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參數(shù)資料
| 型號： | ADM3085AN |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 通用總線功能 |
| 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： | LINE TRANSCEIVER, PDIP8 |
| 封裝： | PLASTIC, DIP-8 |
| 文件頁數(shù)： | 13/14頁 |
| 文件大小： | 316K |
| 代理商： | ADM3085AN |
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PDF資料 |
PDF描述 |
|---|---|
| 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 |
| ADM3088AR | High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| ADM3085AR | 制造商:AD 制造商全稱: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: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: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:Analog Devices 功能描述:High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection |
| ADM3088AN | 制造商:AD 制造商全稱:Analog Devices 功能描述:High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection |
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