參數(shù)資料
| 型號： | ISL3178AEMBZ |
| 廠商： | Intersil |
| 文件頁數(shù)： | 14/14頁 |
| 文件大小： | 0K |
| 描述： | TXRX ESD 3.3V RS485/422 8-SOIC |
| 標準包裝： | 980 |
| 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： | 3 V ~ 3.6 V |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 8-SOIC（0.154"，3.90mm 寬） |
| 供應商設備封裝： | 8-SOICN |
| 包裝： | 管件 |
9
FN6887.2
December 2, 2013
Driver Features
The RS-485/422 driver is a differential output device that
delivers at least 1.5V across a 54
Ω load (RS-485) and at
least 2V across a 100
Ω load (RS-422). The drivers feature
low propagation delay skew to maximize bit width and to
minimize EMI.
The drivers is tri-statable via the active high DE input.
Outputs of the ISL3178AE drivers are not limited, so faster
output transition times allow data rates of at least 10Mbps.
Hot Plug Function
When a piece of equipment powers up, there is a period of
time where the processor or ASIC driving the RS-485 control
lines (DE, RE) is unable to ensure that the RS-485 Tx and
Rx outputs are kept disabled. If the equipment is connected
to the bus, a driver activating prematurely during power up
may crash the bus. To avoid this scenario, the ISL3178AE
versions with output enable pins incorporate a “Hot Plug”
function. During power-up, circuitry monitoring VCC ensures
that the Tx and Rx outputs remain disabled for a period of time,
regardless of the state of DE and RE. This gives the
processor/ASIC a chance to stabilize and drive the RS-485
control lines to the proper states.
ESD Protection
All pins on this device includes class 3 (>7kV) Human Body
Model (HBM) ESD protection structures, but the RS-485
pins (driver outputs and receiver inputs) incorporate
advanced structures allowing them to survive ESD events
in excess of ±15kV HBM and ±15kV IEC61000. The
RS-485 pins are particularly vulnerable to ESD damage
because they typically connect to an exposed port on the
exterior of the finished product. Simply touching the port
pins, or connecting a cable, can cause an ESD event that
might destroy unprotected ICs. These new ESD structures
protect the device whether or not it is powered up, and
without degrading the RS-485 common mode range of -7V
to +12V. This built-in ESD protection eliminates the need
for board level protection structures (e.g., transient
suppression diodes), and the associated, undesirable
capacitive load they present.
IEC61000-4-2 Testing
The IEC61000 test method applies to finished equipment,
rather than to an individual IC. Therefore, the pins most likely
to suffer an ESD event are those that are exposed to the
outside world (the RS-485 pins in this case), and the IC is
tested in its typical application configuration (power applied)
rather than testing each pin-to-pin combination. The lower
current limiting resistor coupled with the larger charge
storage capacitor yields a test that is much more severe than
the HBM test. The extra ESD protection built into this
device’s RS-485 pins allows the design of equipment
meeting level 4 criteria without the need for additional board
level protection on the RS-485 port.
AIR-GAP DISCHARGE TEST METHOD
For this test method, a charged probe tip moves toward the
IC pin until the voltage arcs to it. The current waveform
delivered to the IC pin depends on approach speed,
humidity, temperature, etc. so it is difficult to obtain
repeatable results. The ISL3178AE RS-485 pins withstand
±15kV air-gap discharges.
CONTACT DISCHARGE TEST METHOD
During the contact discharge test, the probe contacts the
tested pin before the probe tip is energized, thereby
eliminating the variables associated with the air-gap
discharge. The result is a more repeatable and predictable
test, but equipment limits prevent testing devices at voltages
higher than ±8kV. The ISL3178AE survives ±8kV contact
discharges on the RS-485 pins.
Data Rate, Cables, and Terminations
The RS-485/422 are intended for network lengths up to
4000, but the maximum system data rate decreases as the
transmission length increases. The device operates at
10Mbps are limited to lengths less than 100.
Twisted pair is the cable of choice for RS-485/422 networks.
Twisted pair cables tend to pick up noise and other
electromagnetically induced voltages as common mode
signals, which are effectively rejected by the differential
receivers in these ICs.
Proper termination is imperative to minimize reflections.
Short networks using the 250kbps versions need not be
terminated, but, terminations are recommended unless
power dissipation is an overriding concern.
In point-to-point, or point-to-multipoint (single driver on bus)
networks, the main cable should be terminated in its
characteristic impedance (typically 120
Ω) at the end farthest
from the driver. In multi-receiver applications, stubs
connecting receiver to the main cable should be kept as
short as possible. Multipoint (multi-driver) systems require
that the main cable be terminated in its characteristic
impedance at both ends. Stubs connecting a transceiver to
the main cable should be kept as short as possible.
Built-In Driver Overload Protection
As stated previously, the RS-485 spec requires that drivers
survive worst case bus contentions undamaged. These
devices meet this requirement via driver output short circuit
current limit circuitry.
The driver output stages incorporate short circuit current
limiting circuitry which ensures that the output current never
exceeds the RS-485 spec, even at the common mode
voltage range extremes. Additionally, these devices utilize a
foldback circuit which reduces the short circuit current, and
thus the power dissipation, whenever the contending voltage
exceeds either supply.
ISL3178AE
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| ISL3178AEMBZ-T | 功能描述:TXRX ESD 3.3V RS485/422 8-SOIC RoHS:是 類別:集成電路 (IC) >> 接口 - 驅動器，接收器，收發(fā)器 系列:- 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,500 系列:- 類型:發(fā)射器 驅動器/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） 供應商設備封裝:16-SOIC 包裝:帶卷 (TR) |
| ISL3178AEMW | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:±15kV ESD Protected, 3.3V, Full Fail-Safe, Low Power, High Speed or Slew Rate Limited, RS-485/RS-422 Transceivers |
| ISL3178E | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:RS-485/RS-422 Transceivers |
| ISL3178EIBZ | 功能描述:RS-422/RS-485 接口 IC 8LD -40+85 3V RS-485 1/2 DUP 10M RoHS:否 制造商:Maxim Integrated 數(shù)據速率: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 安裝風格:SMD/SMT 封裝 / 箱體:SOIC-28 封裝:Tube |
| ISL3178EIBZ-T | 功能描述:TXRX ESD 3.3V RS-485/422 8-SOIC RoHS:是 類別:集成電路 (IC) >> 接口 - 驅動器，接收器，收發(fā)器 系列:- 標準包裝:250 系列:- 類型:收發(fā)器 驅動器/接收器數(shù):2/2 規(guī)程:RS232 電源電壓:3 V ~ 5.5 V 安裝類型:表面貼裝 封裝/外殼:16-TSSOP（0.173"，4.40mm 寬） 供應商設備封裝:16-TSSOP 包裝:帶卷 (TR) |
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