‘1’. The Data# Polling is
valid after the rising edge of fourth WE# (or CE#) pulse for
Program operation. For Sector-, Block- or Chip-Erase, the
Data# Polling is valid after the rising edge of sixth WE# (or
CE#) pulse. See Figure 8 for Data# Polling timing diagram
and Figure 19 for a flowchart.
Software Data Protection (SDP)
The SST39LF200A/400A/800A and SST39VF200A/400A/
800A provide the JEDEC approved Software Data Protec-
tion scheme for all data alteration operations, i.e., Program
and Erase. Any Program operation requires the inclusion of
the three-byte sequence. The three-byte load sequence is
used to initiate the Program operation, providing optimal
protection from inadvertent Write operations, e.g., during
the system power-up or power-down. Any Erase operation
requires the inclusion of six-byte sequence. This group of
devices are shipped with the Software Data Protection per-
manently enabled. See Table 4 for the specific software
command codes. During SDP command sequence, invalid
commands will abort the device to Read mode within TRC.
The contents of DQ15-DQ8 can be VIL or VIH, but no other
value, during any SDP command sequence.
Toggle Bit (DQ6)
During the internal Program or Erase operation, any con-
secutive attempts to read DQ6 will produce alternating 1s
and 0s, i.e., toggling between 1 and 0. When the internal
Program or Erase operation is completed, the DQ6 bit will
stop toggling. The device is then ready for the next opera-
tion. The Toggle Bit is valid after the rising edge of fourth
WE# (or CE#) pulse for Program operation. For Sector-,
Block- or Chip-Erase, the Toggle Bit is valid after the rising
edge of sixth WE# (or CE#) pulse. See Figure 9 for Toggle
Bit timing diagram and Figure 19 for a flowchart.
Common Flash Memory Interface (CFI)
The SST39LF200A/400A/800A and SST39VF200A/400A/
800A also contain the CFI information to describe the char-
acteristics of the device. In order to enter the CFI Query
mode, the system must write three-byte sequence, same
as Software ID Entry command with 98H (CFI Query com-
mand) to address 5555H in the last byte sequence. Once
the device enters the CFI Query mode, the system can
read CFI data at the addresses given in Tables 5 through 9.
The system must write the CFI Exit command to return to
Read mode from the CFI Query mode.
©2007 Silicon Storage Technology, Inc.
S71117-09-000
2/07
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