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參數(shù)資料
| 型號： | ADM489ANZ |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 3/16頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC TXRX RS485 LO SLEW/EN 14DIP |
| 標準包裝： | 25 |
| 類型： | 收發(fā)器 |
| 驅動器/接收器數(shù)： | 1/1 |
| 規(guī)程： | RS422，RS485 |
| 電源電壓： | 4.5 V ~ 5.5 V |
| 安裝類型： | 通孔 |
| 封裝/外殼： | 14-DIP（0.300"，7.62mm） |
| 供應商設備封裝： | 14-PDIP |
| 包裝： | 管件 |
| 產品目錄頁面： | 790 (CN2011-ZH PDF) |
ADM488/ADM489
Rev. D | Page 11 of 16
THEORY OF OPERATION
The ADM488/ADM489 are ruggedized RS-485 transceivers
that operate from a single 5 V supply. They contain protection
against radiated and conducted interference and are ideally
suited for operation in electrically harsh environments or where
cables can be plugged/unplugged. They are also immune to
high RF field strengths without special shielding precautions.
They are intended for balanced data transmission and comply
with both EIA RS-485 and RS-422 standards. They contain a
differential line driver and a differential line receiver, and are
suitable for full-duplex data transmission.
The input impedance on the ADM488/ADM489 is 12 kΩ,
allowing up to 32 transceivers on the differential bus. The
ADM488/ADM489 operate from a single 5 V ± 10% power
supply. A thermal shutdown circuit prevents excessive power
dissipation caused by bus contention or by output shorting.
This feature forces the driver output into a high impedance state
if, during fault conditions, a significant temperature increase is
detected in the internal driver circuitry.
The receiver contains a fail-safe feature that results in a logic
high output state if the inputs are unconnected (floating). A
high level of robustness is achieved using internal protection
circuitry, eliminating the need for external protection com-
ponents such as tranzorbs or surge suppressors. Furthermore,
low electromagnetic emissions are achieved using slew limited
drivers, minimizing interference both conducted and radiated.
The ADM488/ADM489 can transmit at data rates up to
250 kbps. A typical application for the ADM488/ADM489 is
illustrated in Figure 24 showing a full-duplex link where data is
transferred at rates of up to 250 kbps. A terminating resistor is
shown at both ends of the link. This termination is not critical
because the slew rate is controlled by the ADM488/ADM489
and reflections are minimized.
ADM488
D
RO
DI
A
B
Z
Y
DE
5V
0.1F
RS-485/RS-422 LINK
R
ADM489
5V
0.1F
D
RO
DI
DE
GND
VCC
A
B
Z
Y
RE
000
79
-0
24
Figure 24. ADM488/ADM489 Full-Duplex Data Link
The communications network can be extended to include
multipoint connections, as shown in Figure 30. As many as
32 transceivers can be connected to the bus.
Table 6 and Table 7 show the truth tables for transmitting and
receiving.
Table 6. Transmitting Truth Table
Inputs
Outputs
RE
DE
DI
Z
Y
1
0
1
1
0
1
0
Hi-Z
1
0
Hi-Z
1 X = Don’t care.
Table 7. Receiving Truth Table
Inputs
Output
RE
DE
A to B
RO
0
≥ +0.2 V
1
0
≤
0.2 V
0
Inputs O/C
1
0
Hi-Z
1 X = Don’t care.
EFT TRANSIENT PROTECTION SCHEME
The ADM488/ADM489 use protective clamping structures on
their inputs and outputs that clamp the voltage to a safe level
and dissipate the energy present in ESD (electrostatic) and EFT
(electrical fast transients) discharges.
FAST TRANSIENT BURST IMMUNITY (IEC1000-4-4)
IEC1000-4-4 (previously 801-4) covers electrical fast transient
burst (EFT) immunity. Electrical fast transients occur as a result
of arcing contacts in switches and relays. The tests simulate the
interference generated when, for example, a power relay disconnects
an inductive load. A spark is generated due to the well known
back EMF effect. In fact, the spark consists of a burst of sparks
as the relay contacts separate. The voltage appearing on the line,
therefore, consists of a burst of extremely fast transient impulses.
A similar effect occurs when switching on fluorescent lights.
The fast transient burst test, defined in IEC1000-4-4, simulates
this arcing, and its waveform is illustrated in Figure 25. It
consists of a burst of 2.5 kHz to 5 kHz transients repeating at
300 ms intervals. It is specified for both power and data lines.
Four severity levels are defined in terms of an open-circuit voltage
as a function of installation environment. The installation
environments are defined as
Well protected
Protected
Typical industrial
Severe industrial
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| 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 |
| ADM489ARU-REEL | 制造商:Analog Devices 功能描述:Single Transmitter/Receiver RS-422/RS-485 16-Pin TSSOP T/R 制造商:Analog Devices 功能描述:LINE TRNSCVR 1TR 1TX 1RX 16TSSOP - Tape and Reel |
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