2 Mbit / 3 Mbit / 4 Mbit / 8 Mbit Firmware Hub
SST49LF002A / SST49LF003A / SST49LF004A / SST49LF008A
Advance Information
flash memory address range for the SST49LF003A/
Abort Mechanism
004A/008A and 4 boot sectors (16 KByte) for
SST49LF002A. WP# pin write protects the remaining
sectors in the flash memory.
If FWH4 is driven low for one or more clock cycles during a
FWH cycle, the cycle will be terminated and the device will
wait for the ABORT command. The host must drive the
FWH[3:0] with ‘1111b’ (ABORT command) to return the
device to ready mode. If abort occurs during the internal
write cycle, the data may be incorrectly programmed or
erased. It is required to wait for the Write operation to com-
plete prior to initiation of the abort command. It is recom-
mended to check the Write status with Data# Polling (DQ7)
or Toggle Bit (DQ6) pins. One other option is to wait for the
fixed write time to expire.
An active low signal at the TBL# pin prevents Program and
Erase operations of the top boot sectors. When TBL# pin is
held high, write protection of the top boot sectors is then
determined by the Boot Block Locking register. The WP#
pin serves the same function for the remaining sectors of
the device memory. The TBL# and WP# pins write protec-
tion functions operate independently of one another.
Both TBL# and WP# pins must be set to their required
protection states prior to starting a Program or Erase
operation. A logic level change occurring at the TBL# or
WP# pin during a Program or Erase operation could
cause unpredictable results. TBL# and WP# pins cannot
be left unconnected.
Response To Invalid Fields
During FWH operations, the FWH will not explicitly indicate
that it has received invalid field sequences. The response
to specific invalid fields or sequences is as follows:
TBL# is internally ORed with the top Boot Block Locking
register. When TBL# is low, the top Boot Block is hard-
ware write protected regardless of the state of the Write-
Lock bit for the Boot Block Locking register. Clearing the
Write-Protect bit in the register when TBL# is low will have
no functional effect, even though the register may indicate
that the block is no longer locked.
Address out of range: The FWH address sequence is
7 fields long (28 bits), but only the last five address fields
(20 bits) will be decoded by SST49LF00xA.
Address A22 has the special function of directing reads and
writes to the flash core (A22=1) or to the register space
(A22=0).
WP# is internally ORed with the Block Locking register.
When WP# is low, the blocks are hardware write pro-
tected regardless of the state of the Write-Lock bit for the
corresponding Block Locking registers. Clearing the
Write-Protect bit in any register when WP# is low will have
no functional effect, even though the register may indicate
that the block is no longer locked.
The SST49LF003A features are equivalent to the
SST49LF004A with 128 KByte less memory. For the
SST49LF003A, operations beyond the 3-Mbit bound-
ary (below 20000H) are not valid (see Device Memory
Map). Invalid address range locations will read as
00H.
Invalid IMSIZE field: If the FWH receives an invalid size
field during a Read or Write operation, the device will reset
and no operation will be attempted. The SST49LF00xA will
not generate any kind of response in this situation. Invalid-
size fields for a Read/Write cycle are anything but 0000b.
Reset
A VIL on INIT# or RST# pin initiates a device reset. INIT#
and RST# pins have the same function internally. It is
required to drive INIT# or RST# pins low during a system
reset to ensure proper CPU initialization.
Once valid START, IDSEL, and IMSIZE fields are received,
the SST49LF00xA always will respond to subsequent
inputs as if they were valid. As long as the states of device
FWH[3:0] and FWH4 are known, the response of the
SST49LF00xA to signals received during the FWH cycle
should be predictable. The SST49LF00xA will make no
attempt to check the validity of incoming flash operation
commands.
During a Read operation, driving INIT# or RST# pins low
deselects the device and places the output drivers,
FWH[3:0], in a high-impedance state. The reset signal
must be held low for a minimal duration of time TRSTP.
A
reset latency will occur if a reset procedure is performed
during a Program or Erase operation. See Table 18, Reset
Timing Parameters for more information. A device reset
during an active Program or Erase will abort the operation
and memory contents may become invalid due to data
being altered or corrupted from an incomplete Erase or
Program operation.
Device Memory Hardware Write Protection
The Top Boot Lock (TBL#) and Write Protect (WP#) pins
are provided for hardware write protection of device
memory in the SST49LF00xA. The TBL# pin is used to
write protect 16 boot sectors (64 KByte) at the highest
©2001 Silicon Storage Technology, Inc.
S71161-06-000 9/01 504
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