A49LF004 Ver la hoja de datos (PDF) - AMIC Technology
Número de pieza
componentes Descripción
Lista de partido
A49LF004 Datasheet PDF : 32 Pages
| |||
A49LF004
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 A49LF004 will not
generate any kind of response in this situation. Invalid size
fields for a Read/Write cycle are anything but 0000b.
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 A49LF004. The TBL# pin is used to write protect the top
boot block (64 Kbytes) at the highest flash memory address
range for the A49LF004. WP# pin write protects the
remaining blocks in the flash memory. An active low signal
at the TBL# pin prevents Program and Erase operations of
the top boot block. When TBL# pin is held high, write
protection of the top boot block is then determined by the
Boot Block Locking register. The WP# pin serves the same
function for the remaining blocks of the device memory. The
TBL# and WP# pins write protection 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. TBL# is internally ORed
with the top Boot Block Locking register. When TBL# is low,
the top Boot Block is hardware write protected regardless of
the state of the Write-Lock bit for the Boot Block Locking
register. Clearing the Write-Lock 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. WP#
is internally ORed with the Block Locking register. When
WP# is low, the blocks are hardware write protected
regardless of the state of the Write-Lock bit for the
corresponding Block Locking registers. Clearing the Write-
Lock 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.
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. 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 16, 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. In this case, the
device can take up to TRSTE to abort a Program or Erase
operation.
Write Operation Status Detection
The A49LF004 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 software
detection includes two status bits: Data# Polling (I/O7) and
Toggle Bit (I/O6). The End-of-Write detection mode is
incorporated into the FWH Read cycle. The actual
completion of the nonvolatile write is asynchronous 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 conflict with either I/O7
or I/O6. In order to prevent spurious rejection, if an erroneous
result occurs, the software routine should include a loop to
read the accessed location an additional two times. If both
reads are valid, then the device has completed the Write
cycle, otherwise the rejection is valid.
Data# Polling (I/O7)
When the A49LF004 device is in the internal Program
operation, any attempt to read I/O7 will produce the
complement of the true data. Once the Program operation is
completed, I/O7 will produce true data. Note that even
though I/O7 may have valid data immediately following the
completion of an internal Write operation, the remaining data
outputs may still be invalid: valid data on the entire data bus
will appear in subsequent successive Read cycles after an
interval of 1 µs. During internal Erase operation, any attempt
to read I/O7 will produce a ‘0’. Once the internal Erase
operation is completed, I/O7 will produce a ‘1’. Proper status
will not be given using Data# Polling if the address is in the
invalid range.
Toggle Bit (I/O6)
During the internal Program or Erase operation, any
consecutive attempts to read I/O6 will produce alternating
‘0’s and ‘1’s, i.e., toggling between 0 and 1. When the
internal Program or Erase operation is completed, the
toggling will stop.
Multiple Device Selection
The four ID pins, ID[3:0], allow multiple devices to be
attached to the same bus by using different ID strapping in a
system. When the A49LF004 is used as a boot device,
ID[3:0] must be strapped as 0000, all subsequent devices
should use a sequential up-count strapping (i.e. 0001, 0010,
0011, etc.). The A49LF004 will compare the strapping
values, if there is a mismatch, the device will ignore the
remainder of the cycle and go into standby mode. For further
information regarding FWH device mapping and paging,
please refer to the Intel 82801(ICH) I/O Controller Hub
documentation. Since there is no ID support in A/A Mux
mode, to program multiple devices a stand-alone PROM
programmer is recommended.
REGISTERS
There are three types of registers available on the
A49LF004, the General Purpose Inputs Register, Block
Locking Registers, and the JEDEC ID Registers. These
registers appear at their respective address location in the 4
GByte system memory map. Unused register locations will
read as 00H. Any attempt to read or write any register during
an internal Write operation will be ignored. Refer to Table 4
for the FWH register memory map.
PRELIMINARY (November, 2003, Version 0.0)
8
AMIC Technology, Corp.
Share Link: 