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| 型号： | ADM489 |
| 厂商： | Analog Devices, Inc. |
| 英文描述： | Full-Duplex, Low Power,Slew Rate Limited, EIA RS-486 Transceivers(低功耗,全双工,转换速率限制,RS-485收发器) |
| 中文描述： | 全双工，低功耗，限摆率限制，环境影响评估的RS - 486收发器（低功耗，全双工，转换速率限制，RS - 485接口收发器） |
| 文件页数： | 11/12页 |
| 文件大小： | 179K |
| 代理商： | ADM489 |
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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相关代理商/技术参数 |
参数描述 |
|---|---|
| ADM489A | 制造商:AD 制造商全称:Analog Devices 功能描述:Full-Duplex, Low Power, Slew Rate Limited, EIA RS-485 Transceivers |
| ADM489ABRMZ | 功能描述:IC TXRX RS485/422 DIFF 10MSOP RoHS:是 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 标准包装:121 系列:- 类型:收发器 驱动器/接收器数:1/1 规程:RS422，RS485 电源电压:3 V ~ 3.6 V 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-DFN（3x3） 包装:管件 |
| ADM489ABRMZ-REEL7 | 功能描述:IC TXRX RS485/422 DIFF 10MSOP RoHS:是 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 标准包装:121 系列:- 类型:收发器 驱动器/接收器数:1/1 规程:RS422，RS485 电源电压:3 V ~ 3.6 V 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-DFN（3x3） 包装:管件 |
| ADM489ABRZ | 功能描述:IC TXRX RS485/422 DIFF 14SOIC RoHS:是 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 标准包装:121 系列:- 类型:收发器 驱动器/接收器数:1/1 规程:RS422，RS485 电源电压:3 V ~ 3.6 V 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-DFN（3x3） 包装:管件 |
| ADM489ABRZ-REEL7 | 功能描述:IC TXRX RS485/422 DIFF 14SOIC RoHS:是 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 标准包装:121 系列:- 类型:收发器 驱动器/接收器数:1/1 规程:RS422，RS485 电源电压:3 V ~ 3.6 V 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-DFN（3x3） 包装:管件 |
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