©2011 Silicon Storage Technology, Inc. DS25023A 08/11
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1 Mbit / 2 Mbit / 4 Mbit Multi-Purpose Flash
SST39LF010 / SST39LF020 / SST39LF040
SST39VF010 / SST39VF020 / SST39VF040
Data Sheet
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.
Read
The Read operation of the SST39LF010/020/040 and SST39VF010/020/040 devices are 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
6).
Byte-Program Operation
The SST39LF010/020/040 and SST39VF010/020/040 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 Protec-
tion. 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 7 and 8 for
WE# and CE# controlled Program operation timing diagrams and Figure 17 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 written during the internal Pro-
gram operation will be ignored.
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 command 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 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 methods. See Figure 11 for timing waveforms. Any commands written during the
Sector-Erase operation will be ignored.
Chip-Erase Operation
The SST39LF010/020/040 and SST39VF010/020/040 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