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  • 參數(shù)資料
    型號: AM29LV641ML110EI
    廠商: Advanced Micro Devices, Inc.
    元件分類: FLASH
    英文描述: 64 Megabit (4 M x 16-Bit) MirrorBita?? 3.0 Volt-only Uniform Sector Flash Memory with VersatileI/Oa?? Control
    中文描述: 64Mb(4個M x 16位)的MirrorBit,3V,統(tǒng)一扇區(qū)閃存并有Versatile輸入/輸出控制
    文件頁數(shù): 36/60頁
    文件大?。?/td> 640K
    代理商: AM29LV641ML110EI
    34
    Am29LV641MH/L
    December 21, 2005
    D A T A S H E E T
    DQ2: Toggle Bit II
    The “Toggle Bit II” on DQ2, when used with DQ6, indi-
    cates whether a particular sector is actively erasing
    (that is, the Embedded Erase algorithm is in progress),
    or whether that sector is erase-suspended. Toggle Bit
    II is valid after the rising edge of the final WE# pulse in
    the command sequence.
    DQ2 toggles when the system reads at addresses
    within those sectors that have been selected for era-
    sure. (The system may use either OE# or CE# to con-
    trol the read cycles.) But DQ2 cannot distinguish
    whether the sector is actively erasing or is erase-sus-
    pended. DQ6, by comparison, indicates whether the
    device is actively erasing, or is in Erase Suspend, but
    cannot distinguish which sectors are selected for era-
    sure. Thus, both status bits are required for sector and
    mode information. Refer to Table 11 to compare out-
    puts for DQ2 and DQ6.
    Figure 9 shows the toggle bit algorithm in flowchart
    form, and the section “DQ2: Toggle Bit II” explains the
    algorithm. See also the
    DQ6: Toggle Bit I
    subsection.
    Figure 22 shows the toggle bit timing diagram. Figure
    23 shows the differences between DQ2 and DQ6 in
    graphical form.
    Reading Toggle Bits DQ6/DQ2
    Refer to Figure 9 for the following discussion. When-
    ever the system initially begins reading toggle bit sta-
    tus, 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 tog-
    gle 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 operation. The
    system can read array data on DQ7–DQ0 on the fol-
    lowing read cycle.
    However, if after the initial two read cycles, the system
    determines that the toggle bit is still toggling, the sys-
    tem 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 tog-
    gling, since the toggle bit may have stopped toggling
    just as DQ5 went high. If the toggle bit is no longer
    toggling, the device has successfully completed the
    program or erase operation. If it is still toggling, the de-
    vice 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 de-
    termines 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 cy-
    cles, determining the status as described in the previ-
    ous paragraph. Alternatively, it may choose to perform
    other system tasks. In this case, the system must start
    at the beginning of the algorithm when it returns to de-
    termine the status of the operation (top of Figure 9).
    DQ5: Exceeded Timing Limits
    DQ5 indicates whether the program, erase, or
    write-to-buffer time has exceeded a specified internal
    pulse count limit. Under these conditions DQ5 produces a
    “1,” indicating that the program or erase cycle was not suc-
    cessfully completed.
    The device may output a “1” on DQ5 if the system tries
    to program a “1” to a location that was previously pro-
    grammed 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 timing limit
    has been exceeded, DQ5 produces a “1.”
    In all these cases, the system must write the reset
    command to return the device to the reading the array
    (or to erase-suspend-read if the device was previously
    in the erase-suspend-program mode).
    DQ3: Sector Erase Timer
    After writing a sector erase command sequence, the
    system may read DQ3 to determine whether or not
    erasure 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 period is complete, DQ3
    switches from a “0” to a “1.” If the time between addi-
    tional sector erase commands from the system can be
    assumed to be less than 50 μs, the system need not
    monitor DQ3. See also the
    Sector Erase Command
    Sequence
    section.
    After the sector erase command is written, the system
    should read the status of DQ7 (Data# Polling) or DQ6
    (Toggle Bit I) to ensure that the device has accepted
    the command sequence, and then read DQ3. If DQ3 is
    “1,” the Embedded Erase algorithm has begun; all fur-
    ther commands (except Erase Suspend) are ignored
    until the erase operation is complete. If DQ3 is “0,” the
    device will accept additional sector erase commands.
    To ensure the command has been accepted, the sys-
    tem software should check the status of DQ3 prior to
    and following each subsequent sector erase com-
    mand. If DQ3 is high on the second status check, the
    last command might not have been accepted.
    Table 11 shows the status of DQ3 relative to the other
    status bits.
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