SST39VF088 データシートの表示（PDF） - Silicon Storage Technology
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SST39VF088 Datasheet PDF : 22 Pages
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Preliminary Specifications
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.
Read
The Read operation of the SST39VF088 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
impedance state when either CE# or OE# is high. Refer to
the Read cycle timing diagram for further details (Figure 2).
Byte-Program Operation
The SST39VF088 is 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 3 and
4 for WE# and CE# controlled Program operation timing
diagrams and Figure 13 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 issued
during the internal Program operation are ignored.
Sector/Block-Erase Operation
The Sector- (or Block-) Erase operation allows the system
to erase the device on a sector-by-sector (or block-by-
block) basis. The SST39VF088 offers both Sector-Erase
and Block-Erase mode. The sector architecture is based
on uniform sector size of 4 KByte. The Block-Erase mode
is based on uniform block size of 64 KByte. The Sector-
Erase operation is initiated by executing a six-byte com-
mand sequence with Sector-Erase command (50H) and
sector address (SA) in the last bus cycle. The Block-Erase
operation is initiated by executing a six-byte command
8 Mbit Multi-Purpose Flash
SST39VF088
sequence with Block-Erase command (30H) and block
address (BA) in the last bus cycle. The sector or block
address is latched on the falling edge of the sixth WE#
pulse, while the command (30H or 50H) is latched on the
rising edge of the sixth WE# pulse. The internal Erase
operation begins after the sixth WE# pulse. The End-of-
Erase operation can be determined using either Data#
Polling or Toggle Bit methods. See Figures 8 and 9 for tim-
ing waveforms. Any commands issued during the Sector-
or Block-Erase operation are ignored.
Chip-Erase Operation
The SST39VF088 provides a Chip-Erase operation, which
allows the user to erase the entire memory array to the “1”
state. This is useful when the entire device must be quickly
erased.
The Chip-Erase operation is initiated by executing a six-
byte command sequence with Chip-Erase command (10H)
at address AAAH in the last byte sequence. The Erase
operation begins with the rising edge of the sixth WE# or
CE#, whichever occurs first. During the Erase operation,
the only valid read is Toggle Bit or Data# Polling. See Table
4 for the command sequence, Figure 7 for timing diagram,
and Figure 16 for the flowchart. Any commands issued dur-
ing the Chip-Erase operation are ignored.
Write Operation Status Detection
The SST39VF088 provides 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
detection includes two status bits: Data# Polling (DQ7) and
Toggle Bit (DQ6). The End-of-Write detection mode is
enabled after the rising edge of WE#, which initiates the
internal Program 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 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.
©2003 Silicon Storage Technology, Inc.
2
S71227-04-000
11/03
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