S29AL004D90TFI020 Spansion Inc., S29AL004D90TFI020 Datasheet - Page 31
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S29AL004D90TFI020
Manufacturer Part Number
S29AL004D90TFI020
Description
Flash Memory IC
Manufacturer
Spansion Inc.
Specifications of S29AL004D90TFI020
Memory Size
4Mbit
Memory Configuration
512K X 8 / 256K X 16
Ic Interface Type
Parallel
Access Time
90ns
Memory Case Style
TSOP
No. Of Pins
48
Operating Temperature Range
-40°C To +85°C
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
S29AL004D90TFI020
Manufacturer:
SPANSION
Quantity:
4 300
Part Number:
S29AL004D90TFI020H
Manufacturer:
SPANSION
Quantity:
20 000
February 18, 2005 S29AL004D_00_A1
Reading Toggle Bits DQ6/DQ2
DQ5: Exceeded Timing Limits
DQ3: Sector Erase Timer
for erasure. Thus, both status bits are required for sector and mode information.
Refer to
Figure 6, on page 30
section
Toggle Bit I‚ on page 28
timing diagram.
DQ6 in graphical form.
Refer to
initially begins reading toggle bit status, it must read DQ7–DQ0 at least twice in
a row to determine whether a toggle bit is toggling. Typically, the system would
note and store the value of the toggle bit after the first read. After the second
read, the system would compare the new value of the toggle bit with the first. If
the toggle bit is not toggling, the device has completed the program or erase op-
eration. The system can read array data on DQ7–DQ0 on the following read cycle.
However, if after the initial two read cycles, the system determines that the toggle
bit is still toggling, the system also should note whether the value of DQ5 is high
(see the section on DQ5). If it is, the system should then determine again
whether the toggle bit is toggling, since the toggle bit may have stopped toggling
just as DQ5 went high. If the toggle bit is no longer toggling, the device has suc-
cessfully completed the program or erase operation. If it is still toggling, the
device did not completed the operation successfully, and the system must write
the reset command to return to reading array data.
The remaining scenario is that the system initially determines that the toggle bit
is toggling and DQ5 has not gone high. The system may continue to monitor the
toggle bit and DQ5 through successive read cycles, determining the status as de-
scribed in the previous paragraph. Alternatively, it may choose to perform other
system tasks. In this case, the system must start at the beginning of the algo-
rithm when it returns to determine the status of the operation (top of
on page
DQ5 indicates whether the program or erase time has exceeded a specified inter-
nal pulse count limit. Under these conditions DQ5 produces a 1. This is a failure
condition that indicates the program or erase cycle was not successfully
completed.
The DQ5 failure condition may appear if the system tries to program a 1 to a lo-
cation that is previously programmed to 0. Only an erase operation can
change a 0 back to a 1. Under this condition, the device halts the operation,
and when the operation has exceeded the timing limits, DQ5 produces a 1.
Under both these conditions, the system must issue the reset command to return
the device to reading array data.
After writing a sector erase command sequence, the system may read DQ3 to de-
termine whether or not an erase operation has begun. (The sector erase timer
does not apply to the chip erase command.) If additional sectors are selected for
erasure, the entire time-out also applies after each additional sector erase com-
mand. When the time-out is complete, DQ3 switches from 0 to 1. The system
may ignore DQ3 if the system can guarantee that the time between additional
DQ2: Toggle Bit II‚ on page 28
Figure 6, on page 30
Table 6 on page 31
30).
A d v a n c e
Figure 21, on page 45
shows the toggle bit algorithm in flowchart form, and the
subsection.
I n f o r m a t i o n
to compare outputs for DQ2 and DQ6.
for the following discussion. Whenever the system
S29AL004D
Figure 20, on page 44
explains the algorithm. See also the
shows the differences between DQ2 and
shows the toggle bit
Figure 6,
DQ6:
29