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參數資料
| 型號： | ADM489AN |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 通用總線功能 |
| 英文描述： | Full-Duplex, Low Power, Slew Rate Limited, EIA RS-485 Transceivers |
| 中文描述： | LINE TRANSCEIVER, PDIP14 |
| 封裝： | PLASTIC, MS-001AA, DIP-14 |
| 文件頁數： | 11/12頁 |
| 文件大?。?/td> | 212K |
| 代理商： | ADM489AN |
ADM488/ADM489
–11–
REV. 0
T able V. Comparison of RS-422 and RS-485 Interface Standards
Specification
RS-422
RS-485
T ransmission T ype
Maximum Data Rate
Maximum Cable Length
Minimum Driver Output Voltage
Driver Load Impedance
Receiver Input Resistance
Receiver Input Sensitivity
Receiver Input Voltage Range
Number of Drivers/Receivers Per Line
Differential
10 MB/s
4000 ft.
±
2 V
100
4 k
min
±
200 mV
–7 V to +7 V
1/10
Differential
10 MB/s
4000 ft.
±
1.5 V
54
12 k
min
±
200 mV
–7 V to +12 V
32/32
D
R
D
R
D
D
R
R
RT
RT
Figure 25. Typical RS-485 Network
APPLICAT IONS INFORMAT ION
Differential Data T ransmission
Differential data transmission is used to reliably transmit data
at high rates over long distances and through noisy environ-
ments. Differential transmission nullifies the effects of ground
shifts and noise signals, which appear as common-mode volt-
ages on the line. T wo main standards are approved by the
Electronics Industries Association (EIA), which specify the
electrical characteristics of transceivers used in differential
data transmission.
T he RS-422 standard specifies data rates up to 10 MBaud and
line lengths up to 4000 ft. A single driver can drive a transmis-
sion line with up to 10 receivers.
In order to cater to true multipoint communications, the RS-
485 standard was defined. T his standard meets or exceeds all
the requirements of RS-422 and 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. T he 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 a time but the RS-485 standard
contains additional specifications to guarantee device safety in
the event of line contention.
Cable and Data Rate
T he transmission line of choice for RS-485 communications is a
twisted pair. T wisted pair cable tends to cancel common mode
noise and also causes cancellation of the magnetic fields gener-
ated by the current flowing through each wire, thereby reducing
the effective inductance of the pair.
T he ADM488/ADM489 is designed for bidirectional data com-
munications on multipoint transmission lines. A typical applica-
tion showing a multipoint transmission network is illustrated in
Figure 25. 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 simultaneously
be enabled.
As with any transmission line, it is important that reflections are
minimized. T his may be achieved by terminating the extreme
ends of the line using resistors equal to the characteristic imped-
ance 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.
相關PDF資料 |
PDF描述 |
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| ADM488AN | Full-Duplex, Low Power, Slew Rate Limited, EIA RS-485 Transceivers |
| ADM488AR | Full-Duplex, Low Power, Slew Rate Limited, EIA RS-485 Transceivers |
| ADM489AR | Full-Duplex, Low Power, Slew Rate Limited, EIA RS-485 Transceivers |
| ADM489ARU | PHOTODIODE, 0.05A, 1.3V; Area, active:7.5mm2; Case style:SOT-23; Sensitivity:0.6A/W @ 950nm; Wavelength, peak:940nm RoHS Compliant: Yes |
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相關代理商/技術參數 |
參數描述 |
|---|---|
| ADM489ANZ | 功能描述:IC TXRX RS485 LO SLEW/EN 14DIP RoHS:是 類別:集成電路 (IC) >> 接口 - 驅動器，接收器，收發器 系列:- 標準包裝:1 系列:- 類型:線路收發器 驅動器/接收器數:5/3 規程:RS232 電源電壓:3 V ~ 5.5 V 安裝類型:表面貼裝 封裝/外殼:28-SOIC（0.295"，7.50mm 寬） 供應商設備封裝:28-SOIC 包裝:Digi-Reel® 產品目錄頁面:918 (CN2011-ZH PDF) 其它名稱:296-25096-6 |
| ADM489AR | 制造商:Analog Devices 功能描述:Single Transmitter/Receiver RS-422/RS-485 14-Pin SOIC N 制造商:Analog Devices 功能描述:IC TRANSCEIVER RS485 |
| ADM489AR-REEL | 制造商:Analog Devices 功能描述:Single Transmitter/Receiver RS-422/RS-485 14-Pin SOIC N T/R 制造商:Rochester Electronics LLC 功能描述:FULL DUPLEX,RS-485 TRANSCEIVER I.C. - Tape and Reel |
| ADM489AR-REEL7 | 制造商:Analog Devices 功能描述:Single Transmitter/Receiver RS-422/RS-485 14-Pin SOIC N T/R |
| ADM489ARU | 制造商:Rochester Electronics LLC 功能描述:FULL DUPLEX,RS-485 TRANSCEIVER I.C. - Bulk |
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