©2011 Silicon Storage Technology, Inc. DS25028A 08/11
6
16 Mbit / 32 Mbit Multi-Purpose Flash Plus
SST39VF1601 / SST39VF3201
SST39VF1602 / SST39VF3202
Not Recommended for New Designs
Microchip Technology Company
Device Operation
Commands are used to initiate the memory operation functions of the device. Commands are written
to the device using standard microprocessor write sequences. A command 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.
The SST39VF160x/320x also have the Auto Low Power mode which puts the device in a near
standby mode after data has been accessed with a valid Read operation. This reduces the I
DD
active
read current from typically 9 mA to typically 3 µA. The Auto Low Power mode reduces the typical I
DD
active read current to the range of 2 mA/MHz of Read cycle time. The device exits the Auto Low Power
mode with any address transition or control signal transition used to initiate another Read cycle, with
no access time penalty. Note that the device does not enter Auto-Low Power mode after power-up with
CE# held steadily low, until the first address transition or CE# is driven high.
Read
The Read operation of the SST39VF160x/320x 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 4).
Word-Program Operation
The SST39VF160x/320x are programmed on a word-by-word basis. Before programming, the sector
where the word 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
word address and word data. During the Word-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 ini-
tiated after the rising edge of the fourth WE# or CE#, whichever occurs first. The Program operation,
once initiated, will be completed within 10 µs. See Figures 5 and 6 for WE# and CE# controlled Pro-
gram operation timing diagrams and Figure 20 for flowcharts. During the Program operation, the only
valid reads are Data# Polling and Toggle Bit. During the internal Program operation, the host is free to
perform additional tasks. Any commands issued during the internal Program operation are ignored.
During the command sequence, WP# should be statically held high or low.
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 SST39VF160x/320x offer both Sector-Erase and Block-Erase mode. The
sector architecture is based on uniform sector size of 2 KWord. The Block-Erase mode is based on
uniform block size of 32 KWord. 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
Block-Erase operation is initiated by executing a six-byte command sequence with Block-Erase com-
mand (50H) 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 10 and 11
