參數(shù)資料
    型號: TCM129C14A
    廠商: Texas Instruments, Inc.
    元件分類: Codec
    英文描述: Combined Single-Chip PCM Codec And Filter(單片PCM編碼譯碼器和濾波器)
    中文描述: 結(jié)合單芯片的PCM編解碼器和過濾器(單片的PCM編碼譯碼器和濾波器)
    文件頁數(shù): 18/25頁
    文件大?。?/td> 392K
    代理商: TCM129C14A
    TCM29C13A, TCM29C14A, TCM29C16A, TCM29C17A,
    TCM129C13A, TC,129C14A, TCM129C16A, TCM129C17A
    COMBINED SINGLE-CHIP PCMCODEC AND FILTER
    SCTS030E – AUGUST 1989 – REVISED OCTOBER 1996
    18
    POST OFFICE BOX 655303
    DALLAS, TEXAS 75265
    PRINCIPLES OF OPERATION
    system reliability and design considerations
    TCM29C13A, TCM29C14A, TCM29C16A, TCM29C17A, TCM129C13A, TCM129C14A, TCM129C16A, and
    TCM129C17A system reliability and design considerations are described in the following paragraphs.
    latch-up
    Latch-up is possible in all CMOS devices. It is caused by the firing of a parasitic SCR that is present due to the
    inherent nature of CMOS. When a latch-up occurs, the device draws excessive amounts of current and will
    continue to draw heavy current until power is removed. Latch-up can result in permanent damage to the device
    if supply current to the device is not limited.
    Even though the TCM29CxxA and TCM129CxxA devices are heavily protected against latch-up, it is still
    possible to cause latch-up under certain conditions in which excess current is forced into or out of one or more
    terminals. Latch-up can occur when the positive supply voltage drops momentarily below ground, when the
    negative supply voltage rises momentarily above ground, or possibly if a signal is applied to a terminal after
    power has been applied but before the ground is connected. This can happen if the device is hot-inserted into
    a card with the power applied, or if the device is mounted on a card that has an edge connector, and the card
    is hot-inserted into a system with the power on.
    To help ensure that latch-up does not occur, it is considered good design practice to connect a reverse-biased
    Schottky diode (with a forward voltage drop of less than or equal to 0.4 V — 1N5711 or equivalent), between
    each power supply and GND (see Figure 7). If it is possible that a TCM29CxxA- or TCM129CxxA-equipped card
    that has an edge connector could be hot-inserted into a powered-up system, it is also important to ensure that
    the ground edge connector traces are longer than the power and signal traces so that the card ground is always
    the first to make contact.
    device power-up sequence
    Latch-up also can occur if a signal source is connected without the device being properly grounded. A signal
    applied to one terminal could then find a ground through another signal terminal on the device. To ensure proper
    operation of the device and as a safeguard against this sort of latch-up, it is recommended that the following
    power-up sequence always be used:
    1.
    Ensure no signals are applied to the device before the power-up sequence is complete.
    2.
    Connect GND.
    3.
    Apply V
    BB
    (most negative voltage).
    Apply V
    CC
    (most positive voltage).
    Force a power down condition in the device.
    4.
    5.
    6.
    Connect clocks.
    7.
    Release the power-down condition.
    8.
    Apply FSX and/or FXR synchronization pulses.
    9.
    Apply signal inputs.
    When powering down the device, this procedure should be followed in the reverse order.
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