1 Mbit / 2 Mbit / 4 Mbit Multi-Purpose Flash
SST39SF010A / SST39SF020A / SST39SF040
Data Sheet
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 SST39SF010A/020A/040 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 (Figure 5) for further details.
Byte-Program Operation
The SST39SF010A/020A/040 are programmed on a byte-by-byte basis. Before programming, the sec-
tor 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 fall-
ing 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 6 and 7 for WE# and CE# controlled Program
operation timing diagrams and Figure 16 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 per-
form additional tasks. Any commands written during the internal Program 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 load sequence for Software Data Protection with Sector-Erase com-
mand (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 deter-
mined using either Data# Polling or Toggle Bit methods. See Figure 10 for timing waveforms. Any com-
mands written during the Sector-Erase operation will be ignored.
Chip-Erase Operation
The SST39SF010A/020A/040 provide Chip-Erase operation, which allows the user to erase the entire
memory array to the “1s” 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
internal Erase operation, the only valid read is Toggle Bit or Data# Polling. See Table 4 for the com-
mand sequence, Figure 11 for timing diagram, and Figure 19 for the flowchart. Any commands written
during the Chip-Erase operation will be ignored.
©2013 Silicon Storage Technology, Inc.
DS25022B
04/13
7
MICROCHIP [ MICROCHIP ]
