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參數資料
| 型號： | ADM488AR |
| 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, PDSO8 |
| 封裝： | MS-012AA, SOIC-8 |
| 文件頁數： | 11/12頁 |
| 文件大小： | 212K |
| 代理商： | ADM488AR |
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.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| ADM488AR-REEL | 制造商:Analog Devices 功能描述:Single Transmitter/Receiver RS-422/RS-485 8-Pin SOIC N T/R 制造商:Analog Devices 功能描述:LINE TRNSCVR 1TR 1TX 1RX 8SOIC N - Tape and Reel |
| ADM488AR-REEL7 | 制造商:Analog Devices 功能描述:Single Transmitter/Receiver RS-422/RS-485 8-Pin SOIC N T/R |
| ADM488ARZ | 功能描述:IC TX/RX RS-485 LO-SLEW 8SOIC RoHS:是 類別:集成電路 (IC) >> 接口 - 驅動器，接收器，收發器 系列:- 產品培訓模塊:RS-232 & USB Transceiver 標準包裝:2,000 系列:- 類型:收發器 驅動器/接收器數:1/1 規程:RS232 電源電壓:3 V ~ 5.5 V 安裝類型:表面貼裝 封裝/外殼:16-SSOP（0.209"，5.30mm 寬） 供應商設備封裝:16-SSOP 包裝:帶卷 (TR) 其它名稱:296-19849-2 |
| ADM488ARZ | 制造商:Analog Devices 功能描述:IC RS485 TRANSCEIVER 250KBPS 5.5V SOIC8 |
| ADM488ARZ-REEL | 功能描述:IC TXRX RS-485 DIFF LP 8SOIC 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:121 系列:- 類型:收發器 驅動器/接收器數:1/1 規程:RS422，RS485 電源電壓:3 V ~ 3.6 V 安裝類型:表面貼裝 封裝/外殼:10-WFDFN 裸露焊盤 供應商設備封裝:10-DFN（3x3） 包裝:管件 |
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