2 Mbit / 4 Mbit SPI Serial Flash
SST25LF020A / SST25LF040A
Data Sheet
Chip-Erase
The Chip-Erase instruction clears all bits in the device to
FFH. A Chip-Erase instruction will be ignored if any of the
memory area is protected. Prior to any Write operation, the
Write-Enable (WREN) instruction must be executed. CE#
must remain active low for the duration of the Chip-Erase
instruction sequence. The Chip-Erase instruction is initiated
by executing an 8-bit command, 60H. CE# must be driven
high before the instruction is executed. The user may poll
the Busy bit in the software status register or wait TCE for
the completion of the internal self-timed Chip-Erase cycle.
See Figure 10 for the Chip-Erase sequence.
CE#
MODE 3
0
1
2
3
4
5
6
7
MODE 0
SCK
60
SI
MSB
HIGH IMPEDANCE
SO
1242 F10.0
FIGURE 10: CHIP-ERASE SEQUENCE
Read-Status-Register (RDSR)
The Read-Status-Register (RDSR) instruction allows read-
ing of the status register. The status register may be read at
any time even during a Write (Program/Erase) operation.
When a Write operation is in progress, the Busy bit may be
checked before sending any new commands to assure that
the new commands are properly received by the device.
CE# must be driven low before the RDSR instruction is
entered and remain low until the status data is read. Read-
Status-Register is continuous with ongoing clock cycles
until it is terminated by a low to high transition of the CE#.
See Figure 11 for the RDSR instruction sequence.
CE#
MODE 3
MODE 0
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
SCK
SI
05
HIGH IMPEDANCE
MSB
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
SO
MSB
Status
1242 F11.0
Register Out
FIGURE 11: READ-STATUS-REGISTER (RDSR) SEQUENCE
©2006 Silicon Storage Technology, Inc.
S71242-05-000
1/06
14
SST [ SILICON STORAGE TECHNOLOGY, INC ]
