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參數(shù)資料
| 型號(hào)： | ADM1486 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | +5 V Low Power RS-485 PROFIBUS Transceiver |
| 中文描述： | 5 V低功耗RS - 485現(xiàn)場(chǎng)總線收發(fā)器 |
| 文件頁(yè)數(shù)： | 6/8頁(yè) |
| 文件大?。?/td> | 151K |
| 代理商： | ADM1486 |
ADM1486
REV. PrB
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6
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APPLICATIONS INFORMATION
Differential Data Transmission
Differential data transmission is used to reliably transmit
data at high rates over long distances and through noisy
environments. Differential transmission nullifies the effects
of ground shifts and noise signals which appear as
common-mode voltages on the line. There are two main
standards approved by the Electronics Industries Association
(EIA) which specify the electrical characteristics of trans-
ceivers used in differential data transmission.
The RS-422 standard specifies data rates up to 10 MBaud
and line lengths up to 4000 ft. A single driver can drive a
transmission line with up to 10 receivers.
In order to cater for true multipoint communications, the
RS-485 standard was defined. This standard meets or
exceeds all the requirements of RS-422 but also allows for
up to 32 drivers and 32 receivers to be connected to a
single bus. An extended common-mode range of –7 V to
+12 V is defined. The most significant difference between
RS-422 and RS-485 is the fact that the drivers may be
disabled thereby allowing more than one (32 in fact) to be
connected to a single line. Only one driver should be
enabled at time, but the RS-485 standard contains addi-
tional specifications to guarantee device safety in the event
of line contention.
Cable and Data Rate
The transmission line of choice for RS-485
communications is a twisted pair. Twisted pair cable tends
to cancel common-mode noise and also causes cancella-
tion of the magnetic fields generated by the current
flowing through each wire, thereby, reducing the effective
inductance of the pair.
The ADM1486 is designed for bidirectional data commu-
nications on multipoint transmission lines. A typical
application showing a multipoint transmission network is
illustrated in Figure 11. An RS-485 transmission line can
have as many as 32 transceivers on the bus. Only one
driver can transmit at a particular time but multiple
receivers may be enabled simultaneously.
As with any transmission line, it is important that
reflections are minimized. This may be achieved by
terminating the extreme ends of the line using resistors
equal to the characteristic impedance of the line. Stub
lengths of the main line should also be kept as short as
possible. A properly terminated transmission line appears
purely resistive to the driver.
Thermal Shutdown
The ADM1486 contains thermal shutdown circuitry
which protects the part from excessive power dissipation
during fault conditions. Shorting the driver outputs to a
low impedance source can result in high driver currents.
The thermal sensing circuitry detects the increase in die
temperature and disables the driver outputs. The thermal
sensing circuitry is designed to disable the driver outputs
when a die temperature of 150°C is reached. As the device
cools, the drivers are re-enabled at 140°C.
Propagation Delay
The ADM1486 features very low propagation delay
ensuring maximum baud rate operation. The driver is
well balanced ensuring distortion free transmission.
Another important specification is a measure of the skew
between the complementary outputs. Excessive skew
impairs the noise immunity of the system and increases
the amount of electromagnetic interference (EMI).
Receiver Open-Circuit Fail Safe
The receiver input includes a fail-safe feature which
guarantees a logic high on the receiver when the inputs
are open circuit or floating.
PRELIMINARY TECHNICAL DATA
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ADM1486AN | +5 V Low Power RS-485 PROFIBUS Transceiver |
| ADM1486AQ | +5 V Low Power RS-485 PROFIBUS Transceiver |
| ADM1486AR | +5 V Low Power RS-485 PROFIBUS Transceiver |
| ADM1486ARM | +5 V Low Power RS-485 PROFIBUS Transceiver |
| ADM1487E | 5 V, 【15 kV ESD Protected Half-Duplex, RS-485/RS-422 Transceivers |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADM1486_05 | 制造商:AD 制造商全稱:Analog Devices 功能描述:5 V, 0.8 mA PROFIBUS RS-485 Transceiver |
| ADM1486AN | 制造商:AD 制造商全稱:Analog Devices 功能描述:+5 V Low Power RS-485 PROFIBUS Transceiver |
| ADM1486AQ | 制造商:AD 制造商全稱:Analog Devices 功能描述:+5 V Low Power RS-485 PROFIBUS Transceiver |
| ADM1486AR | 功能描述:IC TX/RX RS-485 PRO-BUS 5V 8SOIC RoHS:否 類別:集成電路 (IC) >> 接口 - 驅(qū)動(dòng)器，接收器，收發(fā)器 系列:- 標(biāo)準(zhǔn)包裝:27 系列:- 類型:收發(fā)器 驅(qū)動(dòng)器/接收器數(shù):3/3 規(guī)程:RS232，RS485 電源電壓:4.75 V ~ 5.25 V 安裝類型:表面貼裝 封裝/外殼:28-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:28-SOIC 包裝:管件 |
| ADM1486ARM | 制造商:AD 制造商全稱:Analog Devices 功能描述:+5 V Low Power RS-485 PROFIBUS Transceiver |
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