SST49LF004B-33-4C-EI SST [Silicon Storage Technology, Inc], SST49LF004B-33-4C-EI Datasheet - Page 20

• Manufacturer Part Number: SST49LF004B-33-4C-EI
• Description: 4 Mbit LPC Firmware Flash
• Manufacturer: SST [Silicon Storage Technology, Inc]

Data Sheet
PARALLEL PROGRAMMING MODE
Device Operation
Commands are used to initiate the memory operation func-
tions of the device. The data portion of the software com-
mand sequence is latched on the rising edge of WE#.
During the software command sequence the row address
is latched on the falling edge of R/C# and the column
address is latched on the rising edge of R/C#.
Read
The Read operation of the SST49LF004B device is con-
trolled by OE#. OE# is the output control and is used to
gate data from the output pins. Refer to the Read cycle tim-
ing diagram, Figure 13, for further details.
Reset
A V
Byte-Program Operation
The SST49LF004B device is programmed on a byte-by-
byte basis. Before programming, one must ensure that the
byte that is being programmed is fully erased. The Byte-
Program operation is initiated by executing a four-byte com-
mand load sequence for Software Data Protection with
address (PA) and data in the last bus cycle. During the
Byte-Program operation, the row address (A
latched on the falling edge of R/C# and the column
Address (A
The data bus is latched on the rising edge of WE#. The
Program operation, once initiated, will be completed, within
20 µs. See Figure 17 for timing waveforms. During the Pro-
gram 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 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 com-
mand load sequence for Software Data Protection with
Sector-Erase command (30H) and sector address (SA) in
the last bus cycle. 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 Fig-
ure 18 for Sector-Erase timing waveforms. Any commands
written during the Sector-Erase operation will be ignored.
©2003 Silicon Storage Technology, Inc.
IL
on RST# pin initiates a device reset.
21
-A
11
) is latched on the rising edge of R/C#.
10
-A
0
) is
20
Block-Erase Operation
The Block-Erase Operation allows the system to erase any
of the 8 uniform 64 KByte blocks. The Block- Erase opera-
tion is initiated by executing a six-byte command load
sequence for Software Data Protection with Block-Erase
command (50H) and block address (BA) in the last bus
cycle. The internal Block-Erase operation begins after the
sixth WE# pulse. The End-of-Erase can be determined
using either Data# Polling or Toggle Bit methods. See Fig-
ure 19 for timing waveforms. Any commands written during
the Block- Erase operation will be ignored.
Chip-Erase Operation
The SST49LF004B device provides a Chip-Erase opera-
tion only in PP mode, 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 com-
mand (10H) with address 5555H in the last bus cycle. The
internal Erase operation begins with the rising edge of the
sixth WE#. During the internal Erase operation, the only
valid reads are Toggle Bit or Data# Polling. See Table 13 for
the command sequence, Figure 20 for timing diagram. Any
commands written during the Chip-Erase operation will be
ignored.
Write Operation Status Detection
The SST49LF004B device 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 soft-
ware detection includes two status bits: Data# Polling
(DQ
mode is enabled after the rising edge of WE# which ini-
tiates 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 DQ
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, the device
has completed the Write cycle, otherwise the rejection is
valid.
7
) and Toggle Bit (DQ
4 Mbit LPC Firmware Flash
7
or DQ
6
6
). The End-of-Write detection
. In order to prevent spurious
SST49LF004B
S71232-02-000
12/03