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參數(shù)資料
| 型號(hào)： | ADM3085JR |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 通用總線功能 |
| 英文描述： | High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection |
| 中文描述： | LINE TRANSCEIVER, PDSO8 |
| 封裝： | SO-8 |
| 文件頁(yè)數(shù)： | 12/14頁(yè) |
| 文件大?。?/td> | 316K |
| 代理商： | ADM3085JR |
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ADM3082/ADM3085/ADM3088
–12–
PRELIMINARY TECHNICAL DATA
DETAILED DESCRIPTION
The ADM3082, ADM3085 and ADM3088 are high-
speed RS-485/RS-422 transceivers offering enhanced per-
formance over industry-standard devices All devices in the
family contain one driver and one receiver, but there is a
choice of performance options. The devices feature fail-
safe operation, which means that a logic-high receiver out-
put is
guaranteed
when the receiver inputs are open-circuit
or short-circuit, or when they are connected to a termi-
nated transmission line with all drivers disabled (see the
section on Fail-Safe Operation).
SLEW RATE CONTROL
The ADM3082 features a controlled slew-rate driver that
minimize electromagnetic interference (EMI) and reduce
reflections caused by incorrectly terminated cables, allow-
ing error-free data transmission rates up to 115kbps (see
the section on
Reduced EMI and Reflections).
The ADM3085 offers a higher limit on driver output
slew-rate, allowing data transmission rates up to 500kbps.
The driver slew rate of the ADM3088 is not limited, of-
fering data transmission rates up to 10Mbps.
RECEIVER INPUT FILTERING
The receivers of all devices incorporate input hysteresis.
In addition, when operating in 115kbps or 500kbps mode,
the receivers of the ADM3082 and ADM3085 incorporate
input filtering. This enhances noise immunity with differ-
ential signals that have very slow rise and fall times, but it
does increase propagation delay by 20%.
HALF-/FULL-DUPLEX OPERATION
The ADM3082, ADM3085, and ADM3088 are dedicated
half-duplex devices (driver outputs internally linked to re-
ceiver inputs). Figure 29 shows a typical half-duplex con-
nection between two devices.
THREE-STATE BUS CONNECTION
All the devices have a Driver Enable pin (DE) that en-
ables the driver outputs when taken high or puts the driver
outputs into a high-impedance state when taken low. This
allows several driver outputs to be connected to an
RS-422/RS-485 bus.
Similarly, all the devices have a (active-low) Receiver En-
able pin (
RE
). Taking this low enables the receiver, while
taking it high puts the receiver outputs into a high-imped-
ance state. This allows several receiver outputs to be con-
nected to a serial data bus.
HIGH INPUT IMPEDANCE
The input impedance of the devices is 96k
V
, which is 8
times higher than the standard RS-485 load of 12k
V
. A
standard driver can driver 32 standard loads, so up to 256
ADM308X receivers, or a combination of ADM308X and
other devices up to 32 unit loads, may be connected to an
RS-422/RS485 bus driven by a single driver.
SHUTDOWN MODE
All the devices have a low power shutdown mode that is
enabled by taking
RE
high and DE low.
If shutdown mode is not used, the fact that DE is active-
high and
RE
is active-low offers a convenient way of
switching the device between transmit and receive, by ty-
ing DE and
RE
together. This is useful, for example, in
applications using half duplex operation and where several
receiver outputs are connected to a serial bus.
The device is guaranteed not to enter shutdown mode if
DE and
RE
are driven in this way. If DE is low and
RE
is
high for less than 50ns the device will not enter shutdown.
If DE is low and
RE
is high for greater than 600ns, the
device is guaranteed to enter shutdown.
FAIL-SAFE OPERATION
The ADM3082/ADM3085/ADM3088 offer true fail-safe
operation while remaining fully compliant with the
±200mV EIA/TIA-485 standard. A logic-high receiver
output is guaranteed when the receiver inputs are shorted
together or open-circuit, or when they are connected to a
terminated transmission line with all drivers disabled.
This is done by setting the receiver threshold between
-50mV and –200mV. If the differential receiver input volt-
age (A–B) is greater than or equal to –50mV, RO is logic
high. If A–B is less than or equal to –200mV, RO is logic
low. In the case of a terminated bus with all transmitters
disabled, the receiver’s differential input voltage is pulled
to 0V by ADM308X family, which results in a logic high
with a 50mV minimum noise margin.
ENHANCED ESD PROTECTION
All Analog Devices parts incorporate protection against
electrostatic discharge (ESD) to protect the devices dur-
ing handling, assembly and normal operation. In addition,
the ADM308X family has enhanced ESD protection up to
±15kV on the receiver inputs and driver outputs (A, B) to
protect against severe operational conditions such as line
transients, connection and disconnection.
100n
+5V
(V
CC
)
+5V
(V
CC
)
100n
R
T
R
T
DATA
IN (DI)
RECEIVER
OUTPUT (RO)
DATA
IN (DI)
RECEIVER
OUTPUT (RO)
1
2
3
4
8
7
6
5
D
R
D
R
RECEIVER
ENABLE (
RE)
DRIVER
ENABLE (DE)
5
6
7
8
4
3
2
1
RECEIVER
ENABLE (
RE)
DRIVER
ENABLE (DE)
ADM3082/5/8
ADM3082/5/8
Figure 29. Half-Duplex Configuration for ADM3082, ADM3085 or ADM3088
REV. PrA 02/02
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ADM3088AN | High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection |
| ADM3088AR | High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection |
| ADM3082JN | High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection |
| ADM3082JR | High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection |
| ADM3311E | 15 kV ESD Protected, +2.7 V to +3.6 V Serial Port Transceiver with Green Idle⑩ |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADM3088 | 制造商:AD 制造商全稱:Analog Devices 功能描述:High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection |
| ADM3088AN | 制造商:AD 制造商全稱:Analog Devices 功能描述:High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection |
| ADM3088AR | 制造商:AD 制造商全稱:Analog Devices 功能描述:High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection |
| ADM3088JN | 制造商:AD 制造商全稱:Analog Devices 功能描述:High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection |
| ADM3088JR | 制造商:AD 制造商全稱:Analog Devices 功能描述:High-Speed (10Mbps), Fail-Safe, RS-485/RS-422 Transceivers with Slew-Rate-Limiting and 5kV ESD Protection |
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