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| 型号： | LTC487CSW#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/12页 |
| 文件大小： | 0K |
| 描述： | IC DVR RS485 LOW PWR QUAD 16SOIC |
| 标准包装： | 47 |
| 类型： | 驱动器 |
| 驱动器/接收器数： | 4/0 |
| 规程： | RS422，RS485 |
| 电源电压： | 4.75 V ~ 5.25 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SOIC（0.295"，7.50mm 宽） |
| 供应商设备封装： | 16-SOIC |
| 包装： | 管件 |
| 产品目录页面： | 1354 (CN2011-ZH PDF) |
LTC487
487fc
applicaTions inForMaTion
Lossesinatransmissionlineareacomplexcombinationof
DCconductorloss,AClosses(skineffect),leakage,andAC
losses in the dielectric. In good polyethylene cables such
as the Belden 9841, the conductor losses and dielectric
losses are of the same order of magnitude, leading to
relatively low overall loss (Figure 7).
FREQUENCY (MHz)
0.1
LOSS
PER
100
FT
(dB)
1.0
10
1.0
10
100
LTC487 TA08
Figure 7. Attenuation vs Frequency for Belden 9841
When using low loss cables, Figure 8 can be used as
a guideline for choosing the maximum line length for
a given data rate. With lower quality PVC cables, the
dielectric loss factor can be 1000 times worse. PVC
twisted pairs have terrible losses at high data rates
(> 100kbs) and greatly reduce the maximum cable length.
At low data rates however, they are acceptable and much
more economical.
DATA RATE (bps)
10k
10
CABLE
LENGTH
(FT)
100
1k
10k
100k
1M
10M
LTC487 TA09
2.5M
Figure 8. Cable Length vs Data Rate
Cable Termination
Theproperterminationofthecableisveryimportant.Ifthe
cable is not terminated with its characteristic impedance,
distorted waveforms will result. In severe cases, distorted
(false) data and nulls will occur. A quick look at the output
of the driver will tell how well the cable is terminated. It is
best to look at a driver connected to the end of the cable,
since this eliminates the possibility of getting reflections
from two directions. Simply look at the driver output
while transmitting square wave data. If the cable is termi-
nated properly, the waveform will look like a square wave
(Figure 9).
Rt
DRIVER
DX
RECEIVER
RX
Rt = 120
Rt = 47
Rt = 470
LTC487 TA10
PROBE HERE
Figure 9. Termination Effects
If the cable is loaded excessively (47), the signal initially
sees the surge impedance of the cable and jumps to an
initial amplitude. The signal travels down the cable and is
reflected back out of phase because of the mistermination.
When the reflected signal returns to the driver, the ampli-
tude will be lowered. The width of the pedestal is equal to
twice the electrical length of the cable (about 1.5ns/foot).
If the cable is lightly loaded (470), the signal reflects in
phase and increases the amplitude at the driver output.
An input frequency of 30kHz is adequate for tests out to
4000 feet of cable.
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相关代理商/技术参数 |
参数描述 |
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| LTC487IN | 功能描述:IC DVR RS485 LOW PWR QUAD 16-DIP RoHS:否 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 标准包装:27 系列:- 类型:收发器 驱动器/接收器数:3/3 规程:RS232，RS485 电源电压:4.75 V ~ 5.25 V 安装类型:表面贴装 封装/外壳:28-SOIC（0.295"，7.50mm 宽） 供应商设备封装:28-SOIC 包装:管件 |
| LTC487IN#PBF | 功能描述:IC DVR RS485 LOW PWR QUAD 16-DIP RoHS:是 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 标准包装:1,140 系列:AU 类型:收发器 驱动器/接收器数:1/1 规程:CAN 电源电压:5.3 V ~ 27 V 安装类型:表面贴装 封装/外壳:14-SOIC（0.154"，3.90mm 宽） 供应商设备封装:14-SO 包装:管件 其它名称:935267940512AU5790D14AU5790D14-ND |
| LTC487ISW | 功能描述:IC DVR RS485 LOW PWR QUAD 16SOIC RoHS:否 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 标准包装:27 系列:- 类型:收发器 驱动器/接收器数:3/3 规程:RS232，RS485 电源电压:4.75 V ~ 5.25 V 安装类型:表面贴装 封装/外壳:28-SOIC（0.295"，7.50mm 宽） 供应商设备封装:28-SOIC 包装:管件 |
| LTC487ISW#PBF | 功能描述:IC DVR RS485 LOW PWR QUAD 16SOIC RoHS:是 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 标准包装:27 系列:- 类型:收发器 驱动器/接收器数:3/3 规程:RS232，RS485 电源电压:4.75 V ~ 5.25 V 安装类型:表面贴装 封装/外壳:28-SOIC（0.295"，7.50mm 宽） 供应商设备封装:28-SOIC 包装:管件 |
| LTC487ISW#TR | 功能描述:IC DRIVER RS485 QUAD LP 16SOIC RoHS:否 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 标准包装:27 系列:- 类型:收发器 驱动器/接收器数:3/3 规程:RS232，RS485 电源电压:4.75 V ~ 5.25 V 安装类型:表面贴装 封装/外壳:28-SOIC（0.295"，7.50mm 宽） 供应商设备封装:28-SOIC 包装:管件 |
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