参数资料
| 型号： | ISL81485IBZ-T |
| 厂商： | Intersil |
| 文件页数： | 9/11页 |
| 文件大小： | 0K |
| 描述： | IC TXRX RS485/422 5V HS 8-SOIC |
| 标准包装： | 2,500 |
| 类型： | 收发器 |
| 驱动器/接收器数： | 1/1 |
| 规程： | RS422，RS485 |
| 电源电压： | 4.5 V ~ 5.5 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOICN |
| 包装： | 带卷 (TR) |
7
Driver Features
The RS-485, RS-422 driver is a differential output device that
delivers at least 2V across a 54
load (RS-485), and at least
2.5V across a 100
load (RS-422) even with VCC =4.5V.
The drivers feature low propagation delay skew to maximize
bit width, and to minimize EMI.
The driver is three-statable via the active high DE input.
Outputs of the driver are not slew rate limited, so faster
output transition times allow data rates of at least 30Mbps.
Data Rate, Cables, and Terminations
RS-485/RS-422 are intended for network lengths up to
4000’, but the maximum system data rate decreases as the
transmission length increases. Devices operating at 30Mbps
usually are limited to lengths of a couple hundred feet, but
the larger differential output voltage of this transceiver allows
that distance to be pushed past 350’. Figure 7 illustrates the
30Mbps performance of the ISL81485 driving 350’ of CAT5
cable, terminated in 120
at both the driver and receiver
ends. As shown, the differential signal (A-B) delivered to the
receiver inputs at the end of the cable is still greater than
1.5V (i.e., 7.5 times the required Rx sensitivity). Thus, even
longer cables can be driven if lower noise margins are
acceptable.
Twisted pair is the cable of choice for RS-485, RS-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, when using a 30Mbps
device, to minimize reflections. 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
) 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. 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. The
ISL81485 meets this requirement via driver output short
circuit current limits, and on-chip thermal shutdown 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.
In the event of a major short circuit condition, the device also
includes a thermal shutdown feature that disables the drivers
whenever the die temperature becomes excessive. This
eliminates the power dissipation, allowing the die to cool.
The drivers automatically reenable after the die temperature
drops about 15 degrees. If the contention persists, the
thermal shutdown/reenable cycle repeats until the fault is
cleared. Receivers stay operational during thermal
shutdown.
Typical Performance Curves VCC = 5V, TA = 25oC; Unless Otherwise Specified
FIGURE 7. DRIVER AND RECEIVER WAVEFORMS DRIVING
350 FEET (107 METERS) OF CAT5 CABLE
(DOUBLE TERMINATED WITH 120
)
FIGURE 8. DRIVER OUTPUT CURRENT vs SHORT CIRCUIT
VOLTAGE
TIME (20ns/DIV)
-3
RECEIVER
OUTPUT
(V)
1.5
3
-1.5
0
5
R
E
CEI
VER
INP
U
T
(V)
0
5
DRIVER
INP
U
T
(V)
DI = 30Mbps
RO
DRIVER+CABLE DELAY
(~490ns)
A - B
OUTPUT VOLTAGE (V)
-7 -6
-4
-2
0
2
4
6
8
10
12
OUTP
U
T
CURR
E
N
T
(mA)
-60
-40
-20
0
20
40
60
80
100
120
140
160
-80
-100
-120
Y OR Z = HIGH
-140
-160
Y OR Z = LOW
Y OR Z = HIGH
ISL81485
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL81485IU | 功能描述:IC TXRX RS485/422 5V HS 8-MSOP RoHS:否 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:25 系列:- 类型:收发器 驱动器/接收器数:2/2 规程:RS232 电源电压:4.5 V ~ 5.5 V 安装类型:通孔 封装/外壳:16-DIP（0.300"，7.62mm） 供应商设备封装:16-PDIP 包装:管件 |
| ISL81485IU-T | 功能描述:IC TXRX RS485/422 5V HS 8-MSOP RoHS:否 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:25 系列:- 类型:收发器 驱动器/接收器数:2/2 规程:RS232 电源电压:4.5 V ~ 5.5 V 安装类型:通孔 封装/外壳:16-DIP（0.300"，7.62mm） 供应商设备封装:16-PDIP 包装:管件 |
| ISL81485IUZ | 制造商:Intersil Corporation 功能描述:LINE TRNSCVR 1TR 1TX 1RX 8MSOP - Rail/Tube 制造商:Intersil 功能描述:INTERSIL RS-485 HI SPD 40MBPS IND |
| ISL81485IUZ-T | 制造商:Intersil Corporation 功能描述:LINE TRNSCVR 1TR 1TX 1RX 8MSOP - Tape and Reel 制造商:Intersil 功能描述:INTERSIL RS-485 HI SPD 40MBPS IND |
| ISL81486 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:5V, Ultra High Speed, PROFIBUS, RS-485/RS-422 Transceivers |
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