Datasheet
©2011 Silicon Storage Technology, Inc. DS25008A 08/11
7
64 Mbit Multi-Purpose Flash Plus
SST39VF6401B / SST39VF6402B
Not Recommended for New Designs
A
Microchip Technology Company
ing waveforms and Figure 23 for the flowchart. Any commands issued during the Sector- or Block-
Erase operation are ignored. When WP# is low, any attempt to Sector- (Block-) Erase the protected
block will be ignored. During the command sequence, WP# should be statically held high or low.
Erase-Suspend/Erase-Resume Commands
The Erase-Suspend operation temporarily suspends a Sector- or Block-Erase operation thus allowing
data to be read from any memory location, or program data into any sector/block that is not suspended
for an Erase operation. The operation is executed by issuing one byte command sequence with Erase-
Suspend command (B0H). The device automatically enters read mode typically within 20 µs after the
Erase-Suspend command had been issued. Valid data can be read from any sector or block that is not
suspended from an Erase operation. Reading at address location within erase-suspended sectors/
blocks will output DQ
2
toggling and DQ
6
at “1”. While in Erase-Suspend mode, a Word-Program oper-
ation is allowed except for the sector or block selected for Erase-Suspend.
To resume Sector-Erase or Block-Erase operation which has been suspended the system must issue
Erase Resume command. The operation is executed by issuing one byte command sequence with
Erase Resume command (30H) at any address in the last Byte sequence.
Chip-Erase Operation
The SST39VF640xB provide a Chip-Erase operation, which allows the user to erase the entire mem-
ory 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 555H 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 6 for the command sequence, Figure 9 for timing diagram, and
Figure 23 for the flowchart. Any commands issued during the Chip-Erase operation are ignored. When
WP# is low, any attempt to Chip-Erase will be ignored. During the command sequence, WP# should
be statically held high or low.
Write Operation Status Detection
The SST39VF640xB 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 detection includes two sta-
tus bits: Data# Polling (DQ
7
) and Toggle Bit (DQ
6
). 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 asynchronous 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 conflict 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 rejection is valid.