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  • 參數(shù)資料
    型號(hào): ADM3085
    廠(chǎng)商: Analog Devices, Inc.
    英文描述: High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection
    中文描述: 高速(高達(dá)10Mbps),失效保護(hù),RS-485/RS-422收發(fā)器的擺率限制和5kV的ESD保護(hù)
    文件頁(yè)數(shù): 13/14頁(yè)
    文件大?。?/td> 316K
    代理商: ADM3085
    ADM3082/ADM3085/ADM3088
    –13–
    PRELIMINARY TECHNICAL DATA
    CURRENT LIMIT AND THERMAL SHUTDOWN
    The ADM3082/ADM3085/ADM3088 incorporate two
    protection mechanisms to guard the drivers against short-
    circuits, bus contention or other fault conditions. The first
    is a foldback current-limited output stage that protects the
    driver against short-circuits over the entire common-mode
    voltage range. The second is a thermal shutdown circuit
    that puts the driver outputs into a high-impedance state if
    the die temperature exceeds a safe limit.
    REDUCED EMI AND REFLECTIONS
    The ADM3082 and ADM3085 incorporate slew-rating lim-
    iting in the drivers. This reduces reflections due to incor-
    rect cable termination and minimizes electromagnetic
    interference (EMI).
    Figures 9 to 11 show driver output waveforms and Fourier
    analyses of 20kHz signals for the three different slew-rate
    settings. It can be seen that the harmonic content is greatly
    reduced for the ADM3085 and still further for the
    ADM3082 (Figures 10 and 9 respectively).
    AWAITING DATA
    Figure 9 ADM3082 Driver Output Waveform and FFT Plot
    AWAITING DATA
    Figure 10. ADM3085 Driver Output Waveform and FFT Plot
    AWAITING DATA
    Figure 11. ADM3088 Driver Output Waveform and FFT Plot
    The length of an unterminated stub that can be driven
    with only minor reflections depends on the rise time of
    the transmitter. A conservative estimate for this is given
    by the following equation:
    L (metres) = t
    R
    / 49.2
    where t
    R
    is the transmitter’s rise time in ns (multiply re-
    sult by 3.28 for answer in feet).
    For example, the rise time of the ADM3082 is typically
    1320ns, which results in acceptable waveforms with stub
    lengths up to 27 metres. This is not the ultimate limit on
    unterminated stub length, as a system can still work if the
    waveformis allowed to settle before sampling the data.
    The RS-485/RS-422 standard covers line lengths up to
    4000 feet (1219 metres). Driver output and receiver out-
    put waveforms for the three slew rate settings, driving a
    4000 foot cable, are shown in figures 12 to 14.
    AWAITING DATA
    Figure 12. Driver Input, Driver Output and Receiver Output
    Waveforms of ADM3082, Driving 4000ft (1219m) of Cable
    at 50kHz
    REV. PrA 02/02
    相關(guān)PDF資料
    PDF描述
    ADM3085AN High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection
    ADM3085AR High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection
    ADM3085JN High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection
    ADM3085JR High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection
    ADM3088AN High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection
    相關(guān)代理商/技術(shù)參數(shù)
    參數(shù)描述
    ADM3085AN 制造商:AD 制造商全稱(chēng):Analog Devices 功能描述:High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection
    ADM3085AR 制造商:AD 制造商全稱(chēng):Analog Devices 功能描述:High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection
    ADM3085JN 制造商:AD 制造商全稱(chēng):Analog Devices 功能描述:High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection
    ADM3085JR 制造商:AD 制造商全稱(chēng):Analog Devices 功能描述:High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection
    ADM3088 制造商:AD 制造商全稱(chēng):Analog Devices 功能描述:High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection