參數(shù)資料
型號(hào)： ISL81387
廠商： Intersil Corporation
英文描述： ±15kV ESD Protected, Dual Protocol (RS-232/RS-485) Transceivers(±15kV ESD保護(hù)，雙協(xié)議(RS-232/RS-485)收發(fā)器)
中文描述： ± 15kV的ESD保護(hù)，雙協(xié)議（RS-232/RS-485）收發(fā)器（± 15kV的ESD保護(hù)，雙協(xié)議（RS-232/RS-485）收發(fā)器）
文件頁(yè)數(shù)： 16/27頁(yè)
文件大?。?/td> 1092K
代理商： ISL81387
16
FN6201.1
December 20, 2005
Proper termination is imperative to minimize reflections
when using the 20Mbps speed option. Short networks using
the medium and slow speed options need not be terminated,
but terminations are recommended unless power dissipation
is an overriding concern. Note that the RS-485 spec allows a
maximum of two terminations on a network, otherwise the Tx
output voltage may not meet the required V
OD
.
In point-to-point, or point-to-multipoint (RS-422) networks,
the main cable should be terminated in its characteristic
impedance (typically 120
) at the end farthest from the
driver. In multi-receiver applications, stubs connecting
receivers to the main cable should be kept as short as
possible, but definitely shorter than the limits shown in Table
4. Multipoint (RS-485) systems require that the main cable
be terminated in its characteristic impedance at both ends.
Again, keep stubs connecting a transceiver to the main
cable as short as possible, and refer to Table 4. Avoid “star”,
and other configurations, where there are many “ends”
which would require more than the two allowed terminations
to prevent reflections.
High ESD
All pins on the ISLX1387 include ESD protection structures
rated at
±
4kV (HBM), which is good enough to survive ESD
events commonly seen during manufacturing. But the bus
pins (Tx outputs and Rx inputs) are particularly vulnerable to
ESD events because they connect to an exposed port on the
exterior of the finished product. Simply touching the port
pins, or connecting a cable, can destroy an unprotected port.
ISLX1387 bus pins are fitted with advanced structures that
deliver ESD protection in excess of
±
15kV (HBM), without
interfering with any signal in the RS-485 or the RS-232
range. This high level of protection may eliminate the need
for board level protection, or at the very least will increase
the robustness of any board level scheme.
Small Packages
Many competing dual protocol ICs are available only in
monstrously large 24 to 28 Ld SOIC packages. The
ISL81387’s 20 Ld SSOP is more than 50% smaller than
even a 24 Ld SOIC, and the ISL41387’s tiny 6x6mm QFN is
80% smaller than a 28 Ld SOIC.
Flow Through Pinouts
Even the ISLX1387 pinouts are features, in that the “flow-
through” design simplifies board layout. Having the bus pins
all on one side of the package for easy routing to a cable
connector, and the Rx outputs and Tx inputs on the other
side for easy connection to a UART, avoids costly and
problematic crossovers. Figure 10 illustrates the flow-
through nature of the pinout.
Low Power Shutdown (SHDN) Mode
The ISLX1387 enter the SHDN mode when ON = 0, and the
Tx and Rx are disabled (DEN = 0, RXEN = 0, and RXEN =
1), and the already low supply current drops to as low as
5
μ
A. SHDN disables the Tx and Rx outputs, and disables
the charge pumps if the port is in RS-232 mode, so V+
collapses to V
CC
, and V- collapses to GND.
All but 5μA of SHDN I
CC
current is due to control input (SPB,
SLEW, RXEN) pull-up resistors (~20
μ
A/resistor), so SHDN
I
CC
varies depending on the ISLX1387 configuration. The
spec tables indicate the worst case values, but careful
selection of the configuration yields lower currents. For
example, in RS-232 mode the SPB pin isn’t used, so floating
it or tying it high minimizes SHDN I
CC
.
On the ISL41387, the SHDN I
CC
increases as V
L
decreases. V
L
powers each control pin input stage and sets
its V
OH
at V
L
rather than V
CC
. V
CC
powers the second
stage, but the second stage input isn’t driven to the rail, so
some I
CC
current flows. See Figure 20 for details.
When enabling from SHDN in RS-232 mode, allow at least
20
μ
s for the charge pumps to stabilize before transmitting
data. If fast enables are required, and I
CC
isn’t the greatest
concern, disable the drivers with the DEN pin to keep the
charge pumps active. The charge pumps aren’t used in
RS-485 mode, so the transceiver is ready to send or receive
data in less than 1
μ
s, which is much faster than competing
devices that require the charge pump for all modes of
operation.
Internal Loopback Mode
Setting ON = 0, DEN = 1, and RXEN = 1 or RXEN = 0 (QFN
only), places the port in the loopback mode, a mode that
facilitates implementing board level self test functions. In
loopback, internal switches disconnect the Rx inputs from
the Rx outputs, and feed back the Tx outputs to the
appropriate Rx output. This way the data driven at the Tx
input appears at the corresponding Rx output (refer to
“Typical Operating Circuits”). The Tx outputs remain
connected to their terminals, so the external loads are
reflected in the loopback performance. This allows the
loopback function to potentially detect some common bus
faults such as one or both driver outputs shorted to GND, or
outputs shorted together.
Note that the loopback mode uses an additional set of
receivers, as shown in the “Typical Operating Circuits”.
UART
OR
ASIC
OR
μ
CONTROLLER
RA
DY
Y
Z
A
B
C
ISL81387
FIGURE 10. ILLUSTRATION OF FLOW THROUGH PINOUT
D
R
ISL81387, ISL41387
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
ISL81387_07 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:【15kV ESD Protected, 5V, Dual Protocol (RS-232/RS-485) Transceivers
ISL81387IAZ 功能描述:RS-422/RS-485 接口 IC W/ANNEAL SINGLE 5V MULTIPROTOCOL TRANSC RoHS:否 制造商:Maxim Integrated 數(shù)據(jù)速率:1136 Kbps 工作電源電壓:3 V to 5.5 V 電源電流:5.9 mA 工作溫度范圍:- 40 C to + 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-28 封裝:Tube
ISL81387IAZ-T 功能描述:TXRX ESD RS-485/422 2PORT 20SSOP RoHS:是 類別:集成電路 (IC) >> 接口 - 驅(qū)動(dòng)器，接收器，收發(fā)器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:50 系列:- 類型:收發(fā)器 驅(qū)動(dòng)器/接收器數(shù):1/1 規(guī)程:RS422，RS485 電源電壓:4.75 V ~ 5.25 V 安裝類型:通孔 封裝/外殼:8-DIP（0.300"，7.62mm） 供應(yīng)商設(shè)備封裝:8-PDIP 包裝:管件 產(chǎn)品目錄頁(yè)面:1402 (CN2011-ZH PDF)
ISL81387IAZ-T7A 功能描述:RS-422/RS-485 接口 IC SINGLE 5V MULTIPROTOCOL TRANS RoHS:否 制造商:Maxim Integrated 數(shù)據(jù)速率:1136 Kbps 工作電源電壓:3 V to 5.5 V 電源電流:5.9 mA 工作溫度范圍:- 40 C to + 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-28 封裝:Tube
ISL81387IBZ 功能描述:TXRX ESD RS-485/422 2PORT 20SOIC RoHS:是 類別:集成電路 (IC) >> 接口 - 驅(qū)動(dòng)器，接收器，收發(fā)器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:發(fā)射器 驅(qū)動(dòng)器/接收器數(shù):4/0 規(guī)程:RS422，RS485 電源電壓:4.75 V ~ 5.25 V 安裝類型:表面貼裝 封裝/外殼:16-SOIC（0.154"，3.90mm 寬） 供應(yīng)商設(shè)備封裝:16-SOIC 包裝:帶卷 (TR)
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