SA25F020 Datasheet, PDF (28/37 Pages) List of Unclassifed Manufacturers – 2Mb Serial Flash with 25MHz SPI Bus Interface

Sector Erase (SE)
The SE instruction sets all 512 Kb in the
selected sector to 1. Before it can be
executed, two separate instructions must
be carried out. The device must first be
write enabled via the WREN instruction,
and then a SE sequence, which consists of
four bytes, may be executed. The address
of the memory locations to be written must
be inside the sector to be erased and
outside the protected address field location
selected by the Block Write Protection
level. During an internal SE cycle, all
commands are ignored except the RDSR
instruction.
A SE instruction requires the following
sequence:
1. After the CSb line is pulled low to
select the device, the SE opcode is
transmitted via the SI line, followed
by the 3-byte address.
2. Erasing begins after the CSb pin is
brought high. The CSb pin's
low-to-high transition must occur
during the SCK low time,
immediately after the clock in the
last address bit.
CS
SA25F020 Advanced Information
SAIFUN
28
As soon as CSb is driven high, the
self-timed SE cycle (whose duration is
defined as T_SE) is initiated. While the SE
cycle is in progress, the status register
may be read to check the value of the
/RDY bit. The /RDY bit is 1 during the
self-timed SE cycle, and 0 when it is
completed. The WEN bit is reset at some
unspecified time before the cycle is
completed. The instruction sequence is
shown in Figure 18.
The SA25F020 is automatically returned to
the write disable state at the completion of
an SE cycle.
NOTES:
1. If the device is not write enabled,
the device ignores the SE
instruction and returns to the
standby state when CSb is brought
high. A new CSb falling edge is
required to re-initiate the serial
communication.
2. A SE instruction applied to a sector
that is protected by the Block
Protect (BP1, BP0) bits (as
described in Table 8, page 18, and
Table 9, page 21) is not executed.
SCK
SI
0 1 2 3 4 5 6 7 8 9 10 28 29 30 31
Instruction
24 Bit Address
23 22 21
MSB
3210
Figure 18. Sector Erase (SE) Instruction Sequence